Micallef, Ivana N.

e19501 Background: The current standard of care for patients with relapsed or refractory (RR) diffuse large B-cell lymphoma (DLBCL) following frontline immunochemotherapy (IC) is salvage therapy, followed by high-dose chemotherapy and autologous stem cell transplant (ASCT) rescue in patients responding to salvage therapy. Time to first relapse (or refractory status) and response to salvage therapy in patients with RR DLBCL may reflect the chemosensitivity of the underlying disease. The aim of this study is to determine whether these factors impact post-ASCT outcomes. Methods: Patients with DLBCL that relapsed after R-CHOP or R-CHOP-like frontline therapy who underwent salvage therapy and ASCT at Mayo Clinic or University of Iowa between 07/2000 and 4/2020 were identified from institutional lymphoma and transplant databases. Clinical characteristics, treatment information, and outcome data were abstracted. Progression-free survival (PFS) and overall survival (OS) from the time of ASCT were analyzed using Kaplan-Meier method and Cox proportional hazards models. Results: A total of 437 patients with RR DLBCL who underwent salvage therapy and ASCT were identified. 280 (64%) were male. Median time from initial diagnosis to 1st relapse/salvage was 1.0 years (range 0.1-16.4). A median of 1 line (range 1-3) of salvage therapy was required. Response prior to ASCT was complete response (CR) in 211 (48%), partial response in 199 (46%), stable disease in 24 (5%), and unknown in 3 (1%) patients. Median age at ASCT was 61 years (range 19-78), and median follow up after ASCT was 8.0 years (95% CI 7.2-8.7). Median PFS and OS was 2.7 (95% CI 1.5-4.3) and 5.4 (4.2-7.4) years, respectively. Time to 1st relapse/salvage (≤1 vs 1-2 vs > 2 years) was not associated with PFS (median 0.8 vs 2.4 vs 4.9 years, p = 0.170) but was associated with OS (2.4 vs 7.4 vs 6.8 years, p = 0.013). Patients who required > 1 line of salvage therapy had significantly inferior PFS (median 0.3 vs 4.5 years, p < 0.001) and OS (0.9 vs 7.4 years, p < 0.001). In addition, patients who failed to achieve a CR prior to ASCT had significantly worse PFS (median 0.8 vs 5.3 years, p < 0.001) and OS (2.7 vs 9.2 years, p < 0.001). In multivariate Cox regression models adjusted for age and sex, time to 1st relapse/salvage was not associated with PFS (p = 0.313) or OS (p = 0.081); however, lines of salvage and response prior to ASCT remain significantly prognostic for PFS ( > 1 line of salvage: HR 2.14, 95% CI 1.59-2.87, p < 0.001; non-CR: HR 1.61, 95% CI 1.26-2.05, p < 0.001) and OS ( > 1 line of salvage: HR 2.25, 95% CI 1.66-3.05, p < 0.001; non-CR: HR 1.63, 95% CI 1.26-2.12, p < 0.001). Conclusions: In patients with RR DLBCL following frontline IC, requiring more than 1 line of salvage therapy and failure to achieve CR are strong independent risk factors for poor PFS and OS after ASCT. Novel therapies such as CAR-T cell therapy should be studied in this population.

