Citations

Abstract Introduction There is wide variation in male fertility preservation practices. While physician preference accounts for some of this diversity, practice patterns often reflect multiple extrinsic factors including patient demographics, equipment availability, laboratory protocols, and state law. Objective We sought to characterize national trends in sperm retrieval and storage across reproductive urology practices in the United States. Methods An anonymous 34-item survey characterizing provider demographics, practice settings, fertility preservation procedures, andrology laboratory practices, and cryopreservation expenses was designed. Practicing reproductive urologists were identified using information available through professional societies. Our survey was constructed using the Qualtrics platform and distributed electronically between October 2024 and May 2025. Results 39 responses were received by urologists practicing across 21 states (response rate: 21%, n=189). A majority (74%, n=29) of survey responders practiced at academic medical centers, with others practicing at non-academic hospitals (8%, n=3) and private practices (13%, n=5). The most common indications for fertility preservation reported included oncologic care (42%), gamete storage for planned ART (31%), transgender care (18%), pre-vasectomy sperm banking (10%), and pre-deployment banking for military personnel (5%). Nearly all providers performed microsurgical sperm retrievals (97%, n=38, Figure) and oncologic testicular sperm extractions (85%, n=33) when indicated. More than half of providers offered conventional testicular sperm extractions (72%, n=28), microsurgical epididymal sperm aspirations (59%, n=23), testicular sperm aspirations (56%, n=22), penile vibratory stimulation (54%, n=21), or percutaneous epididymal sperm aspirations (52%, n=20). Fewer providers offered post-mortem sperm retrieval (49%, n=19), pre-pubertal testicular tissue cryopreservation (36%, n=14), or electroejaculation (31%, n=12). Most respondents (62%, n=24) had access to an on-site andrology laboratory. Semen analyses were evaluated using manual (53%, n=20), computer-assisted (11%, n=4), or combinatorial methods (26%, n=10). Though many (37%, n=14) providers were uncertain about institutional costs for semen specimen processing, a plurality of respondents (40%, n=15) reported fees ranging from $100-500 with the remainder (23%, n=9) reporting fees exceeding $500. Respondents most frequently reported semen storage fees ranging between $100-300 per year (39%, n=15), while approximately a third (31%, n=12) estimated these costs to range between $300-600 per year. However, 18% (n=7) of respondents reported higher costs for specimen storage and 13% (n=5) were uncertain about the expense of this service. Conclusions This multi-institutional, geographically diverse survey reveals significant variation in reproductive urology practice patterns and cost associated with semen analyses and storage. Future studies will explore differences in practice patterns to better understand the factors influencing this variation and their effect on male reproductive healthcare. In the absence of society guidelines, reproductive urologists must collaborate, share best practices, and maintain price transparency to ensure sperm retrieval remains accessible and affordable. Disclosure No

Abstract Introduction While most patients with Peyronie’s disease (PD) present with dorsal or lateral curvature, a significant number have ventral curvature (VC). These patients face limited treatment options, as they were excluded from initial clinical trials of collagenase clostridium histolyticum (CCH) due to safety concerns related to the proximity of the injection site to the urethra. However, urethral involvement is rare, as PD plaques develop in the tunica albuginea rather than the corpus spongiosum surrounding the urethra. Moreover, multiple prospective and retrospective studies have demonstrated favorable outcomes with CCH treatment in men with VC. Objective To evaluate the effectiveness and safety of CCH in men with PD and VC in a multicenter, real-world, retrospective study. Methods This is an ongoing phase 4, multicenter, retrospective review of medical records from 15 US physician sites. Eligible patients consisted of patients who are: age ≥18 years with a diagnosis of VC in PD with a palpable plaque that was treated with CCH from 2014 to the study start date at each site. Patients missing baseline (BL; pretreatment) or final (last measurement within 6 months of final CCH treatment) penile curvature measurements were excluded. Effectiveness endpoints included percentage change in VC from BL to last visit, mean change in VC (in degrees) from BL to last visit, and proportion of patients with ≥30% improvement in VC from BL to last visit. Safety was assessed as proportions of patients reporting treatment-related adverse events (TRAEs) throughout the study period. Results As of April 22, 2025, there were 116 patients with mean (SD) age of 58 (10.3) years who were eligible for analysis. Mean baseline VC decreased from 58 degrees to 37 degrees at last visit (37% improvement). An improvement in VC of ≥30% was seen in 73/116 (63%) of patients, with 81/116 (69.8%) experiencing ≥20% improvement. At least 1 TRAE was reported by 12 (10%) patients. TRAEs were mild-to-moderate in severity in 9 (75%) patients and unknown in 3 patients, with most events (14/17 [82%]) related to injection site reactions. As of the data cut, there were no treatment-related serious or treatment-related severe AEs, no reports of urethral involvement or injury, and no reports of corporal rupture. Conclusions Men with PD who present with ventral curvature represent an underserved patient population. Concerns about potential urethral injury pose a significant barrier to both minimally invasive and surgical treatments, thereby limiting available therapeutic options. These updated results from a multi-institutional real-world clinical cohort align with previous findings, and demonstrate that the clinical effectiveness and safety profile of CCH is consistent with the profile of CCH seen in other clinical presentations of PD. Disclosure Yes, this is sponsored by industry/sponsor: Endo USA, Inc Clarification: Industry initiated, executed and funded study Any of the authors act as a consultant, employee or shareholder of an industry for: Endo USA, Inc.

