Melanoma Stage Stage IIIB

This study evaluates the impact of neoadjuvant Programmed cell death Protein 1 (PD-1)-based treatment regimens in patients with resectable stage IIIB-M1a cutaneous or unknown primary melanoma at high risk of relapse without adjuvant therapy after definitive lymphadenectomy and irrespective of pathologic response outcome on the 2-year overall survival (OS). It was hypothesized that neoadjuvant PD1 inhibitor-based treatment without adjuvant treatment does not significantly (non-inferior) impact OS in this study patient population. Patients will be randomized to either two infusions of pembrolizumab or one infusion of ipilimumab plus nivolumab followed by a single infusion of nivolumab. Patients will undergo follow-up and restaging scans to assess event-free survival at 12 months and OS at 24 months after the first neoadjuvant treatment infusion.