Nivolumab Alone and With Ipilimumab in Previously Treated Metastatic Urothelial Carcinoma: CheckMate 032 Nivolumab 1 mg/kg Plus Ipilimumab 3 mg/kg Expansion Cohort Results

PURPOSE CheckMate 032 is an open-label, multicohort study that includes patients with unresectable locally advanced or metastatic urothelial carcinoma (mUC) treated with nivolumab 3 mg/kg monotherapy every 2 weeks (NIVO3), nivolumab 3 mg/kg plus ipilimumab 1 mg/kg every 3 weeks for four doses followed by nivolumab monotherapy 3 mg/kg every 2 weeks (NIVO3+IPI1), or nivolumab 1 mg/kg plus ipilimumab 3 mg/kg every 3 weeks for four doses followed by nivolumab monotherapy 3 mg/kg every 2 weeks (NIVO1+IPI3). We report on the expanded NIVO1+IPI3 cohort and extended follow-up for the NIVO3 and NIVO3+IPI1 cohorts. METHODS Patients with platinum-pretreated mUC were enrolled in this phase I/II multicenter study to receive NIVO3, NIVO3+IPI1, or NIVO1+IPI3 until disease progression or unacceptable toxicity. Primary end point was investigator-assessed objective response rate per Response Evaluation Criteria in Solid Tumors (RECIST) version 1.1, including duration of response. RESULTS Seventy-eight patients were treated with NIVO3 (minimum follow-up, 37.7 months), 104 with NIVO3+IPI1 (minimum follow-up, 38.8 months), and 92 with NIVO1+IPI3 (minimum follow-up, 7.9 months). Objective response rate was 25.6%, 26.9%, and 38.0% in the NIVO3, NIVO3+IPI1, and NIVO1+IPI3 arms, respectively. Median duration of response was more than 22 months in all arms. Grade 3 or 4 treatment-related adverse events occurred in 21 (26.9%), 32 (30.8%), and 36 (39.1%) patients treated with NIVO3, NIVO3+IPI1, and NIVO1+IPI3, respectively. Grade 5 treatment-related pneumonitis occurred in one patient each in the NIVO3 and NIVO3+IPI1 arms. CONCLUSION With longer follow-up, NIVO3 demonstrated sustained antitumor activity alone and in combination with ipilimumab. NIVO1+IPI3 provided the greatest antitumor activity of all regimens, with a manageable safety profile. This result not only supports additional study of NIVO1+IPI3 in mUC, but demonstrates the potential benefit of immunotherapy combinations in this disease.