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Introduction: DDX41, DEAD-box RNA helicase 41 gene located on chromosome 5q25.3, is one of the most mutated genes in patients with germline predisposition to myeloid neoplasms. Germline and somatic mutations often have different locations and patterns of mutation, with some hot-spots displaying diversity based on ethnicity. We aimed to explore clinical outcomes in patients with various DDX41 hot-spots. Methods: A retrospective study of patients at Mayo Clinic with DDX41 mutation identified through Next Generation Sequencing (NGS) between 2016 and 2024. Patients classified as germline DDX41 variants or somatic variants based on confirmed germline testing results. Data regarding mutations recorded at time of patients' first in-house NGS. We completed unadjusted comparisons using continuous or categorical variables, and survival rates assessed using Kaplan-Meier method and cox regression analysis. Median overall survival calculated from time of NGS to last follow-up or death using BlueSky Statistics V.10.3.4 Results: Clinical Characteristics: Eighty-two patients analyzed, predominantly male (69.5%), with median age of diagnosis of 68 years (IQR 62-75). Most common diagnosis was MDS (50%), followed by AML (22%) and myeloproliferative neoplasm (MPN) (7.3%). Fourteen percent were DDX41 mutation carriers, 4.9% clonal cytopenia of undetermined significance (CCUS), and 1.2% chronic neutrophilic leukemia (CNL). MDS-IB2 was the prevalent MDS subtype (56.1%), and 83.3% of AML patients were intermediate risk. Cytogenetics normal in 73.8% of patients, with del20 being the most common abnormality (7.5%). Twenty-five (30.5%) of patients underwent allogeneic hematopoietic cell transplantation (alloHCT). Forty-nine patients (59.8%) had pathogenic DDX41 mutation only, 15 (18.3%) had only VUS, and 18 (22.0%) had both. Molecular Characteristic s: Mutation hot-spots included 12.2% with p.Arg525His only, 28% p.M1I only, 9.8% p.Asp140GlyFs*2 only, 9.8% p.Arg525 with co-mutation other than p.M1I/p.Asp140. Two patients (2.4%) had p.M1I co-mutation with non-p.Arg525 and p.Asp140, while 1 patient (1.2%) had p.M1I and p.Arg525, and 1 patient (1.2%) had p.Asp140 and p.Arg525. Lastly, 33 patients (40.2%) had mutations in hot-spots other than specified in this study. Median hemoglobin (Hg) was lowest in patients with p.Arg525 hotspot mutation (9.9 g/dl), compared to median Hg of 11.2 g/dl in group with p.M1I and 10.4 g/dl in p.Asp140 only group (p=0.87). The most common cytogenetics in patients with only p.Arg525 and only p.M1I hot-spot mutation was normal cytogenetics (70% and 90.9%, p=0.5). In the 16 patients with proven germline DDX41 mutation, 7 (43.8%) had mutations in only p.M1I. Lastly, median (m) VAF was significantly lower in the group with only p.Arg525 hot-spot mutation (9.5%, IQR 5.5-13.8), compared to mVAF of 48% in patients with only p.M1I (IQR 48.0-49.5, p<0.001). Co-mutations: The most frequent co-mutation was DNMT3A (11.0%), followed by JAK2 (9.8%).Mean number of co-mutations in p.Arg525 only was 0.6, 0.3 in p.M1I only, and 0.5 in p.Asp140 only (p=0.8). Most common co-mutation in p.M1I was ASXL1, with 13.0% of patients with p.M1I only having ASXL1 co-mutation (p=0.062). The most common co-mutation in p.Asp140 was DNMT3A (p=0.7). Survival: Median overall survival (mOS) was 21.5 months (IQR 12.4-38.6). mOS for p.Arg525 only group was 31.3, compared to 41.2 months in p.M1I only (p=0.197). At 12- and 24-months, survival rate was 88.9% and 59.3% in the p.Arg525 only group, compared to p.M1I group with 100% survival rate at 12 months and 89.5% at 24 months. p.Asp140 had 87.5% survival rate at both 12 months and 24 months. Males in p.M1I group had lower survival rate at 24 months (81.8%), compared to 100% survival in females. p.M1I only group with alloHCT also had lower 24 month survival at 60% compared to 100% in group who did not undergo alloHCT. Conclusions: The p.M1I hot-spot was commonly seen in patients with germline DDX41 mutation, likely resulting in significantly higher VAF percentage. Co-mutations frequency differed by hot spot mutation while p.Arg525 as second mutation was seen mainly in cases other than p.M1I/pArg140Gly. Overall survival appears to be higher in p.M1I/pArg140Gly compared to p.Arg525His hot-spot mutation, though males with p.M1I and those who underwent alloHCT had lower survival. Findings suggest implications for clinical outcomes based on DDX41 mutation hot-spots.

