J Clin Oncol

Purpose: To report results of the multicenter, open-label IRAKLIA trial (NCT05405166) of isatuximab subcutaneous (SC) versus intravenous (IV), plus pomalidomide and dexamethasone, in relapsed/refractory multiple myeloma (MM), the first Phase 3 MM trial using an on-body delivery system (OBDS).

Methods: Patients with ≥1 prior line of therapy were randomized 1:1 to isatuximab OBDS (1400 mg) or IV (10 mg/kg) weekly in Cycle (C)1, then every 2 weeks, plus pomalidomide (4 mg/day, Day [D]1-21) and dexamethasone (40 mg weekly [age ≥75: 20 mg]) and treated until progression, unacceptable toxicity, or patient request. Co-primary endpoints were overall response rate (ORR; non-inferiority margin, 0.839) and isatuximab Ctrough (C6D1 predose; non-inferiority margin, 0.8). Non-inferiority of OBDS versus IV was demonstrated if both co-primary endpoints achieved non-inferiority.

Results: IRAKLIA randomized 531 patients (OBDS, n=263; IV, n=268). After 12 months median follow-up, ORR was 71.1% (OBDS) and 70.5% (IV; relative risk [95% CI]=1.008 [0.903-1.126]; lower CI exceeded non-inferiority margin). Mean (SD) C6D1 Ctrough was 499 (259) μg/mL (OBDS) and 340 (169) μg/mL (IV). Ctrough geometric mean ratio (90% CI) was 1.532 (1.316-1.784); lower CI exceeded non-inferiority margin. Grade ≥3 treatment-emergent adverse event incidences were 81.7% (OBDS) and 76.1% (IV); infusion reaction incidences were 1.5% and 25.0%. Injection site reactions occurred in 0.4% of OBDS injections (all grade 1-2); 99.9% of injections completed without interruption.

Conclusion: IRAKLIA demonstrated efficacy and pharmacokinetic non-inferiority between isatuximab OBDS and IV. No unexpected safety signal was observed, with excellent local tolerability of isatuximab OBDS. Efficacy and safety were comparable to isatuximab IV in ICARIA-MM, except the lower OBDS infusion reaction rate. These results support potential use of the OBDS, designed to improve practice efficiency.