Maziarz, Richard Thomas

PURPOSE Allogeneic hematopoietic cell transplantation (HCT) is the only potentially curative therapy for myelodysplastic syndromes (MDS), although it is infrequently offered to older patients. The relative benefits of HCT over non-HCT therapy in older patients with higher-risk MDS have not been defined. METHODS We conducted a multicenter biologic assignment trial comparing reduced-intensity HCT to hypomethylating therapy or best supportive care in subjects 50-75 years of age with intermediate-2 or high-risk de novo MDS. The primary outcome was overall survival probability at 3 years. Between January 2014 and November 2018, we enrolled 384 subjects at 34 centers. Subjects were assigned to the Donor or No-Donor arms according to the availability of a matched donor within 90 days of study registration. RESULTS The median follow-up time for surviving subjects was 34.2 months (range: 2.3-38 months) in the Donor arm and 26.9 months (range: 2.4-37.2 months) in the No-Donor arm. In an intention-to-treat analysis, the adjusted overall survival rate at 3 years in the Donor arm was 47.9% (95% CI, 41.3 to 54.1) compared with 26.6% (95% CI, 18.4 to 35.6) in the No-Donor arm ( P = .0001) with an absolute difference of 21.3% (95% CI, 10.2 to 31.8). Leukemia-free survival at 3 years was greater in the Donor arm (35.8%; 95% CI, 29.8 to 41.8) compared with the No-Donor arm (20.6%; 95% CI, 13.3 to 29.1; P = .003). The survival benefit was seen across all subgroups examined. CONCLUSION We observed a significant survival advantage in older subjects with higher-risk MDS who have a matched donor identified and underwent reduced-intensity HCT, when compared with those without a donor. HCT should be included as an integral part of MDS management plans in fit older adults with higher-risk MDS.

TPS7570 Background: Diffuse large B-cell lymphoma (DLBCL) is the most common form of non-Hodgkin lymphoma (NHL), and although > 50% of pts achieve long-term remission with first-line therapy, pts with R/R disease as well as those with R/R grade 3b follicular lymphoma (FL), double-, or triple-hit high-grade lymphomas have poor long-term outcomes (Crump 2017; Kahl 2016; Jain 2012). Autologous (auto) chimeric antigen receptor (CAR) T cell therapy has provided additional options for pts with R/R disease, but only when leukapheresis and manufacturing prove feasible (Jacobson 2020). Allogeneic (allo) CAR-T cells were designed specifically to address these unmet needs by using healthy donor T cells to produce a readily available product and remove the need for bridging chemotherapy. We are currently investigating the safety and efficacy of CTX110, an allo anti-CD19 CAR-T cell product modified by using CRISPR/Cas9-editing to disrupt the endogenous T-cell receptor (TCR) alpha constant (TRAC) locus in order to remove TCR expression and disrupt β2-microglobulin, which eliminates major histocompatibility complex (MHC) class I expression. Disruption of the TCR should significantly reduce or eliminate risks of graft-versus-host disease and elimination of MHC class I expression may increase CAR-T cell persistence by mitigating CTX110 rejection. In addition, the anti-CD19 CAR transgene construct is precisely inserted into the TRAC locus. Methods: The Phase 1 CARBON trial (NCT04035434) is an open-label, multicenter, global study evaluating the safety and efficacy of CTX110 in pts ≥18 y with R/R DLBCL NOS, double- or triple-hit DLBCL, or transformed or grade 3b FL with ≥2 prior lines of therapy or who are ineligible for/refused prior auto hematopoietic stem cell transplant (HSCT). Pts who received prior auto CAR-T or allo HSCT are excluded. Pts will receive lymphodepleting chemotherapy with fludarabine 30mg/m2 and cyclophosphamide 500mg/m2 for 3 days, followed by CTX110 infusion. In part A, dose escalation will be performed using a 3+3 design. Upon completion of dose finding, the cohort will be expanded to further assess safety signals and efficacy including the primary efficacy endpoint of overall response rate. Key secondary efficacy endpoints include duration of response, progression-free survival, and overall survival. The trial is currently open and enrolling. Clinical trial information: NCT04035434.