7542 Background: 60-70% of patients with newly diagnosed diffuse large B-cell lymphoma (DLBCL) can be cured with R-CHOP or R-CHOP-like immunochemotherapy. However, patients ≥80 years of age were either excluded or underrepresented in modern DLBCL trials, and their outcomes are understudied. The aim of this study is to define the survival trends and risk factors for inferior survival in older adult patients with DLBCL. Methods: Patients with newly diagnosed DLBCL were identified from the National Cancer Database (2004-2017, representing the rituximab era). Clinical characteristics, treatment, and outcomes were compared between patients ages ≥ 80, 65-79, and < 65 years. The Kaplan-Meier method and Cox proportional hazards model were used for survival analysis. Results: A total of 231,756 patients with newly diagnosed DLBCL were identified; 46,250 (20%) were ≥80 years, 87,702 (38%) were 65-79 years, and 97,904 (42%) were < 65 years. Patients ≥80 years were more likely to have a higher Charlson-Deyo Comorbidity Index score (CDS) (CDS ≥2, 12% vs 11% vs 8%, p = 0.001), less likely to receive systemic chemotherapy (63% vs 83% vs 89%, p < 0.001), and more likely to receive treatment at a non-academic center (71% vs 65% vs 48%, p < 0.001), compared to patients 65-79 and < 65 years, respectively. Median overall survival (OS) was significantly worse for patients ≥80 years compared to patients 65-79 years (11.6 vs 61.0 months, p = 0.001) and patients < 65 years (11.6 vs 178.1 months, p = 0.001). During the study period, the median OS had only minimally improved for patients ≥80 years (10.6 months in 2004-2007 vs 11.5 months in 2008-2011 vs 12.3 months in 2012-2016, p = 0.006). In contrast, the OS improvement appears more meaningful in patients 65-79 years (median in months: 51 vs 61.2 vs 65.9, p = < 0.001) and patients < 65 years (median in years: 14.6 vs 11.3 vs not reached, p < 0.001) in the prespecified intervals (2004-07, 2008-11, and 2012-16). In multivariate analysis, the most substantial risk factor for worse survival in patients ≥80 years was not receiving systemic therapy (hazard ratio [HR] = 3.26, 95%CI = 3.01-3.54, p = 0.001). Other risk factors associated with worse survival included high-risk IPI score (HR = 2.16, 95%CI = 1.96-2.39, p = 0.001), CDS score ≥2 (HR = 1.56, 95%CI = 1.40-1.73, p = 0.001), male sex (HR = 1.16, 95%CI = 1.09-1.24, p = 0.001), B symptoms at diagnosis (HR = 1.16, 95%CI = 1.08-1.25, p = 0.001), and treatment at a non-academic center (HR = 1.1, 95%CI = 1.01-1.20, p = 0.001). Conclusions: Patients ≥ 80 years of age with DLBCL have a significantly inferior survival which has not meaningfully improved in recent years. More than 1/3 of patients ≥ 80 years did not receive systemic therapy. Older adult patients with DLBCL should be assessed for fitness for chemotherapy using validated geriatric assessment tools. Novel therapeutic strategies with favorable safety profiles are urgently needed for this expanding patient population.

7530 Background: Clinical trials of novel salvage therapies (ST) have encouraging outcomes for relapsed/refractory classic Hodgkin lymphoma (R/R cHL) eligible for autologous stem cell transplant (ASCT). In this observational study, we report efficacies and outcomes of different ST in ASCT-eligible R/R cHL. Methods: Consecutive ASCT-eligible R/R cHL pts at 3 Mayo Clinic sites were included. Demographics and clinical variables at relapse were recorded by medical records review. Time to event endpoints were defined from relapse. Univariate associations were confirmed in multivariate models of age, sex, B symptoms, stage, bulky disease (BD, single mass > 6 cm) extra nodal disease (END), primary refractory disease (PRD) and early relapse (ER, within 1 year). Results: From Jan 2008 to May 2020, 207 ASCT-eligible pts with R/R cHL were included. Median age was 33 (24-43) years, 53% were male, 52% had advanced stage, 24% had BD, 36% had B symptoms, 41% had END, 11% had PRD and 43% had ER. All patients received ST and underwent ASCT; 43 (21%) received 2 ST, 14 (7%) 3 ST and 4 (0.5%) received 4 ST. 6 groups of ST were identified: ifosfamide, carboplatin and etoposide (ICE), bendamustine/brentuximab (BBV), brentuximab vedotin (BV), gemcitabine-based therapy (Gem), checkpoint inhibitor (CPI), and others. Table lists response to first line ST. BBV had significantly higher overall response rate (ORR) and complete response (CR) as first ST in univariate and multivariate models. 