Objectives: In the United States, training for physicians who manage critically ill adult patients (intensivists) evolved through parallel subspecialty critical care medicine (CCM) pathways with significant commonality. The Society of Critical Care Medicine Adult Critical Care Physician Core Knowledge and Skills Task Force aimed to delineate the common core knowledge and skills required of all intensivists. Design: A master list of content areas and procedural skills was compiled from all CCM subspecialty program requirements and blueprints of the certification examinations. Using a modified Delphi approach, participants were asked to categorize the knowledge items as “advanced knowledge is essential,” “general, but not advanced, knowledge is essential,” or “knowledge is not essential.” Procedures were categorized as “intensivist performs routinely,” “intensivist only performs in an emergency,” or “intensivist knows” about the procedure. Setting: Representatives from CCM stakeholder organizations, including accreditation and certification organizations, critical care societies, and program directors’ societies, were invited to participate. SUBJECTS: Members of the Adult Critical Care Physician Core Knowledge and Skills Task Force of the Society of Critical Care Medicine. Interventions: For the first two rounds of the modified Delphi process, Research Electronic Data Capture was used. For the third and fourth rounds, the process was completed through online meetings with Zoom (Zoom Video Corporations, San Jose, CA) utilizing Zoom’s polling feature. Measurements and Main Results: A total of 541 items were determined to be essential, with 145 requiring advanced knowledge and 323 requiring general knowledge. For 73 items, consensus regarding advanced vs. general could not be achieved, but they remained essential. Only eight items were felt to be nonessential. Of the 16 procedures, most were categorized as “intensivist performs.” Conclusions: The large number of items included in the list of essential knowledge and skills demonstrates the complexity of modern CCM. Utilization of a common framework across the subspecialties of CCM could lead to greater harmonization among the fellowship program requirements and certification examinations.

Abstract Wiskott-Aldrich syndrome (WAS), an X-linked disorder characterized by immunodeficiency, thrombocytopenia, autoimmunity, and malignancy, can be effectively treated with allogeneic hematopoietic cell transplantation (HCT). Older age at HCT and mismatched donors are known to affect overall survival (OS). However, the influence of specific clinical manifestations or WAS variant class on OS and factors associated with event-free survival (EFS) remain incompletely defined. We analyzed outcomes of 308 patients with WAS who underwent HCT at 37 institutions of the Primary Immune Deficiency Treatment Consortium from 1990 to 2018. With a median follow-up of 5.3 years, the 5-year OS and EFS were 87.2% and 79.7%, respectively. Age ≥5 years, donor type, and a pre-HCT history of severe infection had a negative impact on OS and EFS, whereas pre-HCT autoimmunity had no impact. Reduced-intensity regimens were associated with lower T-cell and myeloid donor chimerism, particularly when non–busulfan-based regimens were used. Low myeloid donor chimerism was associated with lower platelet counts. Mixed chimerism was not consistently associated with post-HCT autoimmunity. Patients with class I (exon 1-2 missense and intron 5 hot spot variants) and class II variants (all others) had similar pre-HCT clinical symptom severity and no difference in OS, EFS, or platelet recovery post-HCT. In conclusion, our study showed excellent long-term OS and EFS after HCT for WAS, highlighting the importance of early HCT, before the development of severe infections. We confirmed that HCT using busulfan-based conditioning was associated with improved donor chimerism and platelet recovery. This trial was registered at www.clinicaltrials.gov as NCT02064933.