Background: Recent advances in the treatment of myelodysplastic syndrome (MDS) have improved patient survival and quality of life (QOL), while reducing transfusion burden. However, allogeneic hematopoietic cell transplantation (HCT), widely used in younger MDS patients, remains the only curative therapy for MDS. While transplantation outcomes among selected older patients with MDS are similar to younger patients with MDS, early transplantation for older patients is infrequently offered since the relative benefits of HCT over non-HCT therapy in have not been well defined in this patient group. We conducted a multi-center, biologic assignment trial in older individuals with high risk MDS to define the benefit of HCT over non-HCT therapy. Methods: The study was a multicenter, biologic assignment trial in subjects aged 50-75 with higher risk de novo MDS (IPSS Intermediate-2 (Int-2) or High) who were candidates for reduced-intensity conditioning (RIC) allogeneic HCT, comparing outcomes of those with a suitable 8/8 HLA-matched donor to those without a donor. The trial was conducted by the Blood and Marrow Transplant Clinical Trials Network (BMT CTN 1102, NCT02016781). Eligible subjects were enrolled prior to a formal donor search, and before or after MDS treatment was initiated. Biological assignment to the Donor or No Donor arm was based on high-resolution HLA typing of eligible family members and a search of the unrelated donor registries. Subjects were initially assigned to the No Donor arm and re-assigned to the Donor arm when a suitable donor was identified. Subjects who died or whose 90-day donor search ended without identifying a suitable donor remained in the No Donor arm. Subjects in the Donor arm were expected to undergo RIC HCT within 6 months of enrollment. Subjects underwent RIC HCT or non-HCT therapy according to institutional standards. The primary analysis compared three-year overall survival (OS) between arms using adjusted survival estimates to account for the potential bias resulting from biological assignment. The sample size was selected to provide at least 80% power to detect a difference of 15% in 3-year OS. Between January 2014 and November 2018, 384 subjects (Donor n=260, No Donor n=124) were enrolled at 34 centers. The study arms were well balanced for age, gender, KPS, IPSS risk, MDS disease duration and responsiveness to hypomethylating therapy (Table). The median follow-up time for surviving patients was 34.2 months (range: 2.3-38 months) in the Donor arm and 26.9 months (range: 2.4-37.2 months) in the No Donor arm. Results: In an intent-to-treat analysis, adjusted OS at 3 years from study enrollment in the Donor arm was 47.9% (95% CI: 41.3%-54.1%) compared with 26.6% (95% CI: 18.4%-35.6%) in the No Donor arm (p=0.0001, absolute difference 21.3%, 95% CI: 10.2%-31.8%)(Figure). A sensitivity analysis excluding subjects assigned to the No Donor arm who died or withdrew prior to the end of the 90-day search window showed no effect on outcome (Adjusted OS: 48.0% vs. 28.1%, p=0.0004). Leukemia-free survival (LFS) at 3 years was greater in the Donor arm (35.8%, 95% CI: 29.8%-41.8%) compared with the No Donor arm (20.6%, 95% CI: 13.3%-29.1%, p=0.003), with no changes in the sensitivity analysis. An OS and LFS benefit was seen across all subgroups tested (Figure). There were no clinically significant differences in QOL between Donor and No Donor arms as measured by the FACT-G, the MOS-SF36 Physical and Mental Component Scores and the EQ-5D utility score at all time points. The overall non-compliance rate for the trial was 26.3%. Reasons for non-compliance included the use of myeloablative conditioning or failure to proceed to RIC transplant in the Donor arm, and the use of alternative donors in the No Donor arm. In an as-treated analysis, comparison of the HCT and No HCT arms demonstrated a significant advantage in 3-year OS (47.4% vs. 16.0%, p<0.0001) and LFS (39.3% vs. 10.9%, p<0.0001) for subjects who underwent HCT. Conclusions: We observed a significant OS advantage in older patients with Int-2 and High IPSS risk de novo MDS who are RIC HCT