Subcutaneous versus Intravenous Amivantamab, both in Combination with Lazertinib, in Refractory EGFR-mutated NSCLC: Primary Results from the Phase 3 PALOMA-3 Study

Purpose: Phase 3 studies of intravenous amivantamab demonstrated efficacy across EGFR-mutated advanced non-small cell lung cancer (NSCLC). A subcutaneous formulation could improve tolerability and reduce administration time while maintaining efficacy. Patients and methods: Patients with EGFR-mutated advanced NSCLC who progressed following osimertinib and platinum-based chemotherapy were randomized 1:1 to receive subcutaneous or intravenous amivantamab, both combined with lazertinib. Co-primary pharmacokinetic noninferiority endpoints were trough concentrations (Ctrough; on cycle-2-day-1 or cycle-4-day-1) and cycle-2 area under the curve (AUCD1-D15). Key secondary endpoints were objective response rate (ORR) and progression-free survival (PFS). Overall survival (OS) was a predefined exploratory endpoint. Results: Overall, 418 patients underwent randomization (subcutaneous group, n=206; intravenous group, n=212). Geometric mean ratios of Ctrough for subcutaneous to intravenous amivantamab were 1.15 (90% CI, 1.04-1.26) at cycle-2-day-1 and 1.42 (90% CI, 1.27-1.61) at cycle-4-day-1; the cycle-2 AUCD1-D15 was 1.03 (90% CI, 0.98-1.09). ORR was 30% in the subcutaneous and 33% in the intravenous group; median PFS was 6.1 and 4.3 months, respectively. OS was significantly longer in the subcutaneous versus intravenous group (hazard ratio for death, 0.62; 95% CI, 0.42-0.92; nominal P=0.02). Fewer patients in the subcutaneous group experienced infusion-related reactions (13% versus 66%) and venous thromboembolism (9% versus 14%) versus the intravenous group. Median administration time for first infusion was reduced to 4.8 minutes (range, 0-18) for subcutaneous amivantamab from 5 hours (range, 0.2-9.9) for intravenous amivantamab. During cycle-1-day-1, 85% and 52% of patients in the subcutaneous and intravenous groups, respectively, considered treatment convenient; end-of-treatment rates were 85% and 35%, respectively. Conclusion: Subcutaneous amivantamab-lazertinib demonstrated noninferiority to intravenous amivantamab-lazertinib, offering a consistent safety profile with reduced infusion-related reactions, increased convenience, and prolonged survival.