Abstract Background: Treatment of multiple myeloma (MM) has advanced dramatically over the past decade with median overall survival (OS) for newly diagnosed MM patients (pts) now exceeding 10 years. However, outcomes in pts with high-risk disease remain poor. While most pts with high-risk disease are identified through baseline cytogenetic risk stratification, presence of extramedullary disease, or R-ISS stage, there is also a population of pts who may or may not have these traditional high-risk factors who relapse earlier than expected and have similarly poor outcomes. These pts are often delineated as “functional high-risk,” but a standardized definition of this population in the era of modern myeloma therapy is lacking. Methods: Using the ASH Research Collaborative (ASH RC) Data Hub, we retrospectively searched 7,249 pts across 10 participating institutions for those with newly diagnosed multiple myeloma (NDMM) treated with a triplet or quadruplet induction regimen (with or without autologous stem cell transplant) who had response data available. We evaluated duration of response from first line therapy (PD1) on post-PD1 clinical outcomes such as: time to next treatment (TTNT), time to subsequent progression and/or death (PFS2), and OS. We also analyzed characteristics of those who did vs. did not progress at prespecified time points of interest (12-, 18-, 24-, and 36-months) from the start of induction. We utilized recursive partitioning analyses to iteratively explore all possible cutpoints and identify which one(s) provide the greatest differentiation in the risk of subsequent progression and/or death. Results: We identified 1,305 pts who met the eligibility criteria. Of these, 264 had PD1 data including 201 who had response follow-up (f/u) after PD1. Median f/u after PD1 in this population was 3.2 years, and median PFS2 f/u after PD1 (n=201) was 4.4 years. Months to PD1 was significantly associated with PFS2 (p=0.038). All prespecified time points examined showed inferior PFS2 compared to those with PD1 >36 mos, although each subgroup was not statistically significant, likely due to limited numbers in each group: PD1 <12 mos HR=1.44 (n=43; 95% CI: 0.90 – 2.30; p=0.126), PD1 12-24 mos HR=1.65 (n=30; 95% CI: 0.95 – 2.85; p=0.073), and PD1 24-36 mos HR=1.58 (n=52; 95% CI: 0.98 – 2.53; p=0.059). Similarly, timing of PD1 was also associated with OS post-PD1; pts with PD1 <12 mos had significantly lower OS compared to those with PD1 >36 mos (HR=2.35, 95% CI: 1.27 – 4.32; p=0.006). Our recursive partitioning analysis identified 30-months at the cutoff that produced the greatest differential in outcomes between those above vs. below the landmark. Approximately 23% of the pts analyzed had PD1 within 30 mos, and these pts had significantly lower OS compared to those with PD1 ≥30 mos (HR=1.99, 95% CI: 1.21 – 3.27; p=0.006). Similarly, pts who progressed within 30 mos of starting 1L therapy (n=98) had significantly shorter PFS2 (median=12.5 mos vs 22.8 mos; HR=1.55, 95% CI: 1.09 – 2.20; p=0.014) than those who did not (n=103). Those pts who progressed within 30 mos were more likely to have a higher R-ISS stage at diagnosis (p=0.048), but were not more likely to have high-risk cytogenetics (p=0.66) compared to pts with PD1 ≥30 mos. Interestingly, receiving SCT as part of 1L therapy was not significantly associated with improved PFS2 (HR=0.89, 95% CI: 0.62 – 1.29; 0.54) but was significantly associated with improved OS (HR=0.53, 95% CI: 0.31 – 0.90; 0.018) by univariate analysis. Conclusion: Our study is the first to use a large, multicenter, cohort to evaluate the definition of functional high-risk MM in the era of novel induction therapies. Our data suggest that pts who progress within 30 mos of induction on triplet or quadruplet regimens (irrespective of whether they underwent stem cell transplant) have poorer outcomes than those who progress at 30 mos or later, and that progression prior to 30 mos represents functional high-risk disease. These pts represent a clear unmet medical need, and additional focus should be taken to identify them early with the goal of designing trials to optimize their subsequent therapies.

