Kharfan‐Dabaja, Mohamed A.

SummaryReduced‐intensity conditioning (RIC) allogeneic haematopoietic cell transplantation (allo‐HCT) is a curative option for select relapsed/refractory Hodgkin lymphoma (HL) patients; however, there are sparse data to support superiority of any particular conditioning regimen. We analyzed 492 adult patients undergoing human leucocyte antigen (HLA)‐matched sibling or unrelated donor allo‐HCT for HL between 2008 and 2016, utilizing RIC with either fludarabine/busulfan (Flu/Bu), fludarabine/melphalan (Flu/Mel140) or fludarabine/cyclophosphamide (Flu/Cy). Multivariable regression analysis was performed using a significance level of <0·01. There were no significant differences between regimens in risk for non‐relapse mortality (NRM) (P = 0·54), relapse/progression (P = 0·02) or progression‐free survival (PFS) (P = 0·14). Flu/Cy conditioning was associated with decreased risk of mortality in the first 11 months after allo‐HCT (HR = 0·28; 95% CI = 0·10–0·73; P = 0·009), but beyond 11 months post allo‐HCT it was associated with a significantly higher risk of mortality, (HR = 2·46; 95% CI = 0·1.32–4·61; P = 0·005). Four‐year adjusted overall survival (OS) was similar across regimens at 62% for Flu/Bu, 59% for Flu/Mel140 and 55% for Flu/Cy (P = 0·64), respectively. These data confirm the choice of RIC for allo‐HCT in HL does not influence risk of relapse, NRM or PFS. Although no OS benefit was seen between Flu/Bu and Flu/Mel 140; Flu/Cy was associated with a significantly higher risk of mortality beyond 11 months from allo‐HCT (possibly due to late NRM events).

Introduction: Rituximab-based high-dose therapy (HDT) is frequently prescribed to DLBCL patients (pts) undergoing auto-HCT. However data supporting the benefit of adding R to auto-HCT conditioning are not available. Herein, we report the impact of R-based conditioning on auto-HCT outcomes of DLBCL pts. Methods: Using the Center for International Blood and Marrow Transplant Research registry, 862 adult (≥18 years) DLBCL pts undergoing auto-HCT, between 2003-2017 were included. Analysis was limited to pts receiving BEAM (BCNU, etoposide, cytarabine, melphalan)-based HDT, as R was infrequently used with non-BEAM conditioning regimens. All pts received R-containing chemoimmunotherapy in the frontline setting and had chemosensitive disease prior to HCT. Early chemoimmunotherapy failure (ECitF) was defined as not achieving a complete remission (CR) after frontline chemoimmunotherapy or relapsing within 1 year of initial diagnosis. Primary outcome was overall survival (OS). Secondary outcomes included non-relapse mortality (NRM), relapse, progression-free survival (PFS) and infectious complications within 100 days post-HCT. Results: The study cohort was divided into 2 groups; BEAM (n=667) and R-BEAM (n=195). The baseline characteristics of the 2 cohorts were comparable including age at auto-HCT, disease stage, Karnofsky performance score, extranodal involvement, time from diagnosis to auto-HCT, number of prior therapies, remission status, and ECitF. However, significantly more R-BEAM cohort patients received R as part of last therapy line before auto-HCT (75% vs. 86%; P=0.001). Median follow-up of survivors was 48 (range 1-171) and 64 (range 3-142) months in the BEAM and R-BEAM cohorts, respectively. On univariate analysis, the 4 year cumulative incidence of relapse (41% vs 44%), NRM (11% vs 9%), PFS (48% vs 47%; Figure 1) and OS (58% vs 61%; Figure 2) were similar in the R-BEAM and BEAM groups, respectively (Table 1). On multivariate analysis, no significant difference was seen in OS (HR 0.81; 95% CI 0.81-1.31; P=0.83) or PFS (HR 0.94; 95% CI 0.76-1.18; P=0.61) (Table 1) between the two cohorts. Addition of R had no impact on risk of relapse (HR 0.83; 95% CI 0.65-1.07; P=0.15) or NRM (HR 1.43; 95% CI 0.909-2.26; P=0.12). Variables independently associated with lower OS included older age (HR 3.05; 95% CI 1.81-5.13; P&lt;0.001), not being in CR at auto-HCT (HR 1.67, 95% CI 1.39-2.07; P&lt;0.001) and presence of ECitF (HR 1.52, 95% CI 0.54-3.26; P&lt;0.001). Older age (HR 2.26, 95% CI 1.48-3.45; P&lt;0.0002) and not being in CR at auto-HCT (HR 1.78, CI 1.47-2.14; P&lt;0.0001) were also associated with inferior PFS. There was no significant difference in the 100-day cumulative incidence of bacterial, viral or fungal infections between the two cohorts. Disease relapse was the main cause of death in both BEAM and R-BEAM cohorts (66% vs 55%). Conclusion: In this large registry analysis of DLBCL pts undergoing auto-HCT, adding R to BEAM conditioning had no impact on transplantation outcomes. Older age, absence of CR and ECitF were associated with inferior survival. Disclosures Majhail: Mallinckrodt: Honoraria; Incyte: Consultancy; Nkarta: Consultancy; Anthem, Inc.: Consultancy; Atara Bio: Consultancy. Sureda:Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel Support; Gilead: Honoraria; Amgen: Membership on an entity's Board of Directors or advisory committees; Takeda: Consultancy, Honoraria, Speakers Bureau; Novartis: Honoraria; BMS: Honoraria; Roche: Honoraria; Sanofi: Honoraria; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees. Kharfan-Dabaja:Daiichi Sankyo: Consultancy; Pharmacyclics: Consultancy. Hamadani:ADC Therapeutics: Consultancy, Research Funding; Merck: Research Funding; Takeda: Research Funding; Pharmacyclics: Consultancy; Celgene: Consultancy; Medimmune: Consultancy, Research Funding; Janssen: Consultancy; Otsuka: Research Funding; Sanofi Genzyme: Research Funding, Speakers Bureau.

