The primary purpose of this trial is to assess the tolerability and safety of CHS-1000 alone and in combination with toripalimab-tpzi in participants with advanced solid tumors.

Key Inclusion Criteria:

• Histopathologically or cytologically confirmed diagnosis of advanced or metastatic unresectable solid tumors (excluding glioblastoma multiforme (GBM)) by tissue biopsy or archival tumor specimen. Unresectable tumors are defined as tumors with lesions in which clear surgical excision margins cannot be obtained, in close proximity to major blood vessels, not with oligometastatic and with advanced organ and lymph node (LN) involvement, and not leading to significant functional compromise as determined by surgical consult or Tumor Board.
• Participants must have been previously treated or be ineligible for, or intolerant of, available approved standard therapies known to confer clinical benefit (including immunotherapy), or for whom no effective standard therapy exists.
• At least 1 measurable lesion based on Response Evaluation Criteria in Solid Tumors (RECIST) v1.1 as determined by the investigator.

Key Exclusion Criteria:

• Concurrent enrollment in another clinical study or participation in another clinical study within 28 days prior to the 1st dose of CHS-1000, except for observational (noninterventional) studies or the follow-up period of an interventional study.
• Current or prior use of systemic anticancer treatment, including but not limited to chemotherapy, immunotherapy, biologic treatment, hormone therapy, and targeted therapy, if within 8 weeks or 5 half-lives (whichever is shorter) for biologic therapies, or if within 28 days for most other anticancer therapies, prior to the 1st dose of CHS-1000.
• Concurrent or prior radiotherapy within 28 days prior to the 1st dose of CHS-1000 or unresolved treatment-related radiation toxicity. Limited local radiotherapy for palliative intent (eg, to a single site of metastatic disease) is permitted within 28 days prior to the 1st dose of CHS-1000 provided that the participant has no evidence of or has recovered from any treatment-related radiation toxicity.

Note: Other protocol-defined inclusion and exclusion criteria may apply.