Bartlett, Nancy L.

Introduction Emerging evidence suggests that responses to CPI in Hodgkin lymphoma (HL) may be adversely affected by the reductions in microbiome diversity associated with concomitant antibiotic (abx) exposure. Given the increasingly key role that CPI-based regimens (CPI+) appear to have on improving post-ASCT outcomes, we evaluated the potential impact of abx exposure on CPI+ efficacy and post-ASCT outcomes in RRHL patients treated with CPI+ prior to ASCT. Methods This retrospective study of RRHL patients at 11 US academic centers included patients ≥18 who received CPI+ between 1/2012-12/2022. Patient/disease characteristics, treatment histories, outcomes, and abx exposure (2 weeks prior to and 30 days after CPI+) were collected by participating sites and analyzed centrally. Primary and key secondary objectives were overall response rate (ORR) to CPI+ by Lugano criteria, and PFS/overall survival (OS) by abx exposure. PFS/OS were estimated by Kaplan-Meier and compared by log-rank tests. Univariate and multivariate regression models evaluated the impact of abx exposure on ORR/complete response rate (CR)/PFS/OS. Results 237 patients with median follow-up of 3.20 and 2.73 years from CPI+ initiation and ASCT, respectively, were evaluated. At diagnosis: median age 30.6 (range 7.8 - 71.7) years, female (53.6%), nodular sclerosing (75.1%), and stages I-IIB/bulky and III/IV (73.4%). 1L regimens were ABVD/ABVD-like (75.5%), brentuximab vedotin (BV)+AVD (15.2%), and other (9.3%). 65.8% received 6 cycles of chemotherapy, and 10.5% received 1L radiation. End of 1L responses were CR (39.7%), partial response (PR; 13.1%), refractory disease (37.6%), and unknown (8.0%). Median time to first relapse from diagnosis was 0.95 (range 0.15 - 22.2) years. All patients underwent ASCT after 1 (58.2%), 2 (22.8%), or 3+ (19.0%) lines of salvage. CPI+ was given as 1st (65.8%), 2nd (21.5%), or 3rd+ (12.5%) salvage therapy. CPI+ included BV-nivolumab (44.3%) + ipilimumab (7.2%), pembrolizumab, gemcitabine, vinorelbine, and liposomal doxorubicin (P-GVD; 24.5%), and CPI-monotherapy (20.2%). ORR to CPI+ was 88.0% (CR 68.4%) in all lines; as 1st salvage ORR was 91.7% (CR 76.3%). 75.1% of patients underwent ASCT in CR (PR 19.4%) increasing to 91.1% CR after ASCT. At 3-years, PFS was 88.0% (95% CI: 83.5% - 92.8%) and OS was 94.8% (95% CI: 91.3% - 98.3%) for the full cohort. Overall, 46.8% patients were abx exposed during CPI+, 22.8% fluoroquinolone/beta-lactams (BL) prophylaxis (ppx) and 38.8% abx [BL 29.5%, carbapenems (CB) 12.2%, vancomycin (VM) 19.8%, anti-pseudomonas (PA) 24.9%, anti-MRSA (SA) 22.4%, anti-anaerobe (AN) 16.5%] for suspected/documented infection. Use of ppx, BL, CB, VM, PA, SA were significantly higher with CP1+ as 2nd+ vs 1st salvage. At 3-years, PFS (87.0% vs 88.4%, p=0.91) and OS (92.5% vs 95.8%, p=0.47) were similar for abx exposed vs naïve patients, respectively. On univariate analysis, line of salvage and CPI+ regimen (Cytotoxic vs Monotherapy) were associated with ORR/CR, while overall abx exposure was not associated with inferior ORR (OR 0.62; p=0.24), CR (OR 0.85, p=0.56), PFS (HR 0.95, p=0.91), or OS (HR 1.58, p=0.47). When adjusted for line of salvage and CPI+ regimen, exposure to BL, CB, VM, PS, SA, or AN, abx indication (ppx vs treatment), duration of abx exposure (<7 vs ≥7 days) by class were all not associated with ORR/CR or PFS/OS. Conclusion In this large cohort abx exposure does not appear to adversely affect ORR/CR to CPI+ or PFS/OS following ASCT, when adjusted for line of CPI+ salvage and CPI+ regimen. Our findings may be related the high proportion of patients (79.8%) receiving CPI-combinations compared to CPI monotherapy (20.2%), whereas in previous series all patients received CPI without cytotoxic agents. This observation could be related to intrinsic antimicrobial activities of some cytotoxic agents (e.g. gemcitabine and doxorubicin) that may overshadow impact from concomitant abx exposure. Alternatively, the lack of effect could be related to the inherent fitness of patients with RRHL who undergo ASCT, compared to those treated with CPI+ following ASCT or those with solid tumors receiving where abx exposure may indicate an overall sicker/higher-risk population. Overall, our findings demonstrate that combination of CPI with BV or chemotherapy may overcome any adverse impact of abx on the efficacy of CPI+ prior to ASCT.