Introduction: Reduced-intensity and non-myeloablative (RIC/NMA) conditioning regimens are frequently used in alloHCT for NHL, because they are associated with decreased non-relapse mortality (NRM) risk in comparison with myeloablative conditioning regimens and allow older patients and patients with comorbidities to receive alloHCT. However, the optimal RIC/NMA regimen in allo-HCT for NHL is not known. Using the CIBMTR database we compared the transplant outcomes between the commonly used RIC/NMA regimens in NHL. Methods: 1823 adult (≥18 years) NHL patients in CIBMTR registry undergoing alloHCT using matched related or unrelated donors, between 2008-2016 were included. Analysis was limited to patients receiving four commonly used RIC/NMA regimens: fludarabine/ i.v. busulfan (6.4mg/kg) (Flu/Bu), fludarabine/melphalan (140mg/m^2) (Flu/Mel 140), fludarabine/cyclophosphamide (Fly/Cy) and Flu/Cy with 2Gy Total Body Irradiation (Flu/Cy/TBI). Graft-versus-host disease (GVHD) prophylaxis was limited to calcineurin inhibitor-based regimens. Patients who received post transplantation cyclophosphamide for GVHD prophylaxis were excluded. The primary outcome was overall survival (OS). Secondary outcomes included cumulative incidence of NRM, relapse, progression-free survival (PFS) and cumulative incidence of acute and chronic GVHD. Probabilities of OS and PFS were calculated using the Kaplan-Meier estimator. Multivariable regression analysis was performed for GVHD, relapse/progression, NRM, PFS, and OS. Covariates with a p&lt;0.01 were considered significant. Results: The study cohort was divided into 4 groups; Flu/Bu (n=458), Flu/Cy/TBI (n=89), Flu/Mel 140 (n=885) and Flu/Cy (n=391). The baseline characteristics are shown in Table 1. The 4 cohorts were comparable with respect to median patient age, gender, donor type, remission status at alloHCT, and use of prior auto HCT. There was no interaction between NHL histological subtype and type of conditioning regimen. Results of multivariate analysis are shown in Table 2. The Flu/Mel 140 regimen was associated with a higher NRM (HR 1.78, 95% CI 1.37-2.31; p&lt;0.001) when compared to Flu/Bu. Although the risk of relapse with Flu/Mel 140 was lower when compared to Flu/Bu (HR 0.79, 95% CI 0.66-0.94); p=0.007), this did not result in an improvement in PFS. Moreover, the Flu/Mel 140 cohort had an inferior OS (HR 1.34, 95% CI 1.13-1.59; p&lt;0.001) when compared to Flu/Bu. There was no significant difference in terms of OS, PFS, relapse and NRM between Flu/Bu, Flu/Cy and Flu/Cy/TBI. There was no difference in risk of grade 3-4 acute GVHD across the four cohorts and compared to Flu/Cy/TBI, Flu/Mel 140 had a higher risk of chronic GVHD (HR 1.38, 95% CI 1.15-1.65; p&lt;0.001). Four year adjusted PFS was 38% for Flu/Bu, 51% for Flu/Cy/TBI, 39% for Flu/Mel 140 and 35% for Flu/Cy (p=0.07). Four year adjusted OS was 58% for Flu/Bu, 67% for Flu/Cy/TBI, 49% for Flu/Mel 140 and 63% for Flu/Cy (p&lt;0.001). Disease relapse was the most common cause of death across all 4 cohorts. Conclusion: This is the largest analysis comparing the impact of various RIC/NMA conditioning regimens on the outcomes of NHL patients undergoing alloHCT. We report that the choice of RIC/NMA conditioning regimen significantly impacted OS. The most commonly used conditioning regimen, Flu/Mel 140 was associated with a higher NRM and an inferior OS. The Flu/Bu, Flu/Cy, and Flu/CY/TBI conditioning regimens appear to provide comparable OS. Disclosures Ghosh: Janssen: Consultancy, Honoraria, Research Funding, Speakers Bureau; Pharmacyclics LLC, an AbbVie Company: Consultancy, Honoraria, Research Funding, Speakers Bureau; Bristol-Myers Squibb: Honoraria, Speakers Bureau; Gilead: Consultancy, Honoraria, Speakers Bureau; SGN: Consultancy, Honoraria, Research Funding, Speakers Bureau; TG Therapeutics: Consultancy, Honoraria, Research Funding; Celgene: Consultancy, Research Funding; Genentech: Research Funding; Forty Seven Inc: Research Funding; AstraZeneca: Honoraria, Speakers Bureau. Kharfan-Dabaja:Pharmacyclics: Consultancy; Daiichi Sankyo: Consultancy. Sureda:Amgen: Membership on an entity's Board of Directors or advisory committees; Gilead: Honoraria; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees; BMS: Honoraria; Sanofi: Honoraria; Takeda: Consultancy, Honoraria, Speakers Bureau; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel Support; Novartis: Honoraria; Roche: Honoraria. Hamadani:Merck: Research Funding; ADC Therapeutics: Consultancy, Research Funding; Celgene: Consultancy; Otsuka: Research Funding; Medimmune: Consultancy, Research Funding; Takeda: Research Funding; Pharmacyclics: Consultancy; Janssen: Consultancy; Sanofi Genzyme: Research Funding, Speakers Bureau.