Background: The prognosis of patients (pts) with relapsed or refractory B ALL (r/r B-ALL) treated with CAR T-cells and receive a 2nd CART infusion is unknown. Few reports with limited numbers of patients suggest that 2nd CART infusion is feasible with questionable efficacy. This GoCART coalition registry study aimed at compiling data to investigate the indications, efficacy, and toxicity of CART2 infusion in pts with r/r B-ALL. Methods: This is a multicenter, retrospective registry study that included pediatric and adult patients with r/r B-ALL who received autologous CD19-targeted CAR T-cell therapy (CART1) and subsequently were treated with a second administration of CD19 and/or CD22-targeted CAR-T cell therapy (CART2) from 2017 to 2023. Baseline features, prior stem cell transplant (SCT), indications for CART2 and outcomes were collected. Relapse incidence (RI) was defined as overt recurrence, non-relapse mortality (NRM) as death without relapse occurrence, leukemia free survival (LFS) as being alive without occurrence of relapse and overall survival (OS) as being alive. RI and NRM were estimated using cumulative incidence function and OS and LFS Kaplan-Meier estimation. Results: Out of 345 pts who received CART1, 39 (2y cumulative incidence of second CART: 12.4% (95%CI: 8.8-16.6)) received CART2. Reasons for CART2 were overt relapse (n= 26; 66.7%), molecular relapse by measurable residual disease (MRD+) (n=5; 12.8%), and B-cell recovery (BCR) in the absence of relapse (n=8; 20.5%). Seventeen pts (43.6%) were female and median age at CART2 infusion was 19 yrs (range: 6.9-67.1), including 19 children and 20 adults. 74.4% of the pts had received a prior SCT, 25 pts (64%) before CART1, 2 (5.1%) only between CART1 and CART2, and 2 (5.1%) before CART1 and between CART1 and CART2. Among the 31 pts who received CART2 for relapse, this was CD19+ in 24 (92.3%), CD19- in 2 (7.7%), and unknown in 5. CART1 products were varnimcabtagene autoleucel (ARI-0001) (23), tisagenlecleucel (13), brexucabtagene autoleucel (1), and other experimental (2). All CART2 products targeted CD19 except 2 (1 CD22 and 1 dual CD19-CD22). Median time between CART1 and CART2 was 11.0 months. For patients who received CART2 for BCR, median time between CART1 and CART2 was shorter than for those who received it for relapse: 2.4 (IQR: 2.3-3.3) months vs. 12.4 (IQR:6.4-19.3) months. Regarding leukemic burden at the time of CART2 infusion, 19 pts (48.8%) were in overt relapse (14/19 with extramedullary disease, including 7 in CNS), 12 (30.1%) were in complete remission (CR) MRD+ and 8 (20.5%) CR MRD-. With a median follow-up time of 2.3 yrs [95% CI: 1.2-3.4], the 2-yr OS and LFS after CART2 were 47.1% [95% CI: 27.8-64.3] and 39.9% [95% CI: 24-55.3], respectively. 2-yr RI was 54.5% (95% CI: 36.5-69.4) and NRM was 5.6% (95% CI 1-16.8). 2-yr OS, LFS and RI for pts in CR at CART2 infusion irrespective to MRD were 76.1%, 63.3% and 25.6% while for those not in CR these outcomes were 17.7%, 15% and 85%, respectively (p= 0.007, 0.006 and 0.002). 2-yr LFS (71.4% [95% CI 25.8-92]) and RI (0%) was significantly better for pts receiving CART2 for BCR than in those who received it for relapse (31.6% [15.6-48.9] and 68.4% [46.7-82.8]; p= 0.036, p=0.002). Conclusion: This is a large registry study describing indications and outcome of CART2 in patients with r/r B-ALL. At 2-yrs after CART2, the LFS was of 39.9% and for patients receiving CART2 due to B-cell recovery was of 71.4%. These results show that CART2 is associated with low NRM and might be a bridge to SCT or other additional therapies. Updated results with data about subsequent therapies after CART2 will be presented at ASH meeting.

Introduction: Acute myeloid leukemia (AML) has been considered by many to be an oncologic emergency often leading to hospital admission for expeditious evaluation and treatment. Previous studies reported that time from diagnosis to treatment (TDT) does not impact outcomes (Sekeres, Blood, 2009), (Bertoli, Blood, 2013), (Rollig, Blood, 2020), however these analyses were restricted to intensively treated and/or non-United States (US) patients (pts). We report on a multi-center, retrospective analysis of TDT in adults with newly diagnosed AML receiving Hypomethylating agent (HMA) + venetoclax (Ven) using real-world data from the COMMAND. Methods: Eight US academic medical centers with AML expertise performed a review of adult pts within their center treated with HMA+Ven for newly diagnosed AML. TDT was defined as days from diagnosis of AML to initiation of treatment with HMA+Ven. Cytoreduction with hydroxyurea or leukapheresis was included to control for the effects of severity of presentation on TDT. The primary outcome was impact of TDT on overall survival (OS) (defined as date of diagnosis to date of death). TDT was treated continuously for time-to-event analyses. Secondary outcomes included measurable residual disease (MRD) by flow cytometric analysis (sensitivity <0.1%), complete response (CR), complete response with incomplete count recovery (CRi), defined by European LeukemiaNet (ELN) 2022 Guidelines (Dohner, Blood,2022), and early mortality (death within 30 and 60 days of initiation of HMA+Ven). Pre-planned subgroup analyses included those based on disease biology (FLT3 ITD, IDH1/2, TP53 mutation, ELN 2022 risk), HMA used (azacitidine vs decitabine) and age (<75 vs ≥75 years). For those analyses where TDT was significant in univariable analysis (P=0.1), multivariable analysis was conducted controlling for the following: ECOG performance status (PS), age, receipt of cytoreduction, ELN 2022 risk, and presence of individual pathogenic variants detected on broad myeloid gene next generation sequencing panels used at each institution. All analyses were conducted by a central statistician using RStudio statistical package. Results: 488 pts were included in the analysis. Median age was 76 (interquartile range: 70-80) and the majority of pts had an ECOG PS of 0 or 1 (56%). Most pts (67.6%) had adverse risk with 9.4% and 18.6% of pts having favorable and intermediate risk disease by ELN 2022, respectfully. The most common mutations identified were TP53 (27.5%), IDH1/2 (19.3%), NPM1 (16.4%), DNMT3A (16.8%), ASXL1 (15.4%), and FLT3-ITD (13.7%). Twenty-eight