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Blastic Plasmacytoid Dendritic Cell Neoplasm (BPDCN) is an aggressive hematological malignancy; however, some patients achieve durable remission with allogeneic hematopoietic cell transplantation (allo-HCT). We report on all 17 patients with BPDCN who underwent allo-HCT at our center between 2000 and 2020. The median age was 39 (18-67) years. All (n = 16, 94%), except one patient, had systemic disease involving bone marrow and/or other organs. Ten patients (59%) were in first complete remission (CR1) at allo-HCT. The donor source was matched related or unrelated in ten (59%) and alternate donor in seven (41%) patients. Five (31%) patients developed acute graft-versus-host disease (GVHD), all grade I-II. The cumulative incidence (CI) of chronic GVHD at five-year was 34%. The CI of non-relapse mortality at one-year was 29%. Progression-free survival (PFS) rates at two-year and five-year were 49% (95% CI = 22-71%) and 39% (95% CI = 14-64%), respectively. The two-year and five-year overall survival (OS) rates were 65% (95% CI = 38-82%) and 40% (95% CI = 12-68%), respectively. The five-year rate for both PFS and OS was 80% in CR1 patients versus 0% in patients not in CR1. In conclusion, allo-HCT provides long-lasting remissions in BPDCN patients, particularly when performed in CR1.

Recent compelling evidence showed that innate immune effector cells could recognize allogeneic grafts and prime an adaptive immune response. Signal regulatory protein α (SIRPα) is an immunoglobulin superfamily receptor that is expressed on myeloid cells; the interaction between SIRPα and its ubiquitously expressed ligand CD47 elicits an inhibitory signal that suppresses macrophage phagocytic function. Additional studies showed that donor-recipient mismatch in SIRPα variants might activate monocytic allorecognition, possibly as the result of non-self SIRPα-CD47 interaction. However, the frequency of SIRPα variation and its role in hematopoietic stem cell transplantation (HSCT) remains unexplored. We studied 350 patients with acute myeloid leukemia/myelodysplastic syndrome who underwent HLA-matched related HSCT and found that SIRPα allelic mismatches were present in 39% of transplantation pairs. SIRPα variant mismatch was associated with a significantly higher rate of chronic graft-versus-host disease (GVHD; hazard ratio [HR], 1.5; P = .03), especially de novo chronic GVHD (HR, 2.0; P = .01), after adjusting for other predictors. Those with mismatched SIRPα had a lower relapse rate (HR, 0.6; P = .05) and significantly longer relapse-free survival (RFS; HR, 0.6; P = .04). Notably, the effect of SIRPα variant mismatch on relapse protection was most pronounced early after HSCT and in patients who were not in remission at HSCT (cumulative incidence, 73% vs 54%; HR, 0.5; P = .01). These findings show that SIRPα variant mismatch is associated with HSCT outcomes, possibly owing to innate allorecognition. SIRPα variant matching could provide valuable information for donor selection and risk stratification in HSCT.

Over the past few years, cellular immunotherapy has emerged as a novel treatment option for certain forms of hematologic malignancies with multiple CAR-T therapies now routinely administered in the clinic. The limitations of generating an autologous cell product and the challenges of toxicity with CAR-T cells underscore the need to develop novel cell therapy products that are universal, safe, and potent. Natural killer (NK) cells are part of the innate immune system with unique advantages, including the potential for off-the-shelf therapy. A recent first-in-human trial of CD19-CAR-NK infusion in patients with relapsed/refractory lymphoid malignancies proved safe with promising clinical activity. Building on these encouraging clinical responses, research is now actively exploring ways to further enhance CAR-NK cell potency by prolonging in vivo persistence and overcoming mechanisms of functional exhaustion. Besides these strategies to modulate CAR-NK cell intrinsic properties, there are increasing efforts to translate the successes seen in hematologic malignancies to the solid tumor space. This review will provide an overview on current trends and evolving concepts to genetically engineer the next generation of CAR-NK therapies. Emphasis will be placed on innovative multiplexed engineering approaches including CRISPR/Cas9 to overcome CAR-NK functional exhaustion and reprogram immune cell metabolism for enhanced potency.

Relapse after allogeneic hematopoietic cell transplantation (HCT) leads to poor survival in patients with acute myeloid leukemia (AML). A second HCT (HCT2) may achieve durable remission. To determine the outcomes of patients who received an HCT2 for relapsed AML and to evaluate the predictors of overall survival (OS) and progression-free survival (PFS). We retrospectively reviewed medical records of adult patients who underwent an HCT2 for relapsed AML at our institution during 2000 to 2019. Ninety-one patients were identified with a median age of 44 years (range 18-73) at HCT2. Donor types were HLA-identical sibling (n = 37 [41%]), HLA-matched–unrelated (n = 34 [37%]), haploidentical (n = 19 [21%]), and cord blood (n=1 [1%]). Donors were different at HCT2 in 53% of patients. The majority of patients received reduced intensity conditioning (n = 71 [78%]) and were in remission (n = 56 [61%]) at HCT2. The median remission duration after HCT1 was 8.4 months (range 1-70) and the median time between transplants was 14 months (range 3-73). The median follow-up of surviving patients after HCT2 was 66 months (range 2-171), with 32% alive at time of analysis. The most common cause of death was disease recurrence (n = 45 [73%]). At 2 years, the rates of OS, PFS, progression, and nonrelapse mortality were 36%, 27%, 42%, and 18%, respectively. The development of chronic graft-versus-host disease (GVHD) after first HCT and HCT comorbidity index (HCT-CI) ≥2 at HCT2 were associated with inferior PFS and OS after HCT2. A second HCT is feasible in selected patients with AML who have relapsed after HCT1. Long-term survival benefit is possible in patients without chronic GVHD after HCT1 and HCT-CI

High-dose chemotherapy and autologous stem-cell transplant (HDC/ASCT) is standard treatment for chemosensitive relapsed classical Hodgkin lymphoma, although outcomes of high-risk relapse (HRR) patients remain suboptimal. We retrospectively analyzed all HRR classical Hodgkin lymphoma patients treated with HDC/ASCT at our institution between 01/01/2005 and 12/31/2019. HRR criteria included primary refractory disease/relapse within 1 year, extranodal extension, B symptoms, requiring more than one salvage line, or positron emission tomography (PET)-positive disease at ASCT. All patients met the same ASCT eligibility criteria. We treated 501 patients with BEAM (n=146), busulphan/melphalan (BuMel) (n=38), gemcitabine( Gem)/BuMel (n=189) and vorinostat/Gem/BuMel (n=128). The Gem/BuMel and vorinostat/Gem/BuMel cohorts had more HRR criteria and more patients with PET-positive disease at ASCT. Treatment with brentuximab vedotin (BV) or anti-PD1 prior to ASCT, PET-negative disease at ASCT, and maintenance BV increased over time. BEAM and BuMel predominated in earlier years (2005-2007), GemBuMel and BEAM in middle years (2008-2015), and vorinostat/GemBuMel and BEAM in later years (2016-2019). The median follow-up is 50 months (range, 6-186). Outcomes improved over time, with 2-year progressionfree survival (PFS)/overall survival (OS) rates of 58%/82% (2005-2007), 59%/83% (2008-2011), 71%/94% (2012-2015) and 86%/99% (2016- 2019) (P

Cancer immunotherapies are associated with remarkable therapeutic response rates but also with unique and severe toxicities, which potentially result in rapid deterioration in health. The number of clinical applications for novel immune effector-cell therapies, including chimeric antigen receptor (CAR)-expressing cells, and other immunotherapies, such as immune-checkpoint inhibitors, is increasing. In this Consensus Statement, members of the Pediatric Acute Lung Injury and Sepsis Investigators (PALISI) Network Hematopoietic Cell Transplantation-Cancer Immunotherapy (HCT-CI) Subgroup, Paediatric Diseases Working Party (PDWP) of the European Society of Blood and Marrow Transplantation (EBMT), Supportive Care Committee of the Pediatric Transplantation and Cellular Therapy Consortium (PTCTC) and MD Anderson Cancer Center CAR T Cell Therapy-Associated Toxicity (CARTOX) Program collaborated to provide updated comprehensive recommendations for the care of children, adolescents and young adults receiving cancer immunotherapies. With these recommendations, we address emerging toxicity mitigation strategies, we advocate for the characterization of baseline organ function according to age and discipline-specific criteria, we recommend early critical care assessment when indicated, with consideration of reversibility of underlying pathology (instead of organ failure scores) to guide critical care interventions, and we call for researchers, regulatory agencies and sponsors to support and facilitate early inclusion of young patients with cancer in well-designed clinical trials.

Chimeric antigen receptor (CAR) engineering of T cells has revolutionized the field of cellular therapy for the treatment of cancer. Despite this success, autologous CAR-T cells have recognized limitations that have led to the investigation of other immune effector cells as candidates for CAR modification. Recently, natural killer (NK) cells have emerged as safe and effective platforms for CAR engineering. In this article, we review the advantages, challenges, and preclinical and clinical research advances in CAR NK cell engineering for cancer immunotherapy. We also briefly consider the feasibility and potential benefits of applying other immune effector cells as vehicles for CAR expression.Significance:CAR engineering can redirect the specificity of immune effector cells, converting them to a much more potent weapon to combat cancer cells. Expanding this strategy to immune effectors beyond conventional T lymphocytes could overcome some of the limitations of CAR T cells, paving the way for safer and more effective off-the-shelf cellular therapy products.