candidates and have an HLA-matched donor, when compared with those without a donor. The benefit of having a matched donor was seen across subgroups, including those who were of Medicare age (>65) and below. HCT should be offered to all individuals between the ages of 50-75 with Int-2 and High IPSS risk MDS in whom a suitable donor can be identified. Table Disclosures Nakamura: Magenta Therapeutics: Other: Advisory board meeting; Kyowa-Kirin: Other: Support on a meeting presentation; Alexion: Other: Support on a meeting presentation; Merck: Other: advisory board meeting; NapaJen Pharma: Consultancy; Kadmon Corporation: Other: Advisory board meeting; Celgene: Other: Support on seminar; Viracor: Consultancy. Scott:Alexion, Incyte, Novartis, Regeneron: Consultancy; Agios, BMS: Honoraria; BMS, Novartis: Research Funding. Oran:ASTEX: Research Funding; Celgene: Consultancy; Arog Pharmaceuticals: Research Funding. Maziarz:Novartis, Incyte, CRISPR Therapeutics, Artiva Biotherapeutics, and AlloVir: Consultancy; Novartis and Athersys: Other: DSMB participant; Athersys: Patents & Royalties; Incyte, Kite, BMS/Celgene, PACT Pharma, Orca BioSystems, and Omeros: Honoraria; Novartis and Juno: Research Funding. McGuirk:Allo Vir: Consultancy, Honoraria, Research Funding; Gamida Cell: Research Funding; Pluristem Ltd: Research Funding; Bellicum Pharmaceutical: Research Funding; Astellas: Research Funding; Fresenius Biotech: Research Funding; Novartis: Research Funding; Kite Pharmaceuticals: Consultancy, Honoraria, Research Funding, Speakers Bureau; Juno Therapeutics: Consultancy, Honoraria, Research Funding. Sekeres:BMS: Consultancy, Membership on an entity's Board of Directors or advisory committees; Pfizer: Consultancy, Membership on an entity's Board of Directors or advisory committees; Takeda/Millenium: Consultancy, Membership on an entity's Board of Directors or advisory committees. Cutler:Incyte: Consultancy, Membership on an entity's Board of Directors or advisory committees; Kadmon: Consultancy, Membership on an entity's Board of Directors or advisory committees; Jazz: Consultancy, Membership on an entity's Board of Directors or advisory committees; Medsenic: Consultancy, Membership on an entity's Board of Directors or advisory committees; Generon: Consultancy, Membership on an entity's Board of Directors or advisory committees; Mesoblast: Consultancy, Membership on an entity's Board of Directors or advisory committees.

Abstract Comparative outcomes of allogeneic hematopoietic cell transplantation (HCT) for BCR-ABL1− myeloproliferative neoplasms (MPNs) in blast phase (MPN-BP) vs de novo acute myeloid leukemia (AML), and AML with prior myelodysplastic syndromes (MDSs; post-MDS AML), are unknown. Using the Center for International Blood and Marrow Transplant Research (CIBMTR) database, we compared HCT outcomes in 177 MPN-BP patients with 4749 patients with de novo AML, and 1104 patients with post-MDS AML, using multivariate regression analysis in 2 separate comparisons. In a multivariate Cox model, no difference in overall survival (OS) or relapse was observed in patients with MPN-BP vs de novo AML with active leukemia at HCT. Patients with MPN-BP in remission had inferior OS in comparison with de novo AML in remission (hazard ratio [HR], 1.40 [95% confidence interval [CI], 1.12-1.76]) due to higher relapse rate (HR, 2.18 [95% CI, 1.69-2.80]). MPN-BP patients had inferior OS (HR, 1.19 [95% CI, 1.00-1.43]) and increased relapse (HR, 1.60 [95% CI, 1.31-1.96]) compared with post-MDS AML. Poor-risk cytogenetics were associated with increased relapse in both comparisons. Peripheral blood grafts were associated with decreased relapse in MPN-BP and post-MDS AML (HR, 0.70 [95% CI, 0.57-0.86]). Nonrelapse mortality (NRM) was similar between MPN-BP vs de novo AML, and MPN-BP vs post-MDS AML. Total-body irradiation–based myeloablative conditioning was associated with higher NRM in both comparisons. Survival of MPN-BP after HCT is inferior to de novo AML in remission and post-MDS AML due to increased relapse. Relapse-prevention strategies are required to optimize HCT outcomes in MPN-BP.

