Ocio, Enrique M.

e19503 Background: The anti-B-cell maturation antigen (BCMA) antibody-drug conjugate (ADC) belantamab mafodotin is approved in the USA and EU for relapsed/refractory multiple myeloma (RRMM). Understanding treatment options and patient outcomes following ADC failure is clinically important. This study describes post-ADC treatment patterns and clinical outcomes in real-world patients with RRMM. Methods: Adult patients with MM who received an ADC and initiated ≥1 subsequent line of therapy (LOT) were included. The index date was the start of the first post-ADC LOT. Data were obtained from chart reviews at International Myeloma Foundation International Myeloma Working Group (IMF IMWG) academic sites, and US electronic health records from largely community sites (COTA and Guardian Research Network [GRN]). Patient characteristics and index regimens were summarized descriptively. Time to next treatment (TTNT) and overall survival (OS) were estimated with the Kaplan-Meier estimator. Results: The IMF IMWG cohort (n=40) had a mean age of 70.8 years, median of 7 prior LOTs and 82.5% were triple-class refractory (TCR). Overall, 85% received ADC monotherapy (70% belantamab mafodotin) and 15% combination therapy. Pre-ADC and not considering corticosteroids, patients were commonly exposed to lenalidomide (R; 100%), bortezomib (V; 92.5%), daratumumab (D) and pomalidomide (P; 90% each). Over a median follow-up of 26 months after index date, 29 unique index post-ADC regimens were reported, frequently selinexor (27.5%) and bispecific antibodies (15%). CAR T-cell therapy was administered to 5%, with 60% re-treated with a pre-ADC drug class (PI/IMiD/anti-CD38) after ADC. Median (95% CI) TTNT and OS were 10.8 (7.0–20.6) and 19.0 (13.4–25.1) months, respectively. The COTA-GRN cohort (n=39) had a mean age of 67.5 years, median of 8 prior LOTs, and 51.3% were TCR. Overall, 56% received ADC monotherapy (belantamab mafodotin) and 44% combination therapy. Pre-ADC and not considering corticosteroids, patients were commonly exposed to D and R (97.4% each), and carfilzomib, V and P (94.9% each). Over a median follow-up of 9.2 months, 32 unique index post-ADC regimens were reported, frequently selinexor (23.1%) and venetoclax (17.9%) based; 0% received CAR Ts and 54% were re-treated with a pre-ADC drug class (PI/IMiD/anti-CD38) after ADC. Median (95% CI) TTNT and OS were 4.9 (2.8–non-estimable [NE]) and 12.0 (4.9–NE) months, respectively. Conclusions: Findings highlight that most patients with heavily pretreated BCMA-ADC exposed MM were re-treated with similar classes. Academic centers used novel therapies (ie, CAR T, bispecific antibodies) more often and their patients had longer survival than those treated at community sites. However, clinical outcomes remained sub-optimal, emphasizing the unmet need for effective, accessible post-ADC treatments.

