Study of TSR-033 With an Anti-programmed Cell Death-1 Receptor (PD-1) in Participants With Advanced Solid Tumors

This is a multicenter, open-label, first-in-human Phase 1 study evaluating the anti-lymphocyte activation gene-3 (LAG-3) antibody TSR-033 alone, in combination with the anti-PD-1 antibody dostarlimab, and in combination with dostarlimab, modified folinic acid (FOL)/leucovorin, 5-fluorouracil and oxaliplatin (OX) (mFOLFOX6) or FOL/leucovorin, 5-fluorouracil and irinotecan (IRI) (FOLFIRI), and bevacizumab in participants with advanced solid tumors in a broad range of solid tumors. Participants with disease types selected for evaluation in this study are expected to derive clinical benefit with addition of an anti-PD-1. The study will be conducted in two parts with Part 1 consisting of dose escalation to determine the recommended phase 2 dose (RP2D) of TSR-033 as a single agent (Part 1a) and in combination with dostarlimab (Part 1c). RP2D decisions will be based on the occurrence of dose-limiting toxicities (DLTs), pharmacokinetics (PK), as well as pharmacodynamics (PDy) data. Part 2A of the study will investigate the anti-tumor activity of TSR-033 and dostarlimab in combination in participants with advanced or metastatic microsatellite stable colorectal cancer (MSS-CRC). Part 2B of the study will investigate the safety and anti-tumor activity of TSR-033 and dostarlimab in combination with chemotherapy (Cohort B1: mFOLFOX6 and Cohort B2: FOLFIRI) and bevacizumab in participants with advanced or metastatic MSS-CRC.