SX-682 Treatment in Subjects With Metastatic Melanoma Concurrently Treated With Pembrolizumab

Objectives The primary objective is to determine the safety profile of SX-682 alone and in combination with pembrolizumab in subjects with metastatic melanoma, including the maximum dose that can be administered until adverse effects prevent further dose increases, and the dose-limiting toxicity (DLT). The secondary objectives are to: 1) evaluate the efficacy of SX-682 in combination with pembrolizumab on the basis of the objective response rate, the duration of response, and the rate of progression; and 2) characterize the SX-682 single-dose and multidose PK profile. Exploratory objectives are to: 1) assess overall survival (OS); and 2) explore potential biomarkers associated with pharmacodynamic and clinical response to SX-682 alone and combined with pembrolizumab, where the biomarker measures include, but are not limited to, tumor myeloid-derived suppressor cells (MDSC), Tregs and CD69/CD8 T cells, and in the circulation, T- and B-cell subpopulations, neutrophils, the neutrophil-to-lymphocyte ratio (NLR), Tregs, the CD4:CD8 ratio, chemokines, cytokines, and LDH. Overview of Study Design This is a Phase 1, open-label, multi-center, dose-escalation with expansion study of twice-daily SX-682 in subjects with metastatic melanoma treated concurrently with pembrolizumab (Combination Stage) following a 21 day dose-escalation safety evaluation of SX-682 monotherapy (Monotherapy Stage). SX-682 is an oral small-molecule inhibitor of the CXCR1/2 chemokine receptors that are believed involved in MDSC-recruitment to tumor and other pro-tumoral mechanisms. Dosing of SX-682 in the Combination Stage is conditioned on ongoing concurrent treatment with pembrolizumab, and a subject who discontinues pembrolizumab may not receive further doses of SX-682.