Harnett, James

Introduction In ELM-2 (NCT03888105), a Phase 2, open-label, multicohort study, odronextamab monotherapy demonstrated encouraging clinical efficacy, generally manageable safety, and maintenance of patient-reported outcomes in R/R FL (Chong et al. AACR 2024; Tessoulin et al. ASH 2023). In the absence of head-to-head clinical trials comparing CD20×CD3 bispecific antibodies in R/R FL, two unanchored MAICs were conducted to evaluate the efficacy of odronextamab versus mosunetuzumab and epcoritamab in patients with R/R FL in the third-line or later (3L+) setting. Methods Patient-level data from the ELM-2 R/R FL cohort receiving odronextamab (N=128; data cutoff: October 2023) were compared with published data from similar cohorts in the GO29781 trial of mosunetuzumab (N=90; Budde et al. Lancet Oncol 2022) and EPCORE NHL-1 trial of epcoritamab (N=128; Linton et al. Lancet Haematol 2024). To adjust for baseline differences in the trial populations, a priori-identified prognostic variables (progression of disease within 2 years, primary refractory, refractory to last line of therapy [LOT], number of prior LOTs, serum lactate dehydrogenase level, Eastern Cooperative Oncology Group performance status, Follicular Lymphoma International Prognostic Index, age at start of LOT, and Ann Arbor disease stage) were included in the base-case MAICs. Two additional variables (double refractory and prior autologous stem cell transplant), reported in ELM-2 and the comparator studies, were included in a sensitivity analysis. The MAICs reported here were focused on response outcomes as assessed by independent central review, which were reported across trials. Relative treatment effects before and after matching were presented as odds ratios (ORs), along with 95% confidence intervals (CIs). Results The effective sample size for odronextamab was 102.0 after matching with mosunetuzumab and 90.6 after matching with epcoritamab in the base-case MAICs. All key prognostic variables were balanced between ELM-2 and both comparator trials in each analysis. Before and after matching, odronextamab demonstrated comparable objective response rates (ORRs) and significantly higher complete response (CR) rates versus mosunetuzumab (before matching: ORR 80.5% vs 80.0%, OR 1.03 [95% CI 0.52-2.03], p=0.93; CR rate 73.4% vs 60.0%, OR 1.84 [95% CI 1.04-3.28], p=0.04; after matching: ORR 83.5% vs 80.0%, OR 1.27 [95% CI 0.61-2.65], p=0.53; CR rate 75.7% vs 60.0%, OR 2.08 [95% CI 1.12-3.86], p=0.02). Odronextamab demonstrated numerically higher CR rates versus epcoritamab before and after matching (before matching: CR rate 73.4% vs 62.5%, OR 1.66 [95% CI 0.98-2.82], p=0.06; after matching: CR rate 69.4% vs 62.5%, OR 1.36 [95% CI 0.77-2.41], p=0.29). The ORRs of odronextamab and epcoritamab were comparable before matching (ORR 80.5% vs 82.0%, OR 0.90 [95% CI 0.48-1.69], p=0.75) and after matching (ORR 78.1% vs 82.0%, OR 0.78 [95% CI 0.40-1.53], p=0.47). Consistent results were observed in the sensitivity analyses. Conclusions In the absence of head-to-head clinical trials comparing bispecific antibodies in the setting of 3L+ FL, MAICs demonstrate that odronextamab was associated with higher CR rates compared with mosunetuzumab and epcoritamab. Since achieving a CR in the R/R FL setting is an important treatment goal, our results highlight the potential of odronextamab as an effective treatment option in R/R FL.

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.

