A brief report on stable disease among amivantamab-treated patients with post-platinum epidermal growth factor receptor exon 20 insertion–mutated non-small cell lung cancer: A response-based analysis from the CHRYSALIS study

Background

Amivantamab, an EGFR-MET bispecific antibody, is the first approved targeted therapy for patients with EGFR Ex20ins NSCLC after prior platinum-based chemotherapy—a population with historically poor outcomes before amivantamab approval. As antitumor activity in single-arm studies typically focuses on responders, the evaluation of outcomes in patients with stable disease (SD) as best response is of clinical interest.

Patients and methods

Among 114 patients with post-platinum EGFR Ex20ins NSCLC in CHRYSALIS (NCT02609776; data cutoff: March 30, 2021), response was assessed by blinded independent central review via RECIST v1.1. Patients alive and receiving therapy at 12 weeks were grouped by response at this landmark: partial or complete response (PR+), SD, or progressive disease (PD). Progression-free survival (PFS) and overall survival (OS) by response cohort were determined using the Kaplan-Meier method; hazard ratios (HRs) and 95% confidence intervals (CIs) between response cohorts were calculated using Cox proportional hazards regression.

Results

Among patients alive and receiving therapy at 12 weeks (n=107), 42 (39%) had PR+, 52 (49%) had SD, and 13 (12%) had PD. Among patients with PR+ and SD, median PFS was 12.2 and 7.0 months, respectively. A corresponding improvement in OS was observed in patients achieving PR+ (median: not reached; HR vs PD=0.21 [95% CI: 0.08–0.54]) and SD (median: 23.0 months; HR vs PD=0.33 [95% CI: 0.14–0.77]), relative to those with PD (median: 14.0 months).

Conclusion

SD was observed in 49% of patients receiving amivantamab, with corresponding increases in OS that dramatically improved the prognoses of this patient population.