The goal of this interventional clinical trial is to learn about TNG260, a CoREST inhibitor, in combination with pembrolizumab in patients with advanced solid tumors with a known STK11 mutation.

The main question[s] it aims to answer are:

• the recommended dose for Phase 2
• to evaluate the safety and tolerability of the combination therapy
• to determine the pharmacokinetics of TNG260
• to evaluate the initial antineoplastic activity

Participants will receive study treatment until they experience an undesirable side effect, their disease progresses or until they withdraw consent.

This is a first-in-human Phase 1/2, open-label, multicenter, dose-escalation and expansion study designed to determine the maximum tolerated dose and recommended phase 2 dose(s) and evaluate the safety and tolerability, pharmacokinetics, and antineoplastic activity of escalating oral doses of TNG260 when administered with a standard dose of pembrolizumab in participants with locally advanced or metastatic STK11 mutated solid tumors.

Inclusion Criteria:

• Is ≥18 years of age at the time of signature of the main study ICF.
• Has ECOG performance status of 0 or 1.
• Has measurable disease based on RECIST v1.1.
• All participants must have documented STK11 mutation in a solid tumor, which is identified through a validated analytical method
• Has confirmed histologic or cytologic diagnosis of a locally advanced or metastatic solid tumor.
• Adequate organ function/reserve per local labs
• Adequate liver function per local labs
• Adequate renal function per local labs
• Negative serum pregnancy test result at screening
• Written informed consent must be obtained according to local guidelines

Exclusion Criteria:

• Known allergies, hypersensitivity, or intolerance to TNG260, PD-1 antibody or its excipients
• Uncontrolled intercurrent illness that will limit compliance with the study requirements
• Active infection requiring systemic therapy
• Currently participating in or has planned participation in a study of another investigational agent or device
• Impairment of GI function or disease that may significantly alter the absorption of oral TNG260
• Active prior or concurrent malignancy.
• Central nervous system metastases associated with progressive neurological symptoms
• Current active liver disease from any cause
• Clinically relevant cardiovascular disease
• A female patient who is pregnant or lactating