Introduction: Pembrolizumab Gemcitabine Vinorelbine and Liposomal Doxorubicin (P-GVD) has become a commonly employed regimen for the treatment of relapsed or refractory classical Hodgkin lymphoma (CHL), often preceding autologous stem cell transplant in patients with good response. The utilization of P-GVD is based on a 38-evaluable patient prospective trial (Moskowitz et al. JCO 2021). There remains minimal data regarding the efficacy of this regimen in a larger, real-world cohort. Methods:Patients with CHL who received P-GVD at 9 United States centers were retrospectively evaluated to estimate efficacy and safety, with a focus on the second line use of this regimen. Demographic and clinical data were extracted from medical records. Responses reflected Lugano criteria per local investigator assessment. Study objectives were overall response rates (ORR), complete response rates (CRR), progression free survival (PFS), overall survival (OS), and safety. PFS and OS were estimated by Kaplan-Meier. Results: Patients and Treatment: We identified 65 CHL patients who received P-GVD between July 2019 and June 2024, including 43 who were treated in the second line. Enrolled patients included a median age of 31 years (range 17-69 years), 36.9% (24) females, 75.4% (49) nodular sclerosing subtype, and 60% (39) stage III-IV at diagnosis. Patients included 64.6% (42) White and non-Hispanic, 15.4% (10) Hispanic or White and Hispanic, 10.8% (7) Black, 3.1% (2) Asian/Pacific Islander, 3.1% (2) other, and 3.1% (2) unknown. The median number of prior regimens was 1 (range 0-12); these included 3.1% (2) who had prior checkpoint inhibitor (CPI), 50.8% (33) who had prior brentuximab vedotin (BV), and 3.1% (2) who had prior transplant. Patients with primary refractory disease [no initial complete response (CR)] comprised 58.5% (38), and 35.4% (23) had relapse within 1 year of completing initial therapy. The median number of cycles received was 3 (range 1-5). Treatment in a community practice setting was noted for 21.5% (14) patients. Efficacy: At a median follow up of 17.7 months, ORR and CRR after P-GVD were 95% (62/65) and 74% (48/65), respectively. This increased to 95% ORR and 81% CRR when limited to 43 patients who were treated 2nd line. Responses by line included: 1st [n=1; 100% ORR and CRR]; 3rd [n=15; 100% ORR, 73.3% CRR], 4th [n=3; 100% ORR, 33.3% CRR], 5th [n=2; 100% ORR, 0% CRR], and 13th [n=1; SD]. CRR in BV- and CPI-exposed patients were 60.6% and 50%, respectively. Ninety one percent (39) of 2nd line treated patients proceeded to autologous transplant, as well as all 3 patients > age 60. Among 41 response-evaluable second-line patients, CR was achieved in 94% (30/32) who received 2 or 3 cycles of P-GVD, and 56% (5/9) who received 4 cycles of P-GVD. For the entire cohort at 12 and 24 months after starting P-GVD, PFS was 95% (95% CI: 89-100%), 91% (95% CI: 83-100%) and OS was 98% (95% CI: 94-100%), 94% (95% CI: 86-100%), respectively. Ninety five percent (41) of 2nd line transplanted patients remain alive and in remission at a median of 18.5 months (range 3.5-38.7 months). In the primary refractory subset, PFS and OS at 24 months were 91% and 97%, respectively. For the cohort with 2 or more prior lines of therapy, PFS and OS at 24 months were 91% and 94%, respectively. Safety: Immune-related adverse events (IRAEs) were reported in 20% (13) of patients, of which grade 3 IRAEs per NCCN criteria version 1.2024 comprised 38.5%; all others were grades 1-2. Non-IRAE grade 3-4 toxicities per CTCAE version 5.0 were reported in 22% (14) patients. Of 29 patients evaluable for treatment-related interruptions, 7% (2) had therapy discontinued, and 34% (10) had holds, dose reductions, and/or delays. No deaths were attributed to P-GVD treatment. Conclusions:This retrospective study confirms the utility of P-GVD in treating relapsed/refractory CHL in a real-world population. Though fewer CRs and higher rates of grade 3 adverse events were observed, the vast majority of patients were able to proceed to transplant, and outcomes to date are highly encouraging.

