Association of inflammatory markers with survival and durable benefit in heavily pretreated platinum- resistant ovarian cancer receiving pembrolizumab

Background: This study aimed to evaluate the association between peripheral blood inflammatory markers and clinical outcomes in patients with platinum-resistant ovarian cancer treated with pembrolizumab monotherapy, focusing on clinical heterogeneity in later-line settings. We retrospectively analyzed 95 patients with advanced platinum-resistant epithelial ovarian, fallopian tube, or primary peritoneal cancer treated with pembrolizumab between July 2018 and December 2023. The systemic inflammation response index (SII), neutrophil-to-lymphocyte ratio (NLR), and systemic immune-inflammation index (SIRI) were calculated from baseline blood tests. Cox regression models, adjusted for age, Eastern Cooperative Oncology Group (ECOG) performance status, therapy line, and albumin levels, were utilized to assess associations with progression-free survival and overall survival. Results: The median progression-free survival was two months, and the median overall survival was seven months. SIRI and NLR were associated with progression-free survival, while all evaluated inflammatory markers correlated with overall survival. Although the median progression-free survival was similar when stratified by the median SIRI, the survival curves diverged over time. A high SIRI was associated with poorer overall survival (hazard ratio 2.02, 95% CI 1.53–2.67). Notably, long-term survival was predominantly observed in the low SIRI group, demonstrating a 12-month overall survival rate of 49% compared to 13% in the high SIRI group. This trend persisted after adjusting for albumin levels, performance status, and programmed death-ligand 1 expression. Conclusion: Peripheral blood inflammatory markers were associated with distinct clinical courses in platinum-resistant ovarian cancer patients receiving pembrolizumab, particularly regarding long-term disease control. These findings suggest these markers may aid in interpreting later-line treatment outcomes, warranting prospective validation.