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PURPOSE Calcineurin inhibitors (CNI) are standard components of graft-versus-host disease (GVHD) prophylaxis after hematopoietic cell transplantation (HCT). Prior data suggested that CNI-free approaches using donor T-cell depletion, either by ex vivo CD34 selection or in vivo post-transplant cyclophosphamide (PTCy) as a single agent, are associated with lower rates of chronic GVHD (cGVHD). METHODS This multicenter phase III trial randomly assigned patients with acute leukemia or myelodysplasia and an HLA-matched donor to receive CD34-selected peripheral blood stem cell, PTCy after a bone marrow (BM) graft, or tacrolimus and methotrexate after BM graft (control). The primary end point was cGVHD (moderate or severe) or relapse-free survival (CRFS). RESULTS Among 346 patients enrolled, 327 received HCT, 300 per protocol. Intent-to-treat rates of 2-year CRFS were 50.6% for CD34 selection (hazard ratio [HR] compared with control, 0.80; 95% CI, 0.56 to 1.15; P = .24), 48.1% for PTCy (HR, 0.86; 0.61 to 1.23; P = .41), and 41.0% for control. Corresponding rates of overall survival were 60.1% (HR, 1.74; 1.09 to 2.80; P = .02), 76.2% (HR, 1.02; 0.60 to 1.72; P = .95), and 76.1%. CD34 selection was associated with lower moderate to severe cGVHD (HR, 0.25; 0.12 to 0.52; P = .02) but higher transplant-related mortality (HR, 2.76; 1.26 to 6.06; P = .01). PTCy was associated with comparable cGVHD and survival outcomes to control, and a trend toward lower disease relapse (HR, 0.52; 0.28 to 0.96; P = .037). CONCLUSION CNI-free interventions as performed herein did not result in superior CRFS compared with tacrolimus and methotrexate with BM. Lower rates of moderate and severe cGVHD did not translate into improved survival.

Key Points Defibrotide is associated with encouraging responses in the real world, including VOD/SOS after MAC as well as RIC allogeneic HSCT.Early diagnosis, prompt initiation of defibrotide, and minimization of dosing interruptions may be key to successful treatment of VOD/SOS., Visual Abstract, Hepatic veno-occlusive disease or sinusoidal obstructive syndrome (VOD/SOS) is a life-threatening complication of hematopoietic stem cell transplantation (HSCT). Defibrotide is the only medication approved by the US Food and Drug Administration for the management of severe VOD/SOS after HSCT. We report our center’s experience with commercially available defibrotide as treatment of patients with VOD/SOS. We retrospectively identified 28 cases of VOD/SOS, based on the European Society for Blood and Marrow Transplantation criteria, from March 2016 through June 2019. The median day of VOD/SOS onset was 25 days (range, 8-69 days), and defibrotide was initiated on day of diagnosis in 71% of patients. Complete resolution of VOD/SOS occurred in 75% of patients. Day 100 survival was 64% for all HSCT patients and 53% for those with very severe VOD/SOS. Response rates and survival were similar in patients with VOD/SOS after myeloablative or reduced-intensity chemotherapy HSCT. Therapy-related adverse events were mild and included hematuria (43%), epistaxis (18%), and hypotension (11%). Severe hemorrhagic adverse events occurred in 2 patients (pulmonary hemorrhage and upper gastrointestinal hemorrhage; 7%) and both in the setting of progressive VOD/SOS. Early diagnosis, prompt initiation of defibrotide, and minimization of dosing interruptions may be key to successful treatment of VOD/SOS.

We sought to evaluate the impact of cryopreservation of unrelated donor (URD) peripheral blood stem cell (PBSC) grafts on engraftment, chimerism, and immune reconstitution in the context of the COVID-19 pandemic. We reviewed stem cell product characteristics and clinical outcomes in 101 patients receiving cryopreserved PBSCs from URDs between January 1, 2019 and 31 December, 2020, compared with 203 patients receiving fresh URD PBSCs. We observed no differences in 6-month overall survival, progression-free survival, or nonrelapse mortality. Patients receiving cryopreserved PBSCs had delayed platelet engraftment and impaired reconstitution of white blood cells and T-cell subsets at day 30. Thirty-four percent of patients receiving cryopreserved grafts had CD3 chimerism 48 hours old at time of cryopreservation or infusion significantly increased the risk of graft failure (subdistribution hazard ratio = 4.57; 95% confidence interval, 1.71-12.3; P = .0025). Our data indicate that cryopreservation is associated with similar overall short-term clinical outcomes compared with fresh PBSC. However, patients must be monitored closely for increased risk of other potentially adverse outcomes, including graft failure and poor immune recovery, particularly for grafts with older overall age at infusion. Longer-term follow-up is needed to determine impact on relapse and survival.

Accurate and reproducible methods to diagnose, grade and report acute graft vs. host disease (GVHD) are critical for evaluation of new treatments and biomarkers. BMTCTN 1202 created a biorepository and clinical data bank for the study of GVHD biomarkers and other transplant outcomes. To create a representative study population any pt >10 kg undergoing alloHCT was eligible (Table 1). Symptoms suggestive of GVHD, biopsy results, immunosuppressive medications, and possible etiologies were reported weekly until day 100. An end-point review committee (ERC) performed a near real time adjudication of reported symptoms at their onset and assigned a confidence level (Confirmed, Probable, Possible or Negative) for each organ according to Harris, BBMT, 2016. The final repository included 41,468 annotated biospecimens from 1709 alloHCT patients (pts) transplanted at U.S. centers from 2012-2016. Although 90% of pts developed symptoms at least once, physicians suspected GVHD in only 23% of cases and GVHD was considered the only etiology in 12%. Biopsies (bx) were performed in 40% of pts, most often for upper or lower GI symptoms. Bx results were equivocal in 11% although the range among centers was broad (0-45%). Equivocal results were most likely for skin bx and during the 2nd week after transplant. Systemic steroids were administered to 70% of pts at least once, often for non-GVHD reasons (41% of steroid courses). When GVHD was in the differential diagnosis, systemic steroids were started 81% of the time. The ERC adjudicated 2,008 cases with symptoms suggestive of GVHD onset. In 12.3% of cases the ERC modified either the center reported diagnosis of GVHD (4.6%) or the automated generated severity grade (7.7%). GVHD was diagnosed in 1025 pts and categorized as confirmed (31%), probable (50%), or possible (19%). The proportion of definitive diagnoses (Confirmed or Negative) increased with longer time post-transplant (Fig 1). ERC adjudication substantially lowered the incidence of GVHD grade 2-4 from 30% as reported by centers to 23% (confirmed or probable) by ERC. An adjudicated diagnosis of GVHD strongly associated with 6 month NRM, adjusted for patient age, gender and HLA matching (HR = 2.0, p In summary, the largest prospective observational study of GVHD outcomes demonstrated that symptoms in GVHD target organs are almost universal after transplant, their differential diagnosis is broad, tissue biopsies are infrequently done and their results are often equivocal, and steroids are often prescribed for reasons other than acute GVHD. These limitations undermine the current methods of diagnosis and reporting of acute GVHD on clinical trials. A robust reporting and adjudication system has significant value and may improve the chances of success of prospective clinical trials.

Allogeneic hematopoietic cell transplantation (HCT) recipients are at increased risk for varicella zoster virus (VZV) reactivation and associated complications. A nonlive adjuvanted recombinant zoster vaccine (RZV) has been developed to prevent herpes zoster (HZ), but there are no recommendations for use in this population. In this single-center prospective observational cohort study, we assessed the safety and reactogenicity of RZV, as well as incidence of graft-versus-host disease (GVHD) and confirmed cases of HZ after vaccination. Between December of 2018 and June of 2020, patients aged ≥18 years received 2 doses of RZV between 9 and 24 months after HCT, with the doses separated by ≥8 weeks. One hundred and fifty-eight patients (mean age, 55 years; 42% women) received ≥1 dose (total vaccinated cohort), and 150 patients (95%) received 2 doses (modified total vaccinated cohort). Solicited reactions occurred in 92.1% of patients (grade 3, 32.5%), owing mostly to injection site pain, which occurred in 86% (grade 3, 16%). The cumulative incidence of GVHD in the peri-vaccination period was no different than in historical controls (adjusted incidence rate ratio, 1.05; 95% confidence interval, 0.8-1.38). There were 4 cases of HZ in the total vaccinated cohort (2.5%) and 3 cases in the modified total vaccinated cohort (28.3/1000 person-years). Among recipients of allogeneic HCT, RZV was safe, tolerable, and did not increase rates of GVHD. Future clinical trials are needed to determine the immunogenicity and efficacy of RZV in this population.

Key Points With sufficient resources, HSCT can safely continue in the COVID-19 pandemic if primary responsibility for COVID-19 patients is not required. Cryopreservation of unrelated donor products correlated with slightly lower chimerism but no difference in clinical outcomes at 100 days., The novel coronavirus severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), identified in late 2019 as the causative agent of COVID-19, was declared a pandemic by the World Health Organization on 11 March 2020. Widespread community transmission in the United States triggered a nationwide shutdown, raising major challenges for administration of hematopoietic stem cell transplant (HSCT) and chimeric antigen receptor (CAR)-T cell therapies, leading many centers to delay or cancel operations. We sought to assess the impact of the COVID-19 pandemic on operations and clinical outcomes for HSCT and CAR-T cellular therapies at the Dana-Farber Cancer Institute by reviewing administration and outcomes in 127 cell therapy patients treated during the initial COVID-19 surge: 62 adult allogeneic HSCT (allo-HSCT), 38 autologous HSCT (auto-HSCT), and 27 CAR-T patients. Outcomes were compared with 66 allo-HSCT, 43 auto-HSCT, and 33 CAR-T patients treated prior to the pandemic. A second control cohort was evaluated for HSCT groups to reflect seasonal variation in infections. Although there were changes in donor selection and screening as well as cryopreservation patterns of donor products, no differences were observed across groups in 100-day overall survival, progression-free survival, rates of non–COVID-19 infections, including hospital length of stay, neutrophil engraftment, graft failure, acute graft-versus-host disease in allo-HSCT patients, or cytokine release syndrome and neurotoxicity in CAR-T patients. No HSCT patients contracted COVID-19 between days 0 and 100. One CAR-T patient contracted COVID-19 at day +51 and died of the disease. Altogether, our data indicate that cellular therapies can be safely administered throughout the ongoing COVID-19 pandemic with appropriate safeguards., Visual Abstract

The α4s7 integrin is upregulated on naive and memory T cell subsets in patients who subsequently develop gastrointestinal (GI) acute GVHD. Natalizumab (Tysabri®, Biogen Inc.) acts against the α4 subunit that mediates homing of lymphocytes to the GI tract. We initiated a phase II study of natalizumab with corticosteroids for initial treatment of acute GI GVHD. In total, 300 mg IV of natalizumab was given, with steroids initiated up to 3 days prior. Twenty-one subjects were treated, median age was 63 years (range 38–74), and 15 (71%) were male. Eighteen (86%) underwent RIC, 15 (71%) received MUD, and all received PBSCs. Overall GVHD at enrollment was grade II in 4 and grade III in 17. The primary endpoint, day 56 GVHD-free survival rate, was attained in 33.3%. The overall response rate at day 28 and 56 was 57% and 52%, respectively. Six of eight CRs were durable for 1 year. Five experienced toxicity possibly related to natalizumab and ten had infections before day 100. 2-year OS was 43% (95% CI 22–62%) and 2-year NRM was 52% (95% CI 29–71%). Natalizumab with corticosteroids as initial treatment of acute GI GVHD is safe, effective, and durable.

Gastroparesis is a syndrome characterised by delayed gastric emptying in the absence of mechanical obstruction. Symptoms can include early satiety, abdominal pain, bloating, vomiting, and regurgitation which cause significant morbidity in addition to nutritional deficits. There is a higher prevalence in diabetics and females, but the incidence in the Australian population has not been well studied. Management of gastroparesis involves investigating and correcting nutritional deficits, optimising glycaemic control, and improving gastrointestinal motility. Symptom control in gastroparesis can be challenging. Nutritional deficits should be addressed initially through dietary modification. Enteral feeding is a second line option when oral intake is insufficient. Home parenteral nutrition is rarely used, and only accessible through specialised clinics in the outpatient setting. Prokinetic medication classes that have been used include dopamine receptor antagonists, motilin receptor agonists, 5-HT4 receptor agonists, and ghrelin receptor agonists. Anti-emetic agents are often used for symptom control. Interventional treatments include gastric electrical stimulation, gastric per-oral endoscopic myotomy, feeding jejunostomy, and gastrostomy/jejunstomy for gastric venting and enteral feeding. In this article we propose a framework to manage gastroparesis in Australia based on current evidence and available therapies. This article is protected by copyright. All rights reserved.

