This is a Phase 1b, open-label, multicenter, safety, tolerability and efficacy study of HC-7366 in combination with belzutifan (WELIREG™). This is a multipart study that consists of a HC-7366 monotherapy cohort, a combination dose escalation, and a combination dose expansion. Approximately 80 patients will be enrolled in this study (up to 20 patients will be enrolled into the HC-7366 monotherapy cohort, up to 30 patients into the combination dose escalation, and up to 30 patients into the combination dose expansion). The primary purpose of this study is to determine the maximum tolerated dose of HC-7366 in combination with belzutifan in patients with locally advanced (inoperable) or metastatic RCC with predominantly clear cell histology, irrespective of VHL gene mutation status.