Abstract Introduction: We previously reported that plerixafor + G-CSF was as safe as and more effective than placebo + G-CSF in mobilizing hematopoietic stem cell for autologous transplant in patients with non-Hodgkins lymphoma (NHL) through 100 days follow-up (DiPersio ASH 2007). We report herein the 12 months data. Methods: This was a phase 3, multicenter, randomized, double-blind, placebo-controlled study. NHL patients requiring an autologous hematopoietic stem cell transplant were eligible. Patients received G-CSF (10 μg/kg) subcutaneously daily for up to 8 days. Beginning on evening of Day 4 and continuing daily for up to 4 days, patients received either plerixafor (240 μg/kg) or placebo subcutaneously. Starting on morning of Day 5, patients began daily apheresis for up to 4 days or until ≥ 5 x 106 CD34+cells/kg were collected. We report herein the 12 months graft durability and hematology data. Results: As reported previously, 89/150 (59%) patients in the plerixafor group and 29/148 (20%) patients in the placebo group met the primary endpoint of collecting ≥ 5 x 106 CD34+ cells/kg in ≤ 4 days of apheresis, p < 0.001. 135 patients (90%) in plerixafor group and 82 patients (55%) in placebo group underwent transplantation. Median time to neutrophil and platelet engraftment was similar in both groups. There were no differences in graft durability through 12 months follow-up between the two groups. Two plerixa for treated patients had graft failure (one had pre-existing MDS and one developed AML). One plerixafor-treated patient had delayed platelet engraftment. The hematology profiles were similar between the two groups through 12 months follow-up, except that patients in the plerixafor group had significantly higher platelet count at 12 months than patients in the placebo group (p=0.026) (Table 1). During the 12 months follow-up, 14/135 (10.4%) patients in plerixafor group and 10/82 (12.2%) patients in the placebo group died. 7/14 in the plerixafor group and 5/10 in the placebo group died of disease progression. Plerixafor + G-CSF Placebo + G-CSF Hematology data presented as mean ± SD and n= number of patients with available data aAll patients who underwent transplantation bAll patients who underwent transplantation and had laboratory data at the study visit cP values were NS for all variables at all time points between groups except for platelet count at 12 months (p=0.026) Graft durability (n, %) 100 daysa 128/135 (94.8%) 78/82 (95.1%) 6 monthsb 120/123 (97.6%) 77/78 (98.7%) 12 monthsb 110/112 (98.2%) 65/65 (100.0%) Platelet (x 109/L) 100 days 183 ± 83 (n= 113) 169 ± 81 (n=63) 6 months 190 ± 78 (n=100) 180 ± 77 (n=64) 12 monthsc 209 ± 81 (n=50) 170 ± 78 (n=37) Neutrophils (x 109/L) 100 days 3.1 ± 1.7 (n=107) 3.2 ± 2.1 (n=61) 6 months 3.3 ± 1.4 (n=98) 3.8 ± 2.6 (n=64) 12 months 3.5 ± 1.4 (n=50) 4.2 ± 2.7 (n=38) Hemogloblin (mg/dL) 100 days 12.3 ± 1.5 (n=112) 12.3 ± 1.5 (n=63) 6 months 12.5 ± 1.5 (n=100) 12.4 ± 1.5 (n=64) 12 months 13.0 ± 1.4 (n=50) 12.7 ± 1.6 (n=37) Conclusions: The addition of plerixafor to G-CSF resulted in higher CD34+ cell collection in fewer days of apheresis and higher proportion of patients proceeding to transplant than G-CSF alone. Importantly, this 12 months report showed that transplants with cells collected with plerixafor resulted in graft durability rates that were similar to cells collected with G-CSF alone.