Programmed cell death-1 (PD-1)/programmed death ligand-1 blockade may potentially augment graft-vs-tumor effects following allogeneic hematopoietic cell transplantation (alloHCT), but retrospective studies of anti–PD-1 therapy reported substantial toxicity from graft-versus-host-disease (GVHD). Here, we report the results of a prospective clinical trial of PD-1 blockade for relapsed hematologic malignancies (HMs) after alloHCT (NCT01822509). The primary objective in this phase 1 multicenter, investigator-initiated study was to determine maximum tolerated dose and safety. Secondary objectives were to assess efficacy and immunologic activity. Patients with relapsed HMs following alloHCT were eligible. Nivolumab was administered every 2 weeks until progression or unacceptable toxicity, starting with a 1-mg/kg cohort, with planned deescalation based on toxicity to a 0.5-mg/kg cohort. Twenty-eight patients were treated (n = 19 myeloid, n = 9 lymphoid). Median age was 57 years (range 27-76), and median time from alloHCT to enrollment was 21 months (range 5.6-108.5). Two of 6 patients treated at 1 mg/kg experienced dose-limiting toxicity (DLT) from immune-related adverse events (irAEs). Twenty-two patients were treated at 0.5 mg/kg, and 4 DLTs occurred, including 2 irAEs and 2 with fatal GVHD. The overall response rate in efficacy-evaluable patients was 32% (8/25). With a median follow-up of 11 months, the 1-year progression-free survival and overall survival were 23% and 56%, respectively. In this first prospective clinical trial of an anti–PD-1 antibody for post–alloHCT relapse, GVHD and irAEs occurred, requiring dose deescalation, with only modest antitumor activity. Further studies of anti–PD-1 therapy post–alloHCT may require specific toxicity mitigation strategies. This trial was registered at www.clinicaltrials.gov as #NCT 01822509.

Gemtuzumab ozogamicin (GO) therapy before allogeneic hematopoietic cell transplantation (alloHCT) has been historically associated with an increased risk of hepatic veno-occlusive disease/sinusoidal obstruction syndrome (VOD/SOS) in patients with acute myeloid leukemia (AML). The current analysis examined VOD/SOS risk and outcomes in a cohort of patients who in recent years were reported to the Center for International Blood and Marrow Transplant Research. Adults with AML who had GO exposure before myeloablative alloHCT were matched 1:4 by age and disease status at transplant to recipients without GO exposure (control subjects). One hundred thirty-seven patients with GO exposure and 548 matched control subjects who underwent alloHCT between 2008 and 2011 were included in this analysis. With a median ∼8-year follow-up of survivors, the 5-year overall survival probability was similar in the 2 cohorts: 38% and 38% in the GO-exposed versus control groups (P = .97). Incidence of VOD/SOS and severe VOD/SOS, respectively, at 100 days was 4% (95% confidence interval [CI], 1% to 7%) and 3% (95% CI, 1% to 6%) in GO-exposed patients and 3% (95% CI, 2% to 5%) and 1% (95% CI, 0% to 2%) in control subjects. Correspondingly, among patients who developed VOD/SOS, 1-year survival probability after VOD/SOS diagnosis was 33% (95% CI, 5% to 72%) and 27% (95% CI, 11% to 47%; P = .78). In multivariate analyses, GO exposure before alloHCT was not associated with an increased risk of VOD/SOS (odds ratio, 1.10; P = .85) or death (hazard ratio, 1.08; P = .57). Three deaths (3%) in the GO group and 3 deaths (1%) in the control group were attributed to VOD/SOS. Our results suggest that GO treatment before myeloablative alloHCT in the recent era is not associated with an increased risk of post-transplant VOD/SOS or death.

Hematopoietic cell transplantation (HCT) involves the infusion of hematopoietic progenitor cells into patients with hematologic disorders with the goal of re-establishing normal hematopoietic and immune function. HCT is classified as autologous or allogeneic based on the origin of hematopoietic cells. Autologous HCT uses the patient’s own cells while allogeneic HCT uses hematopoietic cells from a human leukocyte antigen-compatible donor. Allogeneic HCT is a potentially curative treatment option for patients with certain types of hematologic malignancies, and autologous HCT is primarily used to support patients undergoing high-dose chemotherapy. Advances in HCT methods and supportive care in recent decades have led to improved survival after HCT; however, disease relapse and posttransplant complications still commonly occur in both autologous and allogeneic HCT recipients. Allogeneic HCT recipients may also develop acute and/or chronic graft-versus-host disease (GVHD), which results in immune-mediated cellular injury of several organs. The NCCN Guidelines for Hematopoietic Cell Transplantation focus on recommendations for pretransplant recipient evaluation and the management of GVHD in adult patients with malignant disease.

Background: Primary mediastinal large B-cell lymphoma (PMBCL) is a subset of aggressive B-cell non-Hodgkin lymphoma (B-NHL) with distinct biological and clinical features. Although most patients are cured with frontline chemoimmunotherapy with or without radiation therapy (RT), relapsed or refractory (rel/ref) PMBCL is much harder to control. Standard treatment of rel/ref PMBCL is similar to other aggressive B-NHLs, including salvage therapy and autologous (auto) stem cell transplantation (SCT) in chemosensitive patients. Recently, immunotherapy with PD-1 blockade and chimeric antigen receptor modified T-cells has proven to be effective in rel/ref PMBCL. Despite this, allogeneic (allo) SCT retains an important potential role as it has curative potential for patients with advanced aggressive B-NHLs. However, there are scant modern data on alloSCT outcomes in patients with PMBCL, limited to case reports or small series. We therefore performed a multicenter retrospective study to evaluate alloSCT outcomes in patients with rel/ref PMBCL. Methods: We retrospectively studied consecutive patients with rel/ref PMBCL who underwent alloSCT at Fred Hutchinson Cancer Center, Dana-Farber Cancer Institute, Massachusetts General Hospital, or City of Hope between 1/2000 and 5/2014. Baseline and transplant characteristics are reported descriptively. Progression-free survival (PFS) and overall survival (OS) were calculated using the Kaplan-Meier method. Incidence of relapse and non-relapse mortality were calculated using competing risks methods. Results: 28 patients with rel/ref PMBCL underwent alloSCT at participating institutions during the study period. Among these patients, median age at SCT was 36 years, 54% were female, median number of prior therapies was 4 (range, 2-7), 57% were refractory to frontline therapy, 86% received prior RT, and 71% had prior autoSCT. At alloSCT, 1 (4%) patient was in complete response (CR), 21 (75%) were in partial response (PR), and 6 (21%) were refractory to pre-alloSCT therapy (18 patients were assessed with PET). Most patients (86%) received reduced intensity conditioning, most commonly fludarabine/melphalan +/- ATG or Zevalin (25%), fludarabine/TBI200 (21%), or fludarabine/busulfan (14%). GVHD prophylaxis most frequently consisted of a calcineurin inhibitor (CNI) with mycophenolate mofetil (12, 43%), CNI with sirolimus +/- methotrexate (8, 29%), or CNI with MTX (4, 14%). 15 (54%) patients had a matched (8/8) related donor, 8 (29%) had a matched unrelated donor, 2 had a mismatched unrelated donor (7/8), and 3 had umbilical cord donors. All patients received peripheral blood stem cell grafts except for the 3 cord recipients. The median follow-up time in survivors was 5.0 (range 0.5-14.0) years. The 2 year PFS and OS in the cohort were 39% and 45%, respectively, while non-relapse mortality (NRM) and cumulative incidence of relapse (CIR) were 32% and 29%, respectively. The 5-year PFS, OS, NRM, and CIR were 34%, 45%, 32%, and 33%, respectively. The cumulative incidence of grade II-IV and III-IV acute GVHD were 39% and 4% at day 100, while the incidence of chronic GVHD at 1 year was 21% (18% extensive). Among patients in CR/PR at the time of alloSCT, the 2-year PFS and OS were 50% and 58%, respectively, as compared to a 2-year PFS and OS of 0% in patients who were refractory at the time of alloSCT (p=0.046 for PFS, p=0.014 for OS). One patient received post-alloSCT lenalidomide as maintenance therapy and remained in ongoing CR. Of the 9 patients who relapsed after alloSCT, 3 out of 4 patients exhibited a response to immunosuppression taper, while 4 out of 5 patients responded to subsequent systemic therapy. 2 patients underwent a donor lymphocyte infusion (DLI) and both developed subsequent GVHD - 1 patient had a CR documented 64 days after DLI while the other had continued disease progression. In the 9 patients who relapsed after alloSCT, the 2-year OS was 33%. Conclusions: AlloSCT can produce durable remissions in a subset of patients with heavily treated, rel/ref PMBCL. Patients with refractory disease at alloSCT had dismal outcomes. Despite the expanding treatment options available for these patients, alloSCT should be considered in the management of patients with rel/ref PMBCL who are sensitive to salvage therapy. Figure 1A PFS and OS After AlloSCT in Patients with Rel/Ref PMBCL Figure 1B PFS in Patients with Sensitive versus Refractory PMBCL at AlloSCT Disclosures Herrera: Merck, Inc.: Consultancy, Research Funding; Genentech: Consultancy, Research Funding; Bristol-Myers Squibb: Consultancy, Research Funding; AstraZeneca: Research Funding; Gilead Sciences: Research Funding; KiTE Pharma: Consultancy, Research Funding; Immune Design: Research Funding; Seattle Genetics: Research Funding; Pharmacyclics: Consultancy, Research Funding. Maloney:Roche/Genentech: Honoraria; GlaxoSmithKline: Research Funding; Juno Therapeutics: Research Funding; Seattle Genetics: Honoraria; Janssen Scientific Affairs: Honoraria. Ho:Jazz Pharmaceuticals: Consultancy. Soiffer:Jazz Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees. Antin:Jazz Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees. Forman:Mustang Therapeutics: Other: Licensing Agreement, Patents & Royalties, Research Funding. Chen:Incyte: Consultancy, Membership on an entity's Board of Directors or advisory committees; REGiMMUNE: Consultancy; Magenta Therapeutics: Consultancy; Takeda Pharmaceuticals: Consultancy. Armand:Otsuka: Research Funding; Affimed: Consultancy, Research Funding; Pfizer: Consultancy; Infinity: Consultancy; Merck: Consultancy, Research Funding; Adaptive: Research Funding; Bristol-Myers Squibb: Consultancy, Research Funding; Roche: Research Funding; Tensha: Research Funding. Shadman:Acerta Pharma: Research Funding; AbbVie: Consultancy; Genentech: Research Funding; Beigene: Research Funding; Verastem: Consultancy; Qilu Puget Sound Biotherapeutics: Consultancy; Mustang Biopharma: Research Funding; Gilead Sciences: Research Funding; AstraZeneca: Consultancy; TG Therapeutics: Research Funding; Pharmacyclics: Research Funding; Celgene: Research Funding; Genentech: Consultancy.

International audience; Anti-PD-1 monoclonal antibodies yield high response rates in patients with relapsed/refractory classic Hodgkin lymphoma (cHL), but most patients will eventually progress. Allogeneic hematopoietic cell transplantation (alloHCT) after PD-1 blockade may be associated with increased toxicity, raising challenging questions about the role, timing, and optimal method of transplantation in this setting. To address these questions, we assembled a retrospective cohort of 209 cHL patients who underwent alloHCT after PD-1 blockade. With a median follow-up among survivors of 24 months, the 2-year cumulative incidences (CIs) of non-relapse mortality and relapse were 14 and 18%, respectively; the 2-year graft-versus-host disease (GVHD) and relapse-free survival (GRFS), progression-free survival (PFS), and overall survival were 47%, 69%, and 82%, respectively. The 180-day CI of grade 3-4 acute GVHD was 15%, while the 2-year CI of chronic GVHD was 34%. In multivariable analyses, a longer interval from PD-1 to alloHCT was associated with less frequent severe acute GVHD, while additional treatment between PD-1 and alloHCT was associated with a higher risk of relapse. Notably, post-transplant cyclophosphamide (PTCy)-based GVHD prophylaxis was associated with significant improvements in PFS and GRFS. While awaiting prospective clinical trials, PTCy-based GVHD prophylaxis may be considered the optimal transplantation strategy for this patient population.

Chronic graft-versus-host disease (cGVHD) is a leading cause of late morbidity and mortality after allogenic hematopoietic stem cell transplantation. Corticosteroid-based therapies are a mainstay of its initial treatment but there is no consensus in how to treat steroid-refractory cGVHD. Ibrutinib is a Bruton tyrosine kinase and IL-2-inducible kinase inhibitor thought to affect pathways driving cGVHD, and it was approved for the treatment of refractory cGVHD by the Food and Drug Administration (FDA) in August 2017 after a landmark phase 1b/2 study. It was the first medication approved for this indication, but how to best treat refractory cGVHD remains an open question, and there has been limited literature on ibrutinib after the FDA approval. This study sought to characterize the utilization and outcomes associated with ibrutinib use in cGVHD via a retrospective single-center study. Fifty-three patients were identified as having been treated with ibrutinib for cGVHD following FDA approval between September 1, 2017, and December 31, 2020, using an institutional data repository. Their records were reviewed for demographics, cGVHD characteristics, and outcomes. For the entire cohort, two-year overall survival was 76% (95% confidence interval [CI], 60% to 86%), with a median follow-up among survivors of 26 months (range, 1.3 to 39.5 months). However, the 2-year failure-free survival (FFS) after initiation of ibrutinib was 9% (95% CI, 2.6% to 20%), and the median FFS was 4.5 months (95% CI, 2.8 to 7.1 months). Events of FFS included treatment change due to lack of response or toxicity, malignant relapse, or non-treatment related mortality. At the time of this report, 11 patients (21%) remained on ibrutinib. At the time of the FFS event or last follow-up, 6 patients (12%) had a complete or partial response, 34 (64%) had stable disease, and 13 (25%) had progressive disease. Ibrutinib use was associated with no reduction in corticosteroid dose between ibrutinib initiation and FFS event or last follow-up (mean difference, 0.00; P = .98). The most frequently used noncorticosteroid cGVHD therapy after ibrutinib was ruxolitinib (n = 14; 33%). The most common adverse events associated with treatment discontinuation were infection (lung, skin, enterocolitis; n = 6), bleeding and bruising (hematoma, epistaxis, gastrointestinal bleed; n = 5), and muscle aches (n = 2). In a real-world setting, ibrutinib is associated with a modest response rate and FFS and its use in a narrower, more targeted patient population may be indicated.