114 (79%) after ICE, 30 (97%) after BBV, 15 (56%) after BV, 25 (76%) after Gem, 8 (73%) after CPI and 15 (79%) after other ST underwent ASCT. Higher number of pts were bridged to ASCT after BBV than ICE (p<0.01). 110 (53%) went to ASCT in CR, 74 (36%) in partial response (PR) and 11% in progressive disease (PD). 43 received BV maintenance (BVm) after ASCT. Pts going to ASCT in PR or PD had significantly lower progression free survival (PFS) compared to pts in CR (2 yr PFS: 62%, 18% vs 77%, respectively, p<0.0001) in univariate and multivariate models. There was no difference in PFS and overall survival (OS) by type of ST. BVm was associated with higher PFS (HR 0.3 (CI95 0.2-0.8)) and higher number of ST was associated with lower OS (HR 2 (CI95 1.4-3)) in multivariate model (p<0.001). For pts transplanted in CR, there was no significant difference in PFS and OS by type of ST but higher number of ST predicted lower OS (HR 2.4 (CI95 1.2-3.5), p<0.01). Conclusions: Type of ST did not predict survival, response to and number of ST did. For pts with CR, number of ST not type of ST predicted survival. BBV had higher response rates, higher rates of bridge to ASCT, and may be a preferable ST than ICE. Large, randomized trials are needed to evaluate efficacy of BBV compared to ICE.[Table: see text]

7522 Background: Patients with newly diagnoseddiffuse large B-cell lymphoma (DLBCL) who achieve event-free survival at 24 months (EFS24) following immunochemotherapy (IC) have excellent overall survival (OS) similar to that of age- and sex-matched general population. The standard of care for patients with relapsed or refractory (RR) DLBCL following frontline IC is salvage therapy followed by autologous stem cell transplant (ASCT). The goal of this study is to evaluate the role of progression-free survival (PFS) at 24 months (PFS24) as a landmark after ASCT in patients with RR DLBCL. Methods: Patients with RR DLBCL after frontline R-CHOP or R-CHOP-like IC who underwent salvage therapy and ASCT at Mayo Clinic or University of Iowa between 07/2000 and 4/2020 were identified from institutional lymphoma transplant databases. Clinical characteristics, treatment information, and outcome data were abstracted. Post-ASCT PFS, OS, and post-relapse survival (PRS) were plotted by Kaplan-Meier method, and cumulative incidences of relapse vs non-relapse mortality (NRM) and different causes of death were compared accounting for competing events. Statistical analyses were performed in EZR v1.54. Results: A total of 437 patients were identified. Median age at ASCT was 61 years (range 19-78), and 280 (64%) were male. After a median post-ASCT follow up of 8.0 years (95% CI 7.2-8.7), 215 patients had a relapse (or disease progression), 180 within 2 years and 35 after 2 years. For the entire cohort, post-ASCT relapse rate was much higher than NRM rate (48.1 vs 9.1% at 5-year). Median PFS and OS after ASCT was 2.7 and 5.4 years, respectively. Lymphoma was the primary cause of death after ASCT. In contrast, for patients who had achieved PFS24 (n = 220), rates of post-PFS24 relapse and NRM were similar (14.8% and 12.3% at 5-year). Median PFS and OS after achieving PFS24 was 10.0 and 11.5 years, respectively. Lymphoma related and unrelated death rates were similar after achieving PFS24 (Table). For all patients who had a post-ASCT relapse, median PRS was 0.7 years (95% CI 0.5-0.9), and late relapse ( > 2 vs ≤2 years after ASCT) was associated with better PRS (median 2.3 [1.7-4.8] vs 0.5 [0.3-0.7] years, p < 0.001). Conclusions: Post-ASCT PFS24 is an important prognostic predictor of post-ASCT outcomes in patients with RR DLBCL following frontline IC.[Table: see text]

e19527 Background: While extra nodal involvement by MCL is relatively common, involvement of the central nervous system (CNS) is a rare ( < 5% of cases) complication with limited treatment options. We report the outcomes of a large cohort of patients (pts) with CNS MCL. Methods: MCL pts with CNS involvement seen at Mayo Clinic between 1/1/1995-9/16/2020 were identified. CNS involvement was defined by histologically confirmed CNS MCL, CSF analysis demonstrating lymphoma cells, and/or neuroimaging findings compatible with CNS lymphoma. Medical records were reviewed for baseline characteristics, treatment, and outcome. Kaplan-Meier method was used for time to event analysis. Results: Out of 1,753 pts with MCL, 36 (2%) had CNS involvement by MCL. Median age at MCL diagnosis was 64 years (range 36-83) and 26 were male (72%). At MCL diagnosis, non-CNS extranodal involvement was seen in 30 pts, 24 with 1 site and 6 with ≥ 2 sites; 24 had bone marrow involvement. 