percent of pts received cytoreduction prior to initiation of HMA+Ven. Azacitidine+Ven was the most common regimen utilized (53.9%). Median number of cycles of HMA+Ven was 3 (IQR: 1-6). MRD (-) CR, MRD (+) CR, and CRi was achieved in 21.5%, 10.5%, and 16.4% of pts after one cycle of HMA+Ven. Median OS for the cohort was 10.4 months (95% CI: 9.4-12.6). Median TDT for the cohort was 9 days (IQR: 5-17). In univariate Cox model, longer TDT was associated with improved OS (HR: 0.989, 95% CI: 0.981 to 0.998; p = 0.013). In multivariable analysis, longer TDT was still associated with improved OS (HR: 0.987; 95% CI: 0.973-0.999; p=0.049). TDT and presence of bZIP in-frame CEBPA mutations were the only factors associated with improved OS, while ECOG PS of 2 or 3-4, when compared to ECOG PS=0 (p=0.035 and 0.0002, respectively) and therapy-related AML (p=0.002), were associated with worse OS. Notably, ELN 2022 risk and IDH1/2 or NPM1 mutation status did not impact OS. Discussion: In this real-world, multi-center, US-based analysis of pts with newly diagnosed AML treated with HMA+Ven we show that longer TDT is associated with improved OS even when controlling for severity of presentation, ELN 2022 risk score, ECOG PS, and age. This finding is consistent with data in pts treated with 7+3. Similar to results published in an electronic medical record-based analysis out of Germany (Baden, Haemotologica, 2024) in pts treated with lower-intensity Ven regimens, our results show that pts with newly diagnosed AML eventually treated with HMA+Ven are best served with a complete appraisal of disease biology and treatment planning before initiation of induction therapy. Given the consistent negative impact of ECOG PS and the findings of our study, future consideration for potential patient optimization strategies to improve ECOG PS prior to therapy initiation are warranted.

Introduction: High-risk smoldering multiple myeloma (SMM) is an asymptomatic precursor disorder to active multiple myeloma (MM) without approved treatment options. However, recent evidence suggests patients at high risk of progression to MM may benefit from early treatment. Daratumumab (DARA) is a human IgGκ monoclonal antibody targeting CD38 with direct on-tumor and immunomodulatory mechanisms of action. DARA is approved as monotherapy for relapsed/refractory MM (RRMM) and in combination with standard-of-care regimens for RRMM and newly diagnosed MM. Based on the encouraging activity and tolerability observed with DARA monotherapy in patients with intermediate- or high-risk SMM in the phase 2 CENTAURUS study, the phase 3 AQUILA study sought to determine if DARA could delay progression to MM versus active monitoring. Here we report the primary analysis from the AQUILA study. Methods: Eligible patients had a confirmed diagnosis of high-risk SMM for ≤5 years, defined as clonal bone marrow plasma cells (BMPCs) ≥10% and ≥1 risk factor (serum M protein ≥30 g/L, IgA SMM, immunoparesis with reduction of 2 uninvolved Ig isotypes, serum involved:uninvolved free light chain ratio ≥8 and <100, and/or clonal BMPCs >50% to <60%). Focal and lytic lesion assessment was performed in screening by CT and MRI and centrally reviewed prior to study enrollment. Patients were randomized 1:1 to receive DARA SC versus active monitoring. DARA (QW in Cycles 1 and 2, Q2W in Cycles 3-6, and Q4W thereafter) was given in 28-day cycles until cycle 39, 36 months, or disease progression, whichever came first. The primary endpoint was progression-free survival (PFS), defined as progression to active MM as assessed by an independent review committee and according to IMWG diagnostic criteria for MM (SLiM-CRAB) or death. Major secondary endpoints included overall response rate (ORR), PFS on first-line MM treatment (PFS2), and overall survival (OS). Results: A total of 390 patients (DARA, n = 194; active monitoring, n = 196) were randomized. Median (range) age (64 [31-86] years) and time from initial SMM diagnosis to randomization (0.72 [0-5.0] years) were balanced between treatment groups. Median treatment duration in the DARA group was 38 cycles (35.0 months). At a median (range) follow-up of 65.2 (0-76.6) months, PFS was significantly improved with DARA versus active monitoring (HR, 0.49; 95% CI, 0.36-0.67; P <0.0001). Median PFS was not reached in the DARA group versus 41.5 months for active monitoring; estimated 60-month PFS rates were 63.1% versus 40.8%, respectively. Prespecified analyses showed generally consistent PFS improvement with DARA versus active monitoring across subgroups. ORR was 63.4% with DARA versus 2.0% with active monitoring (P <0.0001). As of the clinical cutoff, 64 (33.0%) patients in the DARA group and 102 (52.0%) patients in the active monitoring group had started first-line MM treatment. Median time from randomization to the date of first-line MM treatment was not reached with DARA versus 50.2 months with active monitoring (HR, 0.46; 95% CI, 0.33-0.62; nominal P <0.0001). There was a positive trend in favor of DARA for PFS2 (HR, 0.58; 95% CI, 0.35-0.96) and OS (60-month OS rates: DARA, 93.0%; active monitoring, 86.9%; HR, 0.52; 95% CI, 0.27-0.98). A total of 41 deaths were observed, 15 for the DARA group and 26 for the active monitoring group. Grade 3/4 treatment-emergent adverse events (TEAEs) occurred in 40.4% and 30.1% of patients in the DARA and active monitoring groups, respectively. The most common (≥5% in either group) grade 3/4 TEAE was hypertension (DARA, 5.7%; active monitoring, 4.6%). The frequency of TEAEs leading to DARA discontinuation was low (5.7%), as was the incidence of fatal TEAEs in both groups (DARA, 1.0%; active monitoring, 2.0%). Conclusions: DARA monotherapy was well tolerated and demonstrated a clinically meaningful and significant benefit in preventing or delaying progression to active MM compared with active monitoring in patients with high-risk SMM. ORR was significantly higher and time to first-line MM treatment was prolonged with DARA compared with active monitoring. This was accompanied by positive trends for PFS2 and OS in favor of DARA. These results strongly support the benefit of early intervention with DARA monotherapy versus active monitoring, the current standard of care, in patients with high-risk SMM.

