SALVO: Single Arm Trial of Ipilimumab and Nivolumab as Adjuvant Therapy for Resected Mucosal Melanoma.

BACKGROUND: Mucosal melanoma is a rare, aggressive form of melanoma with extremely high recurrence rates despite definitive surgical resection with curative intent. Currently there is no consensus on adjuvant therapy. Data on checkpoint inhibitors (CPI) for adjuvant therapy is lacking. METHODS: We performed a single arm, multicenter clinical trial using flip dose ipilimumab (1mg/kg q3w x4 cycles), and nivolumab (3 mg/kg q3w x4 cycles), then Nivolumab 480 mg q4w x 11 cycles to complete a year of adjuvant therapy. Participants must have had R0/R1 resectionregistration, no prior systemic therapy (adjuvant radiation allowed), ECOG 0/1, no uncontrolled autoimmune disease or other invasive cancer. Patients were recruited through the Midwest Melanoma Partnership/Hoosier Oncology Network. RESULTS: From Sept 2017 to August 2021 35 patients enrolled. Of these, 29 (83%) had R0 resections, and 7 (20%) received adjuvant radiation. Median age was 67 years, 21 (60.0%) female. Relapse-free survival rates at 1 and 2 years were 50% (95% CI 31-66%) and 37% (95% CI 19-55%), respectively. Overall survival rates at 1 and 2 years were 87% (95% CI 68-95%) and 68% (95% CI 46-83%), respectively. Median RFS was 14.3 m (95% CI 5.7-25.8). Most common grade 3 toxicities were diarrhea (14%), hypertension (14%), and hyponatremia (11%), with no grade 4/5 toxicities. CONCLUSIONS: Flip dose ipilimumab and nivolumab after resection of mucosal melanoma is associated with outcomes improved over that of surgical resection alone. Long term follow up, subgroup analyses and correlative studies are ongoing