T cells engineered with chimeric antigen receptors (CARs) have revolutionized the field of cell therapy and changed the paradigm of treatment for many patients with relapsed or refractory B-cell malignancies. Despite this progress, there are limitations to CAR-T cell therapy in both the autologous and allogeneic settings, including practical, logistical, and toxicity issues. Given these concerns, there is a rapidly growing interest in natural killer cells as alternative vehicles for CAR engineering, given their unique biological features and their established safety profile in the allogeneic setting. Other immune effector cells, such as invariant natural killer T cells, γδ T cells, and macrophages, are attracting interest as well and eventually may be added to the repertoire of engineered cell therapies against cancer. The pace of these developments will undoubtedly benefit from multiple innovative technologies, such as the CRISPR-Cas gene editing system, which offers great potential to enhance the natural ability of immune effector cells to eliminate refractory cancers.

Chimeric antigen receptor (CAR) T cells are a rapidly emerging form of cancer treatment, and have resulted in remarkable responses in refractory lymphoid malignancies. However, their widespread clinical use is limited by toxicity related to cytokine release syndrome and neurotoxicity, the logistic complexity of their manufacturing, cost and time-to-treatment for autologous CAR-T cells, and the risk of graft-versus-host disease (GvHD) associated with allogeneic CAR-T cells. Natural killer (NK) cells have emerged as a promising source of cells for CAR-based therapies due to their ready availability and safety profile. NK cells are part of the innate immune system, providing the first line of defence against pathogens and cancer cells. They produce cytokines and mediate cytotoxicity without the need for prior sensitisation and have the ability to interact with, and activate other immune cells. NK cells for immunotherapy can be generated from multiple sources, such as expanded autologous or allogeneic peripheral blood, umbilical cord blood, haematopoietic stem cells, induced pluripotent stem cells, as well as cell lines. Genetic engineering of NK cells to express a CAR has shown impressive preclinical results and is currently being explored in multiple clinical trials. In the present review, we discuss both the preclinical and clinical trial progress made in the field of CAR NK-cell therapy, and the strategies to overcome the challenges encountered.

Cancer immunotherapy has greatly advanced in recent years, with chimeric antigen receptor (CAR) T cells emerging as an innovative technology that harnesses the immune system to fight malignant diseases. These genetically engineered T-cells have shown encouraging results for B-cell lymphoid malignancies and are now being explored for other cancer types. However, this novel adoptive cell therapy is associated with a new spectrum of immune-mediated adverse events and toxicities. As CAR T cells recognize and engage tumour cells, cytokines are secreted and activate other immune cells, frequently leading to rapid development of cytokine release syndrome, which can result in acute deterioration of the patient's clinical condition. In many patients, cytokine release syndrome is mild and easy to manage, but others experience persistent fevers accompanied by hypotension and hypoxia, which require management with immune-modulatory agents. Another deleterious effect of cytokines released by effector cells is immune effector cell-associated neurotoxicity syndrome. This syndrome, caused by a disruption of the blood-brain barrier as a consequence of the immune process, can result in rapid deterioration in cognitive function. This is often associated with subtle changes in handwriting, often progressing to loss of memory and concentration and reduced ability to name objects or follow commands. In some cases, the neurological state is further compromised by seizures and in rare instances with fulminant life-threatening cerebral oedema. In this review, we discuss these toxicities, as well as other CAR T-cell-related immune phenomenon, and address their clinical manifestations, grading, and management options.

Background: Myeloablative conditioning can be given safely to older patients by simply administering busulfan over a longer period (fractionated busulfan regimen) than the standard four-day regimen (Popat et al Lancet Haematology 2018). This longer duration of conditioning regimen allows addition of targeted agents like Venetoclax, which may be synergistic with conditioning chemotherapy and may further improve disease control with this regimen. We therefore added Venetoclax to our ongoing prospective clinical trial with f-Bu-Flu-Cladribine conditioning (NCT02250937). After enrolling 83 patients, the study was amended and venetoclax was added for the next 33 patients. Here we report the safety and preliminary efficacy of venetoclax and fractionated busulfan regimen. Methods: Between 2/2019 and 3/2021, 33 patients with AML (n=21) or MDS (n=10) up to 70 years of age with adequate organ function and 8/8-HLA matched related or unrelated donor were enrolled on a prospective trial. The conditioning regimen was f-Bu to target an area under the concentration vs time curve (AUC) of 20,000 ± 12% μmol.min given over a period of 2-3 weeks. The first two doses of busulfan (80 mg/m2 IV each) were administered either consecutively (days -13 and -12) or with further fractionation, one week apart (days -20 and -13) on outpatient basis. Then, inpatient fludarabine 10 mg/m 2, and cladribine 10 mg/m 2 were given followed by Bu on days -6 to -3. Venetoclax 400mg daily was given from day -22 to -3. Azoles were avoided during this period. GVHD prophylaxis was PTCy 50mg/kg on days 3 and 4 and tacrolimus from day 5. Results: The median age was 59 years (range, 23-69); High or very high disease risk index was present in 21%; Comorbidity index score of >3 was present in 45%; Donor was a sibling in 39%; and peripheral blood stem cells was the graft source in 100%. The median follow up was 8 months. At 1-year, overall survival was 84% (95% confidence interval, 71-100), progression-free survival 77% (64-94), relapse 13% (1-25), and non-relapse mortality 10% (0-20) [Table 1, Figure 1]. Incidence of acute GVHD grade 2-4 was 28% (12-43) and grade 3-4 acute GVHD was 3% (0-9) at day 100. All patients engrafted. The median time to neutrophil engraftment was 15 days (13 -19) and median time to platelet engraftment was 23 days (11-85). Full donor chimerism at day 30 was noted in 76%. Common grade 3 or 4 toxicity were neutropenic fever (58%), mucositis (18%) and pulmonary toxicity in 21%. Conclusion: Venetoclax can be safely added to the fractionated busulfan regimen. Early data on efficacy appear promising. Figure 1 Figure 1. Disclosures Popat: Bayer: Research Funding; Abbvie: Research Funding; Novartis: Research Funding; Incyte: Research Funding. Mehta: CSLBehring: Research Funding; Syndax: Research Funding; Incyte: Research Funding; Kadmon: Research Funding. Hosing: Nkarta Therapeutics: Membership on an entity's Board of Directors or advisory committees. Gulbis: EUSA Pharma: Other: Advisory board participation. Rezvani: AvengeBio: Other: Scientific Advisory Board ; Pharmacyclics: Other: Educational grant, Research Funding; GemoAb: Other: Scientific Advisory Board ; Navan Technologies: Other: Scientific Advisory Board; Bayer: Other: Scientific Advisory Board ; Caribou: Other: Scientific Advisory Board; Takeda: Other: License agreement and research agreement, Patents & Royalties; Virogin: Other: Scientific Advisory Board ; GSK: Other: Scientific Advisory Board ; Affimed: Other: License agreement and research agreement; education grant, Patents & Royalties, Research Funding. Qazilbash: Bristol-Myers Squibb: Other: Advisory Board; Oncopeptides: Other: Advisory Board; Amgen: Research Funding; Angiocrine: Research Funding; NexImmune: Research Funding; Biolline: Research Funding; Janssen: Research Funding. Kadia: Cure: Speakers Bureau; Novartis: Consultancy; Dalichi Sankyo: Consultancy; Cellonkos: Other; Ascentage: Other; Genfleet: Other; Sanofi-Aventis: Consultancy; Genentech: Consultancy, Other: Grant/research support; Astellas: Other; Liberum: Consultancy; BMS: Other: Grant/research support; Amgen: Other: Grant/research support; Aglos: Consultancy; Pfizer: Consultancy, Other; AstraZeneca: Other; AbbVie: Consultancy, Other: Grant/research support; Pulmotech: Other; Jazz: Consultancy. Konopleva: Calithera: Other: grant support, Research Funding; AbbVie: Consultancy, Honoraria, Other: Grant Support, Research Funding; Ascentage: Other: grant support, Research Funding; Cellectis: Other: grant support; Ablynx: Other: grant support, Research Funding; Agios: Other: grant support, Research Funding; Rafael Pharmaceuticals: Other: grant support, Research Funding; Eli Lilly: Patents & Royalties: intellectual property rights, Research Funding; AstraZeneca: Other: grant support, Research Funding; Stemline Therapeutics: Research Funding; F. Hoffmann-La Roche: Consultancy, Honoraria, Other: grant support; Forty Seven: Other: grant support, Research Funding; Sanofi: Other: grant support, Research Funding; Genentech: Consultancy, Honoraria, Other: grant support, Research Funding; Novartis: Other: research funding pending, Patents & Royalties: intellectual property rights; Reata Pharmaceuticals: Current holder of stock options in a privately-held company, Patents & Royalties: intellectual property rights; KisoJi: Research Funding. Shpall: Axio: Consultancy; Magenta: Consultancy; Novartis: Consultancy; Bayer HealthCare Pharmaceuticals: Honoraria; Adaptimmune: Consultancy; Navan: Consultancy; Takeda: Patents & Royalties; Novartis: Honoraria; Affimed: Patents & Royalties; Magenta: Honoraria.

