Study of GS-1811 Given Alone or With Zimberelimab in Adults With Advanced Solid Tumors

Key Inclusion Criteria:

* Disease:

1. Part A: Individuals with histologically or cytologically confirmed advanced solid tumors who have received, been intolerant to, or been ineligible for all treatment known to confer clinical benefit.
2. Part B: Individuals with histologically or cytologically confirmed select indications who have received, been intolerant to, or been ineligible for all treatment known to confer clinical benefit.
3. Part C: Individuals with histologically or cytologically confirmed advanced solid tumors who have received, been intolerant to, or been ineligible for all treatments known to confer clinical benefit or whose disease is indicated for anti- programmed cell death protein 1 or programmed cell death ligand 1 (PD-[L]1) monoclonal antibody monotherapy.
4. Part D: Individuals with pathologically confirmed select advanced solid tumors.
5. Part E: Individuals with pathologically confirmed select advanced solid tumors. Participants must have received, have been intolerant to, or have been ineligible for all treatment known to confer clinical benefit.
6. Part F: Individuals with pathologically-confirmed select advanced solid tumors. Participants must have received, have been intolerant to, or have been ineligible for all treatments known to confer clinical benefit; or, for participants who will undergo combination therapy, have disease which is indicated for anti-PD-(L)1 mAb monotherapy.
7. Measurable disease per Response Evaluation Criteria in Solid Tumors (RECIST) v1.1
8. Eastern Cooperative Oncology Group (ECOG) performance status 0, 1, or 2 for individuals in Parts A, B, and C, and 0 or 1 for individuals in Parts D, E, and F.
9. Adequate organ function.
10. Male individuals and female individuals of childbearing potential who engage in heterosexual intercourse must agree to use methods of contraception.
11. Tissue requirement:

1. Parts A, C, D, E and F: Must provide pre-treatment adequate tumor tissue sample prior to enrollment.
2. Part B and select participants in Parts C and F: Must have fresh pre-treatment and on-treatment biopsies for biomarker analysis.

Key Exclusion Criteria:

1. Concurrent anticancer treatment.
2. Any anti-cancer therapy, whether investigational or approved, within protocol specified time prior to initiation of study including: immunotherapy or biologic therapy (< 28 days), chemotherapy (< 21 days), targeted small molecule therapy (< 14 days), hormonal therapy or other adjunctive therapy (< 14 days) or radiotherapy (< 21 days).
3. Any prior CCR8 directed therapy.
4. Prior allogeneic tissue/solid organ transplantation, including allogeneic stem cell transplantation. Exception: prior corneal transplant without requirement for systemic immunosuppressive agents is allowed.
5. Concurrent active malignancy other than nonmelanoma skin cancer, curatively resected carcinoma in situ, localized prostate cancer, or superficial bladder cancer after undergoing potentially curative therapy with no evidence of disease. Individuals with other previous malignancies are eligible if disease-free for > 2 years.
6. History of intolerance, hypersensitivity, or treatment discontinuation due to severe immune-related adverse events (irAEs) on prior immunotherapy.
7. History of autoimmune disease or active autoimmune disease requiring systemic treatment within 2 years.
8. History of pneumonitis, interstitial lung disease, or severe radiation pneumonitis (excluding localized radiation pneumonitis).
9. Active and clinically relevant bacterial, fungal, or viral infection that is not controlled or requires IV antibiotics.
10. Active hepatitis B virus (HBV) and/or hepatitis C virus (HCV), and/or human immunodeficiency virus (HIV).
11. Positive serum pregnancy test or breastfeeding female.
12. Live vaccines within 30 days prior to first dose.
13. Significant cardiovascular disease.

Note: Other protocol defined Inclusion/Exclusion criteria may apply.