Efficacy and safety of retifanlimab across solid tumors: A systematic review and meta-analysis.

e14585 Background: Retifanlimab is a PD-1 inhibitor with demonstrated activity in several solid tumors, including FDA approved indication in squamous cell carcinoma of the anal canal (SCAC). However, its efficacy and safety across tumor types have not been systematically synthesized. Methods: We conducted a systematic review and meta analysis of prospective trials evaluating retifanlimab in solid tumors. PubMed, Embase, Cochrane Library, ClinicalTrials.gov, and oncology conferences were searched through January 2026. Pooled ORR and CR were estimated using random effects models. Subgroup analyses were performed by tumor type, treatment line, and regimen. Results: Nineteen studies encompassing 1,113 patients across phase I-III trials were included. Tumor types included SCAC, Merkel cell carcinoma (MCC), NSCLC, HNSCC, sarcoma, and MSI-H endometrial cancer. Pooled ORR was 57.2% (95% CI, 48.6–65.9%; I² = 87%); CR rate was 26.3% (95% CI, 19.7–32.8%). First-line treatment showed significantly higher ORR than later lines (79.8% vs 39.5%). By tumor type, higher ORRs were observed in HNSCC (74.8%), NSCLC (74.7%), MCC (69.4%), and SCAC (65.4%). Safety was consistent with PD-1 inhibitor class: any-grade irAEs in 27.8%, grade ≥3 in 6.3%. Conclusions: Retifanlimab demonstrates clinically meaningful antitumor activity across multiple solid tumors, with greatest benefit in first line treatment. Consistency of efficacy and safety signals supports ongoing development. Pooled ORR by tumor type. Tumor Studies Patients ORR (95% CI) SCAC 3 402 65.4% (40.7–90.2%) MCC 2 111 69.4% (37.2–101.6%) NSCLC 2 58 74.7% (39.1–110.3%) HNSCC 2 50 74.8% (53.3–96.4%) Sarcoma 3 88 37.5% (21.8–53.2%)