Background: Myeloablative conditioning can be given safely to older patients by simply administering busulfan (Bu) over a longer period (fractionated (f)-Bu) with fludarabine (Flu) than the standard four-day regimen. (Popat et al Lancet Haematology 2018). We added thiotepa (Thio) to this f-Bu/Flu regimen in patients with haploidentical (haplo) donors to promote engraftment and to reduce relapse. With encouraging results, Thio was then added in matched unrelated (MUD) and sibling (MSD) donor recipients also. However, the optimal doses of Thio and Bu were undefined. To further optimize the regimen, we tested two different f-Bu/Flu/Thio regimens in parallel prospective cohorts: (a) higher dose Bu with lower dose Thio, and (b) lower dose Bu with a higher dose Thio. Patients were enrolled on these cohorts based on age and co-morbidity index (HCT-CI). Herein, we report on the safety and preliminary efficacy of these regimens (NCT02861417). Methods: Patients 60 years with HCT-CI 3, or >60 years with HCT-CI >2, or >70 years irrespective of HCT-CI received f-BU to target AUC of 16,000 with Thio 5mg/kg (Bu16K/Thio5; Cohort 2). In both cohorts, the first two doses of Bu (80 mg/m2 IV each) were given as outpatient on days -20 and -13. The last four Bu doses were given as inpatient following each dose of Flu 40 mg/m2 on days -6 through -3. Thio was given on day -7. GVHD prophylaxis was post-transplant cyclophosphamide (PTCy) 50mg/kg on days 3 and 4, tacrolimus and MMF. Results: 66 patients were enrolled - 25 in cohort 1 and 41 in cohort 2, with a median age 60 years (range, 22-69) vs 62 years (range, 30-74), respectively (P=0.14). Diagnoses were AML/MDS (64% vs 54%), CML/MPD (24% vs 22%), ALL (12% vs 22%) and 1 myeloma; P=0.24. Most had intermediate disease risk index (80% vs 73%, P=0.57); median HCT-CI was 1 (range, 0-6) vs 3 (range, 0-9); P Primary graft failure occurred in 1 patient in cohort 1 and none in cohort 2. The median time to neutrophil engraftment was 17.5 days (range, 14-26) vs 18 days (range, 12-26); P=0.12, respectively; platelet engraftment > 20K was 30 days in both groups; P=0.75. Median donor chimerism at day 30 was 100% in both groups. The incidence of acute GVHD grade III-IV was 4% vs 5%; P=0.88 at day 100; extensive chronic GVHD at 1 year was 13% vs 10%; P=0.83. At 1-year overall survival was 72% vs 78%; P=0.95; relapse was 12% each; non-relapse mortality was 20% vs 17%; P=0.97 [Table 1, Fig 1]. Common grade >3 toxicities were neutropenic fever (64% vs 42%; P=0.13), bacterial infection (44% vs 34%; P=0.45), nausea (12% vs 2%; P=0.15), mucositis (8% vs 5%; P=0.63), pneumonitis (12% vs 7%; P=0.67), hemorrhagic cystitis (8% vs 5%) and sinusoidal obstructive syndrome (8% vs 2.4%). Conclusion: In this population of older patients and/or high co-morbidities, both myeloablative regimens with f-Bu/Flu with thiotepa and PTCy were well tolerated and led to low NRM, low risk of relapse and encouraging survival. Although both regimens led to similar outcomes, the f-Bu/Flu/Thio regimen with Bu16K and thiotepa 5 mg/kg dose may be preferred as this was used in patients who were older and/or had high co-morbidities. Figure 1 Figure 1. Disclosures Popat: Bayer: Research Funding; Abbvie: Research Funding; Novartis: Research Funding; Incyte: Research Funding. Mehta: CSLBehring: Research Funding; Kadmon: Research Funding; Syndax: Research Funding; Incyte: Research Funding. Hosing: Nkarta Therapeutics: Membership on an entity's Board of Directors or advisory committees. Rezvani: Caribou: Other: Scientific Advisory Board; Virogin: Other: Scientific Advisory Board ; AvengeBio: Other: Scientific Advisory Board ; GSK: Other: Scientific Advisory Board ; Bayer: Other: Scientific Advisory Board ; Navan Technologies: Other: Scientific Advisory Board; GemoAb: Other: Scientific Advisory Board ; Takeda: Other: License agreement and research agreement, Patents & Royalties; Pharmacyclics: Other: Educational grant, Research Funding; Affimed: Other: License agreement and research agreement; education grant, Patents & Royalties, Research Funding. Qazilbash: Oncopeptides: Other: Advisory Board; Janssen: Research Funding; Bristol-Myers Squibb: Other: Advisory Board; NexImmune: Research Funding; Amgen: Research Funding; Angiocrine: Research Funding; Biolline: Research Funding. Shpall: Affimed: Patents & Royalties; Adaptimmune: Consultancy; Novartis: Consultancy; Magenta: Consultancy; Magenta: Honoraria; Axio: Consultancy; Takeda: Patents & Royalties; Navan: Consultancy; Novartis: Honoraria; Bayer HealthCare Pharmaceuticals: Honoraria.

The inferior cure rate of T-cell acute lymphoblastic leukemia (T-ALL) is associated with inherent drug resistance. The activating NOTCH1 gene mutations have been reported to cause chemoresistance at the stem cell level1. Direct NOTCH1 inhibition has failed in clinical trials due to a narrow therapeutic window but targeting key oncogenic and metabolic pathways downstream of mutated NOTCH1 may offer novel approaches. We previously reported that rapid transformation of thymocytes at the DN3 differentiation stage into preleukemic stem cells (pre-LSC) requires elevated Notch1 in addition to the presence of Scl/Lmo11. Notably, we showed that cellular metabolism of NOTCH1-mutated T-ALLs depends on Oxidative Phosphorylation (OxPhos) and that OxPhos inhibition using the complex I inhibitor IACS-010759 (OxPhos-i) is efficacious in NOTCH1-mutated T-ALL patient derived xenografts (PDXs)2. Here, we investigated the link between NOTCH1-mutated chemoresistance and OxPhos in pre-leukemic and leukemic cells, utilizing comprehensive molecular and functional assays. We hypothesized that chemotherapy aided by OxPhos-i overcomes chemoresistance, depletes LSCs and combats T-ALL. First, we analyzed the role of OxPhos in downstream Notch1 targets at the pre- and leukemic stage considering four stages of thymocyte differentiation (D1-D4), in a mouse model of human T-ALL1. Gene set enrichment analysis (GSEA) implicated increased expression of Notch1 target genes starting at DN1, and OxPhos target genes were the highest-ranked gene set at DN3. Next, activation of Notch1 by its ligand DL4 and inhibition of OxPhos reduced viability of pre-LSCs, indicating that ligand-dependent activation of Notch1 signaling upregulates the OxPhos pathway and sensitizes pre-LSCs to OxPhos-i. To clarify the role of Notch1 signaling, we examined the effect of IACS-010759 on pre-leukemic thymocytes harboring LMO1, SCL-LMO1, NOTCH1, LMO1-NOTCH1 and SCL-LMO1-NOTCH1 with and without DL4 stimulation. We found that in the absence of DL4, only thymocytes harboring the Notch1 oncogene responded to OxPhos-i, whereas all DL4-stimulated thymocytes responded regardless of Notch1 status (Fig. 1a). In addition, at the leukemic stage, we found elevation of the OxPhos pathway driven by oncogenic Notch1 when we compared transcriptomes of SCL-LMO1 induced T-ALL in the presence or absence of the NOTCH1 oncogene. In line with the murine T-ALL NOTCH1 model, we performed transcriptome analysis of two independent T-ALL patient cohorts prior to chemotherapy, COG TARGET ALL (n=263) and AALL1231 (n=75), comparing transcriptomes of NOTCH1-mutated vs NOTCH1-wt T-ALLs. We found co-segregation of NOTCH1 mutations with significant upregulation of OxPhos and TCA cycle genes and downregulation of apoptosis signaling. Aiming to reverse the NOTCH1-controlled anti-apoptotic program and chemoresistance, we next tested the combination of Vincristine, Dexamethasone and L-Asparaginase (VXL) with IACS-010759. When compared to vehicle, OxPhos-i or VXL alone, only the VXL-OxPhos-i treatment caused an energetic crisis indicated by decreased OCR and ECAR (Seahorse), which translated to a profound reduction of viability (CTG, flow cytometry) in T-ALL cell lines (n=9) and primary T-ALL samples (n=5). Additionally, the IACS-VXL combination in vivo resulted in pan-metabolic blockade, which caused metabolic shut-down and triggered early induction of apoptosis in leukemic cells in peripheral blood, spleen and bone marrow (Fig. 1b). Single cell Proteomic analysis (CyTOF) of spleen showed reduced expression of cell proliferation marker -ki67, c-myc, ERK and p38 proteins, and reduction in number of leukemic cells. Finally, this combination therapy resulted in reduced leukemia burden and extension of overall survival across all three aggressive NOTCH1-mutated T-ALL PDX models (p Disclosures Jabbour: Pfizer: Other: Advisory role, Research Funding; Genentech: Other: Advisory role, Research Funding; BMS: Other: Advisory role, Research Funding; Takeda: Other: Advisory role, Research Funding; Amgen: Other: Advisory role, Research Funding; Adaptive Biotechnologies: Other: Advisory role, Research Funding; AbbVie: Other: Advisory role, Research Funding. Teachey:Sobi: Consultancy; Amgen: Consultancy; Janssen: Consultancy; La Roche: Consultancy. Rezvani:Takeda: Other: Licensing agreement; GemoAb: Membership on an entity's Board of Directors or advisory committees; Adicet Bio: Membership on an entity's Board of Directors or advisory committees; Virogen: Membership on an entity's Board of Directors or advisory committees; Pharmacyclics: Other: Educational grant; Affimed: Other: Educational grant; Formula Pharma: Membership on an entity's Board of Directors or advisory committees. Andreeff:Daiichi-Sankyo; Jazz Pharmaceuticals; Celgene; Amgen; AstraZeneca; 6 Dimensions Capital: Consultancy; Daiichi-Sankyo; Breast Cancer Research Foundation; CPRIT; NIH/NCI; Amgen; AstraZeneca: Research Funding; Centre for Drug Research & Development; Cancer UK; NCI-CTEP; German Research Council; Leukemia Lymphoma Foundation (LLS); NCI-RDCRN (Rare Disease Clin Network); CLL Founcdation; BioLineRx; SentiBio; Aptose Biosciences, Inc: Membership on an entity's Board of Directors or advisory committees; Amgen: Research Funding. Lorenzi:Precision Pathways: Consultancy. Konopleva:Calithera: Research Funding; Kisoji: Consultancy; AbbVie: Consultancy, Research Funding; Sanofi: Research Funding; Genentech: Consultancy, Research Funding; F. Hoffmann La-Roche: Consultancy, Research Funding; Cellectis: Research Funding; Rafael Pharmaceutical: Research Funding; Eli Lilly: Research Funding; Reata Pharmaceutical Inc.;: Patents & Royalties: patents and royalties with patent US 7,795,305 B2 on CDDO-compounds and combination therapies, licensed to Reata Pharmaceutical; Agios: Research Funding; AstraZeneca: Research Funding; Ablynx: Research Funding; Forty-Seven: Consultancy, Research Funding; Amgen: Consultancy; Stemline Therapeutics: Consultancy, Research Funding; Ascentage: Research Funding.