Background Although rituximab‐based high‐dose therapy is frequently used in diffuse large B cell lymphoma (DLBCL) patients undergoing autologous hematopoietic cell transplantation (auto‐HCT), data supporting the benefits are not available. Herein, we report the impact of rituximab‐based conditioning on auto‐HCT outcomes in patients who have DLBCL. Methods Using the Center for International Blood and Marrow Transplant Research (CIBMTR) registry, 862 adult DLBCL patients undergoing auto‐HCT between 2003 and 2017 using BEAM (BCNU, etoposide, cytarabine, melphalan) conditioning regimen were included. All patients received frontline rituximab‐containing chemoimmunotherapy and had chemosensitive disease pre‐HCT. Early chemoimmunotherapy failure was defined as not achieving complete remission (CR) after frontline chemoimmunotherapy or relapse within 1 year of initial diagnosis. The primary outcome was overall survival (OS). Results The study cohort was divided into 2 groups: BEAM (n = 667) and R‐BEAM (n = 195). On multivariate analysis, no significant difference was seen in OS ( P = .83) or progression‐free survival (PFS) ( P = .61) across the 2 cohorts. No significant association between the use of rituximab and risk of relapse ( P = .15) or nonrelapse mortality ( P = .12) was observed. Variables independently associated with lower OS included older age at auto‐HCT ( P < .001), absence of CR at auto‐HCT ( P < .001) and early chemoimmunotherapy failure ( P < .001). Older age ( P < .0002) and non‐CR pre‐HCT ( P < .0001) were also associated with inferior PFS. There was no significant difference in early infectious complications between the 2 cohorts. Conclusion In this large registry analysis of DLBCL patients undergoing auto‐HCT, the addition of rituximab to the BEAM conditioning regimen had no impact on transplantation outcomes. Older age, absence of CR pre auto‐HCT, and early chemoimmunotherapy failure were associated with inferior survival.

PURPOSETo compare the outcomes of patients with Hodgkin or non-Hodgkin lymphoma undergoing nonmyeloablative haploidentical or unrelated cord blood (UCB) hematopoietic cell transplantation.PATIENTS AND METHODSWe retrospectively studied 740 patients with Hodgkin lymphoma (n = 283, 38%) and non-Hodgkin lymphoma (n = 457, 62%) age 18-75 years who received transplantations from 2009 to 2016. Data were reported to the Lymphoma Working Party of the European Society for Blood and Marrow Transplantation, Eurocord, or Center for International Blood and Marrow Transplant Research. Of the 526 patients who received haploidentical transplantation, 68% received bone marrow and 32% received peripheral blood. All patients received a uniform transplantation conditioning regimen (2 Gy of total-body irradiation, cyclophosphamide, and fludarabine) and graft-versus-host disease prophylaxis (calcineurin inhibitor and mycophenolate). In addition, patients who received a haploidentical transplantation received posttransplantation cyclophosphamide.RESULTSCompared with haploidentical bone marrow and peripheral-blood transplantations and adjusted for age, lymphoma subtype, and disease status, survival was lower after UCB transplantation (hazard ratio [HR], 1.55; P = .001; and HR, 1.59; P = .005, respectively). Similarly, progression-free survival was lower after UCB transplantations compared with haploidentical bone marrow and peripheral-blood transplantations (HR, 1.44; P = .002; and HR, 1.86; P < .0001), respectively. The 4-year overall and progression-free survival rates after UCB transplantation were 49% and 36%, respectively, compared with 58% and 46% after haploidentical bone marrow transplantation and 59% and 52% after peripheral-blood transplantation, respectively. Lower survival was attributed to higher transplantation-related mortality after UCB transplantation compared with haploidentical bone marrow and peripheral-blood transplantation (HR, 1.91; P = .0001; and HR, 2.27; P = .0002, respectively).CONCLUSIONWhen considering HLA-mismatched transplantation for Hodgkin or non-Hodgkin lymphoma, the data support haploidentical related donor transplantation over UCB transplantation.