Introduction: Based on a donor versus no-donor analysis, UKALLXII/E2993 showed a survival benefit for adults with acute lymphoblastic leukemia (ALL) who underwent allogeneic hematopoietic cell transplantation (alloHCT) in first complete remission (CR1) compared to consolidation/maintenance chemotherapy alone. The follow-up phase 3 E1910 trial (NCT02003222) randomized BCR::ABL1-negative B-lineage ALL patients (pts) aged 30-70 years in measurable residual disease (MRD)-negative CR1 after intensification to conventional chemotherapy (CC) +/- blinatumomab (blin) and demonstrated significantly improved overall survival (OS) with blin (Litzow, NEJM 2024). The current exploratory subgroup analysis evaluates outcomes of MRD-negative pts randomized on E1910 who underwent alloHCT on trial. Methods: Among pts enrolled on E1910, pts in MRD-negative CR1 by 6-color flow cytometry after intensification who were randomized to CC +/- blin and subsequently underwent alloHCT were identified. We compared baseline characteristics, MRD status post induction, relapse-free survival (RFS) and OS using the Kaplan-Meier method and the two-sided log-rank test and Cox model. A multivariable analysis was performed with alloHCT included as a time-varying covariate as well as a landmark analysis comparing the outcome of pts with unfavorable risk on the CC + blin arm who underwent alloHCT versus those who did not. Results: Of 224 MRD-negative randomized pts, 44 underwent alloHCT on trial: 22 in each arm. The median time from randomization to transplant was 3.2 months (mos). The median follow-up from initial registration was 57.8 mos. Baseline demographics including age (median 55 years), gender (53% male), race (89% white) and ethnicity (89% non-Hispanic/Latino) were equally distributed. Compared to CC + blin, the median peripheral blood white cell (WBC) count and blast percentage at diagnosis were higher in the CC arm at 6,640 vs 3,740/uL and 55 vs 9%, respectively, while median marrow blast percentage and overall unfavorable risk as defined in E1910 (55% vs 64%) were similar. Of the 44 MRD-negative pts who proceeded to alloHCT on study, 77% in the CC arm and 64% in the CC+ blin arm were MRD-negative after induction. Myeloablative conditioning was given to the majority of pts (68% CC arm and 73% CC+blin arm) and the most common graft versus host disease prophylaxis was tacrolimus-based on both arms. Among the 44 pts who underwent alloHCT, the observed hazard ratio (HR) comparing relative risk of death between pts randomized to CC+blin or CC only was 0.59 (95% CI: 0.12-2.11) with a 3-year OS rate of 82% versus 71% and the HR comparing relative risk of relapse/death was 0.52 (CI: 0.15-1.79) with a 3-year RFS rate of 82% versus 67%. For patients with unfavorable risk, 3-year OS and 3-year RFS in each treatment arm were both 71% versus 65%. Among 50 pts with unfavorable risk in MRD-negative CR after intensification who were randomized to CC + blin, a landmark analysis performed at 5 mos post randomization showed 3-year OS and RFS rates of 71% versus 90% and 71% versus 86% between the 14 pts who underwent alloHCT and those who did not, respectively. Receipt of alloHCT was a time-varying covariate in a multivariable analysis with gender, WBC count, platelets, hemoglobin, peripheral blood blasts, bone marrow blasts, performance status, and combined molecular risk category. Age, CD20 status, rituximab use, and intention to receive alloHCT were used as stratification factors. In the entire cohort of MRD-negative pts who were randomized, there was a significant association between improved OS and the receipt of CC+blin vs CC alone (HR 0.46, 95% CI: 0.26 - 0.82; p=0.009), better performance status of 0-1 vs ≥2 and favorable vs unfavorable risk ALL. In contrast, the receipt of alloHCT had no significant effect on OS (HR 1.00, 95% CI: 0.49 - 2.01). Conclusions: Within the constraints of small numbers, this exploratory subgroup analysis demonstrates that in pts with newly diagnosed BCR::ABL1-negative B-ALL treated on E1910 who achieved MRD-negativity after intensification, alloHCT outcomes did not appear to be different with or without blin in consolidation. In a multivariate analysis of all MRD-negative pts, receipt of blin but not alloHCT was associated with improved OS. Further investigation is warranted to characterize the relative benefit of blinatumomab in pts receiving alloHCT in frontline consolidation.