Background: The rising incidence of PCNSL in the elderly represents an unmet need with an undefined standard approach [Villano Br J Cancer 2011]. High-dose methotrexate-based (HD-MTX) therapy is feasible and effective in older patients, but outcomes in this population remain poor. Despite high response rates to HD-MTX induction therapy, poor candidacy for intensive consolidative therapy results in transient disease control that may benefit from maintenance strategies [David Am J Hematol 2023]. Lenalidomide (len) has demonstrated activity in PCNSL even at low doses and represents a potential alternative to consolidation considering its extensive use in maintenance settings [Vu Br J Haematol 2019]. Anecdotal activity in PCNSL by checkpoint inhibitors such as nivolumab (nivo) has been reported [Nayak Blood 2017], and its immune response may be enhanced by len [Görgün Clin Cancer Res 2015]. A051901 evaluates the feasibility of the addition of len and nivo to rituximab (R) and HD-MTX as first line induction therapy followed by len-nivo maintenance in elderly patients with PCNSL not eligible for intensive consolidation. Study Design and Methods: This is a single-arm phase 1 multicenter US study (NCT04609046) conducted by the Alliance for Clinical Trials in Oncology with a traditional 3+3 design. Eligible patients are 18 years of age or older with untreated diffuse large B-cell lymphoma PCNSL diagnosed through brain biopsy or resection, or cerebrospinal (CSF) or vitreous fluid not considered candidates for high dose chemotherapy consolidation. This study is available to all eligible patients, regardless of race, gender, or ethnic origin. Patients must have adequate end-organ function including creatinine clearance of at least 50 mL/min. Use of systemic corticosteroids for disease control to be tapered after initiation of therapy is allowed. Induction consists of six 14-day cycles with rituximab 500 mg/m2 i.v. on day 1, HD-MTX 3g/m2 i.v. on day 2. In the most recent treatment schedule, a 5-day course of lenalidomide PO at different dose levels (dose level (DL) 1 = 10 mg, DL2 = 15 mg, DL3 = 20 mg) is initiated immediately after adequate clearance of HD-MTX. Once a maximum tolerated dose (MTD) of len is defined, a subsequent cohort will evaluate the addition of nivo 240 mg i.v. to the day 14 of the induction cycle of R-HD-MTX plus len at the MTD. Patients who present any clinical benefit from induction with at least stable disease by International PCNSL Collaborative Group response criteria are eligible for maintenance - twelve 28-day cycles of therapy with len 15 mg PO from day 1 to day 21 (regardless of dose during induction) +/- nivo 480 mg i.v. on day 1 (for those who received len and nivo during induction). The primary endpoint of the induction therapy is the MTD of len when given in combination with R-HD-MTX; the primary endpoint of maintenance is its feasibility, defined as the proportion of patients able to remain on maintenance for at least 6 cycles. As of July 2024, 16 patients have been enrolled with a maximum expected sample size of 47 patients with the assumption of 75% of patients being eligible to proceed with maintenance and 50% of those who begin maintenance not progressing in the first 6 cycles. Overall response, adverse events, progression-free and overall survival will be evaluated in all eligible patients with a focus on the outcome of patients treated at the MTD. For patients who consent to biobanking, diagnostic tissue, peripheral blood and CSF from different timepoints are collected and banked with planned exploratory analyses including whole exome sequencing, circulating tumor DNA, proteomics, metabolomics. Support: U10CA180821, U10CA180882. https://acknowledgments.alliancefound.org.

