A Phase 3, Randomized, Multicenter, Open-Label Study of IDRX-42 (GSK6042981) versus Sunitinib in Participants with Metastatic and/or Unresectable Gastrointestinal Stromal Tumors (GIST) after Imatinib Therapy (StrateGIST 3)

Subjects are being asked to participate in this study because they have advanced gastrointestinal stromal tumor (GIST) that has spread to other parts of their body beyond where the cancer was first detected and/or cannot be removed by surgery, and because they experienced worsening of disease or side effects while taking an anti-cancer drug called imatinib. The purpose of this study is to test if IDRX-42 can improve GIST, enhance wellbeing, and be safe and well-tolerated when compared to sunitinib. People who usually have this can be prescribed sunitinib for their cancer. IDRX-42 and sunitinib are referred to as the “study drug” in this trial. IDRX-42 has not been approved by the United States Food and Drug Administration (FDA). IDRX-42 is only given to people who participate in clinical trials. Subjects have one out of two chances of being placed in either the IDRX-42 or sunitinib group. Neither patients nor study doctors can choose the drug, but both will know which one is given. Participants will receive the study drugs orally for as long as the study doctor believes there is no worsening of your disease, and participants do not have serious side effects.

Are you Eligible? (Inclusion Criteria)

• have a metastatic and/or surgically unresectable gastrointestinal stromal tumor - are at least 18 years old - have not had surgery in the past 2 weeks and have recovered completely from previous surgeries - cannot be pregnant or trying to become pregnant