AbstractPrimary appendiceal lymphomas (PAL) are a type of primary gastrointestinal non‐Hodgkin lymphoma (PGINHL) with an incidence of <1%. There is considerable discordance with regard to the optimal management of PGINHL. We describe two cases of PAL, perform a literature review, and discuss the available evidence for optimal treatment.

BACKGROUND: Axi-cel is an autologous anti-CD19 chimeric antigen receptor (CAR) T-cell therapy that is approved for treatment of relapsed/refractory (R/R) large B-cell lymphoma and is associated with high response rates and durable remissions. Recent data show that axi-cel is effective across various adverse prognostic features, namely cell of origin, disease bulkiness, and extranodal disease, among others. Hypoalbuminemia is a known adverse prognostic factor in lymphomas. It is unknown if axi-cel overcomes the adverse prognostic feature of hypoalbuminemia in R/R large B-cell or transformed follicular lymphoma. METHODS: We conducted a retrospective analysis of patients treated with axi-cel across three Mayo Clinic campuses (Rochester, Jacksonville, and Phoenix) from 06/01/2018 until 04/01/2019. The primary objective of this analysis was to assess the impact of hypoalbuminemia (defined at day 0, prior to infusion) on outcome after axi-cel therapy. RESULTS: A total of 50 (male=37, 74%) patients (pts), median age of 53 (26-67) years received axi-cel. The median number of prior lines of therapy was 3 (2-8) (Table 1). Two pts had no available serum albumin levels at time of axi-cel infusion. Seven (15%) of 48 pts had serum albumin levels lower than 3.5 g/dL (median= 3.3 g/dL (range 2.6-3.4)) and the median follow up of survivors was 7.6 (1.9-14.3) months. The best overall response rate (ORR) and complete remission (CR) rates in these pts were 57% and 57%, respectively. One (14%) patient had stable disease and 2 (29%) had disease progression. The median overall survival (OS) for pts with hypoalbuminemia was not reached. On the other hand, 41 (85%) pts had a normal serum albumin level (median=4.0 (range 3.5-5.1) g/dL) and the median follow up for survivors was 6.3 months. The best objective response rate (ORR) and complete remission (CR) rates in these pts were 82% and 44%, respectively. The median OS for pts with normal serum albumin was 14 (95%CI=6.3-29.6) months. There was no significant difference at 6-months and 1-year OS between pts with hypoalbuminemia vs. those with normal baseline serum albumin levels [6-month=100% vs. 79%(95%CI=64-93%); 1-year (100% vs. 54% (95%CI=26-82%), p=0.17] (Figure 1). All grades cytokine release syndrome (CRS) was diagnosed in all 7 pts with hypoalbuminemia (100%) and in 38 of 41 (92%) pts without hypoalbuminemia. There was no difference in the median duration of CRS between pts with or without hypoalbuminemia [6 (range 1-11) days vs 5 (range 1-19) days, p=0.89]. Neurotoxicity (all grades) was observed in 5 (71%) pts with hypoalbuminemia compared 26 (63%) with normal albumin levels. There was no statistically significant difference in median duration of neurotoxicity between pts with hypoalbuminemia and those with normal baseline albumin levels [9 (range 1-10) days vs. 3 (range 0-25) days, p= 0.72]. CONCLUSIONS: Hypoalbuminemia does not have a significant impact on the outcomes of axi-cel therapy, including the incidence of CRS or neurotoxicity. These results need to be validated in a large collaborative multicenter study. Further investigation is needed to assess the prognostic impact of severe hypoalbuminemia (<3g/dL) on axi-cel therapy. Disclosures Ansell: Mayo Clinic Rochester: Employment; Seattle Genetics: Research Funding; Trillium: Research Funding; Trillium: Research Funding; Mayo Clinic Rochester: Employment; Bristol-Myers Squibb: Research Funding; Bristol-Myers Squibb: Research Funding; Affimed: Research Funding; Regeneron: Research Funding; Affimed: Research Funding; Bristol-Myers Squibb: Research Funding; Mayo Clinic Rochester: Employment; LAM Therapeutics: Research Funding; Affimed: Research Funding; Bristol-Myers Squibb: Research Funding; Trillium: Research Funding; Regeneron: Research Funding; Trillium: Research Funding; Affimed: Research Funding; LAM Therapeutics: Research Funding; Mayo Clinic Rochester: Employment; LAM Therapeutics: Research Funding; LAM Therapeutics: Research Funding; Bristol-Myers Squibb: Research Funding; Mayo Clinic Rochester: Employment; Mayo Clinic Rochester: