A Phase 1 Study of the Safety and Tolerability of CTX-10726

This is a Phase 1, open-label, first-in-human study of CTX-10726 monotherapy in patients with metastatic or locally advanced malignancies. The study will be conducted in 2 Cohorts: Cohort 1 Dose Escalation and Cohort 2 Dose Expansion.

Inclusion Criteria: 1. Age 18 years or older. 2. Patients must have a histologically or cytologically confirmed diagnosis of locally advanced unresectable or metastatic disease that is relapsed/refractory to standard therapy or for which no effective standard therapy is available, including: 2a: Renal Cell Carcinoma (RCC) * Histologically confirmed diagnosis of renal cell carcinoma (with clear cell component) with advanced or metastatic disease that is not amenable to cure by surgery or other means. * Patients who have progressed after a minimum of 2 doses of a programmed cell death 1 (PD-1)/ programmed cell death ligand 1 (PDL1) treatment. * Patients must have received at least one regimen including a tyrosine kinase inhibitor (TKI). * Patients who received immunomodulatory drugs (thymosin, interferon, interleukin, etc.) within 2 weeks before the first dose or received major surgical treatment within 3 weeks before the first dose are not eligible. 2b: Hepatocellular Carcinoma (HCC) * Patients who have progressed after a minimum of 2 doses of a PD-1/PDL1 treatment. * Patient must have received one of the following regimens: ipilimumab+nivolumab, tremelimumab+durvalumab, atezolizumab+bevacizumab or lenvatinib+pembrolizumab. * Hepatic function: Child -Pugh A and Child-Pugh B7. * Receipt of local area treatment of the liver more than 4 weeks prior to the first dose is allowed. 2c. Gastroesophageal Cancer (GC) * Patients who have progressed after a minimum of 2 doses of a PD-1/PDL1 treatment. * Patients must have received prior treatment with platinum-based chemotherapy. 2d: Endometrial Cancer (EC) * Patients must have received at least 1 cycle of platinum-based chemotherapy. * Patients with newly diagnosed advanced endometrial cancer that have persistent lesion(s) after standard treatment with surgery and chemotherapy ± radiotherapy. * Patients with MSI- high or deficient DNA mismatch repair (dMMR) tumors who have progressed after a minimum of 2 doses of a PD-1/PDL1 treatment. 3\. Patients must have measurable disease per RECIST 1.1. Tumor sites that are considered measurable must not have received prior radiation. 4\. Eastern Cooperative Oncology Group (ECOG) performance status 0-1. 5\. Adequate organ function including: * Bone marrow function defined by absolute neutrophil (ANC) of ≥ 1.5×109/L, platelet count of ≥ 100.0×109/L, and hemoglobin of ≥ 9.0 g/dL (with or without transfusion). * Hepatic function defined as serum total bilirubin ≤ 1.5 × ULN (\