Key Points Adding venetoclax to FluBu2 reduced-intensity conditioning transplant did not impair engraftment or induce excessive graft-versus-host disease.Monitoring measurable residual disease by ultra-sensitive duplex sequencing revealed complex clonal dynamics before and after transplant., Visual Abstract, Adding the selective BCL-2 inhibitor venetoclax to reduced-intensity conditioning chemotherapy (fludarabine and busulfan [FluBu2]) may enhance antileukemic cytotoxicity and thereby reduce the risk of posttransplant relapse. This phase 1 study investigated the recommended phase 2 dose (RP2D) of venetoclax, a BCL-2 selective inhibitor, when added to FluBu2 in adult patients with high-risk acute myeloid leukemia (AML), myelodysplastic syndromes (MDS), and MDS/myeloproliferative neoplasms (MPN) undergoing transplant. Patients received dose-escalated venetoclax (200-400 mg daily starting day −8 for 6-7 doses) in combination with fludarabine 30 mg/m2 per day for 4 doses and busulfan 0.8 mg/kg twice daily for 8 doses on day −5 to day −2 (FluBu2). Transplant related–toxicity was evaluated from the first venetoclax dose on day −8 to day 28. Twenty-two patients were treated. At study entry, 5 patients with MDS and MDS/MPN had 5% to 10% marrow blasts, and 18 (82%) of 22 had a persistent detectable mutation. Grade 3 adverse events included mucositis, diarrhea, and liver transaminitis (n = 3 each). Neutrophil/platelet recovery and acute/chronic graft-versus-host-disease rates were similar to those of standard FluBu2. No dose-limiting toxicities were observed. The RP2D of venetoclax was 400 mg daily for 7 doses. With a median follow-up of 14.7 months (range, 8.6-24.8 months), median overall survival was not reached, and progression-free survival was 12.2 months (95% confidence interval, 6.0-not estimable). In patients with high-risk AML, MDS, and MDS/MPN, adding venetoclax to FluBu2 was feasible and safe. To further address relapse risk, assessment of maintenance therapy after venetoclax plus FluBu2 transplant is ongoing. This study was registered at clinicaltrials.gov as #NCT03613532.

Allogeneic hematopoietic cell transplantation (HCT) recipients are at increased risk for varicella zoster virus (VZV) reactivation and associated complications. The incidence, timing, and risk factors for severe herpes zoster (HZ) are not well described in the era of acyclovir (ACV) prophylaxis. We performed a retrospective cohort study of all patients who underwent first allogeneic HCT between October 2006 and December 2015 at our institution. Patients were followed until December 2017 for the development of severe HZ, defined as necessitating administration of i.v. antiviral medication. Out of 2163 patients who underwent allogeneic HCT, 22 (1.0%) developed severe HZ at a rate of 1 per 228 person-years, including dermatomal/multidermatomal disease (n = 5), disseminated skin disease (n = 5), HZ ophthalmicus (n = 4), meningitis/encephalitis (n = 4), pneumonia (n = 2), viremia (n = 1), and erythema multiforme (n = 1). Severe HZ infection occurred in a bimodal distribution during the early peri-HCT period and at 12 to 24 months post-HCT (median, 12.7 months). Twelve patients (54.5%) were compliant with ACV prophylaxis at the time of HZ diagnosis. Eleven patients (50%) died during the study period, only 2 of whom (9.1%) with active VZV infection. Mortality was higher in patients on immunosuppressive therapy (62.5% versus 16.7%; P = .045) and with concurrent graft-versus-host disease (75.0% versus 35.7%; P= .044). These data suggest that severe HZ remains an important consideration despite ACV prophylaxis.

The use of immunosuppressive therapies for immune-mediated disease (IMD) is associated with an elevated risk of infections and related comorbidities. While many infectious diseases can generally be prevented by vaccines, immunization rates in this specific patient population remain suboptimal, due in part to uncertainty about their efficacy or safety under these clinical situations. To address this concern, a multidisciplinary group of Canadian physicians with expertise in dermatology, gastroenterology, infectious diseases and rheumatology developed evidence-based clinical guidelines on vaccinations featuring 13 statements that are aimed at reducing the risk of preventable infections in individuals exposed to immunosuppressive agents.

Vaccination using irradiated, adenovirus transduced autologous myeloblasts to secrete granulocyte–macrophage colony-stimulating factor (GVAX) early after allogeneic hematopoietic stem cell transplantation (HSCT) can induce potent immune responses. We conducted a randomized phase 2 trial of GVAX after HSCT for myelodysplastic syndrome with excess blasts or relapsed/refractory acute myeloid leukemia. Myeloblasts were harvested before HSCT to generate the vaccine. Randomization to GVAX vs placebo (1:1) was stratified according to disease, transplant center, and conditioning. Graft-versus-host disease (GVHD) prophylaxis included tacrolimus and methotrexate. GVAX or placebo vaccination was started between day 30 and 45 if there was engraftment and no GVHD. Vaccines were administered subcutaneously/intradermally weekly × 3, then every 2 weeks × 3. Tacrolimus taper began after vaccine completion. A total of 123 patients were enrolled, 92 proceeded to HSCT, and 57 (GVAX, n = 30; placebo, n = 27) received at least 1 vaccination. No Common Toxicity Criteria grade 3 or worse vaccine-related adverse events were reported, but injection site reactions were more common after GVAX (10 vs 1; P = .006). With a median follow-up of 39 months (range, 9-89 months), 18-month progression-free survival, overall survival, and relapse incidence were 53% vs 55% (P = .79), 63% vs 59% (P = .86), and 30% vs 37% (P = .51) for GVAX and placebo, respectively. Nonrelapse mortality at 18 months was 17% vs 7.7% (P = .18), grade II to IV acute GVHD at 12 months was 34% vs 12% (P = .13), and chronic GVHD at 3 years was 49% vs 57% for GVAX and placebo (P = .26). Reconstitution of T, B, and natural killer cells was not decreased or enhanced by GVAX. There were no differences in serum major histocompatibility chain-related protein A/B or other immune biomarkers between GVAX and placebo. GVAX does not improve survival after HSCT for myelodysplastic syndrome/acute myeloid leukemia. This trial was registered at www.clinicaltrials.gov as #NCT01773395.

Background: Disease relapse after hematopoietic cell transplantation (HCT) is a major cause of treatment failure for patients with acute myeloid leukemia (AML). Maintenance therapy following HCT for patients with targetable mutations such as mutated IDH1 or IDH2 may improve outcomes, and clinical trials evaluating this strategy are ongoing. However, current clinical outcomes of IDH1 - and IDH2 -mutated AML patients following HCT have not been well-described. Methods: In this multicenter retrospective analysis, 112 adult patients with either IDH1 - or IDH2 -mutated AML who underwent HCT were identified at Massachusetts General Hospital, Dana Farber Cancer Institute, and Ohio State University. Mutation testing was performed using next-generation sequencing panels. Patient characteristics were collected retrospectively, and their outcomes — including progression-free survival (PFS), overall survival (OS), relapse, and non-relapse mortality — were analyzed. Findings: The median patient age was 64·1 years. 78·5% of patients had intermediate- or adverse-risk disease by European LeukemiaNET criteria. Commonly detected co-mutations were DNMT3A (35·7%), NPM1 (33·1%), and FLT3-ITD (13·4%). The median follow-up was 27·5 months. For IDH1- mutated patients, the 1- and 2-year PFS was 75% and 58%, respectively, and the 1- and 2-year OS was 78% and 74%, respectively. For IDH2- mutated patients, the 1- and 2-year PFS was 64% and 58%, respectively, and the 1- and 2-year OS was 75% and 68%, respectively. Interpretation: Our analysis provides important benchmarks for analysis and interpretation of results emerging from ongoing clinical trials evaluating maintenance IDH1 and IDH2 inhibitor therapy for AML patients following HCT. Funding: This project has no funding source to report. Declaration of Interests: Dr. Eisfeld reports other from Karyopharm, personal fees from Vigeo, outside the submitted work. Dr. E Chen has nothing to disclose. Dr. Li has nothing to disclose. Dr. Luskin has nothing to disclose. Dr. Mims reports other from Jazz, other from Syndax, other from Abbvie, other from Kura oncology, personal fees from Agios, other from Novartis, outside the submitted work. Dr. Jones reports personal fees from Pharmacyclics LLC, outside the submitted work. Dr. Antin has nothing to disclose. Dr. Cutler reports other from Incyte, other from Kadmon, other from Jazz, other from Medsenic, other from Generon, other from Mesoblast, outside the submitted work. Dr. Koreth reports personal fees from Equilium, personal fees from Amgen, personal fees from Moderna Therapeutics, personal fees from Biolojic Design, personal fees from EMD Serono, other from Therakos, other from Cugene, grants from Miltenyi, grants from BMS, grants from Reneron, other from Clinigen, outside the submitted work. Dr. Gooptu has nothing to disclose. Dr. Romee has nothing to disclose. Dr. El-Jawahri has nothing to disclose. Dr. McAfee has nothing to disclose. Dr. Defilipp reports grants from Incyte, grants from Regimmune, personal fees from Syndax, outside the submitted work. Dr. Soiffer reports other from Kiadis, other from Gilead, other from Rheos, other from Cugene, other from Precision Bioscience, other from Mana Therapeutics, other from VOR Biopharma, other from Novartis, other from Juno, other from Celgene, other from Alexion, other from National Marrow Donor Program, outside the submitted work. Dr. YB Chen reports personal fees from Incyte, personal fees from Takeda, personal fees from Magenta, personal fees from Kiadis, other from Actinium, other from Equilium, other from Abbvie, outside the submitted work. Dr. Fathi reports grants from Takeda, personal fees from Boston Biomedical, personal fees from PTC Therapeutics, personal fees from Amphivena, personal fees from Astellas, personal fees from Daiichi Sankyo, personal fees from Novartis, grants and personal fees from Celgene/BMS, personal fees from Trovagene, personal fees from Forty Seven , personal fees from NewLink Genetics , personal fees from Pfizer, personal fees from Abbvie, grants and personal fees from Seattle Genetics , grants and personal fees from Agios, personal fees from Amgen, personal fees from Trillium, personal fees from Kura Oncology, personal fees from Blueprint, personal fees from Genentech, outside the submitted work. Ethics Approval Statement: This study was approved by the Institutional Review Boards at the Dana-Farber Harvard Cancer Center and Ohio State University Comprehensive Cancer Center

Obesity is associated with significant comorbidities, including non-alcoholic fatty liver disease (NAFLD). Given its potential to progress to advanced liver disease, monitoring the extent and progress of liver fibrosis and assessing its fibrosis stage are essential. Although liver biopsy is considered to be the gold standard for liver fibrosis staging, it is an invasive procedure with risk of complications. Considering the rising prevalence of obesity and NAFLD globally, developing non-invasive diagnostic methods is a priority. Transient elastography (TE) is increasingly being used to assess the severity of liver disease. However, in the presence of severe obesity, the increased thickness of subcutaneous adipose tissue and changes in anatomy may affect its diagnostic accuracy. Two-dimensional shear wave elastography (2D-SWE) assesses the liver stiffness in real time along with simultaneous anatomic B-mode ultrasound imaging and allows selection of the region of interest. This would suggest that 2D-SWE has several advantages over TE in patients with severe obesity. The purpose of this review is to examine the current literature addressing the use of 2D-SWE in the assessment of liver fibrosis in patients with NAFLD. This review also examines the evidence on the use of 2D-SWE in patients with obesity and NAFLD and compares it to TE as a novel and non-invasive method of assessing liver fibrosis.

Invasive fungal disease (IFD) can be a severe treatment complication in patients with myeloid malignancies, but current risk models do not incorporate disease-specific factors, such as somatic gene mutations. Germline GATA2 deficiency is associated with a susceptibility to IFD. To determine whether myeloid gene mutations were associated with IFD risk, we identified 2 complementary cohorts of patients with myeloid malignancy, based on (1) the diagnosis of invasive aspergillosis (IA), or (2) the presence of GATA2 mutations identified during standard clinical sequencing. We found somatic GATA2 mutations in 5 of 27 consecutive patients who had myeloid malignancy and developed IA. Among 51 consecutive patients with GATA2 mutations identified in the evaluation of myeloid malignancy, we found that IFD was diagnosed and treated in 21 (41%), all of whom had received chemotherapy or had undergone an allogeneic stem cell transplant. Pulmonary infections and disseminated candidiasis were most common. The 90-day mortality was 52% among patients with IFD. Our results indicate that patients with somatic GATA2 mutations are a vulnerable subgroup of patients with myeloid malignancy who have high risk for treatment-associated IFD and suggest that a focused approach to antifungal prophylaxis be considered.