Abstract Introduction: The impact of transplanted CD34+ cell dose on clinical outcomes remains controversial. The purpose of this study was to examine the relationship between CD34+ cell dose transplanted and platelet, neutrophil, and lymphocyte counts at 100 days, 6, and 12 months following autologous transplantation in patients with non-Hodgkin’s lymphoma (NHL) and multiple myeloma (MM). Methods: Data were obtained from two phase 3 clinical studies that compared the safety and efficacy of plerixafor and G-CSF with placebo and G-CSF in mobilization of hematopoietic blood stem cells for autologous transplantation in NHL patients and in MM patients. The details of the study designs and preliminary safety and efficacy outcomes have been reported (DiPersio, ASH 2007). The following data were obtained from the two clinical study databases: number of CD34+ cells transplanted (first transplant only) as determined by a central laboratory, absolute neutrophil, platelet, red blood cell, and lymphocyte counts at 100 days, 6, and 12 months post-transplant. The proportions of patients who had platelet ≥150 x 109/L or neutrophil ≥2.5 x 109/L or lymphocyte ≥0.5 x 109/L at 100 days, 6, and 12 months were compared among these transplanted CD34+ cell dose categories regardless of mobilization treatment: 2–4 x 106 cells/kg, >4–6 x 106 cells/ kg, and > 6 x 106 cells/kg. Two separate analyses were performed, one for NHL patients and one for MM patients. Results: For the NHL study, 135/150 (90.0%) patients in the plerixafor group underwent transplantation after initial mobilization compared with 82/148 (55.4%) patients in the placebo group, p<0.001. The mean number of CD34+ cells transplanted was 6.06 ± 2.98 x 106 (median 5.41, range 1.79–17.6) for the plerixafor-treated patients and 4.09 ± 1.56 x 106 (median 3.85, range 1.98–8.7) for the placebo-treated patients, p<0.001. For the MM study, 142/148 (95.9%) patients in the plerixafor group and 136/154 (88.3%) patients in the placebo group underwent transplantation. The mean number of CD34+ cells transplanted was 5.84 ± 2.64 x 106 (median 5.34, range 1.9 to 16.7) for the plerixafor-treated patients and 4.37 ± 2.01 x 106 (median 3.98, range 1.8 to 16.9) CD34+ cells/kg for the placebo- treated patients. A significant linear trend with increasing proportion of patients with platelet count ≥150 x 109/L with increasing transplanted cell dose categories was observed at 100 days, 6, and 12 months for NHL patients and at 100 days for MM patients (Table 1). There were no apparent significant relationships between transplanted cell dose categories and other hematopoietic parameters. Table 1: Analysis of percentage of patients reaching a platelet count of ≥ 150 x 109/L by transplanted cell dose categories Transplant Cell Dose (CD34+ cells/kg) 2–4 x 106 ≥ 4–6 x 106 ≥ 6 x 106 P value* NHL Patients N=76 N=75 N=66 100 days 28 (48.3%) 42 (66.7%) 45 (81.8%) <0.001 6 months 31 (56.4%) 36 (66.7%) 42 (76.4%) 0.026 12 months 18 (56.3%) 21 (80.8%) 24 (82.8%) 0.020 MM Patients N=75 N=82 N=64 100 days 41 (68.3%) 57 (90.5%) 47 (88.7%) 0.004 6 months 48 (78.7%) 61 (89.7%) 51 (87.9%) 0.147 12 months 25 (73.5%) 33 (82.5%) 26 (81.3%) 0.435 For all transplanted cell dose categories, the proportions of patients are based on the number of patients with available data at each time point.*p-value for testing linear trend using Mantel-Haenszel Chi-square test Conclusions: Results from these ad hoc analyses confirm previous reports that transplanted cell dose may be associated with better long-term platelet recovery. Due to the small sample size in each transplanted cell dose category and the nature of ad hoc analyses, further studies are warranted to determine if the introduction of plerixafor will allow the mobilization and transplantation of higher quantity of CD34+ cells, which may positively influence long-term hematopoietic recovery.