Abstract Background: Autoimmune hemolytic anemia (AIHA) is a condition in which the immune system erroneously attacks and damages red blood cells. While the epidemiology of AIHA has been examined in various European and Asian nations (Hansen 2020; Kao 2025), there is limited data available from the United States (US). Using US insurance claims data, this research aimed to determine the prevalence and demographic characteristics of AIHA over a five-year span. Methods: Five databases were used: Merative MarketScan Commercial Claims and Encounters; Optum's de-identified Clinformatics® Data Mart Database; Closed and Open claims sourced through HealthVerity; Merative MarketScan Medicare Supplemental Database; Merative MarketScan Multi-State Medicaid. AIHA was defined by ICD-10 diagnosis codes D59.1x in a given calendar year and a second code within 365 days prior. Annual prevalence in years 2019 – 2023 was calculated among people with insurance enrollment for at least 6 months in the calendar year. Annual prevalence was stratified by age group, sex, and prescription fill for an AIHA-related treatment (systemic steroids, immunosuppressants [azathioprine, mycophenolate, cyclosporin, cyclophosphamide, danazol, bortezomib, rituximab], splenectomy) in the calendar year. Extrapolation of prevalence rates for commercial and government assistance insurance to the US population for 2023 was implemented by age and sex-standardization to the US Census population. For data sources that included both commercial and government assistance insurance, patients aged <65 years were analyzed as commercial insurance and aged ≥65 years as government assistance. Results: AIHA prevalence in 2023 across databases ranged from 2.7 to 4.3 per 100,000 for ages <18 years; 4.2 to 9.4 per 100,000 for ages 18 – 34 years; 8.2 to 11.8 per 100,000 for ages 35 – 49 years; 15.4 to 23.9 per 100,000 for ages 50 – 64 years; 26.6 to 37.0 per 100,000 for ages 65 – 74 years; and 30.6 to 61.2 per 100,000 for age 75 years and older. Across databases and over time, the proportion of AIHA patients that were female was 55% – 67%. Across all databases, in year 2023, half (44% - 55%) of patients received any AIHA-related treatment, out of which one third (26%-34%) received systemic steroids, less than one quarter (9% – 17%) received rituximab, and one third (25% – 31%) received a different immunosuppressant. Compared to patients with commercial insurance, Medicaid-insured patients had lower AIHA-related treatment utilization, whereas Medicare-insured patients had higher utilization. Within age group and sex and by insurance type, low and high estimates of prevalence were used to define a range of prevalence. After standardization to the 2023 US Census population, the estimated prevalence in 2023 ranged from 38,459 to 57,235 patients diagnosed with AIHA, corresponding to prevalence rates of 11.6 to 17.3 per 100,000. This marked an increase from 2019 US Census-standardized estimates of 32,777 to 48,482, with corresponding prevalence rates of 10.1 to 14.9 per 100,000. Discussion: AIHA prevalence was higher in older age groups, with a peak prevalence in ages 65 and older. Prevalence increased approximately 15% over a 5-year interval and was notably higher in patients with commercial health insurance compared to government insurance programs, which may in part be due to the older age of the Medicare population. Fewer than half of patients received an AIHA-related treatment in 2023, which could reflect heterogeneity in disease severity necessitating treatment, in addition to the relapse-remitting nature of AIHA whereby patients experience remission for periods of time. Additionally, insurance claims do not specify an indication for treatment nor a reason for discontinuation; some treatments could have been prescribed for an underlying condition contributing to AIHA. Finally, prevalence extrapolation assumes Americans without health insurance are diagnosed with AIHA at the same rate as those with insurance, which may slightly overestimate the total number of diagnosed patients.Conclusion: AIHA prevalence in this study was consistent with estimates from European countries and has been increasing in recent years, providing evidence of consistent disease epidemiology across several geographies.