Dasatinib is a multi-kinase inhibitor with inhibitory activity against Src kinases in addition to the BCR-ABL1 oncoprotein. The Src kinase Lck plays a pivotal role in signalling from the T cell receptor (TCR) and Src kinases also play a central role in signalling from NK cell activating receptors, with key downstream signalling molecules including ZAP70 and LAT. The STAT5 pathway is essential for NK cell function via IL-15, and T cell function through IL-2 signalling. Immune effector cells are thought to play a role in chronic myeloid leukaemia (CML) disease response, with correlation between the frequency of effector cells, including NK cells and CD8+ T cells, and improved outcome (Hughes A., Blood, 2017; Mustjoki, Blood, 2009). Standard licensed dose of dasatinib is 100mg OD but a reduced dose of 50mg OD can also be used (Naqvi, Cancer, 2019). Methods: 18 patients with chronic phase CML on TKI therapy (Dasatinib N=14, Imatinib N=2, Nilotinib N=2) and 7 healthy controls were included. Of the patients on dasatinib, 10 were taking a dose of 100mg OD and 4 were taking 50mg OD. A two-phase ex vivo functional analysis of immune cell subsets, including CD4+ and CD8+ T cells, NK cells and T regulatory cells (Tregs) was performed. We analysed expression of the cytokines, TNFa, IFNg and IL-2, after treatment of cells with OKT3. We also analysed signalling within cells after treatment with the phosphatase inhibitor H2O2. The relative fluorescence intensity (RFI) was calculated as MFI H2O2 sample/MFI unstimulated sample. Results: Patients on dasatinib had lower frequency of total Tregs and effector Tregs than controls and patients with CML taking other TKIs. However, there was no difference in the frequency of total Tregs between patients on 50mg and 100mg doses of dasatinib. Dasatinib significantly inhibited signalling from the TCR and of the STAT5 pathway when compared with patients on other TKIs and healthy controls, in CD4+ and CD8+ T cells, Tregs and NK cells. Patients on 50mg dasatinib had significantly higher RFI than patients on 100mg in CD4+ cells for pZAP70, and in CD4+ and CD8+ cells for pLAT. Similarly, patients on 50mg dasatinib had a higher RFI for pSTAT5 than those on 100mg in CD4+ and CD8+ T cells and also NK cells. Of note, the difference in the RFI of pSTAT5 between Tregs, and that of both CD8+ T cells and NK cells, was significantly higher in patients on 50mg dasatinib compared with 100mg, suggesting a relative sparing of effector immune cell inhibition at the lower dose. Expression of TNFa, IFNg and IL-2 were significantly reduced in patients taking dasatinib compared with healthy controls and patients on other TKIs. Patients on a 50mg dose of dasatinib had significantly higher proportional increase in IL-2 expression after OKT3 activation in CD4+ and CD8+ cells compared with patients on 100mg. Five patients on dasatinib 100mg OD with increased CD8+ T cells were confirmed to have clonal CD8+ lymphocytosis by performing TCR gene rearrangement analysis. These patients had a lower proportion of Tregs, compared to patients on dasatinib without CD8+ lymphocytosis. Importantly, a significantly lower RFI for pZAP70 and pLAT, within isolated Tregs, was also seen in this group, when compared with patients on dasatinib without CD8+ lymphocytosis. Discussion: Dasatinib inhibits key signalling pathways in T cells and NK cells and suppresses pro-inflammatory cytokine expression in T cells, compared to healthy controls and patients with CML taking other TKIs. However, patients taking a 50mg dose appear to have significantly less inhibition of effector cell function. In contrast, dasatinib may enhance immune surveillance mechanisms due to inhibition of Treg suppressive function, by reducing T effector IL-2 production, as well as STAT5 signalling within Tregs, required for FOXP3 transcription. Patients on dasatinib with clonal CD8+ lymphocytosis, as well as a lower frequency of Tregs, have an additional functional deficit within Tregs, with reduced signalling from the TCR. The presence of clonal CD8+ lymphocytosis is linked to improved outcomes, and typically occurs at the approved 100mg dosage. The dose of dasatinib strongly affects the activity of different immune cell subsets with the lower dosage allowing improved effector cell function. However greater inhibition of Tregs is seen in patients with clonal lymphocytosis, typically at the higher dosage, demonstrating the complexity of the immunomodulatory effect of dasatinib. Disclosures Harrington: Bristol Myers Squibb: Research Funding; Incyte: Honoraria, Speakers Bureau. Dillon:Jazz Pharmaceuticals: Honoraria; Amgen: Honoraria, Research Funding; Astellas: Honoraria; Pfizer: Honoraria, Research Funding; Menarini: Honoraria; Novartis: Honoraria; Abbvie: Honoraria, Research Funding. Radia:Novartis: Membership on an entity's Board of Directors or advisory committees, Other: Education events; Blueprint Medicines Corporation: Membership on an entity's Board of Directors or advisory committees. McLornan:CELGENE: Honoraria, Speakers Bureau; NOVARTIS: Honoraria, Speakers Bureau; JAZZ PHARMA: Honoraria, Speakers Bureau. Rousselot:Pfizer: Consultancy, Research Funding; Incyte: Consultancy, Research Funding; Takeda: Consultancy; Novartis: Consultancy; Bristol-Myers Squibb: Consultancy. Rezvani:GemoAb: Membership on an entity's Board of Directors or advisory committees; Takeda: Other: Licensing agreement; Adicet Bio: Membership on an entity's Board of Directors or advisory committees; Formula Pharma: Membership on an entity's Board of Directors or advisory committees; Pharmacyclics: Other: Educational grant; Affimed: Other: Educational grant; Virogen: Membership on an entity's Board of Directors or advisory committees. Kordasti:Novartis: Research Funding; Celgene: Research Funding; Alexion: Honoraria. Harrison:Novartis: Honoraria, Research Funding, Speakers Bureau; Incyte Corporation: Speakers Bureau; Gilead Sciences: Honoraria, Speakers Bureau; Shire: Honoraria, Speakers Bureau; AOP Orphan Pharmaceuticals: Honoraria; Promedior: Honoraria; Roche: Honoraria; Celgene: Honoraria, Research Funding, Speakers Bureau; CTI Biopharma Corp: Honoraria, Speakers Bureau; Sierra Oncology: Honoraria; Janssen: Speakers Bureau. de Lavallade:Pfizer: Honoraria; Novartis: Honoraria; Bristol Myers Squibb: Honoraria, Research Funding; Incyte: Honoraria, Research Funding.

The generation of autologous T cells expressing a chimeric antigen receptor (CAR) have revolutionized the field of adoptive cellular therapy. CAR-T cells directed against CD19 have resulted in remarkable clinical responses in patients affected by B-lymphoid malignancies. However, the production of allogeneic CAR-T cells products remains expensive and clinically challenging. Moreover, the toxicity profile of CAR T-cells means that currently these life-saving treatments are only delivered in specialized centers. Therefore, efforts are underway to develop reliable off-the-shelf cellular products with acceptable safety profiles for the treatment of patients with cancer. Natural killer (NK) cells are innate effector lymphocytes with potent antitumor activity. The availability of NK cells from multiple sources and their proven safety profile in the allogeneic setting positions them as attractive contenders for cancer immunotherapy. In this review, we discuss advantages and potential drawbacks of using NK cells as a novel cellular therapy against hematologic malignancies, as well as strategies to further enhance their effector function.

