CheckMate 067: Long-term outcomes in patients with mucosal melanoma.

10019 Background: Mucosal melanoma is a rare but aggressive malignancy with a poor prognosis. Here we report 5-y outcomes in a subgroup of patients with mucosal melanoma treated in CheckMate 067 with nivolumab plus ipilimumab (NIVO+IPI), NIVO alone, or IPI alone. Methods: Patients with previously untreated stage III or IV melanoma were randomized 1:1:1 to receive NIVO 1 mg/kg + IPI 3 mg/kg for 4 doses Q3W followed by NIVO 3 mg/kg Q2W, NIVO 3 mg/kg Q2W + placebo, or IPI 3 mg/kg Q3W for 4 doses + placebo until progression or unacceptable toxicity. Mucosal histology was not a stratification factor, and patients with mucosal melanoma were identified by local investigators in the study. Descriptive subgroup analyses were performed to evaluate efficacy (objective response rate [ORR], progression-free survival [PFS], overall survival [OS]), and safety. Results: A total of 79 patients with mucosal melanoma were treated. With a minimum follow-up of 60 mo, NIVO+IPI treatment was associated with the highest 5-y ORR (43% [vs 30% with NIVO and 7% with IPI]), PFS (29% [vs 14% and 0%, respectively]), and OS (36% [vs 17% and 7%, respectively]; Table), consistent with trends in the intent-to-treat (ITT) population; however, efficacy outcomes were generally less favorable overall relative to the ITT population. Complete response rates were higher with NIVO+IPI (14%) relative to monotherapy (NIVO, 4%; IPI, 0%) in patients with mucosal melanoma. Safety outcomes, including the grade 3/4 treatment-related adverse event rates of 54%, 26%, and 25%, respectively, were similar to the ITT population. Conclusions: This 5-y analysis showed that patients with mucosal melanoma in CheckMate 067 had similar safety outcomes but poorer long-term efficacy vs the ITT population. Patients with mucosal melanoma treated with NIVO+IPI appeared to have more favorable survival outcomes than those treated with NIVO or IPI alone. Novel therapies are needed to further improve long-term benefit in patients with mucosal melanoma. Clinical trial information: NCT01844505. [Table: see text]