In 2023, Mayo Clinic in Rochester, MN, cared for over 20,000 patients with hematologic malignancies, roughly 42% of whom were rural. Patients residing in rural areas can face challenges in access to care, financial and time burdens due to treatment-related travel, and limited opportunities to participate in clinical trials. In 2021, The Leukemia & Lymphoma Society launched its IMPACT (Influential Medicine Providing Access to Clinical Trials) grant with Mayo Clinic being among its first recipients. The program provides funding to major cancer centers, in partnership with local community oncology centers, to help increase participation of patients traditionally underrepresented in clinical trials, including those who are rural, minority and/or economically disadvantaged. The award allowed significant changes to be made to clinical trial selection and facilitation models increasing access to trials within the rural setting and reducing the socioeconomic barriers noted above. This program included Rochester (IMPACT Hub) and Mayo Clinic Health System (MCHS) sites in Albert Lea, MN (65 miles to Hub), Eau Claire, WI (96 miles to hub), La Crosse, WI (73 miles to Hub), and Mankato, MN (84 miles to Hub). Methods: Two models were deployed; the full activation model where clinical trials were fully opened at MCHS sites, and the hybrid model where clinical trial participants are consented at the Hub and portions of participant care are conducted at MCHS sites. Initial barriers included limitations in clinical trials support staff, insufficient specimen processing equipment, medication storage and shipping limitations, MCHS catchment population unalignment with the Hub trials portfolio, and reduced bandwidth of providers due to patient care responsibilities. To address barriers to trial conduct, community center site champions were identified to streamline trial review and increase collaboration to better define site catchment areas, trial constraints, and site needs. A feasibility specialist was hired to support the program in trial design/implementation, barrier tracking, and to serve as a liaison between community site providers, study staff, and the program. Results: Since 2021, 20 clinical studies including 14 interventional treatment trials have been activated demonstrating 108 total patients accrued with 42 interventional accruals; 5 within the full activation model (13 accruals) and 15 in the hybrid model (29 accruals). Patients showed an average of 216 miles, with an estimated mileage cost of $142/trip based on the 2023 IRS mileage rate of $0.655/mile to the hub location. Nine of those patients traveled over 260 miles, with an estimated mileage cost of $170/visit to access clinical trials. Under the hybrid model, 8 patients transitioned portions of their care to their home city resulting in reduction of an average of 155 miles/visit, and 7 patients were able to reduce their travel time an average of 216 miles/visit. By estimating at least 10 study visits, the travel burden was reduced by 2,160 miles (4320 driving hours) and $1,420 in driving costs alone for participants. Using participant averages the 108 patients would spend a total of $15,336 in travel costs for just the initial visit, but when factoring in the 10-visit estimate, travel reduction could result in a net savings of $153,360. Based on travel data, it is estimated 11 of these patients would have required overnight accommodation using an average of $149/night hotel stay, a savings of $1,490/patient is estimated for the lifecycle of trial participation or $16,390 for the 11-patient cohort requiring accommodation. These results do not include travel companion and time off work costs. Efforts have been made to further develop the full activation model and 5 clinical trials are in activation. Data gathered from the program is being used to design strategies to reduce the administrative burden of clinical trial participation for community providers and launch screening programs. Conclusion: The Mayo Clinic LLS IMPACT program has demonstrated success in addressing barriers to opening clinical trials in the community-center setting and reduced the travel burden and financial impact to clinical trial participation in a cohort of trial participants. Centralized hub support of study activation and conduct and decentralized care to support treatment of patients in proximity of their home can be extended to other hospital systems and settings.

Background: Teclistamab (Tec), a first-in-class BCMA bispecific T-cell antibody, received regulatory approval for the treatment of RRMM based on the MajesTEC-1 study [Moreau et al, NEJM, 2022] which demonstrated an overall response rate (ORR) of 63% and median progression free survival (PFS) of 11.3 months. However, less than 15% (N=24) of patients (pts) enrolled in MajestTEC-1 were ≥75 years, an age cohort that is often underrepresented in clinical trials and comprises approximately one third of MM pts at diagnosis [SEER 22 2017-2021]. In this multicenter retrospective study, we report the real-world safety and efficacy of a large cohort of elderly (≥75 years) RRMM pts treated with Tec. Methods: Pts with RRMM who received standard-of-care Tec across 13 U.S. academic institutions were included in the study. The follow-up data cutoff was 30 April 2024. Pts were divided by age into two groups: age <75 years (<75 group) and age ≥75 years (≥75 group). High-risk cytogenetic abnormalities (HRCA) were defined as the presence of del(17p), t(4;14), t(14;16) and/or gain or amplification of 1q21. Disease response and progression was evaluated using IMWG criteria. Time-to-event analyses were evaluated using the Kaplan-Meier method. Cytokine release syndrome (CRS) and immune effector cell-associated neurotoxicity syndrome (ICANS) assessment was based on the American Society for Transplantation and Cellular Therapy consensus grading. Results: Among 