Age-stratified late outcomes following bispecific antibody therapy in multiple myeloma: A real-world 6-month landmark analysis.

7535 Background: Multiple myeloma (MM) predominantly affects older adults, with a median age at diagnosis of 69 years. Underrepresentation of older adults in clinical trials of Bispecific antibodies (BsAbs) and limited statistical power preclude definitive conclusions about treatment outcomes in this demographic. Some real-world studies report comparable outcomes for BsAbs in older and frail patients, but these are small and heterogeneous. Consequently, limited data exist on the safety and efficacy of BsAbs in older MM patients, especially late outcomes. To address this gap, we conducted a retrospective study comparing the post-6-month outcomes of BsAbs in older adults (≥65 years) with those in younger patients. Methods: We conducted a retrospective cohort study using the TriNetX Global Collaborative Network. We identified MM patients (ICD-10-CM: C90) aged ≥18 years who received any BsAbs (teclistamab, elranatamab, talquetamab, blinatumomab, epcoritamab, mosunetuzumab), stratified by age into two cohorts: (1) age ≥ 65 years (N =1913), and (2) age between 18 and 64 years (N =948). The index event was date of initial administration of BsAbs. Outcomes were analysed within a time window starting 180 days after index event, and patients with outcomes outside the window were excluded. Compared outcomes using Kaplan-Meier survival analysis. Calculated hazard ratios (HRs) and log-rank p-values. Results: After propensity score matching (1:1), each cohort had 736 patients. Median age was 75 years (maximum age 90 years) in cohort 1 vs 57 years in cohort 2. Female (41.7% vs 43.2%), White (60.6% vs 58.6%), African American (22.6% vs 23.4%). All comorbidities and prior therapies, including stem cell transplant (35.2% vs 35.1%), ide-cel CAR-T (6.3% vs 6.7%), and cilta-cel CAR-T (1.4% vs 1.4%), were balanced between groups. Median follow-up was 305.5 days in cohort 1 and 316 days in cohort 2. All-cause mortality did not differ significantly between groups (HR = 1.212, p = 0.229). ER visits (HR = 1.345), neutropenia (HR = 1.311), thrombocytopenia (HR = 1.559), sepsis (HR = 1.398), pneumonia (HR = 1.122), and opportunistic infections (HR = 1.119) were slightly higher, in contrast, anemia (HR = 0.841), blood transfusion (HR = 0.812), and hypogammaglobulinemia (HR = 0.927) were lower in the older cohort but none were statistically significant ( p > 0.05). Conclusions: In this large, real-world study, outcomes of BsAbs among patients aged ≥ 65 years were comparable to those of younger patients, without a significant increase in mortality or toxicities. Our findings, although retrospective, suggest that BsAbs can be safely administered in select patients aged ≥65 years, and advanced age should not, in itself, preclude treatment. Careful assessment and optimization of comorbidities and performance status could ensure that these patients benefit from effective treatments with minimal toxicity.