Amivantamab-Chemotherapy in Non-Small Cell Lung Cancer with EGFR Exon 20 Insertions: Impact of Treatment Crossover and Other Endpoints from the Phase III PAPILLON Study

We aimed to assess time to treatment discontinuation (TTD) and time to subsequent therapy (TTST), at the time of primary analysis for progression-free survival, and the effect of the crossover design on overall survival at the time of interim analysis.

In the phase III PAPILLON study, 308 participants were randomized (amivantamab-chemotherapy, n = 153; chemotherapy, n = 155). Intravenous amivantamab was administered every 3 weeks. Chemotherapy was administered as carboplatin for four cycles and pemetrexed until disease progression. TTD and TTST were evaluated using Kaplan–Meier and Cox proportional hazards models. Crossover-adjusted survival estimates were generated using three established statistical methods.

At a median follow-up of 14.9 months, median TTD was 13.2 versus 7.5 months for amivantamab-chemotherapy versus chemotherapy (hazard ratio [HR] 0.38 [95% confidence interval 0.28–0.51]; nominal p < 0.0001). Median TTST was 17.7 versus 9.9 months (HR 0.35 [95% confidence interval 0.25–0.49]; nominal p < 0.0001). A total of 65/155 participants crossed over from chemotherapy to amivantamab after progression. The crossover-adjusted overall survival continued to demonstrate a favorable survival benefit for amivantamab-chemotherapy versus chemotherapy with HRs of 0.52–0.60, which is more pronounced than the planned interim intention-to-treat overall survival (HR of 0.67; 95% confidence interval 0.42–1.09).

ClinicalTrials.gov Identifier: NCT04538664.