Allogeneic hematopoietic cell transplantation (alloHCT) can cure previously treated high-risk chronic lymphocytic leukemia (CLL) patients if they are suitable for transplant through the graft-versus-leukemia effect. However, since the emergence of targeted therapies, the role of alloHCT for high-risk CLL is less clear. To address this question, we evaluated 108 high-risk CLL patients who underwent alloHCT from 2010 to 2018. Thirty patients from the period of 2013 to 2018 received targeted therapy prior to alloHCT. The median age for the targeted therapy cohort was 60 years (range, 30-71 years), and 20% and 73% had complete and partial remission, respectively: 76% had del(17p), 46.2% had 5 or more cytogenetic abnormalities, and 78.9% were IGHV unmutated. The median number of prior therapies was 4 (range, 1-9). With a median follow-up time of 36 months (range, 10-72 months), the 3-year overall (OS) and progression-free survival (PFS) were 87% and 69%, respectively. The 3-year cumulative incidence of nonrelapse mortality and relapse was 7% and 24%, respectively. For the control cohort of 78 patients who underwent alloHCT from 2010 to 2014 and received only chemoimmunotherapy prior to transplant, the 3-year OS and PFS were 69% and 58%, respectively. Patients treated with targeted therapy prior to alloHCT had a significantly higher number of circulating T and B cells and a lower ratio of CD4 regulatory T cells to CD4 conventional T cells early after transplant. In summary, despite multiple high-risk features, the clinical outcome of CLL patients who receive targeted therapy prior to transplant is excellent and alloHCT should be offered while the disease is under control.

The DNA damage response enables cells to survive and maintain genome integrity. RAD52 is a DNA-binding protein involved in the homologous recombination in DNA repair, and is important for the maintenance of tumour genome integrity. We investigated possible correlations between RAD52 expression and cancer survival and response to preoperative radiotherapy. RAD52 expression was examined in tumour samples from 179 patients who underwent surgery for rectal cancer, including a sub-cohort of 40 patients who were treated with neoadjuvant therapy. A high score for RAD52 expression in the tumour centre was significantly associated with worse disease-free survival (DFS, p = 0.045). In contrast, reduced RAD52 expression in tumour centre samples from patients treated with neoadjuvant therapy (n = 40) significantly correlated with poor DFS (p = 0.025) and overall survival (OS, p = 0.048). Our results suggested that RAD52 may have clinical value as a prognostic marker of tumour response to neoadjuvant radiation and both disease-free status and overall survival in patients with rectal cancer.

Introduction. Class 3 obesity (BMI≥40 kg/m2) is a growing health problem worldwide associated with considerable comorbidity including Type 2 diabetes mellitus (T2DM). The multidisciplinary medical management of obesity can be difficult in T2DM due to potential weight gain from medications including sulphonylureas and insulin. However, newer weight-neutral/losing diabetes medications can aid additional weight loss. The aim of this study was to compare weight loss outcomes of patients with and without T2DM, and in patients with T2DM, to compare diabetes outcomes and change in medications at 6 months.Methods. All patients entering a multidisciplinary weight management metabolic program in a publicly funded hospital clinic in Sydney between March 2018 and March 2019, withBMI≥40 kg/m2and aged ≥18 years were included. Data was collected from patient clinical and electronic notes at baseline and 6 months.Results. Of the 180 patients who entered the program, 53.3% had T2DM at baseline. There was no difference in percentage weight loss in those with or without T2DM (4.2±4.9%vs.3.6±4.7%,p=0.35). Additionally, T2DM patients benefited from a 0.47% reduction in HbA1c (p<0.01) and a reduction in the number of medications from baseline to 6 months (1.8±1.0/patient vs.1.0±1.2/patient,p<0.001). T2DM patients who started on weigh-neutral/losing medications in the program lost more weight than those started on weight-gaining medications (7.7±5.3%vs.2.4±3.8%,p=0.015).Conclusions. Patients with class 3 obesity had significant weight loss at 6 months in this program. Patients with T2DM at baseline had comparable weight loss at 6 months, a significant improvement in glycaemic control, and a reduction in diabetes medication load. Additionally, patients with T2DM who were started on weight-neutral/losing medications lost significantly more weight than those started on weight-gaining medications, and these medications should be preferentially used in class 3 obesity and comorbid T2DM.

A risk score identifying patients at high risk for veno-occlusive disease (VOD) may aid efforts to study preventive strategies for this uncommon complication of hematopoietic cell transplantation (HCT). Patients receiving a first allogeneic HCT between 2008 and 2013 as reported to the Center for International Blood and Marrow Transplant Research (N = 13,097) were randomly divided into training and validation sets. Independent prognostic factors for development of VOD by day +100 after HCT were identified with a multivariate logistic regression model. A risk score was constructed in the training set using the significant factors and confirmed in the validation set. Baseline characteristics of the training and validation sets were balanced. In total, 637 patients (4.9%) developed VOD by day +100. Younger age, positive hepatitis B/C serology, lower Karnofsky performance scale score, use of sirolimus, disease, disease status at transplant, and conditioning regimen were independent prognostic factors. Myeloablative conditioning regimens were associated with higher risk of VOD. Busulfan-based myeloablative conditioning regimens guided by pharmacokinetic monitoring were associated with higher risk than those without pharmacokinetic monitoring. Patients were stratified into 4 distinct, statistically significantly different groups by their risk score percentile. This pretransplant risk score successfully stratified allogeneic HCT patients by risk of developing VOD, was validated in an independent set, and demonstrated strong discriminatory ability to identify a high-risk cohort.

Amphiregulin (AREG) is an epidermal growth factor receptor ligand that can restore integrity to damaged intestinal mucosa in murine models of acute graft-versus-host disease (aGVHD). We previously reported that circulating AREG is elevated in late-onset aGVHD (occurring after 100 days posttransplant), but its clinical relevance in the context of aGVHD risk is unknown. We measured AREG in 251 aGVHD onset blood samples from Blood and Marrow Clinical Trials Network (BMT CTN) primary treatment trials and determined their association with GVHD severity, day 28 complete or partial response (CR/PR) to first-line therapy, overall survival (OS), and nonrelapse mortality (NRM). Every doubling of plasma AREG was associated with a 33% decrease in the odds of day 28 CR/PR (odds ratio [OR], 0.67; P < .01). An AREG threshold of 33 pg/mL or greater divided patients with Minnesota standard-risk (SR) aGVHD into a distinct group with a significantly lower likelihood of: day 28 CR/PR (72% vs 85%; P = .02); greater 2-year NRM (42% vs 15%; P < .01); and inferior OS (40% vs 66%; P < .01). High AREG ≥ 33 pg/mL also stratified patients with Minnesota high-risk (HR) aGVHD: day 28 CR/PR (54% vs 83%; P = .03) and 2-year NRM (53% vs 11%; P < .01), with a trend toward inferior 2-year OS (37% vs 60%; P = .09). High-circulating AREG (≥33 pg/mL) reclassifies patients into HR subgroups and thereby further refines the Minnesota aGVHD clinical risk score.

Corticosteroid resistance after acute graft-versus-host disease (SR-aGVHD) results in high morbidity and mortality after allogeneic hematopoietic cell transplantation. Current immunosuppressive therapies for SR-aGVHD provide marginal effectiveness because of poor response or excessive toxicity, primarily from infection. α1-Antitrypsin (AAT), a naturally abundant serine protease inhibitor, is capable of suppressing experimental GVHD by downmodulating inflammation and increasing ratios of regulatory (Treg) to effector T cells (Teffs). In this prospective multicenter clinical study, we sought to determine the safety and response rate of AAT administration in SR-aGVHD. Forty patients with a median age of 59 years received intravenous AAT twice weekly for 4 weeks as first-line treatment of SR-aGVHD. The primary end point was overall response rate (ORR), the proportion of patients with SR-aGVHD in complete (CR) or partial response by day 28 without addition of further immunosuppression. Treatment was well tolerated without drug-related adverse events. A significant increase in serum levels of AAT was observed after treatment. The ORR and CR rates by day 28 were 65% and 35%, respectively, and included responses in all aGVHD target organs. At day 60, responses were sustained in 73% of patients without intervening immunosuppression. Infectious mortality was 10% at 6 months and 2.5% within 30 days of last AAT infusion. Consistent with preclinical data, correlative samples showed an increase in ratio of activated Tregs to Teffs after AAT treatment. These data suggest that AAT is safe and may be potentially efficacious in treating SR-aGVHD. This trial was registered at www.clinicaltrials.gov as #NCT01700036.

Double-hit lymphomas (DHLs) and double-expressor lymphomas (DELs) are associated with resistance to frontline and salvage immunochemotherapy, as well as autologous stem cell transplantation (SCT). We hypothesized that allogeneic SCT (alloSCT) could overcome the chemoresistance associated with DEL/DHL. We retrospectively studied the impact of DEL/DHL status in a multicenter cohort of patients who underwent alloSCT for relapsed/refractory (rel/ref) aggressive B cell non-Hodgkin lymphoma (B-NHL). Seventy-eight patients transplanted at 3 centers in whom tumor tissue was available for immunohistochemistry and fluorescence in situ hybridization were enrolled; 47% had DEL and 13% had DHL. There were no significant differences in 4-year progression-free (PFS) or overall survival (OS) between patients with DEL compared with patients without DEL (PFS 30% versus 39%, P = .24; OS 31% versus 49%, P = .17) or between patients with DHL compared with patients without DHL (PFS 40% versus 34%, P = .62; OS 50% versus 38%, P = .46). The lack of association between DEL or DHL and outcome was confirmed in multivariable models, although inadequate sample size may have limited our ability to detect significant differences. In our cohort alloSCT produced durable remissions in patients with rel/ref aggressive B-NHL irrespective of DEL and DHL status, justifying its consideration in the treatment of patients with rel/ref DEL/DHL.

Hepatic veno-occlusive disease/sinusoidal obstruction syndrome (VOD/SOS) is an unpredictable condition associated with endothelial-cell damage due to conditioning for hematopoietic stem-cell transplantation (HSCT) or chemotherapy without HSCT. Mortality in patients with VOD/SOS and multi-organ dysfunction (MOD) may be80%. Areas covered: Defibrotide is the only approved drug for the treatment of severe hepatic VOD/SOS after HSCT in the European Union and hepatic VOD/SOS with renal or pulmonary dysfunction in the United States. Its efficacy in patients with VOD/SOS with MOD post-HSCT was demonstrated in a clinical-trial program that included a historically controlled treatment study, a phase 2 trial, and a large T-IND expanded-access program that also included patients without MOD and who received chemotherapy without HSCT. Expert commentary: Defibrotide appears to protect endothelial cells and restore the thrombolytic-fibrinolytic balance. It addresses a significant clinical need and has demonstrated favorable Day +100 survival and overall adverse-event rates that seem similar to control groups receiving supportive care alone. Currently, defibrotide is under investigation for the prevention of VOD/SOS in high-risk pediatric and adult patients.

Background/Aims: High-resolution oesophageal manometry utilises water swallows to evaluate oesophageal function. However, small volumes of water are not representative of normal eating and as a result often produce normal manometry studies in patients with dysphagia. This study sets out to establish optimal diagnostic thresholds for semi-solid solid swallows and evaluate their ability to uncover motility abnormalities in patients with motility disorders. Method: Manometry was performed using ten 5-mL single water swallows followed by two semi-solid and two solid swallows in the upright position. Normative values for the adjunctive tests were obtained from patient controls while patients with major motility disorders were used to establish the optimal diagnostic thresholds. Diagnostic thresholds identified were prospectively tested in patients with normal water swallows but oesophagus related symptoms and in those with minor and major motility disorders. Results: Normal values for semi-solid and solid were determined in patient controls (n = 100). Development of diagnostic thresholds included 120 patients with major motility disorders. Optimal diagnostic thresholds identified for oesophagogastric junction dysfunction in semi-solid and solid swallows (IRP > 15.5 mmHg). Hypercontractilty and spasm used existing thresholds (>8000 mmHg-s-cm and < 4.5 s, respectively) but modified frequency of ≥50% of adjunctive swallows. Diagnostic thresholds were applied to symptomatic patients with normal water swallows (n = 70) identifying 12/70 (17%) to have abnormal adjunctive swallows. One of 30 patients (3%) with ineffective motility had abnormal adjunctive swallow and 12 patients with oesophageal spasm, oesophagogastric junction obstruction, and hypercontractility had abnormal adjunctive swallows that moved them up the motility disorder hierarchy. Conclusions: Semi-solid and solid challenge increase diagnostic yield of motility disorders.