11 (31%) pts had blastoid variant. Median Ki-67 was 40% (range 15-100%). MIPI score was available in 17 pts [low risk (n = 5, 29%), intermediate risk (n = 9, 53%), high risk (n = 3, 18%)]. The most common frontline regimen for MCL was R-CHOP and 14 (39%) pts underwent autologous stem cell transplant in CR1. The incidence of CNS involvement was overall similar over the study period. Median time from MCL diagnosis to CNS involvement was 25 months (m) (range 0-167). 4 (11%) pts presented with CNS involvement at initial diagnosis and 32 presented at relapse (12 isolated CNS relapse and 20 concurrent CNS and systemic relapse. Abnormal CSF was noted in 27 (87%) pts [consistent with MCL diagnosis (n = 26), atypical lymphocytes (n = 1)]. Abnormal CNS imaging was reported in 27 (75%) pts [leptomeningeal (n = 18), leptomeningeal and parenchymal (n = 5), parenchymal (n = 2), ocular (n = 2)]. First line CNS-directed therapy data was available in 33 (92%) pts. 12 (34%) received intrathecal (IT) therapy alone, 19 (54%) received systemic +/- IT therapy, 2 (6%) received radiation alone, and 2 (6%) pts received no treatment (hospice). The overall CNS response to therapy was CR in 13 (42%) pts, PR in 3 (10%), SD in 8 (26%), and PD in 7 (22%) pts. Three pts received BTK inhibitors [ibrutinib (n = 2) or acalabrutinib (n = 1)] as the first CNS-directed therapy. One patient achieved a CR with a response lasting 4 m, another patient achieved a PR with response lasting 10 m. CNS response data was not available in the remaining pts. Median follow up from CNS involvement was 72 m (95% CI: 41-NR). Median EFS for the 1 st CNS-directed therapy was 3.7 m (95% CI: 1.6-6.1). At last follow up, 30 pts were deceased. The cause of death was CNS lymphoma in 10 (33%) pts and systemic lymphoma in 9 (30%) pts. Median OS from CNS involvement was 4.7 m (95% CI: 2.3-6.7). Conclusions: CNS involvement by MCL has dismal outcomes as evident by a median OS of approximately 5 m. BTK inhibitors may have a role in treatment of this rare complication, but further prospective investigation is needed.

AbstractNeurolymphomatosis (NL) is a rare manifestation of lymphoma, with limited evidence for optimal management. The largest patient series, 50 cases of lymphoma and leukemia, was published in 2010 with limited rituximab exposure. This study aims to evaluate the clinical presentation, diagnostic testing, and outcomes of NL in the rituximab era. Forty biopsy-proven cases of NL, in association with non-Hodgkin lymphoma (NHL), at the Mayo Clinic were retrospectively evaluated. B-cell NHL was associated with 97% of NL cases, of which diffuse large B-cell lymphoma (DLBCL) was the most common (68%). Primary NL, defined as neural involvement present at the time of diagnosis of lymphoma, was noted in 52% cases. Seventy percent of patients presented with sensorimotor weakness and neuropathic pain. Magnetic resonance imaging (MRI) was positive in 100% patients. Overall survival (OS) was significantly better for primary NL and NL associated with indolent lymphomas. Relapses were seen in 60% (24/40) of patients; 75% involved the peripheral or central nervous system at relapse. The use of rituximab in the frontline setting significantly impacted progression-free survival (PFS). Transplant consolidation was noted to be associated with improved OS. This study adds to the available literature on NL in the rituximab era. The overall outcomes have improved in recent years. In our experience, MRI and positron emission tomography/computed tomography may be required for accurate assessment of the extent of disease involvement and identification of an optimal biopsy site. The use of rituximab was associated with improvement in PFS, and autologous stem cell transplant was associated with OS.

