Sex-based differences in response to anti-PD-1 or PD-L1 treatment in patients with non-small-cell lung cancer expressing high PD-L1 levels. A systematic review and meta-analysis of randomized clinical trials

Background: In our previous works, we demonstrated that patients' sex affects the efficacy of immune checkpoint inhibitors (ICIs) in patients with several advanced solid tumors. Here, we assessed the sex-based heterogeneity of efficacy of anti-programmed cell death protein 1 (anti-PD-1)/anti-programmed death-ligand 1 (anti-PD-L1) given as monotherapy, for advanced non-small-cell lung cancer (NSCLC) expressing high PD-L1 levels, to evaluate if available evidence supports this therapeutic option for both women and men. Methods: We carried out a systematic review and meta-analysis including all randomized, controlled trials testing anti-PD-1/anti-PD-L1 drugs inmonotherapy, as first-line treatment of advanced NSCLC expressing high PD-L1 levels. The primary endpoint was the difference in efficacy of anti-PD-1/anti-PD-L1 drugs versus chemotherapy, between men and women, measured in terms of the difference in overall survival (OS) log [hazard ratio (HR)] reported in male and female study participants. Results: We analyzed four randomized, controlled trials, including 1672 patients, of whom 1224 (73.2%) were men and 448 (26.8%) were women. The pooled OS-HR comparing anti-PD-1/anti-PD-L1 versus chemotherapy was 0.59 [95% confidence interval (CI), 0.50-0.69] for men and only 0.84 (95% CI, 0.64-1.10) for women. The pooled ratio of the OS-HRs reported in men versus women was 0.71 (95% CI, 0.52-0.98; P-heterogeneity: 0.04), indicating a significantly greater effect for men. No heterogeneity among single-study estimates was observed in either male patients (Q = 2.39, P = 0.50, I-2 = 0%) or in female patients (Q = 1.13, P = 0.50, I-2 = 0%). Conclusion: Evidence available indicates anti-PD-1/anti-PD-L1 monotherapy as highly effective in men but not in women, even in NSCLCs expressing high PD-L1 levels. Prospective trials testing sex-based tailored immunotherapy strategies are needed.