Purpose Several open-label randomized studies have suggested that in vivo T-cell depletion with anti–T-lymphocyte globulin (ATLG; formerly antithymocyte globulin-Fresenius) reduces chronic graft-versus-host disease (cGVHD) without compromising survival. We report a prospective, double-blind phase III trial to investigate the effect of ATLG (Neovii Biotech, Lexington, MA) on cGVHD-free survival. Patients and Methods Two hundred fifty-four patients 18 to 65 years of age with acute leukemia or myelodysplastic syndrome who underwent myeloablative HLA-matched unrelated hematopoietic cell transplantation (HCT) were randomly assigned one to one to placebo (n =128 placebo) or ATLG (n = 126) treatment at 27 sites. Patients received either ATLG or placebo 20 mg/kg per day on days −3, −2, −1 in addition to tacrolimus and methotrexate as GVHD prophylaxis. The primary study end point was moderate-severe cGVHD-free survival. Results Despite a reduction in grade 2 to 4 acute GVHD (23% v 40%; P = .004) and moderate-severe cGVHD (12% v 33%; P < .001) in ATLG recipients, no difference in moderate-severe cGVHD-free survival between ATLG and placebo was found (2-year estimate: 48% v 44%, respectively; P = .47). Both progression-free survival (PFS) and overall survival (OS) were lower with ATLG (2-year estimate: 47% v 65% [ P = .04] and 59% v 74% [ P = .034], respectively). Multivariable analysis confirmed that ATLG was associated with inferior PFS (hazard ratio, 1.55; 95% CI, 1.05 to 2.28; P = .026) and OS (hazard ratio, 1.74; 95% CI, 1.12 to 2.71; P = .01). Conclusion In this prospective, randomized, double-blind trial of ATLG in unrelated myeloablative HCT, the incorporation of ATLG did not improve moderate-severe cGVHD-free survival. Moderate-severe cGVHD was significantly lower with ATLG, but PFS and OS also were lower. Additional analyses are needed to understand the appropriate role for ATLG in HCT.

Background: Chronic graft versus host disease (cGVHD) remains a significant cause of morbidity and mortality following allogeneic hematopoietic stem cell transplantation (HCT), with a cumulative incidence of 50% (Arora et al, Biol Blood Marrow Transplant 2016). Systemic corticosteroids are considered first-line therapy, and best approach to managing steroid-refractory cGVHD is lacking. Abatacept is a recombinant fusion protein consisting of the extracellular domain of human cytotoxic T lymphocyte-associated antigen 4 (CTLA-4) linked to the modified Fc portion of human immunoglobulin G1 (IgG1) to prevent complement fixation and antibody-dependent cellular cytotoxicity. Abatacept is a selective costimulation modulator that binds specifically to CD80 and CD86 on antigen presenting cells, thus attenuating CD28-mediated T cell activation. We previously reported results from a Phase I clinical trial evaluating the safety and clinical efficacy of abatacept in patients with steroid-refractory cGVHD (Nahas et al, Blood 2018 #NCT01954979). Here we report results of the phase II study evaluating the overall clinical response rate of abatacept in patients with steroid-refractory cGVHD. Methods: Allogeneic bone marrow or stem cell transplantation recipients were eligible if they developed cGVHD as defined by NIH consensus criteria and were treated with prednisone ≥ 0.25 mg/kg/day for at least 4 weeks without complete resolution of signs and symptoms. Peripheral blood was drawn prior to each dose of abatacept and following completion of therapy to assess the effect of treatment on circulating T cells. Abatacept was administered at 10mg/kg for a total of 6 doses. Doses 1-3 were administered at two-week intervals. One month after administration of Dose 3, abatacept was given at four-week intervals for Doses 4-6. Patients who completed 6 doses of abatacept and continued to demonstrate response were eligible to receive extended duration therapy with monthly abatacept at a dose of 10mg/kg for up to a total of 12 additional doses. Primary study endpoint was overall response rate (ORR) of using abatacept in treating cGVHD. Complete response (CR) was defined as resolution of all manifestations in each organ or site, and partial response (PR) was defined as improvement in at least one organ or site without progression in any other organ or site as per the 2014 NIH Chronic GVHD Consensus Response Criteria (Lee et al Biol Blood Marrow Transplant 2015). Results: 39 subjects with median age of 62 years (range 25-77 years) had undergone HCT a median of 43 months (range 6-173 months) prior to study entry. Patients were treated with abatacept and received a median of 8 doses (range 2-18). 17 patients had moderate cGVHD and 22 patients had severe cGVHD at baseline. Baseline cGVHD assessment of the 39 evaluable patients showed involvement of the skin in 85% (n=33), mouth in 44% (n=17), eyes in 69% (n=27), gastrointestinal tract (GI) in 18% (n=7), liver in 23% (n=9), lung in 54% (n=21), joints in 82% (n=32), and genital tract in 8% (n=3). The ORR was 49% (19/39 patients) with CR 0% and PR 49%. The organ sites with greatest improvement included lung (33%), eyes (23%), mouth (21%), and joints (21%). Progression of disease occurred in 26% of patients (n=10), with sites of involvement including skin (8%), mouth (10%), eyes (5%), lung (3%), and joints (5%). Baseline median daily dose of prednisone was 20mg with a 27.5% reduction at 1-month follow-up to 14.5mg (p Conclusions: Abatacept is associated with a 49% ORR in steroid refractory cGVHD and leads to durable reduction in prednisone dosing over time. Severe infections are uncommon and the infusions are well tolerated. Abatacept represents a promising novel therapeutic agent for patients with steroid-refractory cGVHD. Disclosures Stroopinsky: The Blackstone Group: Consultancy. Arnason: Juno/BMS: Honoraria. Cutler: Cimeio: Consultancy; Editas: Consultancy; Kadmon: Consultancy; Pfizer: Consultancy; Mallinckrodt: Consultancy; CareDx: Consultancy; Incyte: Consultancy; Omeros: Consultancy; Syndax: Consultancy; Mesoblast: Consultancy; Deciphera: Consultancy; Jazz: Consultancy. Nikiforow: Kite/Gilead: Other: ad HOC Advisory Boards; Novartis: Other: ad Hoc Advisory Boards; Iovance: Other: ad Hoc Advisory Boards; Glaxo Smith Kline (GSK): Other: ad Hoc Advisory Boards. Avigan: Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding; Pharmacyclics: Research Funding; Kite Pharma: Consultancy, Research Funding; Juno: Membership on an entity's Board of Directors or advisory committees; Partner Tx: Membership on an entity's Board of Directors or advisory committees; Karyopharm: Membership on an entity's Board of Directors or advisory committees; Bristol-Myers Squibb: Membership on an entity's Board of Directors or advisory committees; Aviv MedTech Ltd: Membership on an entity's Board of Directors or advisory committees; Takeda: Membership on an entity's Board of Directors or advisory committees; Legend Biotech: Membership on an entity's Board of Directors or advisory committees; Chugai: Membership on an entity's Board of Directors or advisory committees; Janssen: Consultancy; Parexcel: Consultancy; Takeda: Consultancy; Sanofi: Consultancy. Soiffer: Rheos Therapeutics, USA: Consultancy; Kiadis, Netherlands: Membership on an entity's Board of Directors or advisory committees; Juno Therapeutics, USA: Other: Data Safety Monitoring Board; Precision Biosciences, USA: Consultancy; Jazz Pharmaceuticals, USA: Consultancy; Takeda: Consultancy; Jasper: Consultancy; Gilead, USA: Other: Career Development Award Committee; NMPD - Be the Match, USA: Membership on an entity's Board of Directors or advisory committees. Rosenblatt: Attivare Therapeutics: Consultancy; Parexel: Consultancy; Karyopharm: Membership on an entity's Board of Directors or advisory committees; Imaging Endpoints: Consultancy; Wolters Kluwer Health: Consultancy, Patents & Royalties; Bristol-Myers Squibb: Research Funding.

Bronchiolitis obliterans syndrome (BOS) is a highly morbid form of chronic graft-versus-host disease (GVHD) after allogeneic hematopoietic cell transplantation (HCT). Several plasma proteins have been identified as biomarkers for BOS after lung transplantation. The relevance of these biomarkers in BOS patients after allogeneic HCT has not been examined. We hypothesized that biomarkers associated with BOS after lung transplantation are also associated with BOS after allogeneic HCT. We tested plasma samples from 33 adult HCT patients who participated in a phase II multicenter study of fluticasone, azithromycin, and montelukast (FAM) treatment for new-onset BOS (NCT01307462), and matched control samples of HCT patients who had non-BOS chronic GVHD (n = 31) and those who never experienced chronic GVHD (n = 29) (NCT00637689 and NCT01902576). Candidate biomarkers included matrix metalloproteinase-9 (MMP-9), MMP-3, and chitinase-3-like-1 glycoprotein (YKL-40). MMP-9 concentrations were higher in the patients with BOS compared with those with non-BOS chronic GVHD (P = .04) or no chronic GVHD (P.001). MMP-3 concentrations were higher in patients with BOS (P.001) or non-BOS chronic GVHD (P.001) compared with those with no chronic GVHD. YKL-40 concentrations did not differ statistically among the 3 groups. MMP-9 concentrations before starting FAM therapy were higher in patients who experienced treatment failure within 6 months compared with those with treatment success (P = .006), whereas MMP-3 or YKL-40 concentrations did not differ statistically between these 2 groups. Patients with an MMP-9 concentration ≥200,000 pg/mL before starting FAM therapy had worse overall survival compared with those with lower MMP-9 concentrations. Our data suggest that plasma MMP-9 concentration could serve as a relevant biomarker at diagnosis of BOS after allogeneic HCT for prognostication of survival and for prediction of treatment response. Further validation is needed to confirm our findings.

Disease relapse after hematopoietic cell transplantation (HCT) is a major cause of treatment failure for patients with acute myeloid leukemia (AML). Maintenance therapy after HCT for patients with targetable mutations such as mutated IDH1 or IDH2 may improve outcomes, and clinical trials evaluating this strategy are ongoing. However, clinical outcomes of IDH1- and IDH2-mutated AML patients after HCT have not been well described. The primary objective of this study was to describe the clinical characteristics and post-HCT outcomes of IDH-mutated AML patients. Survival outcomes included progression-free survival (PFS), overall survival, and cumulative incidences of relapse and nonrelapse mortality. In this multicenter retrospective analysis, 112 adult patients with IDH1- or IDH2-mutated AML who underwent HCT and did not receive an IDH inhibitor as maintenance therapy after HCT were identified at Massachusetts General Hospital, Dana Farber Cancer Institute, and Ohio State University. Mutation testing was performed using next-generation sequencing panels. Patient characteristics were collected retrospectively, and their survival outcomes were analyzed. Univariate and multivariate analyses were performed. The median patient age was 64.1 years. The median follow-up was 27.5 months. Among patients, 78.5% had intermediate- or adverse-risk disease by European LeukemiaNET criteria. Fifty-eight percent of patients received intensive induction chemotherapy, 82% of patients underwent HCT during first complete remission (CR) or CR with incomplete hematologic recovery (CRi), and 34% of patients received myeloablative conditioning. Frequently detected co-mutations were DNMT3A (35.7%), NPM1 (33.1%), and FLT3-ITD (13.4%); TP53 mutations were detected in 3.6% of patients. For IDH1-mutated patients transplanted during first CR/CRi, the 1- and 2-year PFS was 75% and 58%, respectively. For IDH2-mutated patients transplanted in first CR/CRi, the 1- and 2-year PFS was 64% and 58%, respectively. The 2-year cumulative incidence of relapse was 31% and 25% for IDH1- and IDH2-mutated cohorts, respectively. Multivariable analysis suggested first CR/CRi and age ≤60 was associated with improved outcomes for IDH2-mutated patients. To date, this is the largest multicenter study of outcomes of IDH-mutated AML patients after HCT. Our analysis provides important benchmarks for analysis and interpretation of results emerging from clinical trials evaluating maintenance IDH1 and IDH2 inhibitor therapy for AML patients after HCT.

Pulmonary complications are a significant cause of morbidity, mortality, and resource utilization after hematopoietic stem cell transplantation (HSCT). The objective of this study was to compare antemortem clinical suspicion of pulmonary complications and postmortem findings in a modern HSCT cohort. All patients who underwent allogeneic HSCT at our institution (n = 1854) between January 1, 2000 and June 30, 2010 were reviewed and patients who died of any cause greater than 1 year after HSCT and had an unrestricted autopsy available for analysis were included. Presence of pulmonary graft-versus-host disease (GVHD) was assessed by a pathologist blinded to the autopsy report, as previously described by Yousem (1995). A total of 35 (1.9%) patients had autopsies available for review. Airway disease, vascular disease, and interstitial disease were all clinically under-recognized compared with the pathological findings on autopsy. Varying degrees of pathological changes were detected, including 10 (28.6%) patients having bronchiolitis obliterans (BO) and 12 (34.3%) patients having pulmonary veno-occlusive disease (PVOD). Pulmonary manifestations of chronic GVHD, particularly BO and PVOD, were clinically under-recognized in our cohort. Our results suggest that PVOD, which has traditionally been considered a rare complication, may be clinically and histologically under-recognized.

