Ahn, Kwang Woo

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: Allogeneic hematopoietic stem cell transplantation (HSCT) is currently the only potentially curative therapy in eligible patients with myelodysplastic syndromes (MDS). Reduced-intensity conditioning (RIC) regimens that have been developed to extend HSCT to older patients resulted in encouraging outcomes. However, several retrospective studies have raised concerns about disease control when RIC is used in MDS and the ideal conditioning regimen has not yet been found. In this study, we aimed to compare two most commonly used RIC regimens; intravenous use of fludarabine with busulfan (FluBu) and fludarabine with melphalan (FluMel). Study population: Through the CIBMTR, after excluding patients with ex-vivo T cell depletion, we identified 1045 MDS patients aged ≥ 60 years and underwent first HSCT with matched related or matched (8/8) unrelated donor (MRD and MUD) using RIC between 2007-2016. RIC was defined via CIBMTR criteria as a regimen that incorporated an IV busulfan (BU) total dose ≤ 7.2 mg/kg or low-dose melphalan (MEL) total dose ≤ 150 mg/m2. By that, we identified 697 MDS patients who received FluBu (BU 6.4 mg/kg: 87%, BU 3.2 mg/kg: 13%) and 448 receiving FluMel (MEL 140 mg/m2: 80%, MEL 100 mg/m2: 20%). Results: The two groups, FluBu and FluMel, were comparable for disease and transplant related characteristics except the more frequent use of ATG or Campath in FluBu group (39% vs. 31%). The median age was 67 in both groups, and 26% and 19% of FluBu and FluMel groups were aged ³70, respectively. Hematopoietic comorbidity index (HCT-CI) was ³3 in 61% and 59% of FluBu and FluMel groups and MDS risk score by CIBMTR at HCT was high/very high in 34% in both groups. FluMel was associated with a reduced relapse incidence (RI) after HSCT compared with FluBu as presented in Table 1 and Table 2. Adjusted RI at 1-year was 43% with FluBu and 25% with FluMel (p=&lt;0.0001). On the other hand, transplant related mortality (TRM) was higher with FluMel compared with FluBu (27% vs. 15%, p=&lt;0.0001). The difference persisted at 2- and 3-years after HSCT as presented in the figure. Since the magnitude of improvement in RI was greater with FluMel than the improvement in TRM with FluBu, disease-free survival (DFS) was improved at 1-year and beyond with FluMel compared with FluBu (48% vs. 41% at 1-year, p=0.030, and 38% vs 28% at 3-years, p=0.0030). These outcome differences remained significant when sensitivity analyses were performed excluding patients who received RIC with either BU 3.2 mg/kg or Mel 100 mg/m2. FluMel, did not lead to higher incidence of severe grade 3-4 aGvHD (HR=1.2, 95%CI, 0.9-1.6, p=0.3) or chronic GvHD (HR=0.9, 95%CI=0.7-1.06, p=0.2). However, grade 2-4 aGVHD was observed more often with FluMel than FluBu (HR=1.3, 95%CI, 1.1-1.6, p=0.006). This led to inferior outcomes of GRFS within the first 2 months with FluMel (HR=1.9, HR=1.4-2.6, p&lt;0.001) but superior outcomes of GRFS beyond 2 months with FluMel compared with FluBu (HR=0.7, 95%CI=0.6-0.8, p&lt;0.001). Conclusion: Our results suggest that between the two most commonly used RIC regimens in older MDS patients, FluMel was associated with superior DFS and overall survival compared with FluBu due to reduced RI despite higher TRM. Disclosures Oran: AROG pharmaceuticals: Research Funding; Astex pharmaceuticals: Research Funding. Nakamura:Kirin Kyowa: Other: support for an academic seminar in a university in Japan; Alexion: Other: support to a lecture at a Japan Society of Transfusion/Cellular Therapy meeting ; Celgene: Other: support for an academic seminar in a university in Japan; Merck: Membership on an entity's Board of Directors or advisory committees. Scott:Celgene Corporation: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Alexion: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Novartis: Research Funding; Incyte: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Agios: Speakers Bureau. Popat:Jazz: Consultancy; Incyte: Research Funding; Bayer: Research Funding.

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.

(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.

