IBI310 (anti-CTLA-4 antibody) monotherapy or in combination with sintilimab in advanced melanoma or urothelial carcinoma

IBI310 is a recombinant fully human IgG1 antibody against cytotoxic T lymphocyte antigen 4. This study was conducted to evaluate IBI310 monotherapy or combination therapy with sintilimab in the patients with advanced melanoma or urothelial carcinoma (UC). Patients in phase 1a received IBI310 at 0.3/1/2/3 mg/kg intravenously (IV) every 3 weeks (Q3W) following the accelerated titration and 3 + 3 escalation design. Patients in phase 1b received IBI310 (1/2/3 mg/kg IV, Q3W) plus sintilimab (200 mg IV, Q3W) for four cycles, followed by sintilimab maintenance therapy. The phase 1b expansion of IBI310 plus sintilimab was performed in patients with advanced melanoma or UC. Overall, 53 patients were enrolled, including 10 patients with melanoma in phase 1a, 34 with melanoma, and 9 with UC in phase 1b. Overall, 94.3% of patients (50/53) experienced at least one treatment-related adverse event (TRAE) with most being grade 1-2; 26.4% of patients (14/53) experienced grade 3 or higher TRAEs. In phase 1a, the disease control rate (DCR) was 50.0% (95% confidence interval CI, 18.7%-81.3%). In phase 1b, the objective response rate (ORR) and DCR were 17.6% (95% CI, 6.8%-34.5%) and 44.1% (95% CI, 27.2%-62.1%), respectively, for melanoma, and were 22.2% (95% CI, 2.8%-60.0%) and 66.7% (95% CI, 29.9%-92.5%), respectively, for UC. IBI310 monotherapy or combination therapy with sintilimab was well tolerated with favorable antitumor activity across patients with advanced melanoma and UC.