Phase 1a/1b Open Label Dose-escalation and Expansion Study of TPST-1495 as a Single Agent and in Combination With Pembrolizumab in Subjects With Solid Tumors

This is a first-in-human Phase 1a/1b, multicenter, open-label, dose-escalation, dose and schedule optimization, and expansion study of TPST-1495 as a single agent and in combination with pembrolizumab to determine its MTD, safety, tolerability, pharmacokinetics (PD), pharmacodynamics (PK) and preliminary anti-tumor activity in subjects with advanced solid tumors. Subjects with all histologic types of solid tumors are eligible for the study. However, the preferred tumor types for enrollment are colorectal cancer (CRC), non-small cell lung cancer (NSCLC), squamous cell carcinoma of the head and neck (SCCHN), urothelial cancer, endometrial cancer, and gastroesophageal junction (GEJ) or gastric adenocarcinoma. Tumor prostaglandin production and downstream signaling in both tumor cells and other cell types, including immune suppressive cell population in the tumor microenvironment, is thought to be a principal driver of progression in each of these selected malignancies. To be eligible, subjects must have no remaining standard therapy known to confer clinical benefit.

The study is composed of 3 stages. The Dose-Escalation stage will determine the MTD of single-agent TPST-1495 administered twice a day (BID). The Schedule and Dose Optimization stage will evaluate alternative TPST-1495 single-agent administration schedules and determine an RP2D for the selected schedule. This arm will also evaluate TPST-1495 in combination with pembrolizumab. The Expansion stage will evaluate the activity of TPST-1495 as a single agent and in combination with pembrolizumab at the selected schedule and dose in disease-specific cohorts and in a basket cohort in subjects selected for an activating mutation in PIK3Ca.