Background: Anti CD-19 chimeric antigen receptor T-cell therapy (CAR-T) is approved to treat relapsed/refractory (R/R) aggressive NHL after 2 or more lines of therapy. Randomized clinical trials are ongoing comparing CAR-T and autologous stem cell transplant (ASCT) in second line. In standard of care practice, patients refractory to second line chemotherapy are sometimes treated with third line chemotherapy and taken to ASCT if disease is chemo-sensitive. Current study aims to evaluate the impact of prior lines of therapy on the efficacy of CAR-T and ASCT. Methods: A retrospective review of patients who received ASCT and/or axicabtagene ciloleucel (axi-cel) for R/R aggressive NHL from June 2016 - January 2020 at Mayo Clinic, Rochester was performed. The lymphoma types included in the study were DLBCL, transformed lymphoma (TFL), high grade B-cell lymphoma (HGBL), and primary mediastinal large B-cell lymphoma (PMBCL). Response to all lymphoma-directed therapy was evaluated using 2014 Lugano criteria. Overall survival (OS) was defined as time from CAR-T or ASCT infusion to death, and progression free survival (PFS) was defined as time from CAR-T or ASCT infusion to disease progression, or next treatment. Categorical data was analyzed as Chi-square or fishers exact test as appropriate. Continuous variables were analyzed using Wilcoxon Rank Sum test. Analysis was performed in R3.6.3. Results: A total of 105 patients underwent ASCT and 53 patients underwent CAR-T therapy in the study period with at least 6 months follow-up. Of the 105 ASCT patients, 87 received ASCT after 2 lines of chemotherapy, ASCT(2), and 18 received ASCT after 3 lines of chemotherapy, ASCT(3). Twenty six of the ASCT [n=19, ASCT(2) and n=7, ASCT(3)] patients received CART in subsequent therapy. Baseline characteristics were comparable between the two groups except ASCT(3) had higher percent of refractory disease after first line (table 1). With a median follow up of 17.4 months, the PFS was significantly longer for the ASCT(2) group with a trend toward longer OS (Figure 1; PFS @ 1 year: ASCT(2) 67%, 95%CI 58-79%; ASCT(3) 27%, 95%CI 27-74%; p = 0.036). Among the CAR-T recipients, only 18 (33%) patients received CAR-T in the earliest possible indication, CAR-T(2): after 2 lines of chemotherapy (n=12) and/or after ASCT(2) (n=6), table 1. Compared to patients who received CAR-T in later lines (CAR-T 3+), OS was significantly longer for patients who received CAR-T(2), with a trend toward longer PFS (Figure 1; OS @ 1 year: CAR-T (2) 82%, 95%CI 65-100%; CAR-T later lines 62%, 95%CI 47-82%; p = 0.05). Additionally, 12 (23%) of patients received CAR-T immediately after ASCT (9 after ASCT(2), 3 after ASCT(3)). Baseline demographics in these 12 patients, CAR-T(ASCT), were comparable to the others who had chemoimmunotherapy as the last salvage therapy prior to CAR-T [CAR-T(chemo)], except a smaller proportion received bridging therapy (33% vs. 73%, p = 0.01). The CAR-T (ASCT) group had significantly prolonged PFS (median PFS - not reached [95%CI 3-not reached (NR)] vs. 3 months [95% CI 3-4 months]), and OS (median OS - NR, [95%CI 10.34-NR] vs. 15.1 months, [95%CI 11.9 - NR], p = 0.03). Updated analysis will be presented at the meeting with longer follow up (Figure 1). Conclusion: CAR-T use at the earliest current approved indication may confer survival advantage. Referral for earlier use of CAR-T remains low at only one third of our CAR-T practice volume. CAR-T use for relapse immediately after ASCT appear to have longer PFS and OS than after other systemic salvage therapy, although contributing parameters such as the need for bridging therapy requires further study. While patients who are chemo-refractory to second line chemotherapy may demonstrate chemo sensitivity with third line chemotherapy, PFS is shorter for ASCT(3). Comparison between ASCT(3) and CAR-T (2, chemorefractory) require larger cohorts with longer follow-up. Disclosures Bennani: Affimed: Research Funding; Purdue Pharma: Other: Advisory Board; Kite/Gilead: Research Funding; Verastem: Other: Advisory Board. Ansell:Takeda: Research Funding; ADC Therapeutics: Research Funding; Trillium: Research Funding; Bristol Myers Squibb: Research Funding; Seattle Genetics: Research Funding; Affimed: Research Funding; Regeneron: Research Funding; AI Therapeutics: Research Funding. Lin:Juno: Consultancy; Legend BioTech: Consultancy; Merck: Research Funding; Takeda: Research Funding; Gamida Cells: Consultancy; Sorrento: Consultancy, Membership on an entity's Board of Directors or advisory committees; Vineti: Consultancy; Bluebird Bio: Consultancy, Research Funding; Celgene: Consultancy, Research Funding; Novartis: Consultancy; Janssen: Consultancy, Research Funding; Kite, a Gilead Company: Consultancy, Research Funding.

