XTX101 Monotherapy and XTX101 and Atezolizumab Combination Therapy in Patients With Advanced Solid Tumors

Inclusion Criteria:

Disease Criteria -

Part 1A and 1C: Any histologically or cytologically confirmed solid tumor malignancy that is locally advanced or metastatic and has failed standard therapy, or standard therapy is not curative or available;

Part 1B:

1. Any histologically or cytologically confirmed solid tumor malignancy for which anti-PD-1 or anti-PD-L1 treatment is approved and has progressed on or after prior anti-PD-1 or anti-PD-L1 therapy.
2. Patients with metastatic castrate-resistant prostate cancer if they have progressed on at least 2 lines of systemic therapy
3. Patients with extensive stage small cell lung cancer (SCLC) after at least 1 line of prior therapy
4. Patients with microsatellite stable colorectal cancer after at least 2 lines of prior therapy
5. ECOG performance status of 0 or 1
6. Adequate organ function
7. Part 1B and Part 1C only: measurable disease per iRECIST

Exclusion Criteria:

1. Received prior treatment with anti-CTLA-4 therapy
2. Received prior immune-checkpoint therapy and experienced Grade 3 or greater toxicity lasting greater than 6 weeks
3. Received prior systemic anticancer therapy within 4 weeks prior to study treatment
4. Received prior radiotherapy within 2 weeks prior to study treatment
5. Has a diagnosis of immunodeficiency
6. Has known malignancy (other than disease under study) that is progressing or has required active treatment within the past 3 years
7. Has an active autoimmune disease that has required systemic treatment in past 2 years, including the use of disease modifying agents, corticosteroids or immunosuppressive drugs
8. Has an active infection requiring systemic intravenous therapy within 4 weeks prior to study treatment, or oral therapy within 2 weeks prior to study treatment
9. Has a history of severe hypersensitivity reaction (≥ Grade 3) to any study intervention and/or any of its excipients
10. Has a known psychiatric or substance abuse disorder that would interfere with the participant's ability to cooperate with the requirements of the study