Mesenchymal stem/stromal cells (MSCs) are commonly used as a source of cellular therapy due to their strong immunosuppressive and regenerative effects. One of the key mechanisms of MSC efficacy appears to derive from their paracrine activity. Recently, it has been shown that the secretion of different factors through extracellular vesicles known as exosomes, orchestrate the principle mechanisms of action of MSCs after infusion. The use of MSC-derived exosomes may provide considerable advantages over their counterpart live cells, potentially reducing undesirable side effects including infusional toxicities. In this review, we examine clinical trials of MSC-derived exosomes currently in progress for gene delivery, regenerative medicine, and immunomodulation. In addition, we summarize the limitations and clinical potential of this cell-free therapeutic strategy.

Acute graft-vs.-host (GVHD) disease remains a common complication of allogeneic stem cell transplantation with very poor outcomes once the disease becomes steroid refractory. Mesenchymal stem cells (MSCs) represent a promising therapeutic approach for the treatment of GVHD, but so far this strategy has had equivocal clinical efficacy. Therapies using MSCs require optimization taking advantage of the plasticity of these cells in response to different microenvironments. In this study, we aimed to optimize cord blood tissue derived MSCs (CBti MSCs) by priming them using a regimen of inflammatory cytokines. This approach led to their metabolic reprogramming with enhancement of their glycolytic capacity. Metabolically reprogrammed CBti MSCs displayed a boosted immunosuppressive potential, with superior immunomodulatory and homing properties, even after cryopreservation and thawing. Mechanistically, primed CBti MSCs significantly interfered with glycolytic switching and mTOR signaling in T cells, suppressing T cell proliferation and ensuing polarizing toward T regulatory cells. Based on these data, we generated a Good Manufacturing Process (GMP) Laboratory protocol for the production and cryopreservation of primed CBti MSCs for clinical use. Following thawing, these cryopreserved GMP-compliant primed CBti MSCs significantly improved outcomes in a xenogenic mouse model of GVHD. Our data support the concept that metabolic profiling of MSCs can be used as a surrogate for their suppressive potential in conjunction with conventional functional methods to support their therapeutic use in GVHD or other autoimmune disorders.

PURPOSE BK virus-associated hemorrhagic cystitis (BKV-HC) is a common complication of allogenic hematopoietic stem cell transplantation (AHSCT), particularly in recipients of alternative donor transplants, which are being performed in increasing numbers. BKV-HC typically results in painful hematuria, urinary obstruction, and renal dysfunction, without a definitive therapeutic option. METHODS We performed a clinical trial (ClinicalTrials.gov identifier: NCT02479698 ) to assess the feasibility, safety, and efficacy of administering most closely HLA-matched third-party BKV-specific cytotoxic T lymphocytes (CTLs), generated from 26 healthy donors and banked for off-the-shelf use. The cells were infused into 59 patients who developed BKV-HC following AHSCT. Comprehensive clinical assessments and correlative studies were performed. RESULTS Response to BKV-CTL infusion was rapid; the day 14 overall response rate was 67.7% (40 of 59 evaluable patients), which increased to 81.6% among evaluable patients at day 45 (40 of 49 evaluable patients). No patient lost a previously achieved response. There were no cases of de novo grade 3 or 4 graft-versus-host disease, graft failure, or infusion-related toxicities. BKV-CTLs were identified in patient blood samples up to 3 months postinfusion and their in vivo expansion predicted for clinical response. A matched-pair analysis revealed that, compared with standard of care, after accounting for prognostic covariate effects, treatment with BKV-CTLs resulted in higher probabilities of response at all follow-up timepoints as well as significantly lower transfusion requirement. CONCLUSION Off-the-shelf BKV-CTLs are a safe and effective therapy for the management of patients with BKV-HC after AHSCT.

BackgroundCOVID-19 Convalescent plasma (CCP) is safe and effective, particularly if given at an early stage of the disease. Our study aimed to identify an association between survival and specific antibodies found in CCP.Patients and MethodsPatients ≥18 years of age who were hospitalized with moderate to severe COVID-19 infection and received CCP at the MD Anderson Cancer Center between 4/30/2020 and 8/20/2020 were included in the study. We quantified the levels of anti-SARS-CoV-2 antibodies, as well as antibodies against antigens of other coronavirus strains, in the CCP units and compared antibody levels with patient outcomes. For each antibody, a Bayesian exponential survival time regression model including prognostic variables was fit, and the posterior probability of a beneficial effect (PBE) of higher antibody level on survival time was computed.ResultsCCP was administered to 44 cancer patients. The median age was 60 years (range 37-84) and 19 (43%) were female. Twelve patients (27%) died of COVID-19-related complications. Higher levels of two non-SARS-CoV-2-specific antibodies, anti-HCoV-OC43 spike IgG and anti-HCoV-HKU1 spike IgG, had PBE = 1.00, and 4 SARS-CoV-2-specific antibodies had PBEs between 0.90 and 0.95. Other factors associated with better survival were shorter time to CCP administration, younger age, and female sex.ConclusionsCommon cold coronavirus spike IgG antibodies anti-HCoV-OC43 and anti-HCoV-HKU1 may target a common domain for SARS-CoV-2 and other coronaviruses. They provide a promising therapeutic target for monoclonal antibody production.

Introduction More than one-third of stem cell transplant recipients will develop life threatening viral infections. BK reactivation manifests as hemorrhagic cystitis or nephritis following stem cell and solid organ transplant. In some studies BK has been associated with decreased survival.1 Due to drug interactions and organ toxicity, current antiviral therapies can be challenging. In some instances, there is no standard established antiviral treatment. Virus specific donor lymphocyte infusion is therefore an attractive option as an alternative treatment.

Context Fractionated busulfan/fludarabine (Bu-Flu) myeloablative conditioning yields low non-relapse mortality (NRM) in older patients and those with comorbidities after matched sibling (MSD) or unrelated (MUD) donor transplant (HCT). [Popat et al, Lancet Haematology 2018]. This has not been tested in haploidentical patients, and safety of post-transplant cyclophosphamide (PTCy) GVHD prophylaxis with this approach is unknown; both aims were assessed in the current trial. Objective Primary objective/endpoints were safety/NRM. Design Open label, non-randomized, phase II. Participants Eligibility criteria included any hematologic malignancy, age Interventions Patients received busulfan 80 mg/m2 i.v. either on days -13 and -12 (n=45) or with further fractionation (days -20 and -13; n=10) and fludarabine 40 mg/m2 i.v. plus busulfan (days -6 to -2) dosed to achieve target AUC 20,000 pmol/min per pharmacokinetic studies. Haploidentical patients received thiotepa 5 mg/kg i.v on day -7. GVHD prophylaxis included PTCy 50 mg/kg i.v. and tacrolimus. Haploidentical and later MUD recipients also received mycophenolate mofetil. Results Fifty-five patients were enrolled between 08/2016 and06/2018; median follow-up was 37.6 months (range, 25.3–47.8). Diagnoses were AML/MDS (n=30), CML/MPN (n=9), ALL (n=6), and lymphoma/myeloma (n=10). Donors were haploidentical (n=26, 47%), MUD (n=18, 33%), or MSD (n=11, 20%) with PB (n=33, 60%) or BM graft. DRI was intermediate/high (n=50, 91%); 40% (n=22) had HCT-CI >3. There was no graft failure. Median time to neutrophil and platelet engraftment was 17 days (range, 13–39) and 25 days (range, 11–167). Day 100 NRM was 16.4% (95% CI 6.5–26.2%) and 24.6% (12.6–36.6%) at 3-years. Day 100 grade II–IV and III–IV acute GVHD was 38.2% (95% CI 25.2–51.2%) and 9.1% (95% CI 1.4–16.8%), 3-year chronic GVHD (all extensive) was 15.2% (95% CI 5.3–25.1%). Relapse was 25.5% (95% CI 13.8–37.1%), PFS 50% (95% CI 38.1–65.6%), OS 60.7% (95% CI 48.7–75.6%). Conclusions Myeloablative fractionated Bu-Flu with PTCy is safe and effective in MSD, MUD, and haploidentical HCT. It appears to reduce the severe acute/chronic GVHD without an apparent increase in relapse.

T cells engineered to express chimeric antigen receptors (CARs) have revolutionised the field of cellular therapy for cancer. Despite its success, this strategy has some recognised limitations and toxicities. Hence, there is growing interest in developing novel cellular therapies based on non‐αβ T‐cell immune effector cells, including NK cells that offer clear advantages in cancer immunotherapy. As a result, NK cells are being explored as an alternative platform for CAR engineering and are becoming recognised as important players in the next generation of cellular therapies targeting cancer. In this review, we highlight preclinical and clinical studies of CAR‐NK cells derived from different sources and discuss strategies under investigation to enhance the antitumor activity of these engineered innate immune cells., NK cells can be derived from various sources (PB, UCB, HSC, iPSC, NK cell lines) and can be engineered to express a chimeric antigen receptor (CAR) to target various surface antigens on cancer cells. These CAR‐NK cells can be used as off‐the‐shelf adoptive cellular therapy to treat patients with various malignancies.