7563 Background: Subcutaneous (SC) drug delivery options have become more widely available in multiple myeloma (MM). SC delivery of isatuximab (Isa), an anti-CD38 monoclonal antibody, has been investigated across clinical trials via a novel hands-free on-body injector (OBI). Isa SC OBI features a small, retractable needle, establishing the first device-enabled delivery of an oncologic treatment. The Phase 3 IRAKLIA, Phase 2 IZALCO, and Phase 1b (TCD15484) trials consistently demonstrated similar efficacy and safety of Isa SC OBI vs Isa IV in relapsed/refractory MM (RRMM) patients (pts). Here, we present a cross-trial analysis exploring safety and reliability of Isa SC OBI in RRMM pts. Methods: Pts with RRMM in IRAKLIA (N=263) and the Phase 1b expansion cohort (N=22) received 1400 mg Isa SC OBI plus pomalidomide and dexamethasone (d). In IZALCO, RRMM pts (N=64) received 1400 mg Isa SC OBI + carfilzomib (K)-d. Pts were monitored for 4 hrs (IRAKLIA) or 1-2 hrs (IZALCO) following first administration and for 1 hr for the following cycle (C) 1 administrations to assess local tolerability. Pre-infusion medications included montelukast (C1), steroids, acetaminophen and H1 antihistamines. Pts without systemic infusion-related reactions (IRRs) after 4 consecutive administrations of Isa SC OBI had subsequent pre-medication reassessed at investigator’s discretion. Safety and device performance explored in this cross-trial analysis of company sponsored studies were assessed in the Isa SC OBI cohorts by the duration of injection, IRRs, local injection-site reactions (ISRs), and injection/device success, which were defined similarly across all trials. Results: The median duration of Isa SC OBI injection was 13 mins in IRAKLIA, 12 mins in IZALCO, and 10 mins in the Phase 1b trial (6426 total injections, N=349 pts). IRRs across trials occurred in 6/6426 (0.09%) injections and 4/349 (1.15%) pts. IRRs were mostly grade 1 (G; 3/6426, 0.05%) with 1 G3 (0.02%); none leading to discontinuation. In IRAKLIA, 80/263 (30.4%) pts did not require premedication (931/5145 injections, 18.1%); no IRRs occurred in this group. Across trials, ISRs occurred in 21/349 (6.02%) pts resulting in 35 (0.54%) ISR events. Most ISRs were G1 (33, 0.51%), the remaining were G2 (2, 0.03%) and generally occurred on the day of injection. 99.9% (6421/6426) of injections in 98.6% (344/349) pts were successful (completed without interruption) across all trials. Conclusions: These findings support overall low, self-limiting rates of IRRs and ISRs across trials, with >6000 (99.9%) Isa SC OBI injections successfully delivered. Isa SC OBI shows reproducible safety and reliability in IRAKLIA, IZALCO and Phase 1b trials, supporting it as a novel administration option for MM pts and its potential for future exploration in at-home administration. Clinical trial information: NCT04045795 , NCT05405166 , and NCT05704049 .

Abstract Introduction LINVO, a human B-cell maturation antigen (BCMA)xCD3 bispecific antibody, was recently approved for triple-class exposed (TCE) RRMM after ≥3 prior therapies (EU) or ≥4 prior lines of therapy (US), demonstrating high efficacy and a generally manageable safety profile. Combining LINVO with an anti-CD38 mAb, such as DARA or ISA, may provide additional benefit to pts with RRMM. Here we report pooled safety and efficacy results from the LINVO + DARA and LINVO + ISA cohorts during the dose-finding portion of the Phase 1b LINKER-MM2 trial (NCT05137054). Methods Eligible pts were aged ≥18 years with RRMM that progressed after ≥3 lines of therapy (LoTs), or ≥2 LoTs if TCE or double-class refractory (immunomodulatory drug [IMiD] + proteasome