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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.

Background: Patients with high-risk or multiply relapsed B-lineage acute lymphoblastic leukemia (ALL) have a very high rate of relapse, even after allogeneic hematopoietic cell transplantation (HCT). In an effort to reduce the risk for relapse, we investigated the role of blinatumomab (Blin), a bi-specific T cell immunotherapy targeting CD19, as maintenance therapy following allogeneic HCT for adult patients with advanced B ALL. We rationalized that this is an ideal agent with little cytotoxicity, and the potential to provide immune protection against disease relapse during the first year post HCT when graft versus leukemia (GVL) is still maturing. Methods: Adult patients with B-ALL deemed high risk for relapse defined as disease stage beyond CR1, any active disease including MRD, or presence of high risk molecular mutations or karyotype at time of HCT, or patients with evidence of MRD immediately following HCT, were eligible for study enrollment; prior Blin treatment was allowed. Patients with active disease defined as >5% malignant blasts or active GVHD requiring steroid therapy post HCT were excluded. Patients were scheduled to receive 4 cycles of Blin as a continuous intravenous infusion at the dose of 28 microgram/24 hours over 4 weeks, with the first cycle to be administered within the first 3 months post HCT after count recovery; the subsequent cycles were administered at 6, 9, and 12 months following HCT (day of hematopoietic progenitor cell infusion). Dose escalation for cycle 1 and hospitalization for observation during cycles 1 and 2 followed standard FDA issued guidelines. Results: 14 patients enrolled to date with 12 patients treated with median age 30 years (range, 21-65 years); two patients did not proceed with treatment due to graft versus host disease (GVHD). Patient characteristics and outcomes are listed in Table 1. The median days to start of therapy post HCT was 84 (range, 38-105 days). The treatment was well tolerated with no reported cytokine release syndrome, GVHD, graft failure, or grade 5 adverse events (AE). A cumulative 26 cycles of Blin were administered with 7 Blin-related grade 3 or 4 AEs reported (leukopenia n=4, transaminitis n=2, rash n=1). Grade 2 neurotoxicity manifesting as confusion and dysphagia requiring temporary suspension of therapy and short course steroids noted in 1 patient. Median follow up was 8.5 months post HCT (range 2-35 months). All 4 patients who were MRD positive prior to start of Blin have progressed and 2 have died. None of the 8 patients who were MRD negative post transplant has relapsed. We performed multiparametric flow cytometry studies on serial peripheral blood patient samples collected prospectively at multiple time points to measure T cell subsets, T-cell function and cell surface expression of various checkpoint inhibitors including PD1, TIGIT, Tim3, 2B4 and CD160. Samples were studied on an X-20 Fortessa, and the data analyzed using Kaluza software. Interestingly, the 4 patients who progressed on Blin maintenance had lower CD8 to CD4 ratio compared to non-progressors (17:60 vs. 46:42) (Figure 1). Furthermore, compared to healthy controls, we observed higher levels of checkpoint molecules as multiple checkpoints per cell. PD1 and TIGIT upregulation and co-expression were more common in progressing patients compared to non-progressors (Figure 2). Conclusion: We observed that Blin maintenance following allogeneic HCT for B ALL is well tolerated. More patients need to be treated to confirm the efficacy of this approach. This approach is encouraging for high risk ALL patients who are MRD negative post transplant. Strategies to increase CD8 levels and blockade against checkpoint inhibitors may overcome resistance to therapy. Disclosures Kebriaei: Amgen: Research Funding; Jazz: Consultancy; Pfizer: Honoraria; Kite: Honoraria. Ravandi:Xencor: Consultancy, Research Funding; Selvita: Research Funding; Macrogenix: Consultancy, Research Funding; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Menarini Ricerche: Research Funding; Cyclacel LTD: Research Funding. Jabbour:Adaptive: Consultancy, Research Funding; AbbVie: Consultancy, Research Funding; Amgen: Consultancy, Research Funding; Takeda: Consultancy, Research Funding; BMS: Consultancy, Research Funding; Cyclacel LTD: Research Funding; Pfizer: Consultancy, Research Funding. Kantarjian:AbbVie: Honoraria, Research Funding; Novartis: Research Funding; Jazz Pharma: Research Funding; Agios: Honoraria, Research Funding; Cyclacel: Research Funding; Daiichi-Sankyo: Research Funding; Pfizer: Honoraria, Research Funding; Takeda: Honoraria; Actinium: Honoraria, Membership on an entity's Board of Directors or advisory committees; BMS: Research Funding; Immunogen: Research Funding; Amgen: Honoraria, Research Funding; Astex: Research Funding; Ariad: Research Funding. Champlin:Sanofi-Genzyme: Research Funding; Johnson and Johnson: Consultancy; Actinium: Consultancy.