Background aims Umbilical cord blood is an established source of stem cells in patients with hematologic malignancies who do not have HLA-compatible matched related or unrelated donors. The success of an umbilical cord blood transplant depends on the dose of total nucleated and CD34+ cells infused. Therefore, collecting, banking and listing high-quality cord blood units with high total nucleated and CD34+ cell dose are essential. Methods Here the authors describe their cord blood bank's novel collection technique, which involves both in utero and ex utero collection of a single cord blood unit. The authors also evaluated maternal, neonatal and collection parameters that may impact the cell dose. Results Maternal gestational age and race, and neonatal weight and sex correlated with the total nucleated cell dose. Conclusions The optimized collection of umbilical cord blood is critical for its use as a source of stem cells for transplantation.

Pediatric, adolescent and young adult (AYA) patients receiving novel cancer immunotherapies may develop associated toxicities with overlapping signs and symptoms that are not always easily distinguished from severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection/clinical sequelae. We describe 2 diagnostically challenging cases of SARS-CoV-2 and Multi-Inflammatory Syndrome-Adult (MIS-A), in patients with a history of acute lymphoblastic leukemia following cellular therapy administration and review evolving characterization of both the natural course of SARS-CoV-2 infection and toxicities experienced in younger cancer immunotherapy patients. Vigilant monitoring for unique presentations and epidemiologic surveillance to promptly detect changes in incidence of either condition may be warranted.

Steroid-refractory (SR) lower gastrointestinal (LGI) acute graft-versus-host disease (aGVHD) has poor prognosis, and novel drugs are needed. We describe outcomes of patients with SR-LGI aGVHD treated with vedolizumab. The primary objective was to determine overall response rate (ORR) at days 14, 28, and 56. Secondary outcomes included overall survival (OS), non-relapse mortality and toxicities. Twenty patients, median age 46 years (range, 23-71), were included. All but 2 patients (90%) had grade 3 to 4 aGVHD (45% stage 4, 40% stage 3 LGI). Median time to vedolizumab was 21 days (range, 5-1031) and 13 days (range, 0-533) after diagnosis of LGI aGVHD and SR-LGI aGVHD, respectively. It was given as ≥3rd line (median 3; range 2-6) in 75% after failure of steroids, and additional treatments including ruxolitinib (n = 12) and others. Median follow-up was 17 months (range, 10-34). The days 14, 28 and 56 ORRs were 45% (9/20; complete response [CR] 25%), 35% (7/20; CR 20%), and 25% (5/20; CR 20%), respectively. Among ruxolitinib failures, it was 50% (6/12; CR 25%), 50% (6/12; CR 25%) and 25% (3/12; CR 16.7%), respectively. Fifteen patients died (14 GVHD, 1 leukemia relapse). The actuarial 6-month OS was 35% (95% confidence interval 16-55). No progressive multifocal leukoencephalopathy or infusion reaction occurred. Forty-four infection events (22 viral, 18 bacterial, and 4 fungal) were noted in 16 patients. Vedolizumab was well tolerated and demonstrated potential efficacy even after ruxolitinib failure for SR-LGI aGVHD. Yet the responses were suboptimal, and its use requires further investigation.

Tamara Laskowski and Katayoun Rezvani discuss the recent advances of adoptive cell therapy in cancer., Immunotherapy has made a profound impact in the treatment of cancer in the last decade. Insights from the study of the intricate relationships between immune cells and cancer have led to the clinical development of strategies that redirect the power of the immune system to target and eliminate cancer. Today, immunotherapy represents a rapidly expanding and transformative force comprising multiple modalities.

BACKGROUND BK polymavirus (BKPyV), a member of the family Polyomaviridae, is associated with increased morbidity and mortality in allogeneic stem cell transplant recipients. METHODS In our previous retrospective study of 2477 stem cell transplant patients, BKPyV replication independently predicted chronic kidney disease and poor survival. In this study, using the same cohort, we derived and validated a risk grading system to identify patients at risk of BKPyV replication after transplantation in a user-friendly modality. We used 3 baseline variables (conditioning regimen, HLA match status, and underlying cancer diagnosis) that significantly predicted BKPyV replication in our initial study in a subdistribution hazard model with death as a competing risk. We also developed a nomogram of the hazard model as a visual aid. The AUC of the ROC of the risk-score-only model was 0.65. We further stratified the patients on the basis of risk score into low-, moderate-, and high-risk groups. RESULTS The total risk score was significantly associated with BKPyV replication (P

BACKGROUND: Anti-CD19 chimeric antigen receptor (CAR) T-cell therapy has shown remarkable clinical efficacy in B-cell cancers. However, CAR T cells can induce substantial toxic effects, and the manufacture of the cells is complex. Natural killer (NK) cells that have been modified to express an anti-CD19 CAR have the potential to overcome these limitations. METHODS: In this phase 1 and 2 trial, we administered HLA-mismatched anti-CD19 CAR-NK cells derived from cord blood to 11 patients with relapsed or refractory CD19-positive cancers (non-Hodgkin’s lymphoma or chronic lymphocytic leukemia [CLL]). NK cells were transduced with a retroviral vector expressing genes that encode anti-CD19 CAR, interleukin-15, and inducible caspase 9 as a safety switch. The cells were expanded ex vivo and administered in a single infusion at one of three doses (1×10(5), 1×10(6), or 1×10(7) CAR-NK cells per kilogram of body weight) after lymphodepleting chemotherapy. RESULTS: The administration of CAR-NK cells was not associated with the development of cytokine release syndrome, neurotoxicity, or graft-versus-host disease, and there was no increase in the levels of inflammatory cytokines, including interleukin-6, over baseline. The maximum tolerated dose was not reached. Of the 11 patients who were treated, 8 (73%) had a response; of these patients, 7 (4 with lymphoma and 3 with CLL) had a complete remission, and 1 had remission of the Richter’s transformation component but had persistent CLL. Responses were rapid and seen within 30 days after infusion at all dose levels. The infused CAR-NK cells expanded and persisted at low levels for at least 12 months. CONCLUSIONS: Among 11 patients with relapsed or refractory CD19-positive cancers, a majority had a response to treatment with CAR-NK cells without the development of major toxic effects. (Funded by the M.D. Anderson Cancer Center CLL and Lymphoma Moonshot and the National Institutes of Health; ClinicalTrials.gov number, NCT03056339.)

Purpose: Cytomegalovirus (CMV) antigens occur in glioblastoma but not in normal brains, making them desirable immunologic targets. Patients and Methods: Highly functional autologous polyclonal CMV pp65-specific T cells from patients with glioblastoma were numerically expanded under good manufacturing practice compliant conditions and administered after 3 weeks of lymphodepleting dose-dense temozolomide (100 mg/m2) treatment. The phase I component used a 3+3 design, ascending through four dose levels (5 × 106–1 × 108 cells). Treatment occurred every 6 weeks for four cycles. In vivo persistence and effector function of CMV-specific T cells was determined by dextramer staining and multiparameter flow cytometry in serially sampled peripheral blood and in the tumor microenvironment. Results: We screened 65 patients; 41 were seropositive for CMV; 25 underwent leukapheresis; and 20 completed ≥1 cycle. No dose-limiting toxicities were observed. Radiographic response was complete in 1 patient, partial in 2. Median progression-free survival (PFS) time was 1.3 months [95% confidence interval (CI), 0–8.3 months]; 6-month PFS was 19% (95% CI, 7%–52%); and median overall survival time was 12 months (95% CI, 6 months to not reached). Repeated infusions of CMV-T cells paralleled significant increases in circulating CMV+ CD8+ T cells, but cytokine production showing effector activity was suppressed, especially from T cells obtained directly from glioblastomas. Conclusions: Adoptive infusion of CMV-specific T cells after lymphodepletion with dose-dense temozolomide was well tolerated. But apparently CMV seropositivity does not guarantee tumor susceptibility to CMV-specific T cells, suggesting heterogeneity in CMV antigen expression. Moreover, effector function of these T cells was attenuated, indicating a requirement for further T-cell modulation to prevent their dysfunction before conducting large-scale clinical studies.