Abstract Introduction: Allogeneic hematopoietic stem cell transplantation (HCT) is the only curative therapy for myelofibrosis (MF). Consideration of HCT is recommended by international working groups and national guidelines for MF patients (pts) age <70 with intermediate-1 with adverse indicators, intermediate-2 or high-risk disease by the Dynamic International Prognostic Scoring System (DIPSS) for MF- a recommendation made in the absence of clear data indicating the optimal timing of HCT for MF. In this large multicenter retrospective study, we analyze overall survival in MF pts treated with and without HCT. Methods: Disease characteristics, treatments, and outcome data from MF pts receiving non-transplant therapy at 14 US academic medical centers between 2000-2014 were retrospectively collected. MF pts who underwent HCT were identified from the Center for International Blood and Marrow Transplant Research (CIBMTR). The Cox proportional hazards model was used. The reference time point (time zero) was time of referral for the non-transplant (non-HCT) arm and the time of transplant for the HCT arm. The main effect variable (HCT vs. non-HCT) violated the proportionality assumption where comparing to non-HCT, mortality was higher with HCT in early time period from time zero but then was lower in late time period; therefore, the comparison is presented as early time period and late time period. The Cox model identified 14 months from time zero as the ideal cut point to define early and late time periods. The proportionality assumption is satisfied within each of these two periods. Results: A total of 1377 and 551 pts were included in the non-HCT and HCT arms, respectively (Table 1). In the overall cohort, survival was higher with non-HCT vs. HCT in early time period (relative risk [RR]: 0.34, P< .0001, Figure 1D), but in late time period survival was lower with non-HCT vs. HCT (RR: 2.37, P< 0.001) (Table 2). In the DIPSS low-risk MF group, while survival was higher with non-HCT vs. HCT in the early time period (RR: 0.19, P=0.007, Figure 1A), survival was lower with non-HCT in the late time period, but the latter did not reach statistical significance (RR: 1.45, P=0.39). In the DIPSS intermediate-1 risk group, a survival advantage was present with non-HCT treatments vs. HCT in the early time period (RR: 0.27, P < .0001, Figure 1B), however survival was lower with non-HCT in the late time period (RR: 3.13, P < .0001). Similarly, in those with DIPSS intermediate-2 and high-risk MF, survival advantage was observed with non-HCT in the early time period (RR: 0.41, P< .0001, Figure IC), but survival was lower with non-HCT in the late time period (RR: 2.82, P < .0001). Conclusion: A long-term survival advantage with transplant was observed for pts with intermediate-1 or higher risk MF, but at the cost of potential early mortality. The magnitude of benefit increased as DIPSS risk score increased. Although this retrospective study has limitations, the results have an impact on clinical practice by suggesting that transplantation could be considered earlier in the disease course and supports the recommendation for consideration of HCT in the setting of intermediate-1 risk MF. Disclosures Gowin: Incyte: Consultancy, Other: Scientific Advisory Board, Speakers Bureau. Verstovsek:Celgene: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Incyte: Consultancy; Italfarmaco: Membership on an entity's Board of Directors or advisory committees. Ali:Incyte Corporation: Membership on an entity's Board of Directors or advisory committees. Gupta:Novartis: Consultancy, Honoraria, Research Funding; Incyte: Research Funding. Gerds:Celgene: Consultancy; Apexx Oncology: Consultancy; CTI Biopharma: Consultancy; Incyte: Consultancy.