Employment; Affimed: Research Funding; Regeneron: Research Funding; LAM Therapeutics: Research Funding; Seattle Genetics: Research Funding; Trillium: Research Funding; Affimed: Research Funding; Trillium: Research Funding; Bristol-Myers Squibb: Research Funding; LAM Therapeutics: Research Funding; Mayo Clinic Rochester: Employment; Trillium: Research Funding; Regeneron: Research Funding; LAM Therapeutics: Research Funding; Bristol-Myers Squibb: Research Funding; Mayo Clinic Rochester: Employment; LAM Therapeutics: Research Funding; Seattle Genetics: Research Funding; Trillium: Research Funding; Trillium: Research Funding; Seattle Genetics: Research Funding; Regeneron: Research Funding; Bristol-Myers Squibb: Research Funding; Mayo Clinic Rochester: Employment; Bristol-Myers Squibb: Research Funding; Seattle Genetics: Research Funding; LAM Therapeutics: Research Funding; Regeneron: Research Funding; Affimed: Research Funding; Seattle Genetics: Research Funding; Regeneron: Research Funding; Seattle Genetics: Research Funding; Regeneron: Research Funding; Seattle Genetics: Research Funding; Regeneron: Research Funding; Seattle Genetics: Research Funding; Affimed: Research Funding; Affimed: Research Funding. Bennani:Seattle Genetics: Other: Advisory board; Kite Pharma: Other: Advisory board; Seattle Genetics: Other: Advisory board; Adicet Bio: Other: Advisory board; Seattle Genetics: Other: Advisory board; Purdue Pharma: Other: Advisory board; Adicet Bio: Other: Advisory board; Purdue Pharma: Other: Advisory board; Purdue Pharma: Other: Advisory board; Adicet Bio: Other: Advisory board; Bristol-Myers Squibb: Research Funding; Bristol-Myers Squibb: Research Funding; Kite Pharma: Other: Advisory board; Bristol-Myers Squibb: Research Funding; Kite Pharma: Other: Advisory board. Paludo:Verily Life Sciences: Research Funding; Celgene: Research Funding; Verily Life Sciences: Research Funding; Celgene: Research Funding. Tun:DTRM Biopharma: Research Funding; Mundi-pharma: Research Funding; BMS: Research Funding; Celgene: Research Funding; Curis: Research Funding; TG Therapeutics: Research Funding. Foran:Agios: Honoraria, Research Funding. Kharfan-Dabaja:Daiichi Sankyo: Consultancy; Pharmacyclics: Consultancy.

Introduction Novel high-risk groups have been identified in adult ALL, including secondary (sALL) and Philadelphia-like ALL (Ph-like, based on CRLF2, IgH, ABL2, JAK2 and other tyrosine kinase translocations), and those with minimal residual disease >0.1% (MRD+) after induction therapy. Novel targeted therapies are now routinely incorporated into 1st line regimens, including tyrosine kinase inhibitors (BCR-ABL1-pos), rituximab (CD20+) and blinatumomab (Blina) for MRD+. The impact of these novel high risk groups and therapies after alloHCT is unknown; therefore, we evaluated their impact on overall survival (OS), relapse rate (REL), non-relapse mortality (NRM) and acute and chronic GVHD. Methods We evaluated pts receiving 1st Allo-HCT for ALL at Mayo Clinic (Rochester, Phoenix, and Jacksonville) from 2008-2018 for outcomes of interest, specifically the impact of novel therapies and risk groups. Associations of patient factors with outcomes were examined using univariable (UVA) and multivariable (MVA) Cox proportional hazards regression models, where the cause-specific hazard of the given outcome was modeled to account for the competing risk of death. Results We identified 261 consecutive AlloHCT recipients during the study period. Median age at transplant was 48 years (18-72) and 147 (56.3%) were male. The median comorbidity (HCT-CI) score was 2 (0-8). 213 pts (81.6%) had B-lineage ALL, of which 85 (32.6%) were BCR-ABL-pos, 17 (6.5%) Ph-like (identified by FISH), 16 (6.1%) hypoploidy/near triploidy (Hy/Tri), and 67 (25.7%) pre-B ALL NOS. The remaining 48 (18.4%) had T-ALL. 30 pts (11.5%) had sALL (i.e. prior chemo/radiotherapy for another malignancy). HyperCVAD was the most common 1st line regimen (68.2%). 243 (93.1%) pts achieved Complete Remission (CR1) after induction therapy, and 203 (77.8%) were in CR1 at the time of alloHCT. Blina was administered for MRD+ in 14 pts (5.4%), and for relapsed/refractory ALL (R/R) in 13 (27% of R/R pts), 7 of whom received Blina as initial therapy for R/R. Donors were matched unrelated in 149 (57.1%), matched related in 98 (37.5%), and haploidentical in 14 (5.4%). Peripheral blood (PB) grafts were used in 233 (89.3%). 