Bezuclastinib
An investigational treatment for Systemic Mastocytosis, Mastocytosis and Gastrointestinal Stromal Tumor.
The same compound appears under different names depending on the context. Here is how to identify Bezuclastinib wherever you encounter it, plus the key facts at a glance.
- Generic name
- Bezuclastinib
- Development code
- CGT9486
- Drug class
- Kinase inhibitor (selective KIT inhibitor)
- Manufacturer
- Cogent Biosciences
- How it's taken
- Bezuclastinib is a pill taken by mouth.
An investigational pill from Cogent Biosciences that blocks KIT D816V, the mutation behind most adult systemic mastocytosis. The FDA is reviewing it for nonadvanced systemic mastocytosis, with a decision expected December 30, 2026, and with sunitinib for GIST after imatinib, with a decision expected November 30, 2026. A third application, for advanced systemic mastocytosis, has a decision date of June 29, 2027. It is not FDA approved.
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Where Bezuclastinib fits
If approved, a third targeted option for systemic mastocytosis alongside Ayvakit (avapritinib) and Rydapt (midostaurin). It has not been compared with either in a head-to-head trial.
How Bezuclastinib works
KIT D816V keeps the KIT signal switched on in mast cells, which makes them grow and build up in systemic mastocytosis. Cogent describes bezuclastinib as a selective inhibitor designed to block KIT D816V and other KIT exon 17 mutations, which also appear in advanced GIST[2].
Mechanism: Oral kinase inhibitor designed to selectively block KIT D816V and other KIT exon 17 mutations
Side effects and safety
Bezuclastinib has no FDA label yet, so these figures come from Cogent's report of the SUMMIT trial in nonadvanced systemic mastocytosis. The most common side effects were hair color change (69.5% on bezuclastinib against 5.0% on placebo), altered taste (23.7% against 0%), nausea (22.0% against 13.3%) and rises in the liver enzymes ALT or AST (22.0% against 6.6%; severe in 5.9% against 0%). Serious side effects occurred in 4.2% against 5.0%. Treatment-related side effects led 5.9% to stop, all because of liver enzyme rises, and all resolved, according to Cogent[1].
This is not a complete list of side effects. Talk to your doctor or pharmacist about what to expect and when to seek medical attention.
Taking Bezuclastinib
Bezuclastinib is a pill taken by mouth. It is not approved, so it is available only in clinical trials or through Cogent's expanded access program for people with nonadvanced or advanced systemic mastocytosis (NCT06915766), which a doctor requests[8].
Availability and cost
Only available as the brand-name product.
Access and eligibility
Not approved. Available through clinical trials such as APEX, which was recruiting people with advanced systemic mastocytosis on October 12, 2026, and through an expanded access program for nonadvanced or advanced systemic mastocytosis.
Source: Bezuclastinib expanded access on ClinicalTrials.gov
Access program details are provided for informational purposes and may vary based on insurance coverage, geographic location, and individual circumstances. Confirm current eligibility directly with the manufacturer or your specialty pharmacy.
Clinical trial results
SUMMIT (NCT05186753) randomized adults with nonadvanced systemic mastocytosis to bezuclastinib or placebo on top of their usual medicines. Cogent reported on July 7, 2025 that the total symptom score fell 24.3 points on bezuclastinib against 15.4 points on placebo at 24 weeks, a difference of 8.91 points, and that serum tryptase fell by half or more in 87.4% against 0%[1][5]. In advanced systemic mastocytosis, APEX (NCT04996875) is still recruiting; Cogent reported that 65% of patients responded by mIWG criteria, with 79% free of progression at 12 months[3][6]. In GIST, the Phase 3 PEAK trial (NCT05208047) found that adding bezuclastinib to sunitinib extended median progression-free survival from 9.2 to 16.5 months after imatinib, according to Cogent[4][7].
Main registered trial: NCT04996875 on ClinicalTrials.gov. Check it for the current status, sites and contacts before asking about enrollment.
Development history
Cogent Biosciences develops bezuclastinib under the code CGT9486. On March 16, 2026, Cogent announced that the FDA had accepted its application for nonadvanced systemic mastocytosis with a target action date of December 30, 2026, with no advisory committee planned[2]. Applications for GIST and for advanced systemic mastocytosis followed[4][3].
Explore Systemic Mastocytosis and Mastocytosis and Gastrointestinal Stromal Tumor trials
Other Systemic Mastocytosis & Mastocytosis treatments
Ayvakit is approved for indolent and advanced systemic mastocytosis, and Rydapt for advanced forms. Bezuclastinib's first FDA decision in systemic mastocytosis is due December 30, 2026.
Common questions about Bezuclastinib
▸What is Bezuclastinib?