Objectives The aim of this study was to evaluate the impact of oral health status on bacteremia risk in a cohort of patients with acute myeloid leukemia (AML) who underwent chemotherapy followed by myeloablative allogeneic hematopoietic cell transplantation (allo-HCT). Study Design A retrospective study was conducted in patients with AML from 2007 to 2011. Oral health status was determined from a pre–allo-HCT dental evaluation. Positive blood cultures were recorded from AML induction to post–allo-HCT day +60. Organisms that caused bacteremia were classified as “of possible oral source” by a blinded microbiologist. Two-sided Fisher's exact test was used to compare the oral health status of the entire cohort with that of patients with blood cultures of potential oral source. Results Pre–allo-HCT dental evaluations were completed in 91 (99%) of 92 patients. Of these 91 patients, 13 (14%) with dental pathology (13 of 13 [100%]) completed all required dental treatment before allo-HCT. Bacteremias occurred in 63 of 92 patients (68%), and 12 (19%) of 63 patients had positive blood cultures of potential oral source. Of these, 1 of 12 patients developed bacteremia during AML induction, and 11 of 12 developed bacteremia during allo-HCT. Conclusions Oral health status was not associated with risk of bacteremia of potential oral source either at AML induction or consolidation or at allo-HCT.

Background: Treat-to-target therapy approaches are established for chronic diseases such as diabetes, hypertension, and more recently rheumatoid arthritis, resulting in improved patient outcomes. These approaches do not use patient reported outcomes (PRO) as targets of therapy. Chronic spontaneous urticaria (CSU), also called chronic idiopathic urticaria (CIU), is defined as recurrent urticaria of known and unknown cause, lasting more than 6 weeks. Treatment of CSU can be challenging. However, with the advent of proven therapies and validated instruments for measuring disease activity, the concept of treat-to-target (T2T) can be successfully applied to CSU. Herein, we propose a potential PRO therapeutic target and suggest a T2T approach for the management of patients with CSU. Methods: Principles and recommendations for a treat-to-target approach in CSU (T2T/CSU) were developed by a Canadian task force, consisting of dermatologists, immunologists, and allergists. The task force formulated recommendations for therapeutic targets in CSU on the basis of a systematic literature review and expert opinion. Results: The key features of these T2T/CSU recommendations are the use of a PRO as the principal target, with symptom control as measured by Urticaria Activity Score 7 (UAS7 ≤ 6), targeting symptom remission (UAS7 = 0). Conclusion: Treatment targets such as UAS7 ≤ 6 and UAS7 = 0 provide a benchmark for success in the care of patients with CSU, and will permit the evaluation of a PRO-based T2T approach in the care of these patients and the effect of this approach on improved patient care as seen in other chronic diseases.

Although venous thromboembolism rates and risk factors are well described in patients with cancer, there are limited data on the incidence, risk factors and outcomes of thrombosis after allogeneic stem cell transplantation, a curative therapy for patients with hematologic malignancies. We aimed to determine the incidence and risks associated with venous thrombosis in allogeneic stem cell transplants. We studied 2276 recipients of first transplant between 2002–2013 at our institution with a median follow up of 50 months (range 4–146). Using pharmacy records and subsequent chart reviews, 190 patients who received systemic anticoagulation for venous thrombosis were identified. The 1-and 2-year cumulative incidence of all venous thrombotic events were 5.5% (95% confidence interval (CI) 4.6–6.5%) and 7.1% (95% CI 6.1–8.2%), respectively. There was no difference in age, sex, body mass index, diagnosis, disease risk index, conditioning intensity, donor type or graft source between transplant recipients with and without subsequent thrombosis. In multivariable models, both acute and chronic graft-versus-host disease were independently associated with thrombosis occurrence (Hazard ratio (HR)=2.05, 95% CI 1.52–2.76; HR=1.71, 95% CI 1.19–2.46, respectively). Upper extremity thrombosis differed from all other thromboses in terms of timing, risk factors and clinical impact, and was not associated with non-relapse mortality (HR=1.15; 95% CI 0.69–1.90), unlike all other thromboses which did increase non-relapse mortality (HR=1.71; 95% CI 1.17–2.49). In subgroup analysis evaluating conventional thrombosis predictors by comparing patients with and without thrombosis, a history of prior venous thrombosis was the only significant predictor. Venous thromboembolism has a high incidence after allogeneic stem cell transplant and is associated with graft-versus-host disease and non-relapse mortality.

Introduction: Veno-occlusive disease/sinusoidal obstructive syndrome (VOD/SOS) is a potentially life-threatening complication after hematopoietic cell transplant (HCT). Defibrotide (DF), a mixture of single and double stranded oligonucleotides with profibrinolytic, anti-thrombotic, anti-ischemic and anti-inflammatory activity was approved by the FDA for the treatment of VOD/SOS in 2016. Prior to its FDA approval, its use was mostly restricted to patients with moderate to severe VOD characterized by multiorgan dysfunction. However, following approval, it has been used more liberally. We herein report a "real world experience" for commercially available DF in patients who developed VOD/SOS at our transplant center. Methods: All patients who received DF for the treatment of VOD/SOS after allogeneic HCT from March 2016 until June 2019 were included in this study. Baseline demographic data were retrieved from the Dana Farber Cancer Institute BMT repository, and chart review was performed to obtain additional information for cases. All received DF 6.25 mg/kg/dose every 6 hours for 21-day cycle for the treatment of VOD/SOS. Patients were diagnosed with VOD/SOS if they met at least 2 of the EBMT criteria; total bilirubin ≥ 2mg/dL, painful hepatomegaly, ascites, weight gain >5% or ultrasonographic evidence of VOD. VOD/SOS severity grading was defined per the EBMT VOD guidelines. Results: Twenty-eight patients received DF for the management of VOD/SOS. Of these, 12, 8, and 8 patients had mild-moderate, severe, and very severe VOD/SOS respectively. Median time to diagnosis of VOD/SOS was day +25 after HCT. Five cases were confirmed by liver biopsy and 16 patients had reversal of flow on ultrasound. Twelve and 16 patients received myeloablative and non-myeloablative regimens respectively. DF was started on the day of diagnosis in 71% of patients. Four patients had received inotuzumab ozogamicin prior to VOD/SOS diagnosis. Twenty-one (75%) patients had resolution of VOD/ SOS, defined by complete resolution of clinical symptoms and improvement of laboratory data ascertained via detailed chart review, at a median of 14 days from starting DF. Patients with very severe VOD/SOS took the longest to respond at a median of 21 days as compared to 10 and 11.5 days in the mild-moderate and severe group, respectively (P=0.04). Survival at 28 and 56 days from VOD/SOS diagnosis was 82% and 71% respectively. In univariable analysis, the presence of pulmonary dysfunction (PD) at VOD/SOS diagnosis and early in the course of VOD/SOS was significantly associated with lack of response. Only 1 out of 7 patients with PD responded (14%) as opposed to 20 out of 21 (95%) patients without PD who responded (p=0.0001). With the median follow up of 18 months from the VOD/SOS onset (range 11,33), 1-year overall survival (OS) was 46% for the entire cohort. Disease severity was not associated with OS (p=0.38) or progression-free survival (PFS) (p=0.67) (Figure 1), but response to DF (treated as a time dependent variable in Cox model) was significantly associated with OS (HR 0.14, 95% CI 0.03, 0.69, P=0.016) and PFS (HR 0.19, 95% CI 0.04, 0.84, P=0.029) (Figure 2). All 7 non-responders died within 3 months of onset. Immediate causes of death in non-responders were VOD/SOS (n=2), grade III/IV gastrointestinal hemorrhage (n=1), relapsed disease (n=1) and sepsis (n=3). Attributed causes of death in responders were grade III/IV gut/liver graft versus host disease (n=2), relapsed disease (n=2), sepsis (n=2) and respiratory failure (n=1). Possible therapy-related adverse events were uncommon but included grade III/IV gastrointestinal hemorrhage (n=1), grade III/IV pulmonary hemorrhage (n=1), gross hematuria (n=6) and grade 3 hypotension (n=2), and proved generally manageable. Importantly, 1 out of 4 patients who received inotuzumab ozogamicin did not respond to DF and subsequently died from sepsis, considered unrelated to DF therapy. Conclusion: We report a real world experience of DF post-FDA approval in the USA from 2016 -2019. The majority of our patients received DF as soon as VOD/SOS was diagnosed. We found that use of DF was associated with complete resolution of VOD/SOS in 75% of all patients meeting the EBMT criteria treated with DF. Our overall survival outcomes are encouraging; particularly among responders without severe adverse events. Our results favor early identification and initiation of DF in VOD/SOS after HCT. Disclosures Richardson: Celgene/BMS, Oncopeptides, Takeda, Karyopharm: Research Funding. Soiffer:Gilead: Consultancy; Juno: Other; Celgene: Other; Kiadis: Membership on an entity's Board of Directors or advisory committees; Be The Match/National Marrow Donor Program: Membership on an entity's Board of Directors or advisory committees; Rheos Therapeutics: Consultancy; Cugene: Consultancy; Precision Bioscience: Consultancy; Mana Therapeutics: Consultancy; VOR Biopharma: Consultancy; Alexion: Consultancy; Novartis: Consultancy. Cutler:Jazz: Consultancy, Membership on an entity's Board of Directors or advisory committees; Medsenic: Consultancy, Membership on an entity's Board of Directors or advisory committees; Generon: Consultancy, Membership on an entity's Board of Directors or advisory committees; Mesoblast: Consultancy, Membership on an entity's Board of Directors or advisory committees; Incyte: Consultancy, Membership on an entity's Board of Directors or advisory committees; Kadmon: Consultancy, Membership on an entity's Board of Directors or advisory committees. Nikiforow:Kite: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees; Nkarta: Membership on an entity's Board of Directors or advisory committees. Koreth:Biolojic Design Inc: Consultancy; Regeneron: Other: Research Support; Cugene: Membership on an entity's Board of Directors or advisory committees; Therakos: Membership on an entity's Board of Directors or advisory committees; Miltenyi: Other: Research Support; BMS: Other: Research Support; Amgen: Consultancy; Equillium: Consultancy; Moderna Therapeutics: Consultancy; EMD Serono: Consultancy; Clinigen: Other.