385 pts, 83 (22%) were in the ≥75 group (median age 78, range 75-92) and 302 (78%) in the <75 group (median age 65, range 31-74). Compared to pts in the <75 group, those in the ≥75 group were more often white (78% vs. 63%, p=0.009). Both the ≥75 and <75 age groups had a median of 6 prior lines of therapy, a similar proportion with ECOG ≥2 at start of Tec (29% vs. 24%, respectively; p=0.37), and a high proportion of pts with triple-class-refractory disease (77% vs. 85%, p=0.06) and pts who would have been ineligible MajesTEC-1 (73% vs. 80%, p=0.20). In contrast, pts in the ≥75 group had a lower incidence of adverse MM risk factors compared to the <75 group, including HRCA (44.6% vs. 57.9%, p=0.03), ultra high-risk (≥2 HRCA) MM (12% vs. 24%, p=0.02), extramedullary disease (22% vs. 40%, p=0.02), hemoglobin <8 g/dL (10% vs. 21%, p=0.02) or albumin <3 g/dL (6% vs. 19%, p=0.04) at the time of starting Tec. Moreover, a lower proportion of pts in the ≥75 group had prior autologous stem cell transplantation (43% vs. 72%, p<0.0001) or prior BCMA-directed therapy (33% vs. 55%, p=0.0003). The median time from diagnosis to start of Tec was longer for pts in the ≥75 group (7.21 years vs. 5.81 years, p=0.02). There was no significant difference in rates of any-grade CRS (52% vs. 59%, p=0.27), CRS grade 2-4 (10% vs. 11%, p=0.74) or any-grade ICANS (19% vs. 13%, p=0.12) between the ≥75 and <75 age groups, respectively. Four pts in the entire cohort developed CRS grade 3-4, one of whom was in the ≥75 group. Ten pts developed grade 3 ICANS (none grade 4), three of whom were in the ≥75 group. There was no significant difference between the ≥75 group and <75 group in ORR (62% vs. 53%, p=0.17) and ≥very good partial response (VGPR) rate (53% vs. 44%, p=0.14). After a median follow-up period of 9.9 months (95% CI 9.6-10.6 months), the median PFS in the ≥75 group was 10.7 months (95% CI 6.6-NR) vs. 5.2 months (95% CI 6.6-NR) in the <75 group (p=0.005). At the time of data cut-off, the median overall survival (OS) for pts in the ≥75 group had not been reached (95% CI NR - NR) compared to 16.1 months (95% CI 14.0 - NR) in the <75 group (p=0.048). In multivariable analysis for the entire cohort, age ≥75 was not significantly associated with either PFS (HR 0.87, 95% CI 0.54-1.39; p=0.55) or OS (HR 0.60, 95% CI 0.30-1.19; p=0.15). Conclusions: This analysis of a large cohort of RRMM pts treated with Tec in the real-world setting demonstrates comparable efficacy and safety outcomes in elderly (aged ≥75 years) pts to those reported in the overall study population of MajesTEC-1. The adverse baseline disease characteristics and inferior efficacy in pts <75 years age compared to ≥75 years likely reflect patient selection and prescribing patterns in the early era of access to commercial BCMA bispecific therapy with Tec. In multivariable analysis there was no significant impact of age ≥75 on survival outcomes. OP, DD & LF: co-first authors. KKP, HCL & AGC: co-senior authors

Introduction. Ciltacabtagene autoleucel (cilta-cel) and idecabtagene vicleucel (ide-cel), two anti-B-cell maturation antigen (BCMA) CAR T therapies, have demonstrated remarkable responses and improved survival among patients with relapsed/refractory multiple myeloma (RRMM) in the clinical trials and standard of care (SOC) setting. Here, we compare safety, efficacy, and survival for patients treated with SOC ide-cel and cilta-cel. Methods. Data were from a retrospective chart review of RRMM patients leukapheresed by 12/31/2022 with the intent to receive SOC ide- or cilta-cel at 19 institutions in the US Multiple Myeloma Immunotherapy Consortium. An inverse probability of treatment weighting (IPTW) approach was used to compare outcomes by therapy type (cilta- vs. ide-cel), balancing on age, sex, race and ethnicity, performance status, extramedullary disease, high-risk cytogenetics, prior BCMA therapy, bone marrow plasma cells, penta-refractory status, lymphodepleting chemotherapy, baseline ferritin, low cell dose, and bridging therapy response. Logistic regression and Cox proportional hazard models were used to examine the association of treatment type with safety, efficacy, and survival accordingly, while adjusting for IPTW weights. We employed propensity score matching utilizing the same covariates to identify the association of treatment type with progression-free survival (PFS) within relevant patient sub-groups. Results. A total of 641 patients were leukapheresed by 12/31/2022 with ide-cel (n=386) and cilta-cel (n=255). 586 patients were infused (n=350 for ide-cel; n=236 for cilta-cel) with a median follow-up of 13.0 and 12.6 months, respectively. After IPTW, patient characteristics were well-balanced. Patients treated with cilta-cel were more likely to have grade ≥ 3 cytokine release syndrome (CRS) (OR=5.52, 95% CI=1.76-17.30, p=0.004), infections (OR=2.07, 95% CI=1.44-2.97, p<0.001), and delayed neurotoxicity (NT) (OR=20.97, 95% CI=4.75-92.42, p<0.001) compared to patients treated with ide-cel. In the cilta-cel cohort, 24 patients (10%) experienced delayed NT compared to 2 patients (1%) in the ide-cel cohort. Although not statistically significant, patients treated with cilta-cel were more likely to have any second primary malignancies (SPMs) (OR=1.87, 95% CI=0.94-3.71, p=0.08) and any SPMs excluding non-melanoma skin cancers (OR=1.78, 95% CI=0.78-4.10, p=0.2) but no association was observed for odds of hematologic SPMs (OR=0.98, 95% CI=0.26-3.61). No association was observed for therapy type with any or severe immune effector cell-associated neurotoxicity syndrome, any CRS, severe cytopenias, and non-relapse mortality. Compared to ide-cel, cilta-cel was associated with better treatment responses of ≥ complete response (OR=2.38, 95% CI=1.61-3.51, p<0.001) and ≥ partial response (OR=1.74, 95% CI=0.99-3.05, p=0.06). Patients treated with cilta-cel had a longer PFS and overall survival (OS) than ide-cel (HR=0.47, 95% CI=0.35-0.62, p<0.001 and HR=0.63, 95% CI=0.42-0.93, p=0.02, respectively), and these findings were similar in the intention to treat cohort (PFS: HR=0.44, 95% CI=0.34-0.55, p<0.001; OS: HR=0.55, 95% CI=0.41-0.73, p<0.001, respectively). We observed consistent findings when repeating the analyses restricting the ide-cel cohort to patients infused during the same time-period as FDA approval for cilta-cel (≥ March 2022), restricting to patients with data on all covariates, and restricting to sites that contributed data for both products. In a propensity matched population, (n=380; n=190 for cilta-cel and n=190 for ide-cel), patients treated with cilta-cel had superior PFS compared to those treated with ide-cel in most subgroups with respect to age and disease characteristics including extramedullary disease, high-risk cytogenetics, and elevated baseline ferritin (p<0.05). Conclusion. Our results suggest superior efficacy of cilta-cel with a higher incidence of certain toxicities compared to ide-cel in the SOC setting. This study provides valuable information for patient counseling and guiding the selection of CAR T-cell therapy for specific patient populations. Further validation through similar large-scale real-world experiences or prospective studies is needed to confirm our results and enhance applicability in the clinical setting. *DH, LP, & DD are co-first authors * YL, KP, & SS are co-last authors

Introduction: The optimal induction for younger fit patients (pts) with mantle cell lymphoma (MCL) is unknown; though intensive chemoimmunotherapy (CIT) containing high dose cytarabine has been shown to prolong remission. Achieving molecular remission is an independent predictor of outcomes post induction therapy in patients with MCL. Incorporating undetectable measurable residual disease (uMRD) status into the primary endpoint may be preferable to progression-free survival (PFS), particularly when approaches following induction are varied (e.g., ASCT, maintenance treatment, observation). Induction with 3 cycles of bendamustine and rituximab followed by 3 cycles of cytarabine and rituximab (BR/CR) is associated with high complete metabolic response (CMR) and uMRD rates (Armand et al., BJH 2016; Merryman et al., Blood Adv 2020). Bruton's tyrosine kinase inhibitors (BTKi) including ibrutinib and acalabrutinib (A) in combination with CIT are highly effective in MCL (Wang et al., EHA 2024, LBA 3439). In 2019, the US Intergroup activated EA4181 to explore the efficacy with the addition of fixed duration BTKi, to BR or BR/CR for patients with MCL ≤ 70 years old. Patients and methods: Patients were randomized 1:1:1 (stratified by MIPI risk status) to 6 cycles of BR/CR (control arm), BR/CR-A, or BR-A. Cytarabine was dosed at 2 g/m2 Q12 hours x 4, with dose reductions based on age and creatinine clearance. Acalabrutinib was dosed at 100 mg BID continuously on BR cycles with the BR/CR-A and BR-A arms and at 100 mg BID on days 1-7 and 22-28 with CR cycles on the BR/CR-A arm to mitigate hematologic toxicity. Consolidation approaches following induction were at the discretion of the treating physician. The primary endpoint was a composite of PET/CT CMR and peripheral blood uMRD rate (< 1 in 105). ClonoSEQ (Adaptive Biotechnologies) was performed at baseline and MRD testing was obtained at the end of induction. Secondary clinical objectives included PFS and overall survival (OS) at 36 months (mo), objective response rates (ORR), and toxicity rates. With 108 patients per arm expected, there was 86% power to detect an increase in PET/CT CMR/uMRD rate from 60% in the control arm to 75% in either BR/CR-A or BR-A arms using a Z-test with a 10% alpha (1-sided). Results: Between October 2019 and March 2023, 359 participants were randomized to BR/CR (n = 128), BR/CR-A (n = 129), and BR-A (n = 102). BR-A was closed to further accrual by the DSMC based on interim futility analysis for superiority in Fall 2022. The median (range) age was 61 (25, 70), 30% were ≥ 65 years, 77% were male, 89% were white, 89% were non-Hispanic, 18%/43%/39% were low/intermediate/high risk MIPI. Baseline clonal sequence was identified in 308/326 (95%) among samples received. 281/308 were eligible and treated and 260/281 had an end of treatment MRD test result (BR/CR = 85, BR/CR-A = 98, BR-A = 77). This subset (n = 260) is the focus of the primary analysis; sensitivity analysis included 281 eligible and treated pts with trackable clonal marker. In the primary analysis subset, 94%, 91%, and 90% in BR/CR, BR/CR-A, and BR-A arms, respectively, completed 6 cycles of protocol therapy. The PET/CT CMR/uMRD rates were 82% (BR/CR), 82% (BR/CR-A; p = 0.55 vs BR/CR), and 78% (BR-A; p = 0.76 vs BR/CR). In the sensitivity analysis set, PET/CT CMR/uMRD rates were 74% with BR/CR (n = 94), 76% (p = 0.44) with BR/CR-A (n = 106), and 74% (p = 0.52) with BR-A (n = 81). ORR (CMR) rates were 94% (91%), 99% (90%), and 94% (91%) with BR/CR, BR/CR-A, and BR-A, respectively. At a median follow-up of 27.9 mo, estimated 12-mo PFS/OS were 86%/94% (BR/CR), 89%/98% (BR/CR-A) and 87%/95% (BR-A). The proportion of treatment-related grade 3 or higher adverse events (AE) was 78%/88%/73%, with neutropenia in 52%/58%/27%, anemia in 23%/32%/3%, thrombocytopenia in 55%/66%/6%, and febrile neutropenia in 11%/12%/4%; treatment discontinuation due to AE occurred in 5%/7%/8% in BR/CR, BR/CR-A, and BR-A arms, respectively. Conclusion: High PET/CT CMR uMRD rates were seen in all 3 arms. BR/CR can be considered as a standard induction in pts ≤ 70. Addition of acalabrutinib to the standard arm added toxicity without improvement in efficacy, suggesting acalabrutinib should be avoided during Ara-C cycles. BR-A was found not superior and closed early by the DSMC; however, it is the least toxic arm with similar efficacy, and represents an appealing option to avoid high dose cytarabine.