Abstract Introduction: CTCLs are rare, heterogeneous non-Hodgkin lymphomas (NHL) with significant regional variability in treatment patterns. Prospective studies characterizing CTCL management, particularly in racially and ethnically diverse populations, remains limited. The LEO-MER multi-center prospective cohort study (NCT02736357) is designed to address the persistent disparities in outcomes research by enrolling historically underrepresented groups of patients diagnosed with lymphoma across the United States (US). Here, we present a real-world analysis of CTCL patients that reflects US academic practice, evaluating treatment patterns, as well as prognostic factors influencing survival outcomes. Methods: Patients aged ≥18 years with newly diagnosed CTCL were prospectively enrolled in either the University of Iowa/Mayo Clinic MER cohort (2002-2015) or the expanded LEO cohort (2015-2020), which included 8 US academic centers. Standardized protocols were used to abstract clinical, pathologic, treatment, and outcome data from medical records. ANOVA/Kruskal-Wallis and Fisher's/chi-square tests were used to compare patient distribution across demographic and clinical characteristics based on data distribution and sample size. Overall survival (OS) was calculated from diagnosis to death or last follow-up. Survival analyses employed Kaplan-Meier estimation supplemented by Cox proportional hazards modeling. Results: The LEO-MER cohort enrolled 223 CTCL patients (91 MER and 132 LEO). Subtypes included mycosis fungoides (MF, n=155, 69.5%), Sézary syndrome (SS, n=22, 9.9%), primary cutaneous anaplastic large-cell lymphoma (n=17, 7.6%), subcutaneous panniculitis-like T-cell lymphoma (n=11, 4.9%), cutaneous CD4+ small/medium T-cell lymphoproliferative-disorder (n=9, 4%), and other rarer CTCL subtypes (n=9, 4%). Among the MF/SS cohort, median age was 64 years (Range: 18-89 years), 58.2% (n=103) were male and race/ethnicity distribution included White (n=123, 69.5%), Black (n=29; 16.4%) and others/unknown (n=25; 14.1%). Stage distribution included 62.7% with early-stage (ES) MF (IA-IIA, n=111), 37.2% with advanced-stage (AS) MF (IIB-IVB, n=66). To complete diagnostic workup, T-cell receptor (TCR) testing was performed in 52.6% of skin biopsies (n=92) and 62.5% of blood samples (n=110), with clonal detection rates of 75% (69/92) in skin and 51.8% (57/110) in blood. Paired TCR matching between skin and blood samples was performed in 31.6% (n=56) of cases, demonstrating 53.6% (30/56) concordance. Blood flow cytometry data were reported in 80.1% (89/111) and 84.4% (56/66) of ES and AS MF cases, with T-cell population being detected in 7.2% (8/111) and 62.1% (41/66) of ES and AS cases. Nodal biopsies were obtained in 23.4% (n=41) of patients and clonality assessment was reported in 18.6% (33/177) of these cases. The MF/SS cohort's lifetime treatment exposure data (n=160) revealed topical skin-directed therapies alone (n=49, 31.8%) as the most common approach followed by lifetime exposure to topical skin-directed and systemic therapies (n=45, 29.2%) followed by multimodal exposure of topical skin-directed, radiation and systemic treatments (n=30, 19.5%). Only 5.6% of patients were enrolled in a clinical trial. First-line (1L) systemic regimens were predominantly a) immunomodulatory agents (n=47, 29.3%); including oral retinoid (n=20), extracorporeal photopheresis (n=18), interferon (n=9) followed by b) chemotherapy (n=30, 18.7%) and c) targeted therapies (n=17, 10.6%) including Brentuximab Vedotin (n=6), Romidepsin (n=5), Mogamulizumab (n=3), Vorinostat (n=2) and Pralatrexate (n=1). Multivariable analysis predicting 1L systemic treatment initiation demonstrated a significant association with presence of N2/N3 stage (N2/N3 vs N0/N1: Odds Ratio (OR): 5.45) and elevated LDH (OR: 5.30). At median follow-up of 91.1 months (mon), median OS was 122.3 mon (95% confidence interval 67.2-159.2 mon). In subset analyses, Black race (p=0.001) and SS (p=0.0001) were associated with worse OS outcomes. Conclusion: We present initial data from our prospective LEO-MER cohort, a large US-based multicenter consortia. Our findings demonstrate variability in both diagnostic staging and treatment approaches for MF/SS patients. The cohort demonstrated worse outcomes with high-risk disease and Black race/ethnicity. These findings warrant further study on the impact of underlying social determinant factors, given the variability noted in this population.

