Amivantamab Plus Lazertinib in Atypical EGFR-Mutated Advanced Non–Small Cell Lung Cancer: Results From CHRYSALIS-2

Purpose For patients with advanced non–small cell lung cancer (NSCLC) harboring atypical epidermal growth factor receptor (EGFR) mutations (eg, S768I, L861Q, G719X), efficacy of current treatment options is limited.
Patients and Methods CHRYSALIS-2 Cohort C enrolled participants with NSCLC harboring atypical EGFR mutations (G719X, S768I, L861Q, etc) and ≤2 previous lines of therapy. Participants were treatment-naïve or previously received first- or second-generation EGFR tyrosine kinase inhibitors. Coexisting exon 20 insertions, exon 19 deletions, or exon 21 L858R mutations were exclusionary. Participants received 1,050 mg (1,400 mg if ≥80 kg) intravenous amivantamab once weekly for the first 4 weeks and then once every 2 weeks plus 240 mg oral lazertinib once daily. The primary end point was investigator-assessed objective response rate (ORR).
Results As of January 12, 2024, 105 participants received amivantamab-lazertinib. Most common atypical mutations were G719X (56%), L861X (26%), and S768I (23%), including single and compound mutations. In the overall population (median follow-up: 16.1 months), the ORR was 52% (95% CI, 42 to 62). The median duration of response (mDoR) was 14.1 months (95% CI, 9.5 to 26.2). The median progression-free survival (mPFS) was 11.1 months (95% CI, 7.8 to 17.8); median overall survival (mOS) was not estimable (NE; 95% CI, 22.8 to NE). Adverse events were consistent with previous studies and primarily grade 1 and 2. Among treatment-naïve participants, the ORR was 57% (95% CI, 42 to 71). The mPFS was 19.5 months (95% CI, 11.2 to NE), the mDoR was 20.7 months (95% CI, 9.9 to NE), and mOS was NE (95% CI, 26.3 to NE). Solitary or compound EGFR mutations had no major impact on ORR. The ORR in participants with P-loop and αC-helix compressing, classical-like, and T790M-like mutations was 45% (n = 38), 64% (n = 14), and 67% (n = 3), respectively.
Conclusion In participants with atypical EGFR-mutated advanced NSCLC, amivantamab-lazertinib demonstrated clinically meaningful antitumor activity with no new safety signals.