PURPOSE: The recovery pace of absolute lymphocyte count (ALC) is prognostic after hematopoietic stem cell transplantation (SCT). Previous studies have evaluated a wide range of ALC cutoffs and time points to predict outcomes. We aimed to determine the optimal ALC measure for outcome prediction after SCT from bone marrow grafts (BMT). METHODS: 518 patients who underwent BMT for acute leukemia or myelodysplastic syndrome between 1999 and 2010 were divided into training and test sets to assess the prognostic values of ALC on days 30, 60, 90, 120, 180, as well as, the first post-transplant day on which a patient achieved ALC of 100, 200, 300, 400, 500, and 1000/μL. RESULTS: In the training set, the best predictor of overall survival (OS), relapse-free survival (RFS), and non-relapse mortality (NRM) was ALC on day 60. In the whole patient cohort, multivariable analyses demonstrated significantly better OS, RFS, NRM, and lower incidence of graft-versus-host disease among patients with ALC >300/μL on day 60, both including and excluding patients who had developed graft-versus-host disease prior to day 60. Among the patient-, disease-, and transplant-related factors assessed, only busulfan-based conditioning was significantly associated with higher ALC counts on day 60 in both cohorts. CONCLUSION: The optimal ALC cutoff to predict outcomes after BMT is ALC of 300/μL on day 60 post-transplant.

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). Subsequently, we added post-transplant cyclophosphamide (PTCy) GVHD prophylaxis to our fractionated regimen with a hypothesis that it will reduce GVHD and improve outcomes. Herein, we report the results of our retrospective analysis comparing outcomes of patients with AML who received fractionated busulfan myeloablative conditioning and PTCy versus standard tacrolimus (Tac) and methotrexate (Mtx) GVHD prophylaxis. Methods Patients with AML between 18-70 years of age with adequate organ function and 8/8-HLA matched related or unrelated donor, who were treated on 4 consecutive protocols using fractionated busulfan were included in the analysis. All patients received two fixed doses of busulfan 80mg/m2 as outpatient either on days -13 and -12, or on days -20 and-13 followed by busulfan on day -6 to -3 dosed to achieve target area under the curve (AUC) of 20,000 mol/min for the whole course based on pharmacokinetic studies. Fludarabine ± cladribine were given on day -6 to -3. GVHD prophylaxis was PTCy 50mg/kg on days 3 and 4 and Tac ± mycophenolate mofetil in PTCy cohort (n=53), or standard Tac+ Mtx (n=53). Patients in both the cohorts were matched 1:1 by propensity score. Results Baseline characteristics were similar between the PTCy and Tac/Mtx cohorts. The median age was 60 (range, 18-70) and 58 (range, 24-70) years, respectively, (P=0.3). Forty-nine percent were in CR, and 30% had comorbidity index >3 in each arm. Similar proportion of patients had ELN adverse risk in both arms (43% vs 40%, respectively P=0.7). The median follow up was 19 months (range, 3-36) in the PTCy and 46 months (range, 14-73) in Tac/Mtx cohort. Overall survival at 2-year was 78% vs 58% (P=0.03), non-relapse mortality was 6% vs 13% (P=0.2), incidence of grade 3-4 acute GVHD at 1-year was 6% vs 19% (P=0.07) and chronic GVHD at 2-year was 10% vs 29% (P=0.03) [Table 1 and figure 1]. The median time to neutrophil engraftment was prolonged by 3 days (15 vs 12 days; P Conclusion As compared to Tac/Mtx, PTCy-based GVHD prophylaxis not only reduced severe acute GVHD and chronic GVHD, but also improved overall survival in AML patients up to the age of 70 years who received myeloablative fractionated busulfan conditioning. Prospective randomized trial is warranted to validate these findings.

