Sex-Based Clinical Outcome in Advanced NSCLC Patients Undergoing PD-1/PD-L1 Inhibitor Therapy—A Retrospective Bi-Centric Cohort Study

SIMPLE SUMMARY: Retrospective analyses suggest that men treated with immune-checkpoint inhibitor (ICI) monotherapy for non-small cell lung cancer (NSCLC) have better outcomes than women. However, female patients have more favorable responses when chemotherapy (CHT) is given together with ICI. We aimed to explore the clinical impact of such sex differences in two cohorts, receiving ICI monotherapy or ICI-CHT combination, respectively. We found no significant difference in outcomes between men and women treated with either therapeutic regimen. However, known predictive factors for ICI response such as the expression of programmed-death ligand 1 (PD-L1) on tumor cells or patient performance status had significant implications for men rather than for women. Our results warrant increased research efforts to clarify sex-specific differences in anti-tumor immune response mechanisms and in the efficacy of ICI therapies, especially in women. ABSTRACT: Men with non-small cell lung cancer (NSCLC) have a more favorable response to immune-checkpoint inhibitor (ICI) monotherapy, while women especially benefit from ICI-chemotherapy (CHT) combinations. To elucidate such sex differences in clinical practice, we retrospectively analyzed two cohorts treated with either ICI monotherapy (n = 228) or ICI-CHT combination treatment (n = 80) for advanced NSCLC. Kaplan–Meier analyses were used to calculate progression-free (PFS) and overall survival (OS), influencing variables were evaluated using Cox-regression analyses. No significant sex differences for PFS/OS could be detected in either cohort. Men receiving ICI monotherapy had a statistically significant independent impact on PFS by Eastern Cooperative Oncology Group performance status (ECOG) ≥2 (hazard ratio (HR) 1.90, 95% confidence interval (CI): 1.10–3.29, p = 0.021), higher C-reactive protein (CRP; HR 1.06, 95%CI: 1.00–1.11, p = 0.037) and negative programmed death-ligand 1 (PD-L1) status (HR 2.04, 95%CI: 1.32–3.15, p = 0.001), and on OS by CRP (HR 1.09, 95%CI: 1.03–1.14, p = 0.002). In men on ICI-CHT combinations, multivariate analyses (MVA) revealed squamous histology (HR 4.00, 95%CI: 1.41–11.2, p = 0.009) significant for PFS; and ECOG ≥ 2 (HR 5.58, 95%CI: 1.88–16.5, p = 0.002) and CRP (HR 1.19, 95%CI: 1.06–1.32, p = 0.002) for OS. Among women undergoing ICI monotherapy, no variable proved significant for PFS, while ECOG ≥ 2 had a significant interaction with OS (HR 1.90, 95%CI 1.04–3.46, p = 0.037). Women treated with ICI-CHT had significant MVA findings for CRP with both PFS (HR 1.09, 95%CI: 1.02–1.16, p = 0.007) and OS (HR 1.11, 95%CI: 1.03–1.19, p = 0.004). Although men and women responded similarly to both ICI mono- and ICI-CHT treatment, predictors of response differed by sex.