Abstract Introduction: AITL is a distinct clinicopathologic entity among the mature T-cell and NK-cell lymphomas, accounting for approximately 1-2% of all non-Hodgkin lymphomas. Although autologous HCT (auto-HCT) provides high response rates, there is a high relapse risk associated with this procedure. Allo-HCT may result in a lower risk of relapse in part due to a graft-versus-lymphoma effect mediated by alloreactive donor cells. The role of allo-HCT in AITL with advanced disease (prior auto-HCT failure, or chemorefractory state) is not well described. Using the CIBMTR registry, we report here the outcomes of AITL patients undergoing an allo-HCT. Methods: We evaluated 249 adult (≥18years) patients with AITL who received a first allo-HCT during 2000-2016. Patients receiving mismatched unrelated donor, cord blood or haploidentical donor transplantation were excluded due to small numbers. The primary end-point was overall survival (OS). Secondary endpoints included cumulative incidence of acute graft-versus-host disease (GVHD), chronic GVHD, non-relapse mortality (NRM), relapse/progression (R/P) and progression-free survival (PFS). Results: Baseline patient characteristics are summarized in Table. The median patient age was 56 years (range=21-77 years). The graft source was mainly peripheral blood. Median follow-up of survivors was 49 months (range=4-170 months). The cumulative incidence of grade 2-4 and grade 3-4 acute GVHD at day 180 were 36% (95% CI=30-42)% and 12 (95% CI=8-17)%, respectively. The cumulative incidence of chronic GVHD at 2 years was 58% (95% CI=51-64)%. The 1-year NRM was 19% (95% CI=14-24)%, while the 4-year R/P, PFS, and OS were 21% (95% CI=16-27)%, 49% (95% CI=42-56)% and 56% (95% CI=49-63)%, respectively [Figure]. On multivariate analysis, chemoresistant status at allo-HCT was associated with a significantly higher risk for progression (RR=1.73 95% CI=1.08-2.77), while KPS <90% was associated with a significantly higher risk of mortality (RR=3.46 95% CI=1.75 - 6.87). Subgroup analysis looking at the effect of prior auto-HCT (no prior auto-HCT vs prior auto-HCT), the 4-year PFS (50% vs 47%, p=0.60) and OS (57% vs 54%, p=0.70) were not significantly different. Similarly, on comparing the disease status at allo-HCT (CR1 vs CR>1 vs PR vs refractory), there was no significant difference in the 4-year PFS (58% vs 45% vs 47% vs 38%, p=0.41) or OS (70% vs 54% vs 50% vs 52%, p=0.27). The 1-year NRM was 24%, while the 4-year R/P, PFS, and OS in patients with refractory AITL were 32%, 38%, and 52%, respectively. The most common cause of death was organ failure. Conclusion: In this largest series of mostly advanced AITL patients, allo-HCT was shown to provide durable disease control (4-year PFS=47%) with a clear plateau in relapse at 1-year post-transplantation. Allo-HCT provided durable disease control even in patients with a failed prior auto-HCT and those subjects with refractory disease at the time of allografting. Disclosures Kharfan-Dabaja: Alexion Pharmaceuticals: Speakers Bureau; Incyte Corp: Speakers Bureau; Seattle Genetics: Speakers Bureau. Smith:BMS: Consultancy; Portola: Honoraria. Sureda:Sanofi: Honoraria; Takeda: Consultancy, Honoraria, Speakers Bureau; Merck: Consultancy, Honoraria; Roche: Honoraria; BMS: Consultancy, Honoraria. Hamadani:Merck: Research Funding; Celgene Corporation: Consultancy; ADC Therapeutics: Research Funding; Sanofi Genzyme: Research Funding, Speakers Bureau; Ostuka: Research Funding; Janssen: Consultancy; MedImmune: Consultancy, Research Funding; Takeda: Research Funding; Cellerant: Consultancy.

Abstract Purpose: To develop a prognostic model and cytogenetic risk classification for previously treated patients with chronic lymphocytic leukemia (CLL) undergoing reduced intensity conditioning (RIC) allogeneic hematopoietic cell transplantation (HCT). Experimental Design: We performed a retrospective analysis of outcomes of 606 patients with CLL who underwent RIC allogeneic HCT between 2008 and 2014 reported to the Center for International Blood and Marrow Transplant Research. Results: On the basis of multivariable models, disease status, comorbidity index, lymphocyte count, and white blood cell count at HCT were selected for the development of prognostic model. Using the prognostic score, we stratified patients into low-, intermediate-, high-, and very-high-risk [4-year progression-free survival (PFS) 58%, 42%, 33%, and 25%, respectively, P &lt; 0.0001; 4-year overall survival (OS) 70%, 57%, 54%, and 38%, respectively, P &lt; 0.0001]. We also evaluated karyotypic abnormalities together with del(17p) and found that del(17p) or ≥5 abnormalities showed inferior PFS. Using a multivariable model, we classified cytogenetic risk into low, intermediate, and high (P &lt; 0.0001). When the prognostic score and cytogenetic risk were combined, patients with low prognostic score and low cytogenetic risk had prolonged PFS (61% at 4 years) and OS (75% at 4 years). Conclusions: In this large cohort of patients with previously treated CLL who underwent RIC HCT, we developed a robust prognostic scoring system of HCT outcomes and a novel cytogenetic-based risk stratification system. These prognostic models can be used for counseling patients, comparing data across studies, and providing a benchmark for future interventions. For future study, we will further validate these models for patients receiving targeted therapies prior to HCT.