Introduction Day 15 absolute lymphocyte count (ALC-15) recovery after autologous peripheral blood hematopoietic stem cell transplantation (APBHSCT) is recognized as a prognostic factor for survival. ALC-15 recovery is directly dependent on the amount of collected and infused autograft-absolute lymphocyte count (A-ALC). Our group published a double-blind phase III study which showed that patients infused with an A-ALC ≥ 0.5 x 109 cells/kg experienced superior survival post-APBHSCT. Based on the results from our phase III study, on April 1, 2017, our Bone Marrow Transplant Program changed our standard clinical practice to collect an A-ALC ≥ 0.5 x 109 cells/kg in addition to stem cells for lymphoma patients undergoing APBHSCT. To continue to assess the prognostic ability of A-ALC, we evaluated the overall survival (OS) and progression-free survival (PFS) of diffuse large B-cell lymphoma (DLBCL) patients that underwent APBHSCT after April 1, 2017 compared with a matched-control group in a 1:1:1 ratio with DLBCL patients infused with an A-ALC &lt; 0.5 x 109 cells/kg or an A-ALC ≥ 0.5 x 109 cells/kg prior to April 1, 2017. Methods Eight-five consecutive DLBCL patients after our practice changed on April 1, 2017 received an A-ALC ≥ 0.5 x 109 cells/kg. For each DLBCL patient infused with an A-ALC ≥ 0.5 x 109 cells/kg after April 1, 2017, the set of potential controls was restricted to those DLBCL patients infused with an A-ALC &lt; 0.5 x 109 cells/kg and an A-ALC ≥ 0.5 x 109 cells/kg prior to April 1 2017 . Within this group of potential controls, the subjects were chosen who best matched for the cases in terms of clinical risk variables, including gender, age, stage, lactate dehydrogenase (LDH), performance status, extra-nodal disease, International prognostic index (IPI), and disease status prior to APBHSCT (complete or partial response), using the GREEDY algorithm. Cases were defined as DLBCL patients infused with an A-ALC ≥ 0.5 x 109 cells/kg starting from April 1 2017. Control 1 was defined as DLBCL patients infused with an A-ALC &lt; 0.5 x 109 cells/kg prior to April 1 2017. Control 2 was defined as DLBCL patients infused with an A-ALC ≥ 0.5 x 109 cells/kg prior to April 1 2017. We truncated the survival follow-up to 3 years starting from the date of transplant to match follow-up time between cases and controls. Both matched cases and control groups patients received BEAM conditioning. This retrospective study was approved by the Mayo Clinic Institutional Review Board according to the regulation of the Declaration of Helsinki. Results Cases, control 1 and control 2 were balanced to the clinical risk variables; age (p = 0.8); gender (p = 0.9); LDH (p = 0.6); stage (p = 0.3); performance status (p = 0.5); extra-nodal disease (p = 0.2); IPI (p = 0.6); and clinical status prior to transplant (p = 0.2). Figure 1A showed the OS and figure 1B the PFS. Both the cases and control 2 showed superior OS and PFS in comparison to control 1. Cases and control 2 showed overall similar OS and PFS. Multivariate analysis including all patients continue to depict the A-ALC ≥ 0.5 x 109 cells/kg as an independent predictor for OS (HR = 0.382, 95%CI=0.241-0.605, p &lt; 0.0001) and PFS (HR = 0.437, 95%CI = 0.279-0.629, p &lt;0.0001). Subgroup analysis, including all patients, shows superior OS and PFS for patients infused with an A-ALC ≥ 0.5 x 109 cells/kg for each of the following clinical variables: age [&gt; 60 years: OS (p &lt;0.0001); PFS (p &lt;0.0001) or ≤ 60 years: OS (p &lt;0.01); PFS (p , 0.02)]; extra-nodal disease [&gt; 1: OS (p &lt;0.008); PFS (p &lt;0.01) or ≤1: OS (p &lt; 0.001): PFS (p &lt;0.0005)]; IPI [&gt; 2: OS (p &lt;0.01); PFS (p &lt;0.02) or ≤ 2: OS (p &lt;0.0008); PFS (p &lt;0.0006)]; LDH [abnormal: OS (p &lt;0.006); PFS (p &lt;0.005) or normal: OS (p &lt;0.002); PFS (p &lt;0.002)]; performance status [&gt; 1: OS (p &lt;0.04); PFS (p &lt;0.03) or ≤ 1: OS (p &lt;0.0001); PFS (p &lt;0.0001)]; stage [I/II: OS (p &lt;0.006); PFS (p &lt;0.006) or III/IV: OS (p &lt;0.002); PFS (p &lt;0.001)]; response prior to transplant [complete response: OS (p &lt;0.0007); PFS (p &lt;0.0001) or partial response: OS (p &lt;0.01); PFS (p &lt;0.02)]. Conclusion Our match-control study continues to support the results of our Phase III study showing that the infusion of A-ALC is a prognostic factor for survival of DLBCL patients undergoing APBHSCT. Our studies support the practice of not only collecting enough stem cells (i.e., CD34) for hematologic engraftment, but also enough immune effector cells (i.e., A-ALC) to improve clinical outcomes in DLBCL patients post-APBHSCT. Figure 1 Disclosures Ansell: Regeneron: Research Funding; Bristol Myers Squibb: Research Funding; Trillium: Research Funding; ADC Therapeutics: Research Funding; Takeda: Research Funding; AI Therapeutics: Research Funding; Affimed: Research Funding; Seattle Genetics: Research Funding.

