Study of BGB-290 or Placebo in Participants With Advanced or Inoperable Gastric Cancer

This is a double-blind, placebo controlled, randomized multicenter global phase 2 study comparing the efficacy and safety of single agent poly (ADP-ribose) polymerase (PARP) inhibitor BGB-290 to placebo as maintenance therapy in participants with advanced gastric cancer who have responded to first line platinum based chemotherapy. Participants are randomized 1:1 to BGB-290 (Arm A) or placebo (Arm B). Randomization will be stratified by geography, biomarker status, and ECOG performance status. Participants will undergo tumor assessments at screening and then every 8 weeks, or as clinically indicated. Administration of BGB-290 or placebo will continue until disease progression, unacceptable toxicity, death, or another discontinuation criterion is met. After end of treatment, long-term follow-up assessments include tumor imaging every 8 weeks for those participants without disease progression, survival status, and new anticancer therapy.