Chemoimmunotherapy combination: Potential option for metastatic NSCLC patients with EGFR mutation resistant to osimertinib.

Abstract

e20618 Background: Osimertinib has been emerged as the standard selection in EGFR T790M-positive NSCLC patients who failed prior treatment with EGFR TKIs. However, acquired resistance to osimertinib is a growing clinical challenge. Despite the significant antitumor activity of Chemoimmunotherapy (CIT) combinations in NSCLC, clinical benefit in patients with EGFR mutations has not been shown obviously. Our objective was to assess the effectiveness and tolerability of CIT for metastatic EGFR-mutant NSCLC patients with acquired resistance to Osimertinib. Methods: We conducted a retrospective study in patients with sensitizing EGFR-mutant NSCLC who were resistant to Osimertinib and received anti-PD1 immunotherapy combined with chemotherapy at Chinese PLA General Hospital. Progression-free survival (PFS), overall survival (OS), overall response rate (ORR), and toxicities were examined. Results: Between Oct 2015 and Nov 2018, 11 patients were available for analysis, 45.5% male, 45.5% ECOG PS 0-1, median age 54 years, all pts who failed treatment with Osimertinib had received previously targeted therapies. In this CIT combination group, 6 [54.5%] of 11 pts received pembrolizumab and 5[54.5%] of 11 pts received Nivolumab anti-PD1 therapy, 8 [72.7%] of 11 pts received mono-chemotherapy and 3 [27.3%] of 11 pts received platinum-based doublet chemotherapy. The median PFS was 7.47 months (95% CI 3.04 to 11.89). Despite Median OS was not reached, the OS rate at one year was 6 [54.5%] of 11. The ORR was 5 [45.5%] of 11. Treatment-related adverse events (TRAE) of grade 3 or higher were reported in 6 [54.5%] of 11 patients. The most common grade 3 or worse TRAEs were fatigue (3 [27.3%] of 11) and anemia (3 [27.3%] of 11); The following ≥Grade 3 TRAEs occurred once: decreased neutrophil count, acute kidney injury, gastrointestinal bleeding. One patient discontinued treatment because of immune-associated gastroenteritis. Conclusions: In metastatic NSCLC patients with activating EGFR mutation resistant to Osimertinib, our single institution real-world experience in Chemoimmunotherapy combination shows promising activity and acceptable toxicity profile. Given the small number of patients studied, further clinical trials are warranted.