Allogeneic stem cell transplantation for patients with acute myeloid leukemia (AML) and myelodysplastic syndromes (MDS) has been performed primarily with an HLA-matched donor. Outcomes of haploidentical transplantation have recently improved, and a comparison between donor sources in a uniform cohort of patients has not been performed. We evaluated outcomes of 227 patients with AML/MDS treated with melphalan-based conditioning. Donors were matched related (MRD) (n = 87, 38%), matched unrelated (MUD) (n = 108, 48%), or haploidentical (n = 32, 14%). No significant differences were found between haploidentical and MUD transplantation outcomes; however, there was a trend for improved outcomes in the MRD group, with 3-year progression-free survival for patients in remission of 57%, 45%, and 41% for MRD, MUD, and haploidentical recipients, respectively (P = .417). Recovery of T cell subsets was similar for all groups. These results suggest that haploidentical donors can safely extend transplantation for AML/MDS patients without an HLA-matched donor. Prospective studies comparing haploidentical and MUD transplantation are warranted.

Limited data are available on immunologic responses to primary H1N1 infection in patients with hematologic malignancies. We present a prospective, case-surveillance study of such patients with real-time polymerase chain reaction (RT-PCR) confirmed H1N1-influenza who presented to our institution between September 2009 and January 2010. Ninety-two patients presented with influenza-like symptoms, and 13 had H1N1 infection confirmed by RT-PCR, including 4 allogeneic stem cell transplant recipients (1 with acute myelogenous leukemia, 1 with chronic lymphoblastic leukemia [CLL], 1 with non-Hodgkin lymphoma, and 1 with chronic myelogenous leukemia), 5 patients with multiple myeloma following autologous stem cell transplantation, 1 patient with multiple myeloma perimobilization, 2 patients with NHL post chemotherapy, and 1 patient with CLL. All 13 patients required hospitalization. Six (43%) were admitted to the intensive care unit (ICU), of whom 4 (67%) died. We evaluated B cell and T cell responses to H1N1 infection prospectively in these patients compared with those in 4 otherwise healthy controls. Within 12 weeks of diagnosis, only 6 of 11 patients developed seropositive antibody titers as measured by hemagglutination-inhibition or microneutralization assays, compared with 4 of 4 controls. H1N1-specific T cells were detected in only 2 of 8 evaluable patients compared with 4 of 4 controls. H1N1-specific T cells were functional, capable of producing interferon γ, tumor necrosis factor α, and CD107a mobilization. Furthermore, CD154 was up-regulated on CD4(+) T cells in 3 of 4 controls and 2 of 2 patients who had both B cell and T cell responses to H1N1. Post-H1N1 infection, 5 of 8 patients developed seasonal influenza-specific T cells, suggesting cross-reactivity induced by H1N1 infection. These data offer novel insights into humoral and cell-mediated immunologic responses to primary H1N1 infection.

One hundred thirty-eight patients with hematologic malignancies received myeloablative T cell-depleted peripheral blood stem cell transplant (PBSCT) from an HLA-identical sibling donor. The T cell dose was adjusted to 0.2-1 x 10(5) CD3(+) cells/kg. The CD34 dose was 2.7-16 x 10(6)/kg. Patients with acute graft-versus-host disease (GVHD) grade2 received 1 or 2 donor lymphocyte infusions of 10(7) CD3(+) cells/kg between days 45 and 100. Patients were designated according to relapse probability as standard or high relapse risk (77 and 61, respectively). Overall survival (OS), relapse-free survival, relapse, and transplant-related mortality (TRM) were 58%, 46%, 40%, and 20%, respectively, after a median follow-up of 4 years. Fifty-three (39%) and 21 (15%) patients developed grade 2-4 and 3-4 acute GVHD. Forty-two (36%) had limited and 29 (25%) had extensive chronic GVHD. In multivariate analysis, disease risk was an independent factor for OS and relapse, day-30 lymphocyte count for OS and TRM, and chronic GVHD for OS and relapse. PBSCT with early T cell add back leads to comparable rates of chronic GVHD compared with T cell-replete PBSCT. However, this chronic GVHD after T cell add back is associated with less mortality and retains a protective effect in terms of relapse, at least in the standard-risk patients.

