BGB-290-103: This phase I/II trial is evaluating a new drug (BGB-290) in combination with an oral chemotherapy drug (Temozolomide) in patients with locally advanced or metastatic solid cancersA Phase 1b Study to Assess the Safety, Tolerability and Clinical Activity of BGB-290 in Combination With Temozolomide (TMZ) in Subjects With Locally Advanced or Metastatic Solid Tumors

Inclusion

1. Age ≥18 years old with advanced or metastatic stage solid tumors
2. Eastern Cooperative Oncology Group (ECOG) status ≤ 1 and measurable disease per RECIST V1.1 (except for participants in dose escalation and prostate cancer participants)
3. Additional inclusion criteria for dose expansion cohorts:

Participants with homologous recombination deficiency (HRD+) or known BRCA mutant Ovarian cancer

a. Previously received at least 1 line of platinum containing chemotherapy and No progression or recurrent disease in 6 months from last platinum containing regimen. Participants with HRD+ or known breast cancer susceptibility gene (BRCA) mutant Triple-Negative Breast Cancer

a. 0 - 1 prior platinum-containing regimen (any treatment setting) and received ≤ 3 prior regimens (advanced or metastatic setting).

Participants with HRD+ or known BRCA mutant Prostate cancer

1. Chemotherapy-naïve or previously received ≤2 taxane-based regimens.
2. May have pre-or post-treatment with a novel androgen receptor targeted agent. Participants Small cell lung and gastric cancer

a. Previously received ≤ 2 prior lines of therapy. Participants with HRD+ NSCLC, head and neck cancer, esophageal cancer and soft tissue sarcomas

1. Must have tumors with with HRD+ as centrally determined
2. Must have received at least 1 but not more than 3 prior lines of therapy.

Treatment naïve patients with soft tissue sarcoma might be allowed if standard of care therapy is not suitable or available.