An investigational pill from Cogent Biosciences that blocks KIT D816V, the mutation behind most adult systemic mastocytosis. The FDA is reviewing it for nonadvanced systemic mastocytosis, with a decision expected December 30, 2026, and with sunitinib for GIST after imatinib, with a decision expected November 30, 2026. A third application, for advanced systemic mastocytosis, has a decision date of June 29, 2027. It is not FDA approved.
▸How does Bezuclastinib work?
KIT D816V keeps the KIT signal switched on in mast cells, which makes them grow and build up in systemic mastocytosis. Cogent describes bezuclastinib as a selective inhibitor designed to block KIT D816V and other KIT exon 17 mutations, which also appear in advanced GIST[2].
▸What are the side effects of Bezuclastinib?
Bezuclastinib has no FDA label yet, so these figures come from Cogent's report of the SUMMIT trial in nonadvanced systemic mastocytosis. The most common side effects were hair color change (69.5% on bezuclastinib against 5.0% on placebo), altered taste (23.7% against 0%), nausea (22.0% against 13.3%) and rises in the liver enzymes ALT or AST (22.0% against 6.6%; severe in 5.9% against 0%). Serious side effects occurred in 4.2% against 5.0%. Treatment-related side effects led 5.9% to stop, all because of liver enzyme rises, and all resolved, according to Cogent[1].
▸How is Bezuclastinib taken?
Bezuclastinib is a pill taken by mouth. It is not approved, so it is available only in clinical trials or through Cogent's expanded access program for people with nonadvanced or advanced systemic mastocytosis (NCT06915766), which a doctor requests[8].
▸Is Bezuclastinib FDA approved?
Bezuclastinib is currently in phase 3 clinical trials for Systemic Mastocytosis and Mastocytosis and Gastrointestinal Stromal Tumor. It has not yet received FDA approval.
▸When will the FDA decide on bezuclastinib?
For nonadvanced systemic mastocytosis, the FDA's target date is December 30, 2026, according to Cogent. A GIST decision is expected November 30, 2026 and an advanced systemic mastocytosis decision June 29, 2027. The FDA can act before a target date.
▸Can I get bezuclastinib before it is approved?
Possibly. Cogent runs an expanded access program for people with nonadvanced or advanced systemic mastocytosis (NCT06915766), which your doctor would request, and the APEX trial was recruiting people with advanced disease on October 12, 2026.
▸What are the side effects of bezuclastinib?
In Cogent's report of the SUMMIT trial, the most common were hair color change (69.5%), altered taste (23.7%), nausea (22.0%) and liver enzyme rises (22.0%, against 6.6% on placebo). Liver enzyme rises led 5.9% to stop treatment, and Cogent said all resolved.
Sources and references
Every factual claim on this page is drawn from the public sources listed below. Click any reference to open the original document.
- Cogent Biosciences · 2025-07-07. Cogent Biosciences Announces Positive Top-line Results Achieving Statistical Significance Across All Primary and Key Secondary Endpoints from the SUMMIT Trial. https://investors.cogentbio.com/news-releases/news-release-details/cogent-biosciences-announces-positive-top-line-results-achieving
- Cogent Biosciences · 2026-03-16. Cogent Biosciences Announces FDA Acceptance of New Drug Application for Bezuclastinib in Patients with NonAdvanced Systemic Mastocytosis. https://investors.cogentbio.com/news-releases/news-release-details/cogent-biosciences-announces-fda-acceptance-new-drug-application
- Cogent Biosciences. Cogent Biosciences announces FDA acceptance of new drug application for bezuclastinib in advanced systemic mastocytosis. https://investors.cogentbio.com/news-releases/news-release-details/cogent-biosciences-announces-fda-acceptance-new-drug-1
- Cogent Biosciences. Cogent Biosciences announces FDA acceptance of new drug application for bezuclastinib in GIST. https://investors.cogentbio.com/news-releases/news-release-details/cogent-biosciences-announces-fda-acceptance-new-drug-0
- ClinicalTrials.gov. SUMMIT: bezuclastinib versus placebo in indolent or smoldering systemic mastocytosis. https://clinicaltrials.gov/study/NCT05186753
- ClinicalTrials.gov. APEX: bezuclastinib in patients with advanced systemic mastocytosis. https://clinicaltrials.gov/study/NCT04996875
- ClinicalTrials.gov. PEAK: bezuclastinib plus sunitinib versus sunitinib in GIST. https://clinicaltrials.gov/study/NCT05208047
- ClinicalTrials.gov. Expanded access to bezuclastinib for nonadvanced or advanced systemic mastocytosis. https://clinicaltrials.gov/study/NCT06915766