103 (54.5%) were donor:recipient (D:R) sex-matched, and 86 D:R mismatched [47 (24.9%) M:F; and 39 (20.6%) F:M]. Myeloablative conditioning was used for the majority (78.5%) mostly with Cy/TBI (60.5%). Standard GVHD prophylaxis regimens were used. Outcomes Median follow-up after transplant was 22.4 months (0.5-135), and 51 (19.5%) had REL. The 1, 2 and 5-year survival rates were 71.9%, 64.9%, and 54.1%, respectively (Figure 1). Acute GVHD developed in 144 (55.2%) and chronic GVHD in 100 (38.3%). Ph-like ALL, Blina for MRD+, Blina for R/R, sALL and CD20-pos had no independent impact on OS. In contrast, age>60, Hy/Tri, and >CR1 at alloHCT were associated with worse OS in UVA, however, in MVA only pre-B ALL NOS was associated with better OS. Female:male D:R status was associated with inferior OS. Blina for R/R disease was associated with increased risk of REL in UVA [HR 5.26 95% CI (1.33, 20.00), p=0.017], whereas other novel high risk groups had no impact on REL. In contrast, T-ALL, Hy/Tri and >CR1 at AlloHCT were associated with increased REL in UVA, but only T-ALL and Hy/Tri continued to predict for increased REL in MVA. Secondary ALL was associated with increased NRM in UVA [HR 1.96 95% CI (1.07, 3.57), p=0.028], whereas other novel high risk groups had no impact on NRM. In contrast, age>60, >CR1 at AlloHCT and D:R sex mismatch were associated with higher NRM in UVA, but only sex mismatch and >CR1 at AlloHCT were associated with higher NRM in MVA. TBI use was associated with higher risk of acute GvHD (p=0.008) and ATG use with lower risk chronic GVHD (p<0.001). Similarly non-PB grafts were associated with a lower risk of chronic GVHD (p=0.005). Results for OS, REL, NRM, acute and chronic GVHD analysis are shown in Table 1. Conclusion Novel high risk groups (CD20+, Ph-like and sALL) do not appear to adversely impact OS after alloHCT, although sALL was associated with increased risk of NRM. Interestingly, pre-B-ALL NOS appear to be associated with favorable OS. Novel targeted therapies also do not independently predict outcome, with the exception of Blina for R/R ALL which may be associated with REL after subsequent alloHCT (a subgroup for whom novel maintenance strategies should be explored). Our analysis highlights the importance of allo-HCT for novel high risk ALL subgroups. Disclosures Patnaik: Stem Line Pharmaceuticals.: Membership on an entity's Board of Directors or advisory committees. Kharfan-Dabaja:Daiichi Sankyo: Consultancy; Pharmacyclics: Consultancy. Foran:Agios: Honoraria, Research Funding.

(Text above this line is not copy/pasted in the abstract body) INTRODUCTION Allogeneic HCT using RIC regimens is the standard treatment for patients with relapsed/refractory cHL, however there is significant heterogeneity amongst the different regimens and a lack of data supporting a preferred RIC regimen. Using the CIBMTR database we evaluate the outcomes of the 3 most commonly used RIC regimens for cHL. METHODS In the CIBMTR registry, 492 adult patients underwent a first alloHCT using either a matched related or unrelated donor for cHL between 2008-2016, utilizing a RIC regimen with either fludarabine/ i.v. busulfan (6.4mg/kg) (Flu/Bu, n=102), fludarabine/melphalan 140mg/m^2 (Flu/Mel140, n=318) or fludarabine/cyclophosphamide (Flu/Cy, n=72). Graft-versus-host disease (GVHD) prophylaxis was calcineurin inhibitor (CNI) plus methotrexate, mycophenolate mofitil (MMF) or other agents, however post transplantation cyclophosphamide (post-CY) was excluded. The primary endpoint was overall survival (OS). Secondary endpoints included acute (a) and chronic (c) GVHD, non-relapse mortality (NRM), relapse/progression and progression-free survival (PFS). Probabilities of OS and PFS were calculated using the Kaplan-Meier estimator. Multivariable regression analysis was performed for GVHD, relapse/progression, NRM, PFS, and OS. Covariates with a p<0.01 were considered significant. RESULTS Baseline characteristics are shown in Table 1. The median patient age of the complete study cohort was only 33 years, with more than 80% receiving a prior autologous HCT. On multivariate analysis (Table 2), the 3 conditioning regimen cohorts were not statistically different in either risk of cGVHD nor risk of grade 3-4 aGVHD. No significant differences were seen in the NRM risk between the three regimens (p=0.54). Similarly, the risk of relapse (p=0.02) and PFS was comparable between regimens (p=0.14). Flu/Cy