inhibitor [PI]). Prior treatment (tx) with DARA or ISA was allowed if previously tolerated and ≥6 months (mos) or ≥3 mos washout, respectively, had elapsed since last exposure. Tx began with LINVO monotherapy (Cycle [C]0; 28-day cycle) consisting of 2 step-up doses (5 mg, 25 mg) and 2 full doses (dose level [DL]1 100 mg; DL1b 150 mg; DL2 200 mg) before standard dosing of DARA or ISA was added at C1. LINVO was given once weekly in C1–3 and once every 2 weeks in C4+. At the end of 2024, dosing once every 4 weeks was implemented after C6 if a very good partial response or better (≥VGPR) was achieved. Dexamethasone premedication was required during the first 2 cycles and then given per label for DARA or ISA. Primary endpoints: dose-limiting toxicities (DLTs) and tx-emergent adverse events (TEAEs). Key secondary endpoints: overall response rate (ORR), duration of response (DOR), progression-free survival (PFS), and rate of minimal residual disease (MRD) negativity. The analyses reported here combine the LINVO + DARA and LINVO + ISA cohorts. Results As of May 7, 2025, 42 pts were enrolled. All pts were included in the safety analysis set: DL1 (DARA, n=12; ISA, n=6), DL1b (n=6; n=10), or DL2 (n=8; n=0); 37 were included in the efficacy analysis set: DL1 (DARA, n=11; ISA, n=5), DL1b (n=5; n=9), or DL2 (n=7; n=0). At baseline, all pts had received ≥1 PI (refractory to ≥1 PI: 76%) or ≥1 IMiD (refractory to ≥1 IMiD: 86%), and 21 pts (50%) had received prior DARA or ISA (refractory to DARA or ISA: 33% [DARA, n=4; ISA, n=10]). Median number of prior LoTs was 3 (range 2–8), including 50% of pts with TCE and 21% with triple-class refractory disease. Median age was 68 years (range 42–86); male, 57%; ISS stage III at study entry, 12%; high-risk cytogenetics, 31%; bone marrow plasma cells ≥50%, 31%; and soft tissue plasmacytomas, 33% (extramedullary, 12%). Median follow-up duration was 14.8 mos for DL1 (DARA 21.3; ISA 11.3), 7.6 mos for DL1b (DARA 13.5; ISA 5.2), and 5.9 mos for DL2 (all DARA), with 44%, 50%, and 63% of pts still receiving tx, respectively. The most common TEAEs were anemia (any grade [Gr] 48%; Gr 3/4 26%), neutropenia (41%; 41%), diarrhea (38%; 2%), and thrombocytopenia (38%; 17%). Cytokine release syndrome was reported in 33% of pts (all Gr 1/2 events except 1 Gr 3 event during the step-up period that fully resolved). No pts experienced immune effector cell-associated neurotoxicity syndrome (ICANS). Infections were reported in 32 pts (any Gr 76%; Gr ≥3 40%), and 3 resulted in death (1 tx related: cytomegalovirus [CMV] pneumonia; 2 tx unrelated: C. diff colitis and lower respiratory infection). One DLT was observed at DL1b in the ISA cohort (Gr 3 Epstein–Barr virus pharyngitis) and 1 was observed at DL2 in the DARA cohort (Gr 5 CMV pneumonia). Among efficacy evaluable pts, ORR was 75% at DL1 (12/16; ≥VGPR rate 75%), 93% at DL1b (13/14; ≥VGPR rate 57%), and 86% at DL2 (6/7; ≥VGPR rate 86%). Of 10 MRD-evaluable pts, all were MRD negative (<10−5by clonoSEQ or EuroFlow). The 12-mo DOR rate was 79% (95% confidence interval [CI] 52–92; median DOR not reached) and 12-mo PFS rate was 73% (95% CI 53–86; median PFS not reached). Pharmacokinetic analyses showed LINVO concentrations were not affected by the addition of DARA or ISA. ConclusionsIn pts with heavily pretreated RRMM, half of whom had prior anti-CD38 mAb exposure, the combination of LINVO and DARA or ISA was feasible, inducing a high rate of deep and durable responses, and exhibiting a safety profile similar to that reported for each individual drug. These preliminary data support continued development of LINVO plus an anti-CD38 mAb for the tx of pts with MM.