Increasing numbers of allogeneic hematopoietic stem cell transplantation (allo-SCT) are being performed for patients who have failed a previous allogeneic or autologous SCT. We investigated whether the EBMT risk score could predict outcome after a subsequent allo-SCT. We analyzed prognostic factors in 124 consecutive patients who underwent a second transplantation using an allogeneic donor at our institution. Patients with either a first autologous (N = 64) or first allogeneic (N = 60) SCT were included. Age, disease stage, time interval from diagnosis to transplantation, donor type, and donor-recipient sex combination were used to establish a score from 0 to 7 points, from which 3 groups were identified. The 5-year survival probability decreased from 51.7% for risk scores 0-3 (low, n = 25), to 29.3% for risk score 4 (intermediate, n = 42), and only 10.4% for risk scores 5-7 (high, n = 57), P = .001. We propose that the EBMT risk score can identify patients most likely to benefit from a second transplantation.

The treatment of hematological malignancies by harnessing immune responses has long been pursued. It is well accepted that the success of allogeneic hematopoietic stem cell transplantation (HSCT) as a treatment for hematological malignancies is due primarily to immunologic recognition and elimination of recipient leukemia cells by donor T cells, the so-called graft versus leukemia (GVL) effect. Based on the discovery and identification of leukemia antigens, it is now possible to target leukemia either by specific vaccination or adoptive transfer of in vitro generated anti-leukemia cytotoxic lymphocytes (CTLs). Leukemia antigens can be categorized broadly into 3 classes: (1) ubiquitously expressed alloantigens, also known as minor histocompatibility antigens (mHags), widely expressed by normal tissues in the recipient as well as by leukemia cells, and capable of initiating both GVHD and GVL responses; (2) alloantigens expressed uniquely by cells of the hematopoietic system (tissue-restricted mHags) such as HA-1 and HA-2; and (3) leukemia antigens, including leukemia-specific antigens such as BCR-ABL in Philadelphia-chromosome–positive leukemia and over- or aberrantly expressed leukemia-associated antigens (LAAs) such as proteinase 3 (PR3), Wilms tumor 1 (WT1) and the preferentially expressed antigen of melanoma (PRAME). A number of studies have shown a temporal inverse relationship between circulating T cells directed against mHags or LAAs and minimal residual disease in patients with acute and chronic leukemia after allogeneic HSCT, supporting a role for these antigens in the GVL response.1,2 This review will encompass a bench to bedside approach evaluating strategies for active induction or passive transfer of tumor-specific T cells in patients with hematological malignancies.

Pulmonary function (PF) was studied in 69 consecutive patients with hematologic diseases, with a minimum 5-year (range, 5-13 years) follow-up after allogeneic stem cell transplantation from an HLA-matched sibling. Fifty-six patients (81%) received total body irradiation based myeloablative stem cell transplantation (MT) and 13 (19%) underwent nonmyeloablative stem cell transplantation (NST). Thirty-one patients (45%) developed a late decrease in PF from baseline, 25 with a restrictive and 6 with an obstructive pattern PF abnormality. Twelve patients (17%) were symptomatic, 8 with a severe restrictive PF defect, but none required supplemental oxygen. The incidence of developing a late PF abnormality was comparable in MT (24 of 56) and NST (5 of 13; P = .51). In multivariate analysis, chronic graft-versus-host disease (relative risk, 16) and pretransplantation diffusion capacity for carbon monoxide or forced expiratory volume in the first second