A new phase 1 clinical trial testing the safety, tolerability, pharmacokinetics, and preliminary antitumor activity of IDRX-42 in adults with metastatic and/or surgically unresectable gastrointestinal stromal tumor (GIST) is now recruiting participants.

IDRX-42 is an oral small molecule tyrosine kinase inhibitor. The trial, which is sponsored by the biopharmaceutical company IDRx, aims to recruit 143 patients, aged 18 or more years, at the Dana-Farber Cancer Institute in Boston, Massachusetts, and run until September 13, 2026.

The study will consist of 2 parts. The first will be a dose-escalation phase to assess the safety, tolerability, and clinical and pharmacologic profiles of the treatment to determine the dose and treatment schedule to be tested in part 2. The second part will assess the preliminary antitumor effect of IDRX-42 in a separate cohort of patients and further characterize its safety profile.

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The primary outcome measures are the nature, incidence, and severity of any dose-limiting toxicities, the number of participants with treatment-emergent adverse events, and the objective response rate. 

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Secondary outcome measures include the number of participants with non-dose-limiting toxicity treatment-emergent adverse events, the maximum observed concentration of IDRX-42, the time to response and duration of response, progression-free survival, and overall survival. 

To be eligible to take part in the trial, patients must have histologically or cytologically confirmed metastatic and/or surgically unresectable GIST, progression even on imatinib treatment, and a pathogenic KIT mutation or any PDGFRA mutation other than exon 18 mutations.

IDRX-42 is designed to inhibit the key genetic drivers and drug-resistant mutations in GIST. GIST is a rare soft tissue tumor that develops from the interstitial cells of Cajal and most commonly affects the stomach and small intestine.


A first-in-human (FIH) study of IDRX-42 in participants with metastatic and/or unresectable gastrointestinal stromal tumors. ClinicalTrials.gov. August 5, 2022. Updated August 18, 2022. Accessed August 23, 2022.