Introduction Multiple myeloma (MM) is considered incurable. Despite improved outcomes with novel agents, including BCMA-targeted chimeric antigen receptor (CAR) T-cell therapies, antibody-drug conjugates (ADCs), and bispecific antibodies, patients with relapsed/refractory MM (RRMM) often have poor prognoses. LINKER-MM1 (NCT03761108) is a global, single-arm, Phase 1/2 study of linvoseltamab, a BCMA×CD3 bispecific antibody, in patients with RRMM who were either triple-class exposed (TCE; previously treated with a proteasome inhibitor, immunomodulatory drug, and anti-CD38 antibody) during ≥3 prior lines of therapy (LOTs), or triple-class refractory to these therapies. Here, we present comparisons of clinical outcomes from LINKER-MM1 with those of a current, international, real-world (RW) external control arm (ECA; NCT05673967). Methods The ECA was derived from 16 academic sites of the International Myeloma Foundation International Myeloma Working Group (IMWG) (N=203; 309 eligible LOTs) and compared with linvoseltamab (N=105; Phase 2 200 mg cohort). Patients in the ECA initiated ≥1 anti-MM therapy after meeting key LINKER-MM1 eligibility criteria. Weighted random sampling and inverse probability of treatment weighting were used to select 1 LOT per patient and balance the ECA and trial populations on prespecified prognostic factors (Kumar S, et al. IMS 2023). The primary endpoint was objective response rate (ORR; IMWG criteria) determined by an independent central review committee (ICRC) based on myeloma laboratories. An independent data review committee reviewed comparability of cohorts and endpoint assessments prior to conducting comparative analyses. Results Median follow-up was 14.3 months for the linvoseltamab cohort (data cutoff: Jan 6, 2024) and 13.4 months for the ECA. After weighting, 15 prognostic factors were balanced between cohorts. Patients in the ECA received 68 distinct regimens, most commonly CAR T-cell therapies (11.3%) and ADCs (10.3%). After balancing the cohorts, patients in the ECA evaluable for response had ICRC-assessed ORR of 46.3% (40.8% by treating physician assessment), among whom 24.0% had very good partial response or better (≥VGPR). When including patients who died without evaluable response, ECA ICRC-assessed ORR was 44.2%. Linvoseltamab induced significantly higher ICRC-assessed ORR (69.5% vs 46.3%, odds ratio [OR] 2.65 [95% confidence interval (CI) 1.66-3.69]) and rate of ≥VGPR (62.9% vs 24.0%, OR 5.37 [95% CI 3.61-8.49]) compared with ECA regimens. Conclusion Despite current use of novel therapies, there is no well-established RW standard of care (SOC) for patients with TCE RRMM treated at IMWG sites. To our knowledge, this is the first RW ECA study in MM with a high percentage of anti-BCMA therapies and response ascertainment for all patients by ICRC. Linvoseltamab induced significantly higher response rates, including rate of ≥VGPR, compared with current RW SOC therapies, highlighting its potential as a highly effective treatment in patients with TCE RRMM.

Introduction Linvoseltamab is an investigational, BCMA×CD3 bispecific antibody designed for the treatment of RRMM. High objective response rates (ORR) to linvoseltamab 200 mg in the LINKER-MM1 trial (NCT03761108) were demonstrated across high-risk subgroups, including patients aged ≥75 years, patients with high-risk cytogenetics, and patients with penta-class refractory status. The aim of this study was to compare ORR, overall and in key subgroups, between patients in Phase 2 of the LINKER-MM1 trial and patients in an international RW SOC external control arm (ECA). Methods The ECA was derived from a chart review of 16 academic sites across 10 countries that are part of the International Myeloma Foundation (IMF)-International Myeloma Working Group (IMWG) and 2 US electronic health record databases (COTA and Guardian Research Network [GRN]). Included patients initiated ≥1 anti-MM treatment after meeting key eligibility criteria of LINKER-MM1. Weighted random sampling and inverse probability of treatment weighting (IPTW) were used to select 1 line of therapy (LOT) per patient and balance the overall ECA and trial populations on prespecified prognostic factors (Kumar S, et al. IMS 2023). For ORR assessment, LINKER-MM1 and IMF-IMWG used independent central review committees per IMWG criteria, COTA used algorithmic assessment based on IMWG criteria, and GRN used physician-assessed responses. Prior to conducting comparative analyses, an independent committee of epidemiology and oncology experts reviewed the comparability of the cohorts and endpoint assessments, and approved study continuation. ORR among patients in LINKER-MM1 and patients in the ECA was compared overall and across prespecified subgroups (≥10 patients per subgroup), including age, race, cytogenetic risk score, international Staging System (ISS), presence of extramedullary plasmacytoma (EMP), refractory class, bone marrow plasma cell (BMPC) proportion, and number of prior LOTs. Results Median duration of follow-up was 14.3 months (data cut-off: January 6, 2024) for patients receiving linvoseltamab (n=105) and 13.6 months for the ECA (n=307; n=194, n=72, and n=41 from IMF-IMWG, COTA, and GRN, respectively). Following IPTW, 13 prognostic factors with <30% missingness were balanced between cohorts, with an effective sample size in the ECA of 197. After adjustment, ORR was significantly higher in patients who received linvoseltamab compared with patients in the ECA (69.5% vs 45.7%, odds ratio [OR] 2.5 [95% confidence interval (CI) 1.6-4.1]) and in key subgroups with age 65-74 years (76.9% vs 48.3%, OR 3.6 [1.6-8.6]), age ≥75 years (72.4% vs 48.5%, OR 2.8 [1.1-7.4]), Black or African American race (82.4% vs 25.0%, OR 14.0 [3.0-85.4]), White race (68.9% vs 49.7%, OR 2.2 [1.3-4.0]), standard cytogenetic risk (72.3% vs 51.3%, OR 2.5 [1.3-4.8]), ISS stage III (58.8% vs 19.7%, OR 5.8 [1.5-25.2]), absence of EMP (71.6% vs 49.3%, OR 2.6 [1.5-4.6]), triple-class refractory status (68.2% vs 45.7%, OR 2.6 [1.5-4.4]), quadruple-class refractory status (66.7% vs 45.9%, OR 2.4 [1.3-4.3]), 4-5 prior LOTs (65.1% vs 40.4%, OR 2.8 [1.3-6.0]), and >5 prior LOTs (75.7% vs 36.1%, OR 5.5 [2.4-13.6]). Numerically higher (not statistically significant) or similar ORR was observed for patients receiving linvoseltamab compared with patients in the ECA with age <65 years (59.5% vs 46.8%, OR 1.7 [0.79-3.6]), high-risk cytogenetics (65.0% vs 63.1%, OR 1.1 [0.41-2.9]), ISS stage I (73.3% vs 64.6%, OR 1.5 [0.62-3.7]), ISS stage II (67.6% vs 53.5%, OR 1.8 [0.72-4.7]), presence of EMP (58.8% vs 56.9%, OR 1.1 [0.32-3.8]), penta-class refractory status (64.3% vs 48.5%, OR 1.9 [0.78-4.8]), BMPC <50% (77.0% vs 67.2%, OR 1.6 [0.61-4.3]), BMPC ≥50% (41.7% vs 36.0%, OR 1.3 [0.36-4.7]), and ≤3 prior LOTs (68.0% vs 66.4%, OR 1.1 [0.43-2.9]). Separate findings will be presented for IMF-IMWG and COTA/GRN data at the congress. Conclusions Linvoseltamab induced better ORR vs RW SOC treatments overall, and better or similar ORR in the key subgroups assessed, highlighting its therapeutic value across a range of patients with RRMM with heterogeneous risk profiles and levels of disease burden.