Introduction: Transformation of low grade follicular lymphoma (FL) to diffuse large B cell lymphoma (DLBCL) carries a poor prognosis. In retrospective studies, 5-year survival of transformed DLBCL treated with rituximab, cyclophosphamide, doxorubicin, vincristine and prednisone (R-CHOP) without autologous stem cell transplant is 40-60%, underscoring need to improve frontline treatment of transformed DLBCL beyond R-CHOP. The overall response rate (ORR) to lenalidomide used as a single agent for relapsed transformed non Hodgkin lymphoma was 45% with 21% complete response (CR) rate and a median duration of response of 12 months (Witzig et al, Ann Onc 2011). These data provided the rationale to include patients with transformed DLBCL (with historical and concurrent FL) in MC078E, a phase II clinical trial testing lenalidomide plus R-CHOP (R2CHOP) for patients with new and untreated de novo and transformed DLBCL (NCT00670358). Here we present analysis of the subset of transformed DLBCL patients. Methods: Adult patients with transformed DLBCL and either historical or concurrent FL, stage &gt;=2, measurable disease by Positron Emission Tomography/computed tomography (PET/CT) and adequate organ function were included. Patients with Central Nervous System (CNS) involvement, significant comorbidities, active non-lymphomatous malignancy, life-threatening thromboembolism (TE) and contraindication to aspirin prophylaxis were excluded. Study participants received up to 6 cycles of rituximab (375 mg/m2), cyclophosphamide (750 mg/m2), doxorubicin (50 mg/m2), and vincristine (1.4 mg /m2) on day 1, prednisone (100 mg) on day 1-5, pegfilgrastim on day 2, and Lenalidomide 25 mg day 1-10 of 21 day cycle. Tumor lysis prophylaxis was per local practice; patients also received TE prophylaxis with aspirin. Primary outcome was event free survival (EFS) at 12 months, where an event was defined as death, progression or subsequent anti-lymphoma therapy. Secondary outcomes included ORR, CR, progression free survival (PFS), and overall survival (OS). Response was evaluated by PET/CT after cycle 2 and cycle 6 with revised response criteria (Cheson et al, 2007). Adverse events were recorded according to CTCAE version 3.0. The Kaplan-Meier method was used to estimate time to event endpoints. Results: Thirty-nine patients were accrued from August 5, 2013 to July 28, 2020 and 33 were eligible by central pathology review. Median age was 64 (range 24-80) years and 18 (54%) were &gt;60 years old. Eighteen (54%) were male, and 32 (97%) had ECOG performance status &lt;2. Twenty-three (70%) had historical FL and 10 (30%) had concurrent FL. Twenty-six (79%) had advanced stage (III-IV). Median number of extra nodal sites were 1 (0-4). Thirteen (39%) had high international prognostic index (IPI) (4-5). Thirty-two (97%) completed at least 2 cycles (30 completed all 6 cycles) and were evaluable for response. ORR was 97% (32/33), 29 (88%) had CR and 3 had PR. EFS at 12 months was 87.9% (95% CI: 71.8, 96.6). Two-year PFS and OS were 84.5% (95% CI: 72.8%-98%) and 96.9% (95% CI: 91-100%) (Figure 1). Twenty nine completed study protocol, 4 discontinued protocol early for disease progression (1), adverse event (AE) (1), refusal (1) and noncompliance (1). Thirty (91%) had hematologic AE of grade 3 or above, 27 (82%) had neutropenia, 16 (48%) had thrombocytopenia, and 7 (21%) had anemia. Sixteen (48%) had grade 3 or above non-hematologic AE. Eight (24%) had febrile neutropenia. There were 3 deaths on this study, 1 due to progressive DLBCL, 1 due to AML and 1 due to malignant melanoma. Conclusion: R2CHOP appears effective in transformed DLBCL with high response rates, event free, progression free and overall survival seen in current study. This study supports the inclusion of anthracycline naive patients with transformed DLBCL in future randomized studies of lenalidomide or other novel immunomodulatory (IMiD) analogues. Disclosures Wang: Novartis: Research Funding; Innocare: Research Funding; Incyte: Research Funding. Ansell:Bristol Myers Squibb: Research Funding; Takeda: Research Funding; AI Therapeutics: Research Funding; Regeneron: Research Funding; Trillium: Research Funding; Affimed: Research Funding; Seattle Genetics: Research Funding; ADC Therapeutics: Research Funding. Witzig:Spectrum: Consultancy; Immune Design: Research Funding; Karyopharm Therapeutics: Research Funding; Acerta: Research Funding; Incyte: Consultancy; AbbVie: Consultancy; MorphSys: Consultancy; Celgene: Consultancy, Research Funding. Nowakowski:Celgene/BMS: Consultancy, Research Funding; MorphoSys: Consultancy, Research Funding; Ryvu: Consultancy, Membership on an entity's Board of Directors or advisory committees; Kite: Consultancy; Kymera: Consultancy; Curis: Consultancy; Seattle Genetics: Consultancy; NanoString: Research Funding.

