This is a Phase 1/1b open-label, first-in-human FIH study of IDRX-42, an orally administered small molecule tyrosine kinase inhibitor. Eligible participants will have metastatic and/or surgically unresectable GIST, after failure of at least imatinib due to progression of GIST. The study consists of 2 parts. Phase 1 comprises dose escalation to assess clinical and pharmacologic profile, safety/tolerability, and support choice of the recommended phase 2 dose and schedule (RP2DS). Phase 1b expansion will enroll separate cohorts of participants defined by numbers of lines of prior GIST therapy at the selected RP2DS to assess the preliminary antitumor effect of IDRX-42 and further characterize the safety profile of IDRX-42 at the RP2DS.
This is the first clinical trial of IDRX-42. The study is designed to evaluate the safety, tolerability, PK, and preliminary antitumor activity of IDRX-42 in adult participants with advanced (metastatic and/or surgically unresectable) GIST.