Characterization of molecular alterations in acute myeloid leukemia (AML) has led to development of targeted therapies, including FLT3 and IDH1/2 inhibitors. Maintenance therapy following hematopoietic cell transplantation (HCT) has shown substantial promise. Enasidenib (ENA), a selective IDH2 inhibitor, was associated with impressive rates of response in relapsed/refractory (R/R) AML and is now FDA-approved for this indication. We sought to assess the tolerability and define the maximum tolerated dose (MTD) of ENA as maintenance following HCT for IDH2-mutated myeloid malignancy. HCT-eligible patients (pts) ≥ 18 years with AML in remission, or myelodysplastic syndrome (MDS) with 1000/µL and platelets > 50000/µL). Those with prior HCT, active disease, QTc ≥450ms, and active infections were excluded. ENA was initiated between day 30 and 90 after HCT, at which time the following were required: chimerism ≥70% of donor origin among blood/marrow cells, no acute graft versus host disease (aGVHD) requiring ≥0.5mg/kg/day prednisone or equivalent, and no relapse. ENA was taken orally (po) daily (qd) in 28-day cycles. The period for dose-limiting toxicity (DLT) evaluation was the first cycle, escalation to successive levels was guided by DLT incidence, and 2 levels (50mg,100mg) were studied. Following establishment of MTD or recommended phase 2 dose (RP2D), 10 pts would be enrolled in an expansion cohort. Pts were monitored for relapse and toxicity and continued until disease progression, intolerable toxicity, or receipt of 12 cycles. Nineteen pts have been registered prior to HCT at 3 sites, Massachusetts General Hospital, Dana Farber Cancer Institute, and Johns Hopkins Hospital. Three pts could not initiate ENA following HCT; 2 due to logistic challenges of the COVID pandemic and 1 due to relapse. The remaining 16 pts initiated ENA treatment. The median age was 61 years (range 31-76); 12 (75%) were male, and 13 (81%) were Caucasian. Fourteen (88%) had AML, of which 6 were AML with MDS related changes and 2 had antecedent myeloproliferative neoplasm. Two pts (13%) had MDS. Among these 16 pts, 9 (56%) had IDH2 R140, and 5 (25%) had IDH2 R172 mutations. IDH2 subtype data was unavailable for 2 pts. Of 15 pts with available data from time of diagnosis, 11 (73%) had intermediate-risk and 4 (27%) had adverse-risk cytogenetics. Among these 15 pts, common concurrent mutations were DNMT3A (47%), SRSF2 (33%), and RUNX1 (33%). Eleven AML pts (85%) received intensive versus non-intensive therapies (15%) prior to HCT, and among all pts, 7 (44%) had received ENA prior to HCT. HCT data was available for all 16 pts; 4 pts (25%) received myeloablative, and 12 (75%) received reduced-intensity conditioning. Nine pts (56%) had a matched unrelated, 6 (38%) had haploidentical, and 1 (6%) had a matched related donor HCT. Three pts were enrolled at the 50mg dose level, 6 pts at 100mg, and after no DLTs were detected, the remaining were enrolled in an expansion cohort at 100mg qd. Median follow-up (F/U) for surviving patients is currently 11.7 months (range 1.5-18.9). 2 pts (13%) have relapsed during F/U, at 96 and 364 days post HCT. Additional ≥grade (G) 3 toxicities detected during treatment, possibly or probably related to ENA, included neutropenia, anemia, and bilirubinemia. Six pts (38%) required dose interruptions lasting a median 19 days (range 7-25), 4 required a dose reduction to 50mg, and 1 stopped treatment due to G3 bilirubinemia. In total, 3 pts (18%) discontinued study treatment, 1 for aforementioned G3 bilirubinemia, 1 to pursue a GVHD trial, and 1 for relapse. Six pts have completed the 12-month f/u without relapse, and 7 remain on study. 15 of 16 pts remain alive. Thus far, 3 pts have experienced ≥ G2 aGVHD, and 4 had moderate chronic GVHD. Serial measurement of 2HG is being conducted on samples, and these will be reported. Enasidenib is well-tolerated as post-HCT maintenance therapy for myeloid malignancy at the RP2D of 100mg qd. No DLTs have been detected, and a low rate of post-HCT relapse has been identified to date, although longer f/u is needed. Larger, randomized studies of ENA in the post-SCT setting would determine the true efficacy of this agent as maintenance therapy. Disclosures Fathi: Blueprint: Consultancy; Jazz: Consultancy; Amgen: Consultancy; Newlink Genetics: Consultancy; Pfizer: Consultancy; Abbvie: Consultancy; Seattle Genetics: Consultancy, Research Funding; Agios: Consultancy, Research Funding; PTC Therapeutics: Consultancy; Takeda: Consultancy, Research Funding; Boston Biomedical: Consultancy; Amphivena: Consultancy; BMS/Celgene: Consultancy, Research Funding; Kite: Consultancy; Trovagene: Consultancy; Forty Seven: Consultancy; Novartis: Consultancy; Daiichi Sankyo: Consultancy; Astellas: Consultancy; Trillium: Consultancy; Kura Oncology: Consultancy. Soiffer:Gilead: Consultancy; Novartis: Consultancy; Juno: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees; VOR Biopharma: Consultancy; alexion: Consultancy; Rheos Therapeutics: Consultancy; Cugene: Consultancy; Precision Bioscience: Consultancy; Be the Match/ National Marrow Donor Program: Membership on an entity's Board of Directors or advisory committees; Kiadis: Membership on an entity's Board of Directors or advisory committees; Mana Therapeutics: Consultancy. Levis:Menarini: Honoraria; Amgen: Honoraria; FujiFilm: Honoraria, Research Funding; Astellas: Honoraria, Research Funding; Daiichi-Sankyo: Honoraria. Mims:Novartis: Speakers Bureau; Kura Oncology: Membership on an entity's Board of Directors or advisory committees; Leukemia and Lymphoma Society: Other: Senior Medical Director for Beat AML Study; Agios: Consultancy; Syndax Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees; Jazz Pharmaceuticals: Other: Data Safety Monitoring Board; Abbvie: Membership on an entity's Board of Directors or advisory committees. Devine:Magenta Therapeutics: Consultancy. Defilipp:Incyte: Research Funding; Regimmune: Research Funding; Syndax Pharmaceuticals: Consultancy. Spitzer:Jazz Pharmaceuticals, Inc.: Membership on an entity's Board of Directors or advisory committees; Bluebird Bio: Membership on an entity's Board of Directors or advisory committees. Frigault:Celgene: Consultancy; Arcellx: Consultancy; Novartis: Consultancy, Research Funding; Gilead/Kite: Consultancy, Research Funding. Amrein:Amgen: Research Funding; AstraZeneca: Consultancy, Research Funding; Takeda: Research Funding. Hobbs:Incyte: Research Funding; Merck: Research Funding; Bayer: Research Funding; Constellation: Honoraria, Research Funding; Jazz: Honoraria; Celgene/BMS: Honoraria; Novartis: Honoraria. Brunner:Janssen: Research Funding; Acceleron Pharma Inc.: Consultancy; GSK: Research Funding; Xcenda: Consultancy; Takeda: Consultancy, Research Funding; Novartis: Consultancy, Research Funding; Jazz Pharma: Consultancy; Forty Seven, Inc: Consultancy; Celgene/BMS: Consultancy, Research Funding; Biogen: Consultancy; Astra Zeneca: Research Funding. Narayan:Genentech: Other: Prior Spouse employment within 24 months and prior spouse equity divested within past 24 months; Takeda: Other: Prior Spouse employment within 24 months; Sanofi-Genzyme: Other: Current Spouse employment . Chen:AbbVie: Other: Data and Safety Monitoring Board Member; Incyte Corporation: Consultancy; Takeda: Consultancy; Actinium: Other: Data and Safety Monitoring Board Member; Equillium: Other: Data and Safety Monitoring Board Member; Magenta: Consultancy; Kiadis: Consultancy. OffLabel Disclosure: Enasidenib as post-transplant maintenance therapy

Background: The outcomes for patients (pts) with myeloid malignancies who relapse after allogeneic hematopoietic cell transplantation (HCT) is poor, and relapse occurs more frequently for those with high-risk mutations or cytogenetics. The oral selective BCL-2 inhibitor and BH3 mimetic venetoclax (VEN) increases mitochondrial apoptotic priming even in chemoresistant myeloblasts. Reasoning that VEN would selectively increase the anti-leukemic effect of HCT conditioning chemotherapy without undue toxicity, we evaluated the safety and efficacy of adding VEN to fludarabine and busulfan (FluBu2) reduced intensity conditioning (RIC) chemotherapy. Here, we report on the completed dose-escalation and expansion cohorts from the phase 1 trial. Methods: Pts received escalating doses of VEN (dose level (DL)1, 200 mg on Days -8 to -3 (n=3); DL2, 200 mg on Days -8 to -2 (n=3); DL3, 400 mg on Days -8 to -2 (n=16)) in combination with FluBu2 (fludarabine 30 mg/m2/d on Days -5 to -2 and IV busulfan 0.8 mg/kg bid on Days -5 to -2), followed by PBSC infusion on Day 0 and tacrolimus/methotrexate GVHD prophylaxis. Eligible pts included those with adverse risk AML per ELN criteria or secondary AML in complete remission (CR); MDS (t-MDS; Int-2 or higher IPSS; presence of TP53 or RAS pathway gene mutation) or MDS/MPN (including +8; chr 7 abnl; complex karyotype; or ASXL1 mutation) with £10% blasts pre-transplant; and an 8/8 HLA-matched donor. Dose-limiting toxicity (DLT) was defined (first dose of VEN until Day +28) as any treatment-related death, failure to achieve an absolute neutrophil count (ANC) ≥ 500/mL on 2 consecutive occasions, or any gr 4 non-heme toxicity or tumor lysis syndrome. Targeted sequencing of 88 genes on a clinical assay (sensitivity 1-3%) was performed on pre-VEN and day +100 marrow samples. Flow cytometry-based BH3 profiling was performed on pre-VEN treatment bone marrow in pts with measurable residual myeloblasts. Results: Twenty-two pts (median age 64 y, range 25-71) were treated including 9 AML, 11 MDS, and 2 MDS/MPN cases. 45% of the cohort had an ECOG 2 (n=10). A mutation in TP53 was identified immediately pre-transplant in 55% of pts (n=12). Median HCT-CI score was 4 (range 1-8). 35% and 65.2% had intermediate- and adverse- cytogenetic risk. 20 received HLA-matched unrelated and 2 received HLA-matched related grafts. Median bone marrow leukemia blasts prior to study was 5% (range 5-10). The most common grade 3 or higher non-heme toxicity observed were grade 3 ALT (n=3), diarrhea (n=3), and rash (n=4). Neutrophil engraftment was achieved in all 22 patients (100%). Median days to neutrophil and platelet recovery were 15 (range 12-33) and 14 (range 10-19), respectively. Median donor-derived myeloid chimerism at day +28 was 100% (range, 97-100). No DLTs were observed at DL1-DL3. Acute and chronic GVHD were detected in 12 (GrI, n=7; GrII, n=4; GrIII, n=1) and 6 patients (NIH moderate, n=4; severe, n=2), respectively. At day +100, 16 out of 21 (76%) evaluable patients were in CR. Of the total 22 pts treated to date, 6 have died (5 from disease relapse and 1 from GVHD-related complications). Overall, 7 of 22 pts have relapsed; 2 of these 7 pts subsequently achieved CR2 (one after tapering immunosuppression alone and another after receiving chemotherapy). Median follow-up time among 16 surviving pts is 7.4mo (range, 2.6-19.5). Median OS has not been reached. Median PFS is 11.9 mo (95% CI 6.0 mo, not estimable) (Fig 1). For the entire cohort, the 6-month OS and PFS were 84% and 76%, respectively. Univariable analysis demonstrates pts with an ECOG 0/1 predicted OS and PFS in univariate analysis (p=0.025, 0.001, respectively). Of 21 pts with available paired pre-VEN and day +100 samples, 5 had persistent mutation by NGS (Fig 2). BH3 profiling analysis is underway. Conclusions: The addition of VEN (400 mg; RP2D) to the backbone of FluBu2 conditioning chemotherapy for allo-HCT is not associated with increased toxicity. VEN/FluBu2 combination demonstrates promising clinical activity supporting further evaluation for high risk disease features. To further reduce disease relapse, we are testing VEN/FluBu2 conditioning chemotherapy with VEN/hypomethylating agent maintenance therapy. Disclosures Garcia: Eli Lily: Research Funding; Pfizer: Research Funding; Genentech: Research Funding; AbbVie: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding. Cutler:Incyte: Consultancy, Membership on an entity's Board of Directors or advisory committees; Kadmon: Consultancy, Membership on an entity's Board of Directors or advisory committees; Jazz: Consultancy, Membership on an entity's Board of Directors or advisory committees; Medsenic: Consultancy, Membership on an entity's Board of Directors or advisory committees; Generon: Consultancy, Membership on an entity's Board of Directors or advisory committees; Mesoblast: Consultancy, Membership on an entity's Board of Directors or advisory committees. Stone:Astellas: Consultancy; Argenix: Other; Syros: Consultancy; Novartis: Consultancy, Research Funding; Janssen: Consultancy; Celgene: Consultancy, Other; Daiichi-Sankyo: Consultancy; Syndax: Consultancy, Research Funding; Macrogenics: Consultancy; Stemline: Consultancy; Pfizer: Consultancy; Trovagene: Consultancy; Aztra-Zeneca: Consultancy; Jazz: Consultancy; Actinium: Consultancy, Membership on an entity's Board of Directors or advisory committees; Arog: Consultancy, Research Funding; Biolinerx: Consultancy; Takeda: Other: DSMB; Syntrix: Other: DSMB; Agios: Consultancy, Research Funding; Gemoab: Consultancy; Abbvie: Consultancy, Research Funding. Koreth:EMD Serono: Consultancy; Cugene: Membership on an entity's Board of Directors or advisory committees; Regeneron: Other: Research Support; Equillium: Consultancy; Biolojic Design Inc: Consultancy; Therakos: Membership on an entity's Board of Directors or advisory committees; BMS: Other: Research Support; Amgen: Consultancy; Moderna Therapeutics: Consultancy; Miltenyi: Other: Research Support; Clinigen: Other. Nikiforow:Nkarta Therapeutics: Honoraria; Novartis: Honoraria; Kite/Gilead: Honoraria. Steensma:Takeda: Consultancy; BMS/Celgene: Consultancy; Onconova: Consultancy; Arena: Current equity holder in publicly-traded company; CRISPR: Current equity holder in publicly-traded company; Aprea Therapeutics: Research Funding; Arrowhead Pharmaceuticals: Current equity holder in publicly-traded company; Astex Pharmaceuticals, Onconova Therapeutics, Pfizer, Stemline Therapeutics, Summer Road: Consultancy; H3 Biosciences: Research Funding. Letai:AbbVie: Consultancy; AstraZeneca: Consultancy; Chugai: Other; Dialectic: Membership on an entity's Board of Directors or advisory committees; Flash Therapeutics: Membership on an entity's Board of Directors or advisory committees; Novartis: Research Funding; Zentalis: Membership on an entity's Board of Directors or advisory committees. Lindsley:Jazz Pharmaceuticals: Consultancy, Research Funding; MedImmune: Research Funding; Takeda Pharmaceuticals: Consultancy; Bluebird Bio: Consultancy. Soiffer:Celgene: Other; Juno: Other; Alexion: Consultancy; Novartis: Consultancy; VOR Biopharma: Consultancy; Mana Therapeutics: Consultancy; Precision Bioscience: Consultancy; Cugene: Consultancy; Rheos Therapeutics: Consultancy; Gilead: Consultancy; Be The Match/National Marrow Donor Program: Membership on an entity's Board of Directors or advisory committees; Kiadis: Membership on an entity's Board of Directors or advisory committees. DeAngelo:Forty-Seven: Consultancy; Shire: Consultancy; Blueprint Medicines Corporation: Consultancy, Research Funding; Takeda: Consultancy; Abbvie: Research Funding; Glycomimetics: Research Funding; Pfizer: Consultancy; Novartis: Consultancy, Research Funding; Incyte Corporation: Consultancy; Jazz: Consultancy; Agios: Consultancy; Amgen: Consultancy; Autolos: Consultancy. OffLabel Disclosure: venetoclax with conditioning chemotherapy in the context of a clinical trial