Abstract Introduction: Midostaurin, a multitargeted tyrosine kinase inhibitor (TKI), plus induction and consolidation chemotherapy followed by single-agent midostaurin maintenance therapy resulted in significant benefits in event-free and overall survival (OS) in adults with newly diagnosed FLT3-mutated acute myeloid leukemia (AML) compared with placebo (RATIFY study; Stone et al, N Engl J Med, 2017). In RATIFY, patients who received allogeneic hematopoietic stem cell transplant (alloSCT) did not receive midostaurin maintenance. Despite alloSCT providing the highest likelihood of sustained remission, relapse rates remain high (30%-59%; Schiller et al, Biol Blood Marrow Transplant, 2016), especially in patients with FLT3-internal tandem duplication-positive (ITD+) AML. Posttransplant maintenance therapy may improve this outcome. Here, we report the primary results from RADIUS, a randomized, open-label, phase 2 exploratory trial (NCT01883362) that investigated whether the addition of midostaurin to standard of care (SOC) after alloSCT could reduce the risk of relapse in patients with FLT3-ITD+ AML. Methods: Adults (aged 18-70 y) who had undergone myeloablative alloSCT in first complete remission (CR1), had achieved hematologic recovery, and were transfusion independent were eligible. Patients enrolled postengraftment and were randomized to receive SOC with or without midostaurin 50 mg twice daily continuously (4-week cycles) for up to 12 cycles. Study treatment started 28 to 60 days post-alloSCT and patients were followed for ≥24 months post-alloSCT. The primary endpoint was relapse-free survival (RFS) at 18 months post-alloSCT. Secondary endpoints included safety and disease-free survival (DFS), OS, and RFS at 24 months post-alloSCT. The study was not adequately powered to detect a statistical difference between the 2 arms; a sample size of 60 was calculated to detect a 50% reduction in the risk of relapse. Results: 60 patients were randomized (30 per arm). Baseline characteristics were generally balanced between the 2 arms. Overall, 30 patients completed 12 cycles of study treatment (14 with SOC; 16 with midostaurin). The median exposure to midostaurin was 10.5 months (range, 0.2 to 12.0 months) and the median dose intensity was 93 mg/day (range, 15-100 mg/day). Early treatment discontinuations were similar between arms (15 in the SOC arm; 13 in the midostaurin arm), frequently due to adverse events (AEs; 3% vs 23%) and consent withdrawal (20% vs 7%). Among 6 patients who withdrew consent in the SOC arm, 2 did so to pursue other TKI therapies. Midostaurin dose modifications occurred in 19 patients (63%), mostly due to AEs (84%); 1 instance was due to receiving a concomitant CYP3A4 inhibitor. With an estimated 18-month RFS (95% CI) of 76% (54%-88%) in the SOC arm and 89% (69%-96%) in the midostaurin arm, estimated relapse rates were 24% and 11%, respectively, which is a 46% relative reduction in the risk of relapse with the addition of midostaurin (Figure 1). At 18 months, the median RFS was not reached in either arm. Longer follow-up at 24 months (data not yet matured) will be presented, including RFS, OS, and DFS. In the SOC and midostaurin arms, AEs were reported in 87% and 100% of patients, respectively (the most common any-grade AE was vomiting: 23% vs 73%; Figure 2); serious AEs were reported in 57% and 30% of patients, respectively, with diarrhea (7% vs 13%), nausea (10% vs 3%), vomiting (10% vs 3%), and pyrexia (7% vs 7%) being the most common. Overall, 8 patients discontinued midostaurin therapy due to AEs (mostly gastrointestinal related) and 12 died on study (all during the follow-up phase; 8 in the SOC arm and 4 in the midostaurin arm [n=4 vs n=2 due to AML disease progression]). Rates of graft-vs-host disease (GVHD) were generally similar between the SOC and midostaurin arms (overall, 70% vs 73%; acute GVHD, 53% vs 57% [grade 2/3 events: 37% vs 30%; no grade 4 events]; chronic GVHD, 47% vs 37% [most events were mild or moderate; severe events: 1 with SOC and 2 with midostaurin]). Conclusions: Adding midostaurin to SOC reduced the risk of relapse at 18 months post-alloSCT by 46% (vs SOC). The safety profile of single-agent midostaurin was consistent with previous reports; no major safety concerns were identified when adding midostaurin to SOC following alloSCT. These data suggest that midostaurin monotherapy can be safely administered for ≤1 year and may improve outcomes in patients who undergo alloSCT in CR1. Disclosures Maziarz: Novartis Pharmaceuticals Corporation: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Incyte: Consultancy, Honoraria; Juno Therapeutics: Consultancy, Honoraria; Kite Therapeutics: Honoraria; Athersys, Inc.: Patents & Royalties. Scott:Agios: Consultancy; Novartis: Research Funding; Celgene: Consultancy, Research Funding; Alexion: Consultancy. Deol:Kite Pharmaceuticals: Consultancy; Novartis: Consultancy. Kim:Novartis: Consultancy, Honoraria, Research Funding; Briston-Meyers Squibb: Consultancy, Honoraria, Research Funding; Paladin: Consultancy; Pfizer: Consultancy. Haines:Novartis: Employment. Bonifacio:Novartis: Employment. Rine:Novartis: Employment. Purkayastha:Novartis Pharmaceuticals Corporation: Employment.

