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Oncology · Clinical trials

Gastrointestinal Stromal Tumour (GIST) Clinical Trials

Approved therapies, the pivotal-trial endpoints they were judged on, the magnitude of benefit — and the drugs that failed their endpoints, and why.

Indication overview

About gastrointestinal stromal tumour (gist) — and why its trials are hard

Gastrointestinal stromal tumours are the most common mesenchymal neoplasms of the GI tract, arising from the interstitial cells of Cajal and driven in roughly 80% of cases by activating KIT mutations and in about 5-10% by PDGFRA mutations. GIST is the landmark success story of targeted therapy in solid tumours: before imatinib, metastatic disease was chemotherapy- and radiotherapy-refractory with dismal survival. Sequential tyrosine kinase inhibitors now define care across lines, matched increasingly to specific mutations (exon 11, exon 9, PDGFRA D842V). Surgery remains curative for localised disease, with adjuvant imatinib for high-risk resected tumours. Key challenges include acquired resistance through secondary KIT mutations, the historically drug-resistant PDGFRA D842V subtype (now addressed by avapritinib), and rare wild-type/SDH-deficient and paediatric variants that respond poorly to standard TKIs. Molecular genotyping at diagnosis is now standard to guide first-line selection and sequencing, making GIST a model for precision oncology in a rare tumour.

Indication
Gastrointestinal Stromal Tumour (GIST)
ICD-10-CM
C49.A0 — GIST, unspecified site

Approved therapies & pivotal evidence

What's been approved — and by how much it moved the endpoint

Drug (brand)ApprovedSettingPivotal trialPrimary endpointMagnitude of benefit
Imatinib (Gleevec/Glivec)2002First-line unresectable/metastatic KIT+ GIST; also adjuvant after resection (2008, extended 2012)B2222 (phase 2); adjuvant ACOSOG Z9001, SSGXVIII/AIOObjective response rate; recurrence-free survival (adjuvant)ORR ~68% in B2222; 3 years adjuvant improved RFS and overall survival vs 1 year in SSGXVIII
Sunitinib (Sutent)2006Second-line after imatinib failure/intolerancePhase 3 (A6181004)Time to tumour progressionMedian TTP 27.3 vs 6.4 weeks vs placebo
Regorafenib (Stivarga)2013Third-line after imatinib and sunitinibGRID (phase 3)Progression-free survivalMedian PFS 4.8 vs 0.9 months (HR ~0.27)
Avapritinib (Ayvakit/Ayvakyt)2020Unresectable/metastatic PDGFRA exon 18 (incl. D842V) mutant GISTNAVIGATOR (phase 1)Objective response rateORR ~84-89% in D842V subtype previously refractory to all TKIs
Ripretinib (Qinlock)2020Fourth-line, after >=3 prior TKIs including imatinibINVICTUS (phase 3)Progression-free survivalMedian PFS 6.3 vs 1.0 months vs placebo (HR ~0.15)

Where trials have failed

Drugs that missed their endpoint — and what contributed

The most instructive lessons in gastrointestinal stromal tumour (gist) development come from programmes that failed the endpoint that mattered.

Drug / trialEndpoint outcomeWhat contributed
Nilotinib — ENESTg1 (phase 3, first-line vs imatinib)Did not demonstrate superiority/non-inferiority to imatinib in first-line GISTImatinib set a very high efficacy bar; nilotinib CNS/GI penetration and mutation coverage insufficient to displace it
Ripretinib — INTRIGUE (phase 3, second-line vs sunitinib)Failed to beat sunitinib on PFS in overall second-line populationBenefit confined to KIT exon 11 mutant subset; broad all-comer design diluted signal

Choosing the right endpoint

Primary endpoints that matter in gastrointestinal stromal tumour (gist) trials

  • Progression-free survival (PFS) — Primary endpoint in most later-line TKI trials (GRID, INVICTUS); robust in a disease where responses are often stabilisation rather than shrinkage
  • Objective response rate (ORR) — Key for accelerated/mutation-specific approvals (B2222, NAVIGATOR); Choi criteria (density plus size) often more sensitive than RECIST for TKI effect
  • Recurrence-free survival (RFS) — Primary adjuvant endpoint (Z9001, SSGXVIII) capturing delay of relapse after complete resection
  • Overall survival (OS) — Gold standard but confounded by crossover and effective post-progression TKI sequencing
  • Time to progression (TTP) — Used in the pivotal sunitinib trial; excludes non-progression deaths

How iNGENū runs gastrointestinal stromal tumour (gist) trials

Physician-led design, built for FDA submission

Endpoint & biomarker strategy

Board-certified specialists design endpoints and patient selection aligned to current FDA guidance for this indication.

FDA-ready data

Built to ICH-GCP and 21 CFR 312.120, with direct FDA submission — data accepted by the FDA, EMA and MHRA.

Faster, lower-cost delivery

~4-week ethics via the TGA CTN scheme, up to 43.5% R&D rebate, and 80–90% below US CRO cost.

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Frequently asked questions

Gastrointestinal Stromal Tumour (GIST) clinical trials — FAQs

Why is GIST considered a model for targeted therapy?
Nearly all GISTs are driven by a single activating mutation in KIT or PDGFRA, and imatinib directly inhibits these kinases. This transformed a chemo-resistant, rapidly fatal cancer into a controllable disease and validated matching drug to driver mutation.
Why does GIST eventually stop responding to imatinib?
Tumours acquire secondary resistance mutations in KIT (commonly in exons 13, 14, 17, 18). Because these vary between and within lesions, later-line TKIs with broader kinase coverage (sunitinib, regorafenib, ripretinib) are needed in sequence.
What made PDGFRA D842V historically untreatable?
The D842V mutation locks the kinase in an active conformation that imatinib and other early TKIs cannot bind. Avapritinib was engineered to target this activation-loop mutation, producing high response rates where prior drugs failed.

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