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Testing IDRX-42 in patients with advanced gastrointestinal stromal tumors

A First-in-human (FIH) Study of IDRX-42 in Participants With Metastatic and/or Unresectable Gastrointestinal Stromal Tumors (GIST) [Study ID: StrateGIST 1]

Phase 1 Interventional IDRX, Inc., a wholly owned subsidiary of GSK, LLC · NCT05489237

This study is testing a new oral medication called IDRX-42 to see if it can help adults with advanced gastrointestinal stromal tumors that haven't responded to other treatments.

Quick facts

PhasePhase 1
Study typeInterventional
Enrollment278 (estimated)
Ages18 Years and up
SexAll
SponsorIDRX, Inc., a wholly owned subsidiary of GSK, LLC Industry-sponsored
Drugs / interventionsimatinib, sunitinib, ripretinib, bezuclastinib
Locations31 sites (Miami, Florida and 30 other locations)
Trial IDNCT05489237 on ClinicalTrials.gov

What this trial studies

This clinical trial is the first to evaluate IDRX-42, an orally administered small molecule tyrosine kinase inhibitor, in adult participants with advanced gastrointestinal stromal tumors (GIST) that are metastatic or unresectable. The study is divided into two parts: a Phase 1 dose escalation to assess safety and pharmacologic profile, followed by a Phase 1b expansion to evaluate preliminary antitumor activity and further characterize safety at the recommended doses. Participants must have documented progression on imatinib and meet specific eligibility criteria, including having measurable lesions. A substudy will also assess the effects of IDRX-42 on ECG parameters in a subset of participants.

Who should consider this trial

Good fit: Ideal candidates are adults aged 18 and older with confirmed metastatic or unresectable GIST who have progressed on imatinib.

Not a fit: Patients with GIST who have not received prior treatment or those with exon 18 mutations in PDGFRA may not benefit from this study.

Why it matters

Potential benefit: If successful, this treatment could provide a new therapeutic option for patients with advanced GIST who have not responded to existing therapies.

How similar studies have performed: While this is a first-in-human study, previous studies of similar tyrosine kinase inhibitors have shown promise in treating GIST.

Eligibility criteria

Show full inclusion / exclusion criteria 
Inclusion Criteria:

Phase 1

1. Male or female participants ≥18 years of age
2. Histologically or cytologically confirmed metastatic and/or surgically unresectable GIST
3. Documented progression on imatinib (Phase 1)
4. Documented pathogenic mutation in KIT OR any PDGFRA mutation other than exon 18 mutations, determined through local testing
5. At least one measurable lesion by mRECIST v1.1 for participants with GIST
6. Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1
7. Resolution of any toxicities from prior treatment(s) to ≤ Grade 1 by NCI CTCAE v5.0 criteria, or have resolved to baseline, at the time of first dose of study drug.
8. Willing and able to comply with scheduled visits, drug administration plan, laboratory tests, or other study procedures and study restrictions.

Additional for Phase 1b Exploratory Cohorts

1. For Cohort 1, progressed on imatinib only (second line therapy) and refused or are ineligible for other standard of care (SOC) therapies.
2. For Cohort 2, progressed on both imatinib and sunitinib (third line therapy) or progressed on imatinib, sunitinib, and an additional agent (i.e., regorafenib or ripretinib) (fourth line therapy) or progressed on imatinib, sunitinib, regorafenib, and ripretininb (fifth line or greater therapy)
3. For Cohort 3 \[US, UK, China, and Japan only\], treatment naïve (first line therapy) and refused or are ineligible for other standard of care (SOC) therapies.
4. For Cohort 4, met the same criteria as Cohort 2 (third line or greater) and have also had prior treatment with investigational agents NB003 or THE-630 or a line of therapy of bezuclastinib plus sunitinib combination.

Exclusion Criteria:

1. Any prior exposure to the following investigational agents NB003 or THE-630 or bezuclastinib plus sunitinib combination (except for participants treated in Cohort 4 of Phase 1b).
2. GIST with no documented mutation in both KIT and PDGFRA genes.
3. Primary brain malignancy or known untreated or active central nervous system metastases.
4. Has an active uncontrolled infection, including, but not limited to, the requirement for intravenous antibiotics.
5. Has significant, uncontrolled, or active cardiovascular disease.

Where this trial is running

Miami, Florida and 30 other locations

Study contacts

How to participate

  1. Review the eligibility criteria above with your treating physician.
  2. Visit the official trial page on ClinicalTrials.gov for the most current contact information and recruitment status.
  3. Contact the listed study coordinator or principal investigator to request pre-screening. Pre-screening is free and never obligates you to enroll.
View on ClinicalTrials.gov → Find more trials like this →
Conditions Gastrointestinal NeoplasmsGastrointestinal Stromal TumorDigestive System DiseaseGastrointestinal DiseasesMetastatic CancerGISTIDRXIDRX-42
Last reviewed 2026-06-13 by the Find a Trial editorial team. Information on this page is for educational purposes and is not medical advice. Always consult qualified healthcare professionals about clinical trial participation.