Study to Assess Safety, Tolerability and Clinical Activity of BGB-290 in Combination With Temozolomide (TMZ) in Participants With Locally Advanced or Metastatic Solid Tumors

Key Inclusion Criteria:

1. Age ≥18 years old with advanced or metastatic stage solid tumors
2. Eastern Cooperative Oncology Group (ECOG) status ≤ 1
3. Have disease either evaluable (dose-escalation cohort) or measurable (dose-escalation and -expansion cohorts) per RECIST V1.1, except for prostate cancer participants
4. Agree to provide archival tumor tissue
5. Additional inclusion criteria for dose expansion cohorts:

   * Participants with homologous recombination deficiency (HRD+) or known BRCA mutant ovarian cancer Previously received at least one line of platinum-containing therapy in the advanced or metastatic setting and No progression or recurrent disease within 6 months from last platinum-containing regimen.
   * Participants with HRD+ or known BRCA mutant triple-negative breast cancer Up to one prior platinum-containing treatment in any treatment setting and up to 3 prior lines of therapy in the advanced or metastatic setting
   * Participants with HRD+ or known BRCA mutant prostate cancer Chemotherapy-naïve or previously received up to two taxane-based chemotherapy regimens, with documented prostate cancer progression
   * Participants with small cell lung cancer and gastric cancer, previously received ≤ 2 prior lines of therapy
   * Other HRD+ solid tumors of multiple indications

Key Exclusion Criteria: All participants

1. Prior treatment with a poly adenosine diphosphate-ribose polymerase (PARP) inhibitor.
2. Refractory to platinum-based therapy (dose-expansion cohort).

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