e19057 Background: In ELM-2 (NCT03888105), a Ph 2, single arm, open label trial, odronextamab demonstrated robust efficacy, generally manageable safety, and overall maintenance of patient-reported outcomes (PROs) in R/R FL pts (Villasboas et al. ASH 2023). In FL, pts with disease progression within 2 yrs of frontline chemoimmunotherapy (POD24) are hard to treat with poor clinical outcomes, representing an unmet need. We report PROs by POD24 status in pts with Grade 1–3a R/R FL from ELM-2. Methods: Pts received IV odronextamab in 21-day cycles (C): 80 mg QW in C1–4, with C1 dose step up to mitigate cytokine release syndrome, then 160 mg Q2W (Q4W if complete response ≥9 mo) until progression. PROs were collected at baseline (BL), Wks 2–4, 10, then Q8W in Yr 1, and Q12W in Yr 2. Post-hoc POD24 subgroup analyses were performed on six EORTC QLQ-C30 scales, the EQ-5D-3L VAS, and FACT-Lym LymS. Estimated mean change from BL (CFB) was analyzed using mixed models for repeated measures (MMRM) through Wk 42 (≥10 pts at last assessment). Published meaningful CFB thresholds were used to define deterioration/improvement in responder analyses. Results: By Jan 31, 2023, 140 pts with R/R FL had received odronextamab. Pts with POD24 (n=70) were younger than pts without POD24 (n=70; median age 57.5 vs 62.0 y), had fewer prior Tx lines (median 2 vs 3), and a higher proportion double refractory to anti-CD20 Ab + alkylator (53% vs 29%). Objective response rate was similar in evaluable pts with (n=63; 79%) and without (n=65; 80%) POD24. PRO questionnaire completion ranged from 52–95% through Wk 42 across groups. Descriptive analyses suggest BL PRO scores were similar by POD24 status, showing good HRQoL/functioning and low symptom burden, and were generally maintained through Wk 42 with minimal between-group differences (overlapping 95% CIs for LS mean CFB [Table]). In both groups, more pts reported PRO maintenance or improvement vs deterioration across visits, except for fatigue at Wk 10 in pts without POD24. Conclusions: In pts with heavily pretreated R/R FL, odronextamab Tx maintained HRQoL, functioning, and symptoms irrespective of POD24 status. Clinical trial information: NCT03888105 . [Table: see text]

7561 Background: Pts with TCE RRMM have poor outcomes and a high unmet need, with no established SOC tx. LINKER-MM1 (NCT03761108) is a single-arm, Phase 1/2 study investigating linvoseltamab, a B-cell maturation antigen × CD3 bispecific antibody, in pts with RRMM who were previously treated with a proteasome inhibitor, immunomodulatory drug, and anti-CD38 antibody, or were triple-class refractory (TCR) to these tx. The aim of this study was to contextualize LINKER-MM1 by comparing outcomes with linvoseltamab vs a real-world (RW) external control arm (ECA). Methods: A RW ECA was derived from 2 US electronic health record databases (COTA, Guardian Research Network) of pts who started a new line of therapy (LOT) after classification as TCE or TCR and met key eligibility criteria for LINKER-MM1. Eligibility was assessed at the initiation of each new LOT, and all eligible LOTs were included in the ECA. Data in Phase 2 pts who received linvoseltamab 200 mg in LINKER-MM1 were included (data cutoff: Sep 8, 2023). Inverse probability of tx weighting (IPTW) was used to reduce imbalances between the RW and LINKER-MM1 cohorts. Key prognostic factors were identified using a systematic review and rank ordered by an international committee of MM experts (Kumar et al., 2023). Outcomes included overall response rate (ORR), progression-free survival (PFS), time to next treatment (TTNT), and overall survival (OS). An independent committee of epidemiology and oncology experts reviewed the comparability of the cohorts and endpoint assessments prior to conducting comparative analyses. Results: Comparative analyses were performed in 105 pts in the linvoseltamab cohort and 101 RW pts (137 LOTs). Following IPTW, the distribution of cytogenetic risk, age, TCR status, Eastern Cooperative Oncology Group Performance Status, and platelet count were balanced between the 2 cohorts (absolute standardized mean difference <0.10). After adjustment, pts receiving linvoseltamab had significantly improved ORR, PFS, TTNT, and OS vs the RW ECA (see table). Conclusions: Linvoseltamab significantly improved outcomes vs RW SOC in the US, highlighting its potential as a highly effective tx in pts with TCE RRMM. [Table: see text]