7012 Background: DLBCL with expression of MYC and BCL2 (double expressor lymphoma, DEL), has an adverse prognosis. Venetoclax, an inhibitor of BCL2, was previously studied in combination with R-CHOP. A051701 is a phase II/III randomized trial of chemoimmunotherapy +/- venetoclax in DEL and double hit lymphoma cohorts. Here we report initial phase II results from the DEL cohort. Methods: Patients (pts) age ≥ 18 years (y) with untreated DEL were randomized 1:1 to R-CHOP (Arm 1) or R-CHOP-venetoclax (Arm 2). DEL was defined as MYC expression ≥40% and BCL2 expression ≥50%, without double hit cytogenetics. Enrollment was based on local pathology results that were centrally confirmed. Venetoclax 800 mg was given orally days 4-8 of cycle 1 and days 1-5 of subsequent cycles for up to 6 cycles. All cycles were supported by GCSF or peg-GCSF. The primary endpoint was progression-free survival (PFS) with 84% power to detect a HR of 0.518 corresponding to 2y PFS rate of 65% in Arm 1 and 80% in Arm 2 (1-sided α=0.20). Results: 119 DEL pts were enrolled: 60 Arm 1; 59 Arm 2. Analyses were performed for the modified intent-to-treat population, defined as eligible pts with confirmed DEL histology (n=113; 56 Arm 1, 57 Arm 2). Median age was 64 y (range 22-85); baseline demographic factors were well balanced except for advanced stage (more common in Arm 1; (77% vs 60%, p=0.051). Most pts were non-germinal center B cell-like by immunohistochemistry (Arm 1 72%, Arm 2 58%), high-intermediate/high risk IPI (Arm 1 54%, Arm 2 51%) and ECOG performance status 0-1 (Arm 1 95%, Arm 2 86%). BCL2 rearrangements were detected in 25% and 33% of pts on Arm 1 and Arm 2, respectively. Most pts completed therapy per protocol (84% Arm 1, 75% Arm 2). Median follow up is 27 months (m). No difference in PFS was observed with 12-m PFS estimates of 77% in Arm 1, 76% in Arm 2 [HR = 0.98 (95% CI: 0.48 – 2.01), p=0.95]. The end of treatment (EOT) overall and complete response rates among patients with an EOT assessment were 87.5% and 70% in Arm 1, and 90% and 82% in Arm 2. Overall survival (OS) was not statistically significantly different with 12-mo OS estimates of 94% in Arm 1 and 79% in Arm 2 [HR = 1.27 (95% CI: 0.57 – 2.79), p=0.56]. Grade ≥3 adverse events (AEs) occurred more frequently in Arm 2 (42% vs 76%). The most commonly increased grade ≥3 AEs included neutropenia (20% vs 47%), anemia (4% vs 25.5%), thrombocytopenia (5.5% vs 24%), febrile neutropenia (7% vs 16%) and fatigue (0% vs 11%). No grade 5 AEs on treatment were reported on Arm 1, and 3 were reported on Arm 2 (lung infection and sudden death NOS, both possibly related; respiratory failure, unlikely related). Conclusions: Adding venetoclax to R-CHOP in DEL pts did not improve PFS and resulted in increased toxicity. The study did not meet its primary endpoint in phase II, and so did not proceed to phase III. Clinical trial information: NCT03984448 .