Summary Background Haemopoietic stem-cell transplantation (HCT) conditioning regimens that can reduce risk of relapse without increasing non-relapse mortality are needed. We aimed to test the safety of timed-sequential delivery of low-dose versus high-dose myeloablative busulfan in older patients and patients with comorbidities. Methods This non-stratified, open-label, randomised phase 2 trial was done at The University of Texas MD Anderson Cancer Center (Houston, TX, USA). Patients with haematological cancers aged between 5 and 75 years were eligible to participate in the study. Patients who had HIV or uncontrollable infections were excluded. Eligible patients were randomly assigned (1:1 by a computer-generated programme in block sizes of four) to receive a total intravenous busulfan dose to achieve an area under the curve of 16 000 μmol/min (16K group) or 20 000 μmol/min (20K group) on the basis of pharmacokinetic analysis, plus intravenous fludarabine 40 mg/m2 for 4 days. The investigators and the research nurses were masked to the block size to conceal allocation. The primary outcome was day 100 non-relapse mortality. All analyses were by modified intention to treat, including only patients who received at least one dose of the study drug. No interim analyses were planned and accrual is complete. This study is registered with ClinicalTrials.gov, number NCT01572662. Findings Between April 18, 2012, and Dec 9, 2015, 98 patients were enrolled. 49 patients were randomly assigned to the 16K group and 49 to the 20K group, one of which was removed from the study before starting the intervention. Median age was 60 years (IQR 54–67). 50 (52%) patients had an HCT-specific comorbidity index score of 3 or more, and 41 (42%) had a high or very high Disease Risk Index score. Day 100 non-relapse mortality was 4% (95% CI 0–10) in the 16K group and 6% (0–13) in the 20K group (p=0·65). Infection was the most common grade 3–5 toxicity in both the 20K group (25 [52%] of 48 patients) and the 16K group (24 [49%] of 49 participants). Mucositis (nine [19%] of 48 patients vs three [6%] of 49 patients), idiopathic pneumonia syndrome (nine [19%] of 48 patients vs two [4%] of 49 patients), and culture-negative neutropenic fever (16 [33%] of 48 patients vs eight [16%] of 49 patients) were more common in the 20K group than in the 16K group. Interpretation Myeloablative doses of busulfan administered in a timed-sequential manner with fludarabine is associated with low non-relapse mortality in older patients and patients with comorbidities. Additional studies are required to show whether this approach can reduce the risk of relapse. Funding Cancer Center Support Grant (US National Cancer Institute, National Institutes of Health).

In 2017, an autologous chimeric antigen receptor (CAR) T cell therapy indicated for children and young adults with relapsed and/or refractory CD19+ acute lymphoblastic leukaemia became the first gene therapy to be approved in the USA. This innovative form of cellular immunotherapy has been associated with remarkable response rates but is also associated with unique and often severe toxicities, which can lead to rapid cardiorespiratory and/or neurological deterioration. Multidisciplinary medical vigilance and the requisite health-care infrastructure are imperative to ensuring optimal patient outcomes, especially as these therapies transition from research protocols to standard care. Herein, authors representing the Pediatric Acute Lung Injury and Sepsis Investigators (PALISI) Network Hematopoietic Stem Cell Transplantation (HSCT) Subgroup and the MD Anderson Cancer Center CAR T Cell Therapy-Associated Toxicity (CARTOX) Program have collaborated to provide comprehensive consensus guidelines on the care of children receiving CAR T cell therapy., Chimeric antigen receptor (CAR) T cell therapies have impressive activity in the treatment of cancer but are associated with potentially fatal toxicities. In light of the approval of CAR T cell therapy for paediatric patients, a panel of experts from the Hematopoietic Stem Cell Transplantation (HSCT) Subgroup of the Pediatric Acute Lung Injury and Sepsis Investigators (PALISI) Network, the CAR T Cell Therapy-Associated Toxicity (CARTOX) Program at The University of Texas MD Anderson Cancer Center, and several other institutions have developed consensus guidelines for the use and management of these treatments in paediatric patients, which are presented herein.

Natural killer (NK) cells are part of the innate immune system and represent the first line of defense against infections and tumors. In contrast to T cells, NK cells do not require prior antigen sensitization to induce cytotoxicity and do not cause graft-versus-host disease. These, along with other advantages, make NK cells an attractive candidate for adoptive cellular therapy. Herein, we describe the mechanisms of NK cell cytotoxicity, which is governed by an intricate balance between various activating and inhibitory receptors, including the killer cell immunoglobulin-like receptors (KIRs). We illustrate the advantages of NK alloreactivity as demonstrated in various types of hematopoietic stem cell transplants (HSCT), such as haploidentical, human leukocyte antigen-matched related or unrelated donor and umbilical cord blood transplant. We elaborate on different models used to predict NK cell alloreactivity in these studies, which are either based on the absence of the ligands for inhibitory KIRs, presence of activating NK cell receptors and KIR genes content in donors, or a combination of these. We will review clinical studies demonstrating anti-tumor efficacy of NK cells used either as a stand-alone immunotherapy or as an adjunct to HSCT and novel genetic engineering strategies to improve the anti-tumor activity of NK cells.

In the coronavirus disease 19 (COVID-19) pandemic era, the number of haploidentical hematopoietic cell transplantations (HCTs) with peripheral blood (PB) grafts increased significantly compared with HCTs with bone marrow (BM) grafts, which may be associated with adverse outcomes. We compared outcomes of HCT in BM graft and PB graft recipients age ≥18 years with hematologic malignancies who underwent T cell- replete haploidentical HCT and received graft-versus-host disease (GVHD) prophylaxis with post-transplantation cyclophosphamide, tacrolimus, and mycophenolate mofetil. Among the 264 patients, 180 (68%) received a BM graft and 84 (32%) received a PB graft. The median patient age was 50 years in both groups. The majority (n = 199; 75%) received reduced-intensity conditioning. The rate of acute leukemia or myelodysplastic syndrome was higher in the BM graft recipients compared with the PB graft recipients (85% [n = 152] versus 55% [n = 46]; P < .01). The median times to neutrophil and platelet engraftment and the incidence of grade II-IV and grade III-IV acute GVHD (aGVHD) were comparable in the 2 groups. Among the patients with grade II-IV aGVHD, the rate of steroid-refractory aGVHD was 9% (95% confidence interval [CI], 5% to 18%) in the BM group versus 32% (95% CI, 19% to 54%) in the PB group (hazard ratio [HR], 3.7, 95% CI, 1.5 to 9.3; P = .006). At 1 year post-HCT, the rate of chronic GVHD (cGVHD) was 8% (95% CI, 4% to 13%) in the BM group versus 22% (95% CI, 14% to 36%) in the PB group (HR, 3.0; 95% CI, 1.4-6.6; P = .005), and the rate of systemic therapy-requiring cGVHD was 2.5% (95% CI, 1% to 7%) versus 14% (95% CI, 7% to 27%), respectively (HR, 5.6; 95% CI, 1.7 to 18; P = .004). The PB group had a significantly higher risk of bacterial and viral infections, with no appreciable advantage in the duration of hospitalization, immune reconstitution, relapse, nonrelapse mortality, or survival. Our data suggest a benefit of the use of BM grafts over PB grafts for haplo-HCT.

Compared to reduced-intensity conditioning regimen, myeloablative conditioning (MAC) for hematopoietic stem cell transplantation (HCT) reduces relapse but is avoided in older patients because of higher non-relapse mortality (NRM). To meet the need for a myeloablative regimen for older patients, we developed a novel fludarabine and busulfan MAC regimen. We fractionated the dose of busulfan and gave it for 6 days over a 2-week period and demonstrated the feasibility and safety of this approach. However, the disease-specific efficacy of this regimen is not known. The purpose of this study was to estimate the efficacy of fractionated busulfan regimen by estimating diseases specific survival outcomes. The conditioning regimen consisted of busulfan and fludarabine. On days −13 and −12 before HCT, patients received 80 mg/m2 busulfan intravenously (IV) daily in an outpatient clinic. Additional chemotherapy was administered during inpatient treatment from day −6 through day −3, including fludarabine 40 mg/m2 and busulfan IV once daily. The dosing of busulfan was determined from pharmacokinetic analyses to achieve for the course a target area under the curve of 20,000 ± 12% μmol/min, which is close to the average exposure of myeloablative dose of busulfan. One hundred fifty patients with high-risk hematological malignancies up to 75 years were enrolled in this prospective phase II study. The objective was to evaluate NRM, relapse, survival, the rates of graft-versus-host disease (GVHD), and long-term complications. The median age of the patient population was 61 years (interquartile range, 55-67). The most common diagnoses were acute myeloid leukemia (AML; N = 59 [39.3%]), myelodysplastic syndrome (MDS; n = 29 [19.3%]), and myelofibrosis (MF; N = 22 [14.7%]). Most had an unrelated donor (n = 93 [62%]) and received peripheral blood graft (n = 110 [73.3%]). Over half had an HCT-specific comorbidity index of ≥3 (n = 79 [52.7%]). The median follow-up among survivors was 43.4 months (interquartile range, 38.9-50.4). In patients with AML in complete remission, MDS, and myelofibrosis, 3-year overall survival was 66.7% (95% confidence interval [CI], 50.2-88.5%), 43.6% (95% CI, 28.6-66.4%), and 59.1% (95% CI, 41.7-83.7%) respectively. The cumulative incidence of NRM was 22% (15.3%-28.7%), extensive chronic GVHD was 27% (95% CI, 20-34%), bronchiolitis obliterans was 4.7% (95% CI, 1.3-8.1%), and secondary malignancy was 8.7% (95% CI, 4.1-13.2%) at 3 years. Lengthening the duration of busulfan (fractionation) permits safe delivery of myeloablative conditioning in older patients, leading to prolonged survival. © 2021 American Society for Blood and Marrow Transplantation. Published by Elsevier Inc. All rights reserved.