e23310 Background: Chimeric antigen receptor T-cell therapy (CAR T) is FDA-approved in pts with triple-class exposed (TCE) relapsed/refractory (RR) MM after four or more prior lines of therapy (LOTs). Real-world access to CAR T remains challenging due to manufacturing capacity, financial barriers, and pt fitness. Pts with certain pre-existing comorbidities (e.g., central nervous system disease, heart disease, secondary malignancies) are commonly excluded from clinical trials, including those investigating CAR T. The objective of this study was to identify the factors associated with the use of CAR T in pts with TCE RRMM to better understand the unmet need in this population. Methods: We conducted an observational cohort study using Medicare fee-for-service data; each pt in the CAR T intention-to-treat (ITT) population between 2021 and 2023 was matched to three non-CAR T pts, without replacement. Pts were eligible if they had an initial MM diagnosis, were continuously enrolled, were TCE, and did not receive treatment in a clinical trial. The index date was the ITT date. Baseline characteristics included age, sex, race/ethnicity, census region, three comorbidity indexes (Charlson, Elixhauser, CMS hierarchical condition categories [HCCs]), a claims-based frailty index (CFI), and dual enrollment in Medicare and Medicaid (as a proxy to social economic status [SES]). Logistic regression was used to derive odds ratios (ORs) and 95% confidence intervals (CIs) comparing the characteristics of CAR T vs non-CAR T pts. Results: Seventy-three ITT CAR T pts (nine underwent apheresis but did not receive CAR T) were matched to 219 non-CAR T pts by LOT and index year. Matched pts were treated with varied standard regimens (daratumumab-containing: 63%). Median prior LOTs were similar in the two cohorts (8; range 2–13). Median time from MM diagnosis to index date was 44.6 and 51.9 months for CAR T and non-CAR T pts, respectively. Compared with non-CAR T pts, pts in the CAR T population were younger (aged < 75 years: 59% CAR T vs 36% non-CAR T), less frail (mean CFI: 0.18 vs 0.20) and had higher SES (without dual enrollment in Medicare and Medicaid: 96% vs 81%), but were similar in terms of sex, region, and race/ethnicity. Variation in individual comorbidity prevalence was observed between CAR T and non-CAR T pts. In a multivariable regression analysis, factors strongly associated with lower odds of CAR T use included age ≥75 years (OR 0.29; 95% CI 0.16–0.53), comorbidities (lung/other severe cancers [OR 0.39; 95% CI 0.20–0.74] and chronic obstructive pulmonary disease [OR 0.32; 95% CI 0.10–0.99] defined by HCCs), and SES (OR 0.09; 95% CI 0.02–0.37). Conclusions: Older age, certain comorbidities, and lower SES are associated with lower odds of receiving CAR T in real-world pts with TCE RRMM, demonstrating an unmet need for more accessible and effective treatment options with acceptable safety profiles for these pts.

e23309 Background: BCMA-directed T-cell–engaging therapies have been introduced into clinical practice for the treatment of TCE RRMM. While efficacious, such treatments are associated with safety considerations such as cytokine release syndrome (CRS), immune effector cell-associated neurotoxicity syndrome (ICANS), and serious infections. These treatments also vary in reported efficacy, administration processes, and hospitalization requirements. The aim of this study is to quantify patient preferences and tradeoffs regarding these attributes. Methods: A discrete choice experiment (DCE) was designed to elicit preference weights corresponding to seven attributes related to efficacy (objective response rate [ORR], overall survival [OS]), safety (all-grade CRS, all-grade ICANS, serious infections) and treatment procedures (treatment administration, hospitalization requirements). Attribute levels were based on plausible ranges of potential values. Patients in the United States (US) with a physician-confirmed diagnosis of TCE RRMM were recruited. Pre-test interviews with patients were conducted and the final survey deployed online in 2023. A random-parameters logit model was used to estimate preference weights. Conditional relative importance (CRI) was calculated to rank the relative importance of each attribute. The minimum acceptable benefit (MAB) and maximum acceptable risk (MAR) were calculated to estimate the tradeoffs between efficacy and safety attributes. Results: The sample included 200 respondents (mean [standard deviation] age: 61 [6.4] years; 43% female; 46% White; 10% African American). A total of 197 participants reported having responded to prior treatment, of whom 195 had relapsed or become refractory. In the DCE, a 24-month increase in OS was found to be the most important attribute, with a CRI of 32.0%. Next most important were avoiding a 60% risk of serious infection (CRI 17.3%), avoiding 14-day hospitalization requirements (CRI 15.0%), and a 38% increase in ORR (CRI 13.7%). A treatment that could be started immediately and administered weekly or up to every 4 weeks was preferred over a CAR T-like procedure with a waiting period. Fewer initial hospitalization days was significantly preferred over more hospitalization days. The MABs for OS when the risk of serious infection was increased from 20% to 60%, CRS from 40% to 95%, and ICANS from 3% to 20% were 24.2, 17.1, and 18.0 months, respectively. When OS was increased from 12 to 36 months, the estimated MARs for serious infections, CRS, and ICANS were > 60%, > 95%, and > 20%, respectively. Conclusions: This study highlights US patient preferences regarding treatment attributes for TCE RRMM. Treatment benefits and risks and the mutual tradeoffs considered by patients should be evaluated when developing and selecting therapeutic approaches.