Background: CD19-directed chimeric antigen receptor T-cell (CAR-T) therapy is an established treatment with high efficacy in treating relapsed or refractory (R/R) mantle cell lymphoma (MCL). However, with CAR-T therapy, refractory disease occurs and a continuous pattern of relapse over time has been observed. Limited data exist about post-CAR-T progression of disease (POD) management and outcomes in MCL. Such data would meaningfully inform practice and set a critical benchmark for future studies in the post-CAR-T setting. We characterized treatment patterns and outcomes for pts with POD after CD19 CAR-T therapy for R/R MCL. Methods: We queried institutional databases to identify pts with R/R MCL who received CD19-directed CAR-T therapy. Treatment may have occurred as standard-of-care or in a clinical trial. We performed chart review to extract variables and categorized therapies by mechanism(s) of action. We used descriptive statistics to characterize patient/disease characteristics and treatment patterns, the reverse Kaplan-Meier method to calculate follow-up, the Kaplan-Meier method to calculate survival, and Cox proportional hazards to associate clinical and disease features with survival outcomes. Results: Across 9 sites, we identified 306 pts who received CD19 CAR-T for R/R MCL, of which 104 (34%) experienced POD and were investigated in detail: pts with POD were mostly men (73%), had a median age of 67 yrs (range 36-86) at infusion, and had received a median of 3 lines of therapy pre-leukapheresis, including a BTK inhibitor (BTKi) in 97% of patients; 36% of BTKi-exposed patients had BTKi-unresponsive disease. High-risk tumor features were common pre-CAR-T: 47/68 (69%) with a TP53 mutation, 66/93 (71%) with Ki67 ≥50%, and 47/102 (46%) with blastoid/pleomorphic MCL. Most pts (75%) received bridging therapy. Pts received brexucabtagene autoleucel (88%) or lisocabtagene maraleucel (12%). Regarding best CAR-T response for pts with POD, 71% had a complete response (CR), 13% partial response (PR), and 15% had no response. The median time from CAR-T infusion to POD was 6 months (IQR 3-12). At time of POD, high-risk MCL features were again common: 55% blastoid/pleomorphic, 42/56 (75%) Ki67 ≥50%, 51/83 (61%) MIPIb high-risk, and 21/35 (60%) TP53-mutated MCL. Among 69 pts with CD19 assessed on a post-POD biopsy, 8 (12%) had CD19-negative disease. 30% of pts had an ECOG performance status of ≥2 at time of POD. After POD occurred, 15 pts received no anti-lymphoma therapy (Tx), 11 pts underwent excision or radiation, and 78 pts received systemic therapy. The most commonly used first-line systemic Tx post-CAR-T progression included: pirtobrutinib in 13 pts [overall response rate (ORR) 31%], chemoimmunotherapy in 12 pts (ORR 25%), venetoclax in 10 patients (ORR 20%), bispecific antibodies (BsAb) in 10 pts (ORR 60%), and small molecule combinations (at least 2 of BTK inhibitor, BCL2 inhibitor, and lenalidomide) in 8 patients with ORR 50%. The ORR to all first systemic Tx post-POD was 42%. The median follow-up from POD is 15.2 months among survivors. The median progression-free and overall survival (OS) from time of POD were 2.3 (95% CI 1.9-3.4) and 5.4 months (95% CI 4.5-9.4), respectively, and 1-year OS rate was 33%. TP53 mutations predicted inferior OS (HR 2.83, 95% CI 1.08-7.43, P = 0.026) as did age ≥65 years at time of POD (HR 1.83, 95% CI 1.07-3.15, P = 0.023), MIPIb high-risk (HR 3.56, 95% CI 1.08-11.7, P = 0.042), and non-response to CAR-T (HR 3.55, 95% CI 1.93-6.53, P < 0.001). Discussion: Our data, the largest reported cohort of pts with POD post-CAR-T with R/R MCL, confirm the poor prognosis in this patient population, with a median OS of 5.4 months. BsAbs showed promise with an overall response rate of 60%. The presence of a TP53 mutation significantly predicted inferior OS, corroborating the prognostic importance of this finding in the post-CAR-T context. Data from pts treated at additional sites and updated analyses will be presented at the meeting.