LBA7005 Background: Despite recent advances, there remains a need for novel therapies for pts with R/R DLBCL. BV, an anti-CD30 antibody-drug conjugate, has shown efficacy and safety when combined with lenalidomide (len) and with rituximab (R) in heavily pretreated populations (Bartlett 2022; Ward 2022). The double-blind, global phase 3 ECHELON-3 study (NCT04404283) compared BV with R+len (R2) vs R2 in pts with R/R DLBCL who are ineligible for HSCT or CAR T-cell therapy. Here, we present results from the interim analysis (IA) for overall survival (OS). Methods: Pts with R/R DLBCL received BV+R2 or placebo+R2 (randomized 1:1). Pts received BV (1.2 mg/kg) or placebo q3w, R (375 mg/m2) q3w, and len (20 mg) qd. The primary endpoint was OS in the intent-to-treat population. Secondary endpoints were investigator-assessed progression-free survival (PFS), objective response rate (ORR), and complete response (CR) rate. The preplanned IA was performed at 134 OS events with a prespecified efficacy boundary of 2-sided P=0.0232. Results: 230 pts were randomized: 112 to BV+R2 and 118 to R2; all but 2 pts (both in R2 arm) received ≥1 dose of study drug. Median age was 71 yrs (range, 21-89), 56.5% were male, and 10.9% had an ECOG of 2. Median prior lines of therapy was 3 (range, 2-8); 29% had prior CAR T-cell therapy and 68% were CD30- (<1% CD30 tumor expression). At median follow-up of 16.4 months (mos) (range, 0.1-31.5) (cut-off: January 22, 2024), median OS was 13.8 mos (95% CI: 10.3-18.8) with BV+R2 vs 8.5 mos (95% CI: 5.4-11.7) with R2 (HR 0.629; 95% CI: 0.445-0.891; P=0.0085); OS benefit was consistent across key subgroups. Median PFS was 4.2 mos (95% CI: 2.9-7.1) with BV+R2 vs 2.6 mos (95% CI: 1.4-3.1) with R2 (HR 0.527; 95% CI: 0.380-0.729; P<0.0001). ORR was 64.3% (95% CI: 54.7-73.1) with BV+R2 vs 41.5% with R2 (95% CI: 32.5-51.0; P=0.0006); CR rate was 40.2% vs 18.6%, respectively. In CD30+ vs CD30- subgroups, ORR/CR was 72.2%/38.9% vs 60.5%/40.8% with BV+R2, respectively, and 50.0%/26.3% vs 37.5%/15.0% with R2, respectively. Efficacy analysis including cell of origin will be presented. The safety profile of BV+R2 was tolerable vs R2: Grade (Gr) ≥3 treatment-emergent adverse events (TEAEs) were 88% vs 77%, serious TEAEs were 60% vs 50%, and Gr 5 TEAEs were 12% vs 8%, respectively. Most common TEAEs were neutropenia (46% vs 32%), anemia (29% vs 27%), and diarrhea (31% vs 23%). Rates of peripheral neuropathy for BV+R2 vs R2 were 31% vs 24% (all Gr) and 6% vs 2% (Gr 3). Median treatment duration was 3.6 mos with BV+R2 vs 2.0 mos with R2. Conclusions: Treatment with BV+R2 triplet, compared to R2, demonstrated statistically significant and clinically meaningful improvements in all key efficacy outcomes including OS in high-risk subgroups, with manageable safety. This triplet regimen represents a novel treatment option for pts with heavily pretreated R/R DLBCL. Clinical trial information: NCT04404283 .

Abstract Although initial therapy of mantle cell lymphoma (MCL) is not standardized, bendamustine plus rituximab (BR) is commonly used in older patients. Rituximab (R) maintenance after induction is often used. Thus, the open-label, randomized phase 2 ECOG-ACRIN Cancer Research Group E1411 trial was designed to test 2 questions: (1) does addition of bortezomib to BR induction (BVR) and/or (2) addition of lenalidomide to rituximab (LR) maintenance improve progression-free survival (PFS) in patients with treatment-naïve MCL? From 2012 to 2016, 373 previously untreated patients, 87% aged ≥60 years, were enrolled in this trial. At a median follow-up of 7.5 years, there is no difference in the median PFS of BR compared with BVR (5.5 vs 6.4 years; hazard ratio [HR], 0.90; 90% confidence interval [CI], 0.70-1.16). There were no unexpected additional toxicities with BVR treatment compared with BR, with no impact on total dose/duration of treatment received. Independent of the induction treatment, addition of lenalidomide did not significantly improve PFS, with median PFS in R vs LR (5.9 vs 7.2 years; HR, 0.84; 90% CI, 0.62-1.15). Most patients completed the planned 24 cycles of LR at the scheduled dose. In summary, adding bortezomib to BR induction does not prolong PFS in treatment-naïve MCL, and LR maintenance was not associated with longer PFS compared with R alone after BR. Nonetheless, the &gt;5-year median PFS outcomes in this prospective cooperative group trial indicate the efficacy of BR followed by R maintenance as highly effective initial therapy for older patients with MCL. This trial was registered at www.clinicaltrials.gov as #NCT01415752.

