Epidemiology of PD-L1 and ALK expression and EGFR mutational status in Argentinian patients with lung cancer.

Abstract

e20565 Background: Until now, the results of the correlation between PD-L1, ALK expression and EGFR mutations remain controversial. We prospectively evaluated patterns among EGFR mutant, ALK positive and PD-L1 positive lung cancer patients. Methods: PD-L1 and ALK expression was evaluated in 342 adenocarcinomas (AD) of the lung using inmunohistochemestry (anti-PD-L1 22C3, anti-ALK D5F3), and EGFR mutations using real time PCR (therascreen EGFR RGQ PCR Kit version 2). PD-L1 was also evaluated in 36 squamous (SQ) cell carcinomas. Results: 181 of 342 patients with AD were positive for PD-L1. 108 were positive with a TPS value between 1 and 49, and 73 were positive with a TPS value higher than 50 (p = 0.002). 25 of 36 patients with SQ were positive for PD-L1. 17 were positive with a TPS value between 1 and 49, and 8 were positive with a TPS value higher than 50. 133 samples with AD PD-L1 positive and 97 PD-L1 negative were tested for EGFR and ALK, 33 and 14 respectively were positive for EGFR mutations (p = 0.15), with 45% for exon 19 deletions (p = 0.003), 5 and 0 respectively were positive for ALK translocations (p = 0.053). 210 of 342 patients were men and 132 were women, 117 and 64 were positive for PD-L1 expression respectively (p > 0.1). Conclusions: NSCLC with EGFR mutation showed a trend for higher frequency of positive PD-L1 expression and NSCLC harboring ALK rearrangement was significantly associated with PD-L1 expression. These findings might contribute to the understanding of the regulation of PD-L1 expression in lung cancer and its relation to ALK expression and EGFR mutation.