Neoadjuvant PD-1 Blockade in Patients with Stage IIB/C Melanoma

The main purpose of this study is to determine the rate of positive sentinel lymph nodes (i.e. the closest draining lymph node(s) to the primary melanoma site) and to test whether treatment with pembrolizumab before surgery to remove melanoma reduces the rate of positive sentinel lymph nodes in patients with Stage IIB/C melanoma. Subjects with stage II melanoma will receive one dose of pembrolizumab 200 mg, then undergo standard definitive surgery with wide excision and sentinel lymph node (SLN) biopsy approximately 3 weeks after the initial dose of pembrolizumab. Post-operatively, subjects will receive up to 1 year of adjuvant pembrolizumab 200 mg every 3 weeks.