Neoadjuvant Pembrolizumab and Lenvatinib for Mucosal Melanoma

Inclusion Criteria: * Written informed consent * Histologically confirmed diagnosis of fully-resectable mucosal melanoma * Pathological ± clinical confirmation that the presenting lesion(s) does not represent metastasis from an unknown primary cutaneous or ocular melanoma * Measurable disease per RECIST * Availability of a newly obtained core or excisional biopsy of an affected lesion which has not been previously irradiated * Ability to swallow and retain oral medication * ECOG 0 - 1 * Adequate organ function per laboratory values * Adequately controlled blood pressure with or without anti-hypertensive medications, defined as ≤ 150/90 mmHg at screening * Anticpated life expectabcy of \> 12 months. Exclusion Criteria: * A diagnosis of uveal or cutaneous melanoma * A WOCBP who has a positive serum pregnancy test within 72 hours prior to starting study treatment * Prior therapy with an anti-PD-1, anti-PD-L1, or anti PD L2 agent or with an agent directed to another stimulatory or co-inhibitory T-cell receptor for any disease * Prior systemic treatment for mucosal melanoma including investigational agents. Prior surgery is acceptable * Major surgery within 3 weeks prior to first dose of lenvatinib * Patients who have not recovered adequately from any toxicity from other permitted anti- cancer treatment regimens * Prior radiotherapy within 2 weeks of start of study treatment * Received a live vaccine or live-attenuated vaccine within 30 days before the first dose of study treatment * Patient is currently participating in or has participated in a study of an investigational agent or has used an investigational device within 4 weeks prior to the first dose of study treatment * A diagnosis of immunodeficiency or is receiving chronic systemic steroid therapy (in dosing exceeding 10 mg daily of prednisone equivalent) or any other form of immunosuppressive therapy within 14 days prior to the first dose of study treatment * Active autoimmune disease that has required systemic treatment in the past 12 months * Known additional malignancy that is progressing or has required active treatment within the past 3 years * Has known central nervous system metastases and/or carcinomatous meningitis * A history of (non-infectious) pneumonitis//interstitial lung disease that required steroids or has current pneumonitis or current interstitial lung disease * Active infection requiring systemic therapy * Known history of Human Immunodeficiency Virus, active Hepatitis B or C * Has a known history of active TB * A current diagnosis of any gastrointestinal condition that might affect the absorption of lenvatinib * Has a pre-existing ≥ Grade 3 gastrointestinal adverse event or a non-gastrointestinal fistula * Prolonged QT interval \>480 ms * History of, or current cardiovascular disease * Has a history of, or a current bleeding or thrombotic disorders or patients at risk for severe haemorrhage * Active haemoptysis * Patients with a ≥2+ (≥100 mg/dL) proteinuria on urine dipstick testing * Pregnant or breastfeeding, or expecting to conceive or father children within the projected duration of the study * Has had an allogenic tissue/solid organ transplant.