CD6 is a co-stimulatory receptor expressed on T cells that binds activated leukocyte cell adhesion molecule (ALCAM), a ligand expressed on antigen-presenting cells and various epithelial and endothelial tissues. The CD6-ALCAM pathway modulates T cell activation, proliferation and trafficking playing a central role in inflammation. Early studies by Soiffer and colleagues demonstrated that ex-vivo depletion of CD6+ donor T cells prior to hematopoietic cell transplantation (HCT) decreased the incidence of acute graft versus host disease (aGVHD), highlighting the importance of CD6+ cells in GVHD pathogenesis. Itolizumab, a humanized IgG1 anti-CD6 monoclonal antibody, has been shown to block CD6 signaling, leading to a reduction in T cell activation and proliferation. The aim of this study was to characterize expression of CD6 early after HCT and to examine the effects of Itolizumab on T cell responses in the setting of aGVHD. We analyzed immune reconstitution in 95 adult patients who underwent allogeneic HCT for hematological malignancies. Patients received myeloablative (50.5%) or reduced intensity (49.5%) conditioning. Almost all patients received peripheral blood stem cell grafts from HLA-matched related (MRD; 27.4%), matched unrelated (MUD; 66.3%) or mismatched unrelated donors (MMUD; 6.3%). Tacrolimus and methotrexate were used for GVHD prophylaxis. Forty-two of 95 patients developed grade I-IV aGVHD at a median of 50 days (range 20-294) after HCT and systemic immunosuppression was started in 81% of these cases. aGVHD grade severity was 38.1%, 40.5%, 7.1% and 14.3% of grade I, II, III and IV, respectively. Patient samples were collected at 1, 2, 3 and 6 months after HCT and analyzed using multi-color flow cytometry. Nine healthy donors (HD) were analyzed as controls. Suppressive activity of Itolizumab was tested in vitro using peripheral blood mononuclear cells (PBMCs) obtained from HD and patients before (preGVHD) and after aGvHD onset (postGVHD) after 72 hour stimulation with antiCD3/CD2/CD28 coated beads. T cell proliferation was measured by CFSE dilution, while T cell activation and maturation were monitored by expression of CD25 and CD45RO, respectively. To test if Itolizumab activity was dependent on the presence of the CD6 cognate ligand, ALCAM, HD CD3+ T cells were stimulated with anti-CD3 antibody with or without ALCAM-Fc for 96 hours. CD6+ T cells reconstituted early after transplant, accounting for 77.8% (range, 69.9-93.7) of CD4Treg, 98.1% (range, 96.5-99.5) of CD4Tcon, 84% (range, 77.1-92.1) of CD8 T cells at 1 month. This pattern remained unchanged at 2, 3 and 6 months and in HD. CD6 expression (MFI) was the highest in Tcon and lowest in Treg in patients as well as in HD. Compared to HD, CD6 MFI in CD4 Treg was significantly lower in patients at 1,2,3 and 6 months after HCT (p Prior to GVHD onset, Itolizumab inhibited CD4 and CD8 T cell proliferation in a similar fashion to HD control. This effect was less prominent in T cells collected after GVHD onset, when patients were already receiving immunosuppressive medications, especially for the CD8 T cells (Fig 1D). Similar results were observed for CD25 and CD45RO expression (Fig 1D). Addition of ALCAM-Fc to anti-CD3 antibody enhanced T cell proliferation, activation and maturation. Itolizumab efficiently inhibited T cell proliferation, activation and maturation in the presence of ALCAM-Fc and anti-CD3 antibody, while no effect was observed in the presence of anti-CD3 antibody alone (Fig 2A). Finally, Itolizumab alone did not induce significant CDC, ADC or ADCC in vitro (Fig 2B). In conclusion, we demonstrate that CD6 positive T cells reconstitute rapidly after HCT with higher levels of expression in Tcon compared to Treg and CD8 T cells. Percentages of CD6+ T cells do not change during aGVHD, but levels of CD6 expression decrease in Tcon and Treg after aGVHD. Itolizumab efficiently inhibits T cell proliferation and activation after in vitro TCR stimulation of PBMCs from patients with aGvHD. Functional inhibition of the CD6-ALCAM pathway without T cell depletion may be a novel therapeutic strategy for treating aGvHD. A phase I/II study using Itolizumab as first line treatment in combination with steroids for patients with aGVHD is currently ongoing (NCT03763318). Disclosures Rambaldi: Equillium: Research Funding. Koreth:EMD Serono: Consultancy; Biolojic Design Inc: Consultancy; Cugene: Membership on an entity's Board of Directors or advisory committees; Regeneron: Other: Research Support; BMS: Other: Research Support; Miltenyi: Other: Research Support; Clinigen: Other; Therakos: Membership on an entity's Board of Directors or advisory committees; Equillium: Consultancy; Moderna Therapeutics: Consultancy; Amgen: Consultancy. Cutler:Generon: Consultancy, Membership on an entity's Board of Directors or advisory committees; Mesoblast: Consultancy, Membership on an entity's Board of Directors or advisory committees; Incyte: Consultancy, Membership on an entity's Board of Directors or advisory committees; Kadmon: Consultancy, Membership on an entity's Board of Directors or advisory committees; Jazz: Consultancy, Membership on an entity's Board of Directors or advisory committees; Medsenic: Consultancy, Membership on an entity's Board of Directors or advisory committees. Nikiforow:Kite: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees; Nkarta: Membership on an entity's Board of Directors or advisory committees. Soiffer:Juno: Membership on an entity's Board of Directors or advisory committees; Gilead: Consultancy; Celgene: Membership on an entity's Board of Directors or advisory committees; Be the Match/ National Marrow Donor Program: Membership on an entity's Board of Directors or advisory committees; Cugene: Consultancy; alexion: Consultancy; Kiadis: Membership on an entity's Board of Directors or advisory committees; Precision Bioscience: Consultancy; Mana Therapeutics: Consultancy; Rheos Therapeutics: Consultancy; Novartis: Consultancy; VOR Biopharma: Consultancy. Ampudia:Equillium: Current Employment, Current equity holder in publicly-traded company. Ng:Equillium: Current Employment, Current equity holder in publicly-traded company. Connelly:Equillium: Current Employment, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees. Ritz:Rheos Medicines: Consultancy; Amgen: Research Funding; Avrobio: Consultancy; Talaris Therapeutics: Consultancy; LifeVault Bio: Consultancy; Infinity Pharmaceuticals: Consultancy; Equillium: Research Funding; Falcon Therapeutics: Consultancy; Kite Pharma: Research Funding; TScan Therapeutics: Consultancy.

Background Relapse of acute myeloid leukemia (AML) after allogeneic stem cell transplant has a poor prognosis with limited treatment options. Cytokine-induced memory like natural killer (CIML NK) cells are a novel therapy with enhanced cytotoxicity independent of KIR ligand interactions able to induce remission of relapsed/refractory AML (Romee et al, Science TM 2016). We are evaluating the safety and potential efficacy of donor-derived CIML NK cells in patients with relapsed myeloid malignancies after haploidentical donor transplant (haploSCT) in a phase 1/1b study (clinicaltrials.gov: NCT040247761). Here we report on manufacturing, safety, and in vivo correlative biology of the adoptively transferred CIML NK cells in the first 3 enrolled patients. Methods The primary endpoint is to identify the maximum-tolerated dose (MTD) of CIML NK cells in patients with MDS, MPN, or AML who relapsed after haplo-SCT. NK cells were enriched from donor-derived non-mobilized leukapheresis product via two-step CD3 depletion followed by selection of CD56+ cells using the CliniMACS reagent system (Miltenyi Biotec). The enriched NK cell product was cultured for 12-16 hours in X-VIVO 15 media containing rhIL-12, rhIL-15, and rhIL-18 to generate CIML NK cells (Figure 1A). Patients in the current cohort were lymphodepleted with fludarabine 25mg/m2 daily for 3-5 days and cyclophosphamide 60mg/kg daily for 2 days followed by CIML NK cells at a dose of 5-10 x 106 cells/kg and IL-2 106 IU/m2 QOD for 7 doses. Dose-limiting toxicities were evaluated for 6 weeks following NK cell infusion. Response to therapy was assessed at day+28 following CIML NK cell infusion. Results Patient #001 has FLT3-ITD AML that relapsed 5 months after a reduced intensity (RIC) haploSCT. She received 7.4x106 NK cells/kg followed by IL-2 106 IU/m2 QOD for 7 doses. Her day+28 bone marrow had no leukemia blasts although FLT3-ITD mutation remained detectable. Two months post-CIML NK the leukocyte and granulocyte chimerism were 88% and 89%, respectively. Patient #002 has AML with multiple pathogenic variants, including a potentially pathogenic variant in TP53. His disease relapsed 15 months post haplo-SCT with repeat marrow showing all the original mutations, including the TP53 variant (VAF 50.5%). He received 9.5x106 NK cells/kg followed by IL-2 106 IU/m2 QOD for 7 doses. His day+28 marrow had trilineage hematopoiesis without any mutations, including no TP53 mutation (Figure 1B). Two months post-CIML NK the leukocyte and granulocyte chimerism were both 99%. Patient #003 has MDS whose disease relapsed 8 months post RIC haploSCT with persistence of all her diagnostic pathogenic mutations. She received approximately 9.2x106 NK cells/kg and has only just completed IL-2 106 IU/m2 QOD for 7 doses. Among the 3 patients, the main toxicity was prolonged cytopenia requiring stem cell boost in one case. Donor NK cells demonstrated a dramatic shift from a predominantly CD56dimCD16hi (88% of NK cells) to a CD56dimCD16lo phenotype (49% of NK cells) as CIML NK cells. Infused CIML NK cells expanded massively, with approximately 50-fold, 10-fold, and 15-fold maximum in vivo expansion in the first three patients, respectively (Figure 1C). CIML NK cells were the major population in the day+28 marrows in both patients #001 and #002, with CD56+CD7+ cells constituting 89% of the cellularity in the former and 48% in the latter (Figure 1C). CIML NK cells persisted for 3 and 6 months post-infusion in the first two patients. The NK cells were predominantly mature, with most expressing CD16 and low levels of the inhibitory receptor NKG2A. PD-1 expression was much lower on the expanded NK cells vs the pre-infusion donor-derived NK cells. There was minimal concurrent expansion of CD4+CD25+ T-regulatory cells (Figure 1D). Conclusion We show with the first 3 patients in this trial that CIML NK cells can be generated and infused safely, can expand massively in the peripheral blood and bone marrow within the first 30 days post-infusion, and can persist for several months. In addition, CIML NK cell infusion can reduce the burden of pathogenic variant alleles to below the limit of detection, including the burden of high-risk mutations such as in TP53. Though our results are preliminary, the massive in vivo expansion and long-term persistence of adoptively transferred CIML NK cells underscores the unique biology of these cells that makes them an attractive option for cellular therapy protocols. Disclosures Nikiforow: Kite: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees; Nkarta: Membership on an entity's Board of Directors or advisory committees. Rambaldi:Equillium: Research Funding. Cutler:Incyte: Consultancy, Membership on an entity's Board of Directors or advisory committees; Kadmon: Consultancy, Membership on an entity's Board of Directors or advisory committees; Jazz: Consultancy, Membership on an entity's Board of Directors or advisory committees; Medsenic: Consultancy, Membership on an entity's Board of Directors or advisory committees; Generon: Consultancy, Membership on an entity's Board of Directors or advisory committees; Mesoblast: Consultancy, Membership on an entity's Board of Directors or advisory committees. Koreth:Cugene: Membership on an entity's Board of Directors or advisory committees; Regeneron: Other: Research Support; Clinigen: Other; Miltenyi: Other: Research Support; BMS: Other: Research Support; Therakos: Membership on an entity's Board of Directors or advisory committees; Equillium: Consultancy; EMD Serono: Consultancy; Biolojic Design Inc: Consultancy; Amgen: Consultancy; Moderna Therapeutics: Consultancy. Wu:Pharmacyclics: Research Funding; BionTech: Current equity holder in publicly-traded company. Soiffer:Juno: Membership on an entity's Board of Directors or advisory committees; Novartis: Consultancy; VOR Biopharma: Consultancy; Mana Therapeutics: Consultancy; Precision Bioscience: Consultancy; Cugene: Consultancy; Rheos Therapeutics: Consultancy; Kiadis: Membership on an entity's Board of Directors or advisory committees; Gilead: Consultancy; Celgene: Membership on an entity's Board of Directors or advisory committees; alexion: Consultancy; Be the Match/ National Marrow Donor Program: Membership on an entity's Board of Directors or advisory committees. Ritz:TScan Therapeutics: Consultancy; Talaris Therapeutics: Consultancy; Rheos Medicines: Consultancy; LifeVault Bio: Consultancy; Avrobio: Consultancy; Kite Pharma: Research Funding; Equillium: Research Funding; Amgen: Research Funding; Falcon Therapeutics: Consultancy; Infinity Pharmaceuticals: Consultancy.