conditioning was associated with decreased risk of mortality in first 11months after alloHCT (OR 0.28, 95% CI 0.10-0.73, p=0.009, but beyond 11 months post alloHCT it was associated with a significantly higher risk of mortality, (OR 2.46, 95% CI 0.1.32-4.61, p=0.005; Figure 1) [11months post alloHCT cutoff chosen on the basis of the maximum likelihood value in the Cox model]. Four year adjusted PFS and OS were similar across the three regimens at 29% for Flu/Bu, 37% for Flu/Mel140 and 25% for Flu/Cy (p=0.07) for PFS and 62% for Flu/Bu, 59% for Flu/Mel140 and 55% for Flu/Cy (p=0.64) for OS, respectively. Relapse was the most common cause of death across all the regimens, followed by organ failure and GVHD. CONCLUSIONS The most commonly used RIC regimen in alloHCT for cHL is Flu/Mel140, which was compared to Flu/Bu and Flu/Cy, the next most frequently used regimens. The choice of conditioning regimen, in these young cHL patients (median age 33 years) did not confer any benefit in terms of the risk of relapse, decrease in NRM or improvement in PFS. There was no OS benefit between, Flu/Bu and Flu/Mel 140, but Flu/Cy was associated with a significantly higher risk of mortality in patients beyond 11 months from allo-HCT. Novel approaches are still needed to decrease post-HCT relapse risk and improve overall results. Figure 1 Disclosures Ghosh: Seattle Genetics: Consultancy, Speakers Bureau; Genentech: Research Funding; Gilead/Kite: Consultancy, Speakers Bureau; Pharmacyclics: Consultancy, Research Funding, Speakers Bureau; T G Therapeutics: Consultancy, Research Funding; Celgene: Consultancy, Research Funding, Speakers Bureau; Forty Seven Inc: Research Funding; Spectrum: Consultancy, Speakers Bureau; AbbVie: Consultancy, Speakers Bureau; Astra Zeneca: Speakers Bureau. Kharfan-Dabaja:Daiichi Sankyo: Consultancy; Pharmacyclics: Consultancy. Sureda:Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel Support; Gilead: Honoraria; Novartis: Honoraria; Amgen: Membership on an entity's Board of Directors or advisory committees; BMS: Honoraria; Roche: Honoraria; Sanofi: Honoraria; Takeda: Consultancy, Honoraria, Speakers Bureau; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees. Hamadani:Merck: Research Funding; Janssen: Consultancy; Otsuka: Research Funding; Takeda: Research Funding; Medimmune: Consultancy, Research Funding; ADC Therapeutics: Consultancy, Research Funding; Celgene: Consultancy; Sanofi Genzyme: Research Funding, Speakers Bureau; Pharmacyclics: Consultancy.

Background: Axicabtagene ciloleucel (axi-cel) is an autologous anti-CD19 chimeric antigen receptor (CAR) T cell therapy approved for the treatment of adult patients who have relapsed/refractory large B cell lymphoma (LBCL) and have had ≥ 2 prior systemic therapies. In ZUMA-1, the registrational study of axi-cel in patients with refractory LBCL, the objective response rate was 83% (complete response rate, 58%), with ongoing responses in 39% after a median follow-up of 27.1 months (Locke FL, et al. Lancet Oncol. 2019). Despite the success of axi-cel, approximately 60% of patients have no response or relapse after treatment, indicating that additional strategies are needed for patients with relapsed/refractory LBCL. Preclinical murine studies have shown that rituximab augmented the tumor-suppressing effects of anti-CD19 CAR T cells, and the combination led to higher rates of tumor reduction (Mihara K, et al. Br J Haematol. 2010; Rufener GA, et al. Cancer Immunol Res. 2016). The IMiD® immunomodulatory agent lenalidomide has shown activity in patients with relapsed/refractory diffuse large B cell lymphoma and has also been shown to enhance the antitumor functions of anti-CD19 and anti-CD20 CAR T cells in mice (Otahal P, et al. Oncoimmunology. 2016). In ZUMA-14, the aim is to investigate the efficacy and safety of axi-cel in combination with rituximab or lenalidomide in adult patients with refractory LBCL. Methods: This Phase 2 study (NCT04002401) has a planned enrollment of approximately 60 patients aged ≥ 18 years with refractory LBCL, defined as a response of either progressive disease or stable disease to previous chemotherapy or progressive disease or relapse ≤ 12 months after an autologous stem cell transplant. Patients with prior IMiD® treatment, including lenalidomide, prior CAR T cell therapy, and/or prior CD19-targeted therapy are excluded. After leukapheresis, patients will be assigned 1:1 to receive