PS1379 SAFETY AND EFFICACY OF ONCE‐WEEKLY CARFILZOMIB DOSING IN FRAIL PATIENTS: A SUBGROUP ANALYSIS FROM THE PHASE 3 A.R.R.O.W. STUDY

Background: A.R.R.O.W. demonstrated superior progression‐free survival (PFS) with once‐weekly carfilzomib (K, 70 mg/m 2 ) and dexamethasone (Kd70) vs twice‐weekly K (27 mg/m 2 ) and dexamethasone (Kd27) in relapsed and refractory (RRMM) patients (pts), regardless of age. For a comprehensive measure of fitness, frailty scales were developed incorporating age, comorbidities, and functional status (Palumbo Blood 2015;125:2068–74; Facon Blood 2015;126:4239). Aims: Here, we assessed post‐hoc pt outcomes by frailty status. Methods: PFS and safety were assessed by treatment arm and a frailty algorithm which incorporated age, Charlson Comorbidity Index derived from medical history, and ECOG performance status; pts with frailty scores of 0, 1, or ≥2 were classified as fit, intermediate, or frail, respectively. PFS was assessed using the Kaplan‐Meier method. Safety was assessed in pts who received ≥1 treatment dose. Results: The distribution of pts by frailty status was generally balanced between treatment arms (Table). Once‐weekly Kd70 vs twice‐weekly Kd27 resulted in median PFS for fit, intermediate, and frail pts of 15.7 vs 5.7 months (hazard ratio [HR] 0.53 [95% confidence interval (CI), 0.33–0.86]), 11.1 vs 7.7 months (HR 0.81 [95% CI, 0.55–1.19]), and 10.3 vs 6.6 months (HR 0.76 [95% CI, 0.49–1.16]), respectively. Rates of grade ≥3 treatment‐emergent adverse events (TEAEs) of interest were similar between treatment arms across frailty subgroups (Table). In the once‐weekly Kd70 subgroups, there was no grade ≥3 peripheral neuropathy and grade ≥3 cardiac failure rates were ≤4%. Summary/Conclusion: Once‐weekly Kd70 resulted in PFS benefits vs twice‐weekly Kd27, regardless of frailty level. These results support weekly Kd70 as a treatment option for fit and frail RRMM pts.