Abstract Fluorescence in situ hybridization (FISH) is an effective alternative for the analysis of cytogenetic abnormalities of low proliferative entities such as Waldenström macroglobulinemia (WM) but, to date, no studies have been carried out to explore the potential impact of molecular cytogenetics on disease evolution. Deletion of the long arm of chromosome 6 (6q-) is the most frequent cytogenetic abnormality in WM. In this study we have analyzed the incidence of this aberration (using both conventional cytogenetics and FISH analysis) in 102 WM patients, and we have correlated it with disease characteristics. Deletion of 6q21 was detected in 6% of patients by conventional cytogenetics, while FISH studies increased this incidence up to 39%. Moreover, in those patients analyzed by cIgM-FISH, the incidence of 6q- was higher (54%). Interestingly, 6q- patients displayed features associated with adverse prognosis (higher levels of ESR, CRP and beta-2 microglobulin), and a greater tendency to display anemia and hypoalbuminemia. Other differentiating variables without reaching statistical significance were a tendency of displaying a higher bone marrow lymphoplasmacytoid infiltration and the amount of monoclonal component in 6q- patients (table). In addition, patients with 6q- displayed shorter survival from time of diagnose (log-rank; p=0.09). In summary, our results show that 6q deletion in WM patients is currently the most frequently found cytogenetic abnormality. Patients with this deletion also shows a trend towards an aggressive disease and poorer outcome in WM. Further studies should focus on possible tumor suppressor genes in the minimal area of deletion at 6q and to determine their role in disease progression. table del6q present del6q absent p-value n 40 (39%) 62 (61%) β2M ≥4mg/dL 48% 16% 0.005 CRP ≥3.5 mg/dL 47% 11% 0.006 Albumin <4mg/dL 86% 55% 0.006 ESR ≥100 mm/h 73% 44% 0.02 Hb <11 g/dL 63% 40% 0.02 serum IgM >20 g/L 86% 73% 0.10 BM infiltration >40% 44% 31% 0.20

Abstract The outcome of patients (pts) with WM, a rare B-cell malignancy, varies widely. The international community has convened a panel to develop a prognostically meaningful staging system for survival after treatment initiation. Toward establishing IPSS, we performed multivariate analyses with bootstrap validation in a series of 587 pts (median age 67, range: 28 to 95, M/F ratio: 1.7) diagnosed between September 1979 and December 2001. Diagnostic and treatment criteria fulfilled recommendations of the 2nd international WM workshop. Front-line treatment was initiated at diagnosis in 69% and 4 mo to 164 mo later in the remaining pts. Criteria for initiation of therapy included cytopenia, constitutional symptoms, organomegaly, hyperviscosity, IgM-related disorders, which pertained to 51%, 44%, 35%, 31% and 13%, respectively. Treatment regimens comprised alkylating agents, fludarabine and rituximab in 369, 195 and 23 subjects, respectively. Baseline parameters included age>65 yr in 57%, Hb≤11.5 g/dL in 65%, platelet count ≤100 x109/L in 9%, granulocyte count ≤1.5 x109/L in 9%, B2M >3 mg/L in 56%, albumin ≤3.5 g/dL in 36% and monoclonal protein >7.0 g/dL in 7%. With a median follow-up of 64 mo (range, 6 mo–182 mo), the median survival after treatment initiation was 87 mo (95%CI 79–103) regardless of the type of therapy applied (p=0.3). Using results of univariate survival analyses, recursive partitioning and martingale residuals analyses, 7 adverse characteristics for inclusion in multivariate analyses were identified during an expert meeting: age >65 yr, platelet count ≤ 100x109/L, B2M >3 mg/L, M-protein >7.0 g/dL, granulocytes ≤1.5 x109/L, Hb ≤11.5 g/dL and albumin ≤3.5 g/dL. The Cox proportional hazard model with stepwise selection selected the first 6 covariates. Bootstrap resampling (500 replicates) validated the selection of the first 4 covariates in at least 80% of the replicates. Selection of at least one of the last 2 covariates in more than 80% of the replicates indicated a correlation between these 2 covariates, and validated the inclusion of Hb only. Using the combination of age, Hb, platelet count, B2M and M-protein, low risk was defined by the presence of ≤1 adverse characteristic except age, high risk by the presence of >2 adverse characteristics; the remaining patients with 2 adverse characteristics or age >65yr had intermediate risk, comprising 27%, 38% and 35% of patients with 5-yr survival rates of 87%, 68% and 36% (p<0.0001), independent of treatment and age. IPSS split each subgroup identified by previous scoring systems (Morel, Merlini, Dhodapkar). Conversely, log-rank test was significant only when the latter prognostic system was assessed in low IPSS-risk pts. Thus the combination of age, B2M, M-protein and blood counts provides simple prognostic model for survival in WM, hopefully serving as an objective basis for initiation of therapy and comparison of treatment results.