axi-cel with either rituximab (Cohort 1) or lenalidomide (Cohort 2). Patients will receive lymphodepleting chemotherapy of fludarabine (30 mg/m2) and cyclophosphamide (500 mg/m2) on days -5 to -3 before axi-cel infusion (2 × 106 cells/kg) on Day 0. Cohort 1 will receive rituximab (375 mg/m2) every 28 days starting on Day -5 for a total of 6 doses. Cohort 2 will receive lenalidomide (10 mg) daily starting 7 days after leukapheresis through Day 3 and for 5 additional cycles (20 mg, first 21 days of each 28-day cycle) beginning after axi-cel infusion starting on Day 21. Patients may not receive any therapy other than conditioning therapy and rituximab or lenalidomide, as specified by cohort, between leukapheresis and axi-cel infusion. The primary endpoint is investigator-assessed complete response rate per the Lugano classification (Cheson BD, et al. J Clin Oncol. 2014). Key secondary endpoints include safety, objective response rate, duration of response, progression-free survival, overall survival, and pharmacokinetics (levels of blood CAR T cells over time). Exploratory endpoints for both cohorts include pharmacodynamic assessment of cytokine profiles and the rate of CD19-negative relapses. An additional exploratory endpoint for Cohort 2 is to investigate immunomodulation of the tumor microenvironment, including the number and activation of T cells and natural killer cells. Enrollment is expected to start in September 2019. Disclosures Neelapu: Cell Medica: Consultancy; Pfizer: Consultancy; BMS: Research Funding; Kite, a Gilead Company: Consultancy, Research Funding; Novartis: Consultancy; Precision Biosciences: Consultancy; Acerta: Research Funding; Karus: Research Funding; Incyte: Consultancy; Merck: Consultancy, Research Funding; Unum Therapeutics: Consultancy, Research Funding; Celgene: Consultancy, Research Funding; Cellectis: Research Funding; Allogene: Consultancy; Poseida: Research Funding. Kharfan-Dabaja:Daiichi Sankyo: Consultancy; Pharmacyclics: Consultancy. Oluwole:Pfizer: Consultancy; Spectrum: Consultancy; Gilead Sciences: Consultancy; Bayer: Consultancy. Krish:Celgene: Consultancy, Research Funding, Speakers Bureau; Genetech: Consultancy, Speakers Bureau; Pharmacyclics: Consultancy, Research Funding, Speakers Bureau; Takeda: Research Funding; Curis: Research Funding; MEI Pharma: Research Funding; Bristol Meyers Squibb: Research Funding; Xencor: Research Funding; Roche: Research Funding; AstraZeneca: Consultancy, Research Funding, Speakers Bureau; Sunesis: Consultancy, Research Funding. Reshef:BMS: Consultancy; Shire: Research Funding; Incyte: Consultancy, Research Funding; Kite, a Gilead Company: Consultancy, Honoraria, Research Funding; Atara: Consultancy, Research Funding; Magenta: Consultancy; Pfizer: Consultancy; Pharmacyclics: Consultancy, Research Funding; Celgene: Research Funding. Riedell:Bayer: Honoraria, Speakers Bureau; Kite/Gilead: Honoraria, Research Funding, Speakers Bureau; Verastem: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Research Funding. Stiff:Amgen: Research Funding; Gamida-Cell: Research Funding; Incyte: Research Funding; Cellectar: Research Funding; Unum: Research Funding; Gilead/Kite Pharma: Consultancy, Honoraria, Research Funding. Goyal:Kite, a Gilead Company: Employment. Kawashima:Kite, a Gilead Company: Employment, Equity Ownership. Milletti:Roche: Employment, Equity Ownership, Other: Travel Expenses, Patents & Royalties; Gilead: Employment, Equity Ownership, Other: Travel Expenses, Patents & Royalties; Kite, a Gilead Company: Employment. Oliva:Kite, a Gilead Company: Employment. Sun:Kite, A Gilead Company: Employment. Munoz:Pharmacyclics /Janssen: Consultancy, Research Funding, Speakers Bureau; Bayer: Consultancy, Speakers Bureau; Merck: Consultancy; Kyowa: Consultancy, Honoraria, Speakers Bureau; Seattle Genetics: Consultancy, Honoraria, Research Funding, Speakers Bureau; Celgene/Juno: Consultancy, Research Funding; Genentech: Consultancy, Research Funding, Speakers Bureau; Kite/Gilead: Consultancy, Research Funding, Speakers Bureau; Bristol-Myers Squibb: Consultancy; Alexion: Consultancy; Pfizer: Consultancy; Fosunkite: Speakers Bureau; AstraZeneca: Speakers Bureau; Portola: Research Funding; Incyte: Research Funding. OffLabel Disclosure: ZUMA-14 is a clinical trial evaluating the investigational combination of axicabtagene ciloleucel with either rituximab or lenalidomide in refractory large B cell lymphoma