A Phase 1 Study to Evaluate the Safety, Tolerability, and Preliminary Efficacy of GS-1811, an Afucosylated Anti-CCR8 Monoclonal Antibody, as Monotherapy and in Combination With an Anti-PD-1 Monoclonal Antibody in Adults With Advanced Solid Tumors

Primary Outcome Measures :

1. Percentage of Participants Experiencing Dose Limiting Toxicities (DLTs) [ Time Frame: Day 1 Through Day 21 ]
   
2. Percentage of Participants Experiencing Adverse Events (AEs) According to the National Cancer Institute (NCI) Common Terminology Criteria for Adverse Events (CTCAE) Version 5.0 [ Time Frame: First dose to End of Treatment (up to 12 months for monotherapy and 24 months for combination therapy) plus 90 days ]
   
3. Percentage of Participants Experiencing Laboratory Abnormalities According to the NCI CTCAE v5.0 [ Time Frame: First dose to End of Treatment (up to 12 months for monotherapy and 24 months for combination therapy) plus 90 days ]

Key Inclusion Criteria:

• Disease
  • 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
  • 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
  • Part C: 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 or whose disease is indicated for anti-PD-(L)1 monoclonal antibody monotherapy
  • Part D: Individuals with pathologically confirmed select advanced solid tumors.
• Measurable disease per Response Evaluation Criteria in Solid Tumors (RECIST) v1.1
• 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 Part D
• Adequate organ function
• Male individuals and female individuals of childbearing potential who engage in heterosexual intercourse must agree to use methods of contraception
• Tissue requirement:
  • Part A, Part C, and Part D: Must provide pre-treatment adequate tumor tissue sample prior to enrolment
  • Part B: Must have fresh pre-treatment and on-treatment biopsy for biomarker analysis

Key Exclusion Criteria:

• Concurrent anticancer treatment
• 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)
• Any prior CCR8 directed therapy
• Prior allogeneic tissue/solid organ transplantation, including allogeneic stem cell transplantation
• 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
• History of intolerance, hypersensitivity, or treatment discontinuation due to severe immune-related adverse events (irAEs) on prior immunotherapy
• History of autoimmune disease or active autoimmune disease requiring systemic treatment within 2 years
• History of pneumonitis, interstitial lung disease, or severe radiation pneumonitis (excluding localized radiation pneumonitis)
• Active and clinically relevant bacterial, fungal, or viral infection that is not controlled or requires IV antibiotics
• Active hepatitis B virus (HBV) and/or hepatitis C virus (HCV), and/or human immunodeficiency virus (HIV)
• Positive serum pregnancy test or breastfeeding female
• Live vaccines within 30 days prior to first dose
• Significant cardiovascular disease

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