Abstract Background and Significance Somatic gain-of-function mutations in the PIK3CA gene can result in a range of vascular malformations (VMs). These rare disorders include lymphatic anomalies and PIK3CA-related overgrowth spectrum (PROS). VMs are noncancerous lesions that may be managed with treatments such as surgery, sclerotherapy, sirolimus, and non-mutant-selective PI3Kα inhibitors; however, use of systemic therapies in patients is frequently limited by drug-related adverse effects. In particular, inhibition of wild-type PI3Kα results in significant toxicity, including hyperglycemia, diarrhea and rash. RLY-2608 is a novel, allosteric, pan-mutant and isoform-selective oral PI3Kα inhibitor designed to have higher potency and improved tolerability. In a PIK3CAH1047R HUVEC xenograft mouse model, RLY-2608 demonstrated greater lesion regression and less insulin induction across clinically relevant dose levels than alpelisib (Llambi, VAC 2025). ReInspire (RLY-2608-201; NCT06789913) is an ongoing, global, multicenter study in patients with PIK3CA-driven VMs to assess the safety, pharmacokinetics, recommended adult and pediatric dosing, and efficacy of RLY-2608 based on target lesion volume and clinical outcome assessments. The design of this study, including dose selection, was informed by clinical data from the first-in-human study of RLY-2608 in adult patients with advanced solid tumors, including breast cancer (Varkaris et al, 2024). Study Design and Methods ReInspire is a 3-part study evaluating the safety and efficacy of RLY-2608 in approximately 277 patients two years of age and older with PIK3CA-driven VMs and PROS. RLY-2608 is administered orally in continuous cycles. The primary endpoints are safety, tolerability, recommended Phase 2 dose (RP2D), and efficacy of RLY-2608 per volumetric reduction on MRI (≥20% reduction from baseline to Week 24 in the sum of target lesion volumes) by blinded independent central review. Other endpoints include duration of response and change in age-appropriate clinical outcome assessments. Patients are enrolled in a staggered fashion by age, beginning with adult and adolescent participants 12 years and older (Group 1), and may be extended to pediatric participants 6 to <12 years (Group 2) and 2 to <6 years, based on review of cumulative clinical data. Part 1 is the open-label dose-finding portion, which initiates with randomization of Group 1 patients (n=45) to one of three dose levels with stratification according to prior alpelisib use, and will be followed by weight-based dose escalation using a Bayesian optimal interval (BOIN) design in Groups 2 and 3, if opened. Part 2 is a basket-style, open-label dose expansion that will evaluate the clinical activity of RLY-2608 at one or more RP2Ds in various populations in cohorts of 20 patients each based on Part 1 findings. Depending on the results of Parts 1 and 2, Part 3, a double-blinded, placebo-controlled, 2:1 randomized study (n=90), may be opened to patients 6 years of age and older. To enroll, patients are required to have a clinical diagnosis of PROS or a malformation within the ISSVA classifications, and the majority must have a documented activating PIK3CA mutation per local assessment of lesional tissue and/or cell-free DNA from the lesion or blood. Patients with other known pathogenic somatic or germline driver mutations (such as TIE2 (TEK) and AKT1) are not eligible. Patients must be a candidate for investigational systemic therapy; have severe, symptomatic, and/or progressive disease; and at least one target lesion amenable for volumetric assessment. Additionally, patients who have received disease-directed therapy must undergo a washout period for systemic treatment and local therapies including radiation, surgery and other procedures. Patients with Type 1 or 2 diabetes requiring antihyperglycemic medication or fasting plasma glucose ≥140 mg/dL, or glycosylated hemoglobin (HbA1c) ≥7.0% (≥53 mmol/mol) are not eligible. Statistical analyses will be primarily descriptive in nature in Parts 1 and 2, with statistical comparisons between RLY-2608 and placebo at Week 24. ReInspire is open to enrollment. Patients ≥12 years are now enrolling in Part 1. For more information, contact clinicaltrials@relaytx.com