Chimeric antigen receptor (CAR) T cell therapy is being increasingly used to treat patients with advanced hematologic malignancies; however, the symptoms related to standard of care CAR T cell therapy during the first year after treatment have not been assessed using patient-reported outcome (PRO) measurements. This study aimed to quantify patients' perspectives of symptom burden and functional status using PROs during the first year after CAR T cell therapy for hematologic malignancies, especially in patients who experienced grade 2-4 toxicities. Sixty patients were enrolled in this observational cross-sectional study at any time during their first 12 months post-treatment. All 60 had received CAR T cell therapy as standard of care at MD Anderson Cancer Center in 2019. PROs were measured using the MD Anderson Symptom Inventory (MDASI), the PROs Measurement Information System 29 (PROMIS-29), the global health tool EQ5D-5L, and the single-item health-related quality of life scale (HRQoL). Twenty-two additional symptoms related to CAR T cell therapy, as identified by an expert panel, were also evaluated. CAR T cell therapy-related toxicities were rated according to the ASTCT consensus grading criteria. The majority of patients (52 of 60; 87%) received axicabtagene ciloleucel (Yescarta). One-third of the patients developed grade 2-4 cytokine release syndrome or neurotoxicity. The first 90 days after infusion represented the most symptomatic period, in which >10% of patients rated 18 symptoms as severe (ie, MDASI symptom score of 7 to 10 on scale of 0 to 10), strongly indicating the need for effective symptom management. Physical functioning, measured by interference on the "general activity" item on the MDASI and this domain on the PROMIS-29, were significantly worse in patients who underwent therapy during the first 30 days compared with those who underwent therapy over 90 days (all P < .05 with the Hochberg step-up procedure), whereas the EQ5D-5L and single-item HRQoL did not detect such differences. Compared with patients who had mild cytokine release syndrome or neurotoxicity (grade 0-1), patients who developed grade 2-4 toxicities persistently reported multiple severe symptoms after 30 days following therapy (all P < .05). Furthermore, although using a different recall period, patient-reported scores on several PROMIS-29 domains were significantly correlated with the scores of corresponding MDASI symptom items. This real-world quantitative PRO symptoms study provides evidence of unique profiles of the physical, psychological, and cognitive symptom burden in patients undergoing CAR T cell therapy that varies within the first year after infusion and demonstrates differences among PRO measurement scales. These results support the need for validation of fit-for-purpose PRO measurements for routinely monitoring symptom and toxicity burdens in CAR T cell therapy care settings.

Graft versus host disease (GVHD) remains a major cause of morbidity and mortality following allogeneic hematopoietic stem-cell transplantation (HSCT). Despite the use of prophylactic GVHD regimens, a significant proportion of transplant recipients will develop acute or chronic GVHD following HSCT. Corticosteroids are standard first-line therapy, but are only effective in roughly half of all cases with ~50% of patients going on to develop steroid-refractory disease, which increases the risk of nonrelapse mortality. While progress has been made with improvements in survival outcomes over time, corticosteroids are associated with significant toxicities, and many currently available salvage therapies are associated with increased immunosuppression, infectious complications, and potential loss of the graft versus leukemia (GVL) effect. Thus, there is an unmet need for development of newer treatment strategies for both acute and chronic GVHD to improve long-term post-transplant outcomes and quality of life for HSCT recipients. Here, we provide a concise review of major emerging therapies currently being studied in the treatment of acute and chronic GVHD.

Relapse has emerged as the most important cause of treatment failure after allogeneic hematopoietic stem cell transplantation (HSCT). To test the hypothesis that natural killer (NK) cells can decrease the risk of leukemia relapse, we initiated a phase 1 dose-escalation study of membrane-bound interleukin 21 (mbIL21) expanded donor NK cells infused before and after haploidentical HSCT for high-risk myeloid malignancies. The goals were to determine the safety, feasibility, and maximum tolerated dose. Patients received a melphalan-based reduced-intensity conditioning regimen and posttransplant cyclophosphamide-based graft-versus-host disease (GVHD) prophylaxis. NK cells were infused on days −2, +7, and +28 posttransplant. All NK expansions achieved the required cell number, and 11 of 13 patients enrolled received all 3 planned NK-cell doses (1 × 105/kg to 1 × 108/kg per dose). No infusional reactions or dose-limiting toxicities occurred. All patients engrafted with donor cells. Seven patients (54%) developed grade 1-2 acute GVHD (aGVHD), none developed grade 3-4 aGVHD or chronic GVHD, and a low incidence of viral complications was observed. One patient died of nonrelapse mortality; 1 patient relapsed. All others were alive and in remission at last follow-up (median, 14.7 months). NK-cell reconstitution was quantitatively, phenotypically, and functionally superior compared with a similar group of patients not receiving NK cells. In conclusion, this trial demonstrated production feasibility and safety of infusing high doses of ex vivo–expanded NK cells after haploidentical HSCT without adverse effects, increased GVHD, or higher mortality, and was associated with significantly improved NK-cell number and function, lower viral infections, and low relapse rate posttransplant.

Summary There is limited information regarding the immunological predictors of post-allogeneic stem cell transplant (alloSCT) outcome in chronic lymphocytic leukaemia (CLL), such as mixed T-cell chimerism. We analysed 143 consecutive patients with relapsed/refractory CLL, transplanted between 2000 and 2012, to determine the prognostic relevance of mixed chimerism post-alloSCT and the ability of post-transplant immunomodulation to treat relapse. Mixed T-cell chimerism occurred in 50% of patients at 3 months and 43% at 6 months post-alloSCT; upon 3- and 6-month landmark analysis, this was associated with inferior progression-free survival (PFS) [Hazard ratio (HR) 1·93, P = 0·003 and HR 2·58, P

The establishment of long-lived pathogen-specific T cells is a fundamental property of the adaptive immune response. However, the mechanisms underlying long-term persistence of antigen-specific CD4+ T cells are not well-defined. Here we identify a subset of memory CD4+ T cells capable of effluxing cellular toxins, including rhodamine (Rho), through the multidrug efflux protein MDR1 (also known as P-glycoprotein and ABCB1). Drug-effluxing CD4+ T cells were characterized as CD161+CD95+CD45RA-CD127hiCD28+CD25int cells with a distinct chemokine profile and a Th1-polarized pro-inflammatory phenotype. CD4+CD161+Rho-effluxing T cells proliferated vigorously in response to stimulation with anti-CD3/CD28 beads and gave rise to CD161- progeny in vitro. These cells were also capable of self-renewal and maintained their phenotypic and functional characteristics when cultured with homeostatic cytokines. Multidrug-effluxing CD4+CD161+ T cells were enriched within the viral-specific Th1 repertoire of healthy donors and patients with acute myeloid leukemia (AML) and survived exposure to daunorubicin chemotherapy in vitro. Multidrug-effluxing CD4+CD161+ T cells also resisted chemotherapy-induced cytotoxicity in vivo and underwent significant expansion in AML patients rendered lymphopenic after chemotherapy, contributing to the repopulation of anti-CMV immunity. Finally, after influenza vaccination, the proportion of influenza-specific CD4+ T cells coexpressing CD161 was significantly higher after 2 years compared with 4 weeks after immunization, suggesting CD161 is a marker for long-lived antigen-specific memory T cells. These findings suggest that CD4+CD161+ T cells with rapid efflux capacity contribute to the maintenance of viral-specific memory T cells. These data provide novel insights into mechanisms that preserve antiviral immunity in patients undergoing chemotherapy and have implications for the development of novel immunotherapeutic approaches.

We investigated the long-term safety and disease control data obtained with i.v. busulfan (Bu) combined with clofarabine (Clo) in patients with acute lymphoblastic leukemia (ALL) undergoing allogeneic hematopoietic stem cell transplantation (HSCT). A total of 107 patients, median age 38 years (range, 19 to 64 years) received a matched sibling donor (n = 52) or matched unrelated donor (n = 55) transplant for ALL in first complete remission (n = 62), second complete remission (n = 28), or more advanced disease (n = 17). Nearly one-half of the patients had a high-risk cytogenetic profile as defined by the presence of t(9;22) (n = 34), t(4;11) (n = 4), or complex cytogenetics (n = 7). Clo 40 mg/m2 was given once daily, with each dose followed by pharmacokinetically dosed Bu infused over 3 hours daily for 4 days, followed by hematopoietic cell infusion after 2 days of rest. The Bu dose was based on the drug clearance as determined by a test Bu dose of 32 mg/m2. The target daily area under the curve was 5500 µmol/min for patients aged 59 years. With a median follow-up of 3.3 years among surviving patients (range, 1 to 5.8 years), the 2-year progression-free survival (PFS) for patients undergoing HSCT in first complete remission (CR1), second complete remission (CR2), or more advanced disease was 62%, 34%, and 35%, respectively. The regimen was well tolerated, with nonrelapse mortality (NRM) of 10% at 100 days and 31% at 2 years post-HSCT. The incidence of grade II-IV and III-IV acute graft-versus-host disease (GVHD) was 35% and 10%, respectively; 18% patients developed extensive chronic GVHD. The 2-year overall survival (OS) for patients undergoing HSCT in CR1, CR2, or more advanced disease was 70%, 57%, and 35%, respectively. Among 11 patients aged >59 years treated with reduced-dose Bu in CR1 (n = 7) or CR2 (n = 4), 4 remain alive and disease-free, with a median follow-up of 2.6 years (range, 2 to 4.7 years). Only the presence of minimal residual disease at the time of transplantation was associated with significantly worse PFS and OS in multivariate analysis. Our data indicate that the Clo-Bu combination provides effective disease control while maintaining a favorable safety profile. OS and NRM rates compare favorably with those for traditional myeloablative total body irradiation-based conditioning regimens.