Efficacy and safety of dacomitinib as first-line treatment for advanced non-small cell lung cancer patients with epidermal growth factor receptor 21L858R mutation: A multicenter, case-series study in China.

Objective: To provide real-world evidence for the application of first-line dacomitinib treatment for epidermal growth factor receptor (EGFR) 21L858R mutant non-small cell lung cancer (NSCLC) patients in China and to explore the factors influencing the efficacy and safety.

Methods: A longitudinal, consecutive case-series, multicenter study with mixed prospective and retrospective data was conducted. The primary endpoint was progression-free survival (PFS), and the secondary endpoints included duration of treatment (DOT), overall survival (OS), objective response rate (ORR), disease control rate (DCR) and safety.

Results: A total of 155 EGFR 21L858R mutant patients treated with first-line dacomitinib were included. The median follow-up time for these patients was 20.4 months. Among 134 patients with evaluable lesions, the ORR was 70.9% and the DCR was 96.3%. The median PFS was 16.3 [95% confidence interval (95% CI), 13.7-18.9] months. Multivariate Cox regression analysis suggested that the baseline brain metastasis (BM) status [with vs. without BM: hazard ratio (HR), 1.331; 95% CI, 0.720-2.458; P=0.361] and initial doses (45 mg vs. 30 mg: HR, 0.837; 95% CI, 0.427-1.641; P=0.604) did not significantly affect the median PFS. The median DOT was 21.0 (95% CI, 17.5-24.6) months and the median OS was not reached. Genetic tests were performed in 64 patients after progression, among whom 29 (45.3%) patients developed the EGFR 20T790M mutation. In addition, among the 46 patients who discontinued dacomitinib treatment after progression, 31 (67.4%) patients received subsequent third-generation EGFR-tyrosine kinase inhibitors. The most common grade 3-4 adverse events were rash (10.4%), diarrhea (9.1%), stomatitis (7.1%) and paronychia (4.5%). The incidence of grade 3-4 rash was significantly higher in the 45 mg group than that in the 30 mg group (21.9% vs. 7.5%, P=0.042).

Conclusions: First-line dacomitinib treatment demonstrated promising efficacy and tolerable adverse events among EGFR 21L858R mutant NSCLC patients in China.