Introduction The molecular basis for the clinical heterogeneity observed in DLBCL was initially elucidated with gene expression profiling, identifying three distinct subgroups with prognostic relevance based on COO namely activated B-cell like (ABC), germinal center B-cell like (GCB) and a type 3 subtype. Shortly afterwards the Han's algorithm was developed allowing for widespread applicability and correlation of gene expression with protein expression. GCB profile at diagnosis is generally associated with superior long term outcomes compared to non-GCB in patients treated with conventional chemo-immunotherapy. Patients with relapsed/refractory disease (R/R) after front-line therapy undergo salvage treatment and, upon demonstration of objective response, proceed with high dose therapy and autologous transplantation (auto-HCT). Whether COO by Han's algorithm retains its prognostic significance post auto-HCT in patients with R/R DLBCL is not well established. Methods A retrospective analysis was carried out using the Mayo database across all three sites. It included all patients between 18-75 years of age who were diagnosed with de-novo DLBCL and underwent first auto-HCT for R/R disease. Patients must have received salvage treatment and shown chemotherapy sensitive disease. Patients with transformed DLBCL or other variants and those who underwent auto-HCT in first complete remission for high risk disease were excluded. Patients who had less than a partial response at time of transplantation and still underwent auto-HCT were also excluded. Primary endpoints included overall survival (OS); relapse and relapse-free survival (RFS). Continuous variables were summarized as mean (standard deviation) and median (range). Categorical variables were reported as frequency (percentage). Continuous baseline variables were compared between GCB and non-GCB using Wilcoxon rank sum test and categorical baseline variables were compared with Chi-squared test. Kaplan-Meier method was used to estimate 5 and 10-year rates of freedom from long-term events and draw corresponding survival curves. Multivariate Cox regression models were used to evaluate the impact of cell of origin on long-term survival after adjusting for baseline factors. All tests were two-sided with alpha level set at 0.05 for statistical significance. Results A total of 357 patients underwent auto-HCT between 2005 and 2018. Cell of origin was determined for 284 patients and these were included in the analysis. Median age was 61 (range: 19-78) years, and 64% patients were male. GCB and non-GCB patients did not differ significantly with regards to baseline factors (Table 1). During a median follow up of 1.7 years, 139 patients died, 151 had relapse and 175 either died or had relapse. Five year OS for GCB patients versus (vs) non-GCB was at 44% vs 64% (p=0.004) (Figure 1); relapse was at 67% vs 49% (p=0.012) and RFS was at 28% vs 50% (p=0.003). The difference between GCB and non-GCB groups remained statistically significant in multivariate analysis, with GCB patients 60% more likely to die and 50% more likely to experience relapse compared to non-GCB patients. The only other factor that retained significance in multivariate analysis for both endpoints was response at the time of transplant (Table 2A-C). Conclusions In this analysis, GCB DLBCL results in worse OS and higher relapse vs. non-GCB DLBCL following an auto-HCT. It is unclear if relapse/progression of GCB subtype after front-line therapy alters its natural history into a more aggressive disease. Disclosures Ansell: Trillium: Research Funding; ADC Therapeutics: Research Funding; Affimed: Research Funding; Bristol Myers Squibb: Research Funding; AI Therapeutics: Research Funding; Takeda: Research Funding; Seattle Genetics: Research Funding; Regeneron: Research Funding. Foran:Xencor: Research Funding; Trillium: Research Funding; Takeda: Research Funding; Kura Oncology: Research Funding; Aptose: Research Funding; Aprea: Research Funding; Actinium: Research Funding; Boehringer Ingelheim: Research Funding; Abbvie: Research Funding; BMS: Membership on an entity's Board of Directors or advisory committees; Pfizer: Membership on an entity's Board of Directors or advisory committees; Servier: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees; Revolution Medicine: Consultancy; H3Biosciences: Research Funding; Agios: Honoraria, Research Funding. Tun:Celgene: Research Funding; Mundipharma: Research Funding; Curis: Research Funding; TG Therapeutics: Research Funding; Acrotech: Research Funding; DTRM Biopharma: Research Funding; Bristol-Myers Squibb: Research Funding. Kharfan-Dabaja:Daiichi Sankyo: Consultancy; Pharmacyclics: Consultancy.