Abstract Although it is evident that standard-dose whole-brain radiotherapy as consolidation is associated with significant neurotoxicity, the optimal consolidative strategy for primary central nervous system lymphoma (PCNSL) is not defined. We performed a randomized phase 2 clinical trial via the US Alliance cancer cooperative group to compare myeloablative consolidation supported by autologous stem cell transplantation with nonmyeloablative consolidation after induction therapy for PCNSL. To our knowledge, this is the first randomized trial to be initiated that eliminates whole-brain radiotherapy as a consolidative approach in newly diagnosed PCNSL. Patients aged 18 to 75 years were randomly assigned in a 1:1 manner to induction therapy (methotrexate, temozolomide, rituximab, and cytarabine) followed by consolidation with either thiotepa plus carmustine and autologous stem cell rescue vs induction followed by nonmyeloablative, infusional etoposide plus cytarabine. The primary end point was progression-free survival (PFS). A total of 113 patients were randomized, and 108 (54 in each arm) were evaluable. More patients in the nonmyeloablative arm experienced progressive disease or death during induction (28% vs 11%; P = .05). Thirty-six patients received autologous stem cell transplant, and 34 received nonmyeloablative consolidation. The estimated 2-year PFS was higher in the myeloablative vs nonmyeloablative arm (73% vs 51%; P = .02). However, a planned secondary analysis, landmarked at start of the consolidation, revealed that the estimated 2-year PFS in those who completed consolidation therapy was not significantly different between the arms (86% vs 71%; P = .21). Both consolidative strategies yielded encouraging efficacy and similar toxicity profiles. This trial was registered at www.clininicals.gov as #NCT01511562.

Abstract A041202 (NCT01886872) is a phase 3 study comparing bendamustine plus rituximab (BR) with ibrutinib and the combination of ibrutinib plus rituximab (IR) in previously untreated older patients with chronic lymphocytic leukemia (CLL). The initial results showed that ibrutinib-containing regimens had superior progression-free survival (PFS) and rituximab did not add additional benefits. Here we present an updated analysis. With a median follow-up of 55 months, the median PFS was 44 months (95% confidence interval [CI], 38-54) for BR and not yet reached in either ibrutinib-containing arm. The 48-month PFS estimates were 47%, 76%, and 76% for BR, ibrutinib, and IR, respectively. The benefit of ibrutinib regimens over chemoimmunotherapy was consistent across subgroups of patients defined by TP53 abnormalities, del(11q), complex karyotype, and immunoglobulin heavy chain variable region (IGHV). No significant interaction effects were observed between the treatment arm and del(11q), the complex karyotype, or IGHV. However, a greater difference in PFS was observed among the patients with TP53 abnormalities. There was no difference in the overall survival. Notable adverse events with ibrutinib included atrial fibrillation (afib) and hypertension. Afib was observed in 11 patients (pts) on BR (3%) and 67 pts on ibrutinib (18%). All-grade hypertension was observed in 95 pts on BR (27%) and 263 pts on ibrutinib (55%). These data show that ibrutinib regimens prolong PFS compared with BR for older patients with treatment-naïve CLL. These benefits were observed across subgroups, including high-risk groups. Strikingly, within the ibrutinib arms, there was no inferior PFS for patients with abnormalities in TP53, the highest risk feature observed in CLL. These data continue to demonstrate the efficacy of ibrutinib in treatment-naïve CLL.