Abstract Abstract 3094 The HLA class II DRB1 antigen DR15 is an important immunobiologic marker in immune mediated marrow failure states. DR15 has also been reported in small studies to be associated with favorable outcomes (reduction in acute GVHD and reduced relapse resulting in improved overall survival) after allogeneic hematopoietic cell transplant. To elucidate the impact of DR15 on major transplant outcomes, we conducted a retrospective study of 2, 891 recipients of first marrow or mobilized peripheral blood stem cell transplantation for the treatment of acute myeloid leukemia (n=1038), acute lymphoblastic leukemia (n=700), chronic myeloid leukemia (n=948), or myelodysplastic syndrome (n=205) between 1990–2008 and reported to the CIBMTR registry. Selection was confined to HLA-identical sibling transplantation to avoid HLA-disparity as a driving force for observed differences. All patients received conventional myeloablative conditioning, T-replete grafts and cyclosporine plus methotrexate- based GVHD prophylaxis. DNA-based HLA typing allowed categorization of 732 (25.3%) patients as positive and 2159 (74.7%) patients as negative for DRB1*15 :01 or *15 :02 (DR15). There were no significant differences in baseline characteristics between the HLA DR15-positive and -negative groups. In univariate analysis, HLA-DR15 status had no impact on neutrophil engraftment, acute graft-versus-host disease (GvHD) II-IV or III-IV, chronic GVHD, treatment related mortality, relapse, disease-free survival or overall survival. Confining the univariate analysis to myeloid malignancies did not alter these findings. Multivariate analysis models were constructed with DR15 status forced into the models in all steps of model building and the final model regardless of its statistical significance. Other variables tested included: donor/recipient age, CMV status, disease, disease stage, graft source, Karnofsky score, race and year of transplant. Variables that attained a p-value ≤0.05 were held in the final multivariate models. In multivariate analysis, DR15 status showed no significant difference in the primary outcomes of acute GVHD II-IV or III-IV, chronic GVHD, overall survival, or relapse. In conclusion, DR15 status had no impact on major HLA-matched sibling donor hematopoietic cell transplantation outcomes in this large and homogenous cohort of leukemia and MDS patients. Disclosures: No relevant conflicts of interest to declare.

Abstract Abstract 3110 High-dose therapy followed by autologous stem cell transplantation (ASCT) is standard therapy for patients with relapsed or refractory Hodgkin Lymphoma (HL), although the optimal conditioning regimen remains uncertain. The three drug alkylating agent regimen, BuMelTt, has been established as our institutional regimen. We performed a retrospective review of outcomes obtained with BuMelTt compared to those achieved with other standard conditioning regimens. 133 patients with relapsed/refractory HL who underwent ASCT between January 1990 and December 2009 were analyzed. 62 patients received BuMelTt and 71 patients received other standard preparative regimens (Standard) consisting of CBV (44), CyVp16TBI (20), BEAM (4), CyTBI (2), and Mel (1). The median follow-up (range) was 4.3 years (0.01–14.24) in BuMelTt and 3.9 years (0.07–20.21) in Standard. The two groups (BuMelTt vs Standard) were balanced for gender (65% male vs 65% male), median age (29 vs 33), median number of prior regimens (2 vs 2), and pre-transplant disease status. Disease status was categorized as PR2/CR2 (48% vs 42%), primary induction failure sensitive (16% vs 17%), and Other which included PIF-refractory, 1st relapse refractory, and greater than 1st relapse (35% vs 41%). The 5 year overall survival (OS) was superior for patient who received BuMelTt conditioning (74% vs 54%, p = 0.03). There was also a trend for improved 5 year event free survival (EFS) for BuMelTt at 56% vs 39% for Standard (p=0.07). Other risk factors for outcome after ASCT were also analyzed and included disease status, more than 2 chemotherapy regimens before ASCT, Karnofsky score < 90% at ASCT, time from diagnosis to ASCT < 12 months, prior extranodal involvement, and age > 40 years. By univariate analysis, >2 chemotherapy regimens before ASCT (HR 1.7, p=0.05) and disease status of Other (HR 2.8, p<0.01) were predictive for lower OS. There was a trend for influence on OS for BuMelTt (HR 0.6, p=0.07) and PIF-sensitive (HR 1.9, p=0.09). By multivariate analysis, disease status of PIF-sensitive