Study to Assess the Efficacy and Safety of Rina-S in Participants With Advanced Gastrointestinal (GI) Cancers

This Phase 2 study will be conducted in different countries around the world with up to about 160 participants. The purpose of this study is to evaluate how well Rina-S works against GI cancers. The medication in this study is Rina-S monotherapy (by itself; no other cancer treatments). All participants will receive active drug; no one will be given placebo. Participation in the study will require visits to the study site(s). During site visits, there will be various tests (such as blood draws) and procedures (such as recording of heart activity, imaging/X-rays) to monitor whether the study treatment is safe and effective. The duration of the study will be different for every participant, but an average study duration of 22 months is expected for participants. This will include a treatment period (expected to last an average of 12 months), plus data collection periods before and after treatment. Participants will be asked to attend 1 to 5 visits at the study clinic for each cycle (duration of an individual cycle is 21 days). If a participant's cancer stays the same or gets better, and there are not any serious problems, participants can keep getting study treatment for as long as the study is open.