Introduction: AutoHCT is an effective therapy for patients (pts) with DLBCL who are refractory or relapse following first-line chemotherapy, but long term outcomes remain suboptimal. The BTK inhibitor ibrutinib has shown promising activity in pts with ABC-DLBCL (Wilson et al, Nat Med 2015). In 2016 we launched a randomized phase III clinical trial to evaluate the addition of ibrutinib to AutoHCT as part of conditioning and as consolidation therapy for pts with relapsed/refractory ABC-DLBCL. Patients and Methods: Following assessment of open-label treatment in a safety cohort of 6 pts, we randomly assigned pts with chemotherapy-sensitive persistent or relapsed ABC-DLBCL to receive ibrutinib 560 mg [Arm A] or placebo [Arm B] concurrently with conditioning on days -6 to -1 of AutoHCT (Cycle 1). Following count recovery and resolution of acute toxicities, pts continued ibrutinib 560 mg in Arm A or placebo in Arm B for 12 additional 28-day cycles. Crossover to Arm A using single agent ibrutinib was allowed for pts progressing on Arm B. Central pathology review was performed for disease confirmation and subtype assignment. Initially, ABC subtype assignment was performed using the Nanostring Lymphoma Subtyping Test (LST) but the study was amended to use the IHC-based Hans classifier for non-GCB on 8/15/19. Other key eligibility criteria included receipt of no more than 3 prior regimens, no active CNS involvement, no need for long-term anticoagulation, and no prior progression on Ibrutinib. Pts were stratified by time to relapse (&lt;=12 mos vs &gt;12 mos), type of conditioning (BEAM or CBV) and prior ibrutinib use. The original design required 296 patients with 82% power to detect a difference in 2-year progression-free survival (PFS) rates of 67% vs. 50% with a two-sided alpha of 0.05. A revised statistical design allowed an interim futility analysis to be conducted after 40 pts were enrolled and followed for 2 years. Even though the study met criteria to continue accrual to a target of 160 pts, we decided to close it early due to declining accrual on 12/20/2022. We hereby present the primary analysis of the evaluable patients enrolled (data as of 07/17/2023). Results: Between 2/6/17 and 8/24/18, we screened 255 pts but enrolled only 34 (13%) largely due to long assay turnaround times and performance characteristics with the LST. Following the switch to the IHC-based Hans classifier (after 8/15/19), 60 out of 110 pts screened were enrolled (54%) in line with our a priori expectation. In total, 45 pts were randomized to Arm A vs. 43 to Arm B, with 39 and 38, respectively, being evaluable for the primary endpoint at this time. Median age was 61 years (range 20-75 years), median number of prior lines of therapy was 2, 46% of the pts were female, 21% were refractory or had early relapse, 94% were planned to receive BEAM conditioning. Overall, 87% of pts in Arm A and 88% in Arm B underwent conditioning while 70% and 67% respectively, started maintenance therapy. The median number of cycles received was 6 in Arm A vs. 5 in Arm B. The primary endpoint of 2-year PFS was 57.6% (95% CI: 42.1%, 78.8%) in Arm A vs. 40.8% (95% CI: 26.5, 62.8%) in Arm B (HR=0.54; 95% CI: 0.26, 1.10; log-rank p = 0.087). Median PFS was 26.5 months (95% CI: 10.2, not reached [NR]) in Arm A vs. 8.1 months (95% CI: 5.4, NR) in Arm B. Only one pt crossed over to Arm A after progression on Arm B. The most common grade 3-4 AEs in each of the arms were: neutropenia (A: 14%, B: 14%), febrile neutropenia (A: 11%, B: 9%), and thrombocytopenia (A: 11%, B: 7%). Rates of any grade atrial fibrillation were similar between arms (12.8% in Arm A vs. 10.5% in Arm B); one patient had grade 3 and one patient had grade 4 atrial fibrillation, both in Arm B. Six pts had reported grade 5 events (Arm A: 2 sepsis, 1 COVID-19, 1 respiratory failure and 1 disease progression and Arm B: 1 disease progression) but only one grade 5 event (sepsis, Arm A) was deemed probably related to treatment. Conclusions: Despite an early high rate of screen failures and declining accruals due to competition with CAR-T cell therapy, the primary analysis suggests that ibrutinib with and following AutoHCT in relapsed/refractory ABC-DLBCL is well-tolerated and may improve PFS in this high-risk patient population. This trial was supported by: U10CA180821, U10CA180882, U24CA196171; U10CA180820, UG1CA233234 (ECOG-ACRIN); U10CA180868 (NRG); U10CA180888 (SWOG) ClinicalTrials.gov Identifier: NCT02443077 https://acknowledgments.alliancefound.org