Abstract Introduction With a median age of 60-70 years at diagnosis, many patients with MCL are ineligible for aggressive treatment. Bendamustine and rituximab (BR) is a standard therapy for older patients with MCL. Venetoclax (VEN) has shown pre-clinical evidence of synergy with chemotherapy. Thus, PrE0405 was designed to evaluate the addition of VEN to BR in previously untreated older patients with MCL. We have previously reported on response rate and short-term survival (Portell et al. ASH 2023). Here, we update survival and include minimal residual disease (MRD) at end of treatment (EOT). Methods Eligible patients included those that were previously untreated and diagnosed with MCL by presence of t(11;14) or cyclin D1 expression. Patients must have been ≥60 years of age at the start of therapy with a good performance status (ECOG 0-2). Adequate marrow and organ function was required, specifically a creatinine clearance ≥ 40 ml/min. Eligible subjects were treated with bendamustine 90mg/m2 D1-2 and rituximab 375mg/m2 IV D1 every 28 days for a planned 6 cycles of therapy. For patients ≥75 years, 70mg/m2 of bendamustine was allowed. VEN was given concurrently with BR. During Cycle 1, VEN was dose escalated weekly, as done in chronic lymphocytic leukemia, from 20mg to 200mg. For Cycle 2-6, VEN was administered as 400mg PO daily on days 1-10 only. Maintenance rituximab was encouraged but was per investigator discretion. Primary end point was PET-negative complete remission (CR) at EOT by Lugano Criteria and was confirmed by a negative bone marrow biopsy if involved at screening. MRD was assessed at EOT by next-generation sequencing (Clonoseq). Amended accrual goal was 33 patients with a planned 32 being eligible and treated. This provided an 81% statistical power to detect a 17% difference in CR rate (from 60% [E1411, Smith et al Blood 2024] to 77%) using an exact binomial test with a 1-sided alpha of 11.6%. Thus, BR-VEN would be considered promising if 23 or more subjects attained a CR. Results From 1/2020 to 3/2022, 33 subjects were enrolled, deemed eligible, and treated on study. Subjects were followed until 7/2024. Median age was 71 (range 61-80) and 76% (n=25) were male. All but 1 subject (97%, n=32) were White. MIPI was high in 67% (n=22), intermediate in 27% (n=9) and low in 6% (n=2). Ki67 was available in 25 (76%) subjects and was ≥30% in 14 (56%) and ≥50% in 7 (28%). Only one subject started bendamustine treatment at 70mg/m2; though 6 others had dose reductions during treatment. Thirty (90%) subjects completed all 6 cycles of therapy. Maintenance rituximab was administered in 19 (56%) of subjects and 9 completed all 12 recommended doses. Treatment was generally well tolerated. During BR-VEN, Grade ≥3 treatment-related adverse events (TRAE) occurring in >10% (i.e., 4 or more) of subjects were neutropenia (n=8, 24%), and thrombocytopenia (n=5, 15%). Other common TRAE of all grades were nausea/vomiting (n=19, 58%), diarrhea (n=10, 30%), and fatigue (n=19, 58%). At EOT with BR-VEN, overall response and CR rate was 97% (32 of 33) and 85% (28 of 33) respectively. The study met its primary endpoint of at least 23 subjects with a CR best response (p=0.002). EOT MRD sample (blood or marrow aspirate) was available for 28 subjects (85%). At EOT, MRD was undetectable for 100% (n=28) of evaluable subjects at a sensitivity of 10-4 and 10-5. At a sensitivity of 10-6, 64% (n=18) were undetectable, 4% (n=1) were detectable and 32% (n=9) were indeterminate. With a median follow up of 39.1 months, 3-year progression free survival (PFS) was 68.9 and 3-year overall survival (OS) was 70.0%. There were 11 total PFS events during follow up. Four subjects in remission died due to COVID-19, 1 died from influenza, one died from HSV encephalitis, and 2 others died from other causes. Two subjects died shortly after progression and 1 subject is alive following disease progression. As this study enrolled during the height of the COVID-19 pandemic, a sensitivity analysis was performed censoring the COVID-19 attributable deaths – PFS and OS at 3 years was 78.7% and 80.0%. Conclusions BR-VEN was generally well tolerated as induction therapy in older patients with MCL. It achieved a high CR rate of 85% with 100% MRD undetectable rate at 10-5 sensitivity in those evaluable. However, there were competing risks for survival in this older population as, of the 11 PFS events, only 3 events were due to progression; 8 were due to death without progression.