or Other predicted worse outcomes for OS (HR 2.4 & 2.9, p 0.03 & <0.01, respectively), and there was still a trend for benefit with BuMelTt (HR 0.6, p=0.09), although >2 chemotherapy regimens lost significance (p=0.22). For EFS, disease status of PIF-sensitive or Other were prognostic in univariate analysis (HR 2.1 or 2.3, p=0.02 or <0.01, respectively), and there was a trend for improved EFS with BuMelTt (HR 0.66, p=0.08). In multivariate analysis, disease status of PIF-sensitive or Other remained prognostic (p=0.03 & 0.004, respectively), while BuMelTt was not significant (p=0.27). There was no significant difference in 100 day non-relapse related mortality for BuMelTt vs Standard conditioning (5% vs 3%, p=0.88). More patients developed NCI CTCAE grade 3/4 mucositis with BuMelTt than Standard (89% vs 61%, p<0.01), but fewer patients had bacteremia with BuMelTt than Standard (7% vs 23%, p=0.02). There was no difference in duration of hospitalization, episodes of febrile neutropenia, incidence of veno-occlusive disease, time to neutrophil engraftment, or time to platelet engraftment. Our results suggest that BuMelTt may improve OS and EFS compared to standard conditioning regimens with increased but manageable toxicity. A case matched control study is planned. Disclosures: No relevant conflicts of interest to declare.

Abstract Few data are available on the outcomes of patients who fail to engraft following URD transplantation. We describe the results of 122 patients reported to the National Marrow Donor Program (NMDP) between 1990 and 2005, who received a second bone marrow (BM) or peripheral blood (PB) URD transplant after failing to achieve an absolute neutrophil count of ≥ 500/mm3 without evidence of recurrent disease. Patients were transplanted for leukemia (n=83), myelodysplastic disorders (n=16), severe aplastic anemia (n=20) and other disease (n=3). The median age at first transplant was 29 years. Approximately one third were in each age range, < 20 (33%), 20–40 (37%) and >40 (29%). The initial transplant was BM in 84% of patients while 51% received BM for the subsequent transplant. One hundred ten of these patients received two transplants, 11 received three and one received 4 transplants. Twenty four used a different donor whereas 98 used the original donor for the second transplant; 28 of these used cells that had been cryopreserved at the initial transplant date. Nearly two thirds of the patients received reduced intensity conditioning or no conditioning for the second transplant. Sixty one percent had ATG as a component of their second transplant. The median interval from first transplant to second transplant was 48 (range, 18–126) days. The median nucleated cell dose was 2 × 108/kg (range, <1–23) for the first transplant and 2 × 108/kg (range, <1–50) for the second. The median follow up of survivors after second transplant was 77 (range, 2–144) months. Univariate probabilities of outcomes for these patients after second transplant were: Outcome N eval Probability (95% CI) *cumulative incidence Neutrophil engraftment* 122 @ 28 days 43 (34–52) % @100 days 48 (39–57) % 30 day mortality 122 39 (31–48) % 100 day mortality 122 75 (67–82) % Overall survival (OS) @ 1 year 122 11 (6–17) % Treatment related mortality (TRM) @ 1 year* 99 86 (79–92) % Disease free survival (DFS) @ 1 year 99 7 (2–12) % Of the 122 patients analyzed, only 10 remain alive. The most common causes of death were graft failure or rejection (33%), organ failure/interstitial pnuemoniatis (22%), infection (15%), GVHD (14%) and recurrent disease (6%). Of the 37 patients who had persistent graft failure 21 (57%) died from infectious causes. We observed no differences between patients who received a graft from the same donor vs. different donor, fresh vs. cryopreserved cells, or small initial graft size vs. large initial graft size. Patients who received a T-cell depleted graft at the time of their first transplant had significantly worse survival at 1 year after their second transplant, 4% (95% CI, 0–11) compared to those patients who had a non T-cell depleted initial graft, 16% (95 % CI, 8–25)(P = 0.02). It appears that a second salvage transplant strategy may be effective in a small group of patients, although the overall DFS at 1 year of only 7% is disappointing. To improve these results, efforts might focus on early identification and treatment of those at highest risk for non engraftment to determine whether such a strategy can alter the natural history we have described.