Phase II study of sintilimab combined with nab-paclitaxel in the treatment of platinum-resistant recurrent ovarian cancer.

5560 Background: Platinum-resistant recurrent ovarian cancer (PROC) remains a major therapeutic challenge with limited effective treatment options. This single-arm phase II trial aimed to evaluate the efficacy, safety, and tolerability of sintilimab combined with nab-paclitaxel in patients with platinum-resistant recurrent epithelial ovarian, fallopian tube, or primary peritoneal cancer. Methods: A total of 28 patients were enrolled and received intravenous sintilimab (200 mg, day 1) plus nab-paclitaxel (260 mg/m², day 1) every 3 weeks. The primary endpoint was objective response rate (ORR); secondary endpoints included progression-free survival (PFS), disease control rate (DCR), overall survival (OS), and safety. Results: The median age was 57 years (range: 37–74 years), with 96.4% having high-grade serous histology, 67.9% being BRCA wild-type, 57.1% with prior bevacizumab exposure, and 50% with a PD-L1 combined positive score (CPS) ≥1. After a median follow-up of 11.8 months, the ORR was 35.7% (10 partial responses), DCR was 64.3%, median PFS was 4.28 months, and median OS was 15.83 months. Patients with CPS ≥1 had a higher ORR (42.9% vs. 28.6%) and DCR (71.4% vs. 57.1%) than those with CPS <1, but no significant difference in PFS (3.83 vs. 4.13 months, p = 0.18). Similar trends were observed for CPS ≥5 and CPS ≥10, with ORRs of 44.4% and 50.0%, respectively, but no significant PFS differences (all p > 0.05).Notably, patients with tumor-infiltrating lymphocytes (TILs) ≥10% exhibited a significantly higher ORR (72.7% vs. 12.5%, p = 0.005) and longer median PFS (15.57 months vs. 3.4 months, p = 0.005). Treatment-related adverse events (TRAEs) were mainly leukopenia (28.6%), neutropenia (25.0%), anemia (46.4%), and peripheral neuritis (28.6%), with rare grade 3–4 toxicities. Conclusions: Sintilimab combined with nab-paclitaxel shows promising efficacy and acceptable safety in PROC, with TILs ≥10% and a high CD8⁺/CD4⁺ ratio emerge as potential predictive biomarkers, while PD-L1 CPS shows limited utility. This regimen represents a potential new therapeutic option for this difficult-to-treat population and warrants further investigation in randomized controlled trials. Clinical trial information: 2000031890.