Patient features, PD-L1 expression, and immune cell (IC) status in the tumor microenvironment (TME) were explored to see if they were linked to PD-1 blocking therapeutic outcomes. Between January 2016 and March 2018, researchers analyzed patients with advanced EGFR-mutant NSCLC treated with PD-1 blocking (nivolumab or pembrolizumab). The TME was examined for PD-L1 expression and the types and distribution of ICs (CD8, PD-1, CD204, tumoral, and stromal). Only 39 of the 57 EGFR-mutant NSCLC patients treated with PD-1 inhibition had enough tissues to analyze the TME. The patients’ overall response rate (ORR) to PD-1 blocking was 12.3%. Only tumoral CD8 positive (CD8+) IC status (median tumoral CD8+ ICs: 299/mm2 vs 115/mm2, P<0.01) was linked with response. About 5 (83.3%) of the 6 patients with high PD-L1 expression (TPS: ≥50%) and high tumoral CD8+ ICs (≥205/mm2) had a response and a significantly longer progression-free survival (PFS: 9.4M vs. 1.8M, P<0.01). None of the 7 patients with strong PD-L1 expression but low tumoral CD8+ ICs (<205/mm2) responded. In EGFR-mutant patients, strong PD-L1 expression and high tumoral CD8+ ICs could predict response and PFS to PD-1 blocking therapy.
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