Cogent's Bezuclastinib Notches Third Simultaneous NDA

Cogent Biosciences said on 15 September 2026 that FDA has accepted its New Drug Application for bezuclastinib in advanced systemic mastocytosis (AdvSM), setting a Prescription Drug User Fee Act target action date of 29 June 2027. FDA told the company it does not currently plan to hold an advisory committee meeting and has not identified potential review issues. It is a routine-sounding filing milestone wrapped around an unusual fact: this is the third bezuclastinib indication now moving through FDA review at the same time, for the same drug, from the same sponsor.

What the acceptance signals

An NDA acceptance is not an approval, and FDA does not typically flag review issues this early even when they exist — but the specific language Cogent reported is still informative. FDA told the company it does not currently plan an advisory committee meeting for the AdvSM application, and has not identified potential review issues at this stage. Read against a June 2027 target date roughly nine and a half months out from acceptance, that timeline is consistent with a standard review clock rather than an accelerated one, despite bezuclastinib's rare-disease indication. For a sponsor benchmarking review pathways in hematologic malignancy, the absence of Priority Review here — contrasted with the GIST indication's Priority Review status — is itself a data point about how FDA is triaging across this molecule's three applications.

The trial behind the filing

The AdvSM application rests on the Phase 2 APEX trial, most recently detailed at the 2026 European Hematology Association congress. As of a 31 March 2026 data cutoff, bezuclastinib produced an overall response rate of 65% by the mIWG-MRT-ECNM criteria most commonly used to assess AdvSM treatment response, and 81% by pure pathologic response criteria — a measure of mast cell burden reduction. The company also reported 12-month progression-free and overall survival rates of 79% and 87%, respectively, and said 91% of patients achieved at least a 50% reduction in mast cell burden, with effects observed as early as eight weeks. AdvSM is a rare, aggressive blood disorder driven in most patients by the KIT D816V mutation — the same mutation bezuclastinib, an oral tyrosine kinase inhibitor, is designed to selectively target.

One molecule, three regulatory clocks

What sets this filing apart operationally is not the AdvSM data on its own, but where it sits alongside Cogent's other bezuclastinib programs. The company's NDA for bezuclastinib in non-advanced systemic mastocytosis is already under FDA review, with a PDUFA date of 30 December 2026. Its NDA for bezuclastinib in combination with sunitinib in gastrointestinal stromal tumors — a solid-tumor indication built on Breakthrough Therapy Designation and Real-Time Oncology Review following Phase 3 PEAK results — carries Priority Review and a PDUFA date of 30 November 2026. With the AdvSM acceptance, Cogent now has three separate NDAs for the same molecule working through three separate FDA review teams and three separate PDUFA clocks within roughly a seven-month window of each other. That is an unusually compressed filing cadence for a single asset, and it puts real pressure on the sponsor's regulatory affairs, manufacturing-supply, and labeling-coordination functions to keep three concurrent submissions internally consistent while responding to potentially divergent agency feedback on each.

It also sharpens the competitive picture in AdvSM specifically. Blueprint Medicines' avapritinib, marketed as Ayvakit, has held FDA approval for AdvSM since June 2021 and is the incumbent KIT D816V inhibitor in the indication. Bezuclastinib's AdvSM filing positions it as a second-in-class challenger, with its differentiation argument — selectivity and a cleaner side-effect profile relative to earlier KIT inhibitors — still to be tested against avapritinib's established track record once both the review and, if cleared, any head-to-head clinical or real-world evidence accumulate.

Frequently asked questions

What did FDA accept on 15 September 2026?

Cogent Biosciences' New Drug Application for bezuclastinib in patients with advanced systemic mastocytosis (AdvSM). FDA assigned a PDUFA target action date of 29 June 2027 and told the company it does not currently plan to hold an advisory committee meeting.

What is bezuclastinib, and what is it built on?

Bezuclastinib is an oral, selective tyrosine kinase inhibitor targeting the KIT D816V mutation and related KIT exon 17 mutations that drive systemic mastocytosis. The AdvSM filing is supported by the Phase 2 APEX trial, which showed a 65% overall response rate by mIWG-MRT-ECNM criteria and an 81% response rate by pure pathologic response criteria, as of a 31 March 2026 data cutoff.

Is this Cogent's first bezuclastinib filing?

No — it's the third indication now under simultaneous FDA review. The company's NDA for bezuclastinib in non-advanced systemic mastocytosis (NonAdvSM) has a PDUFA date of 30 December 2026, and its NDA for bezuclastinib plus sunitinib in gastrointestinal stromal tumors (GIST), which carries Priority Review, has a PDUFA date of 30 November 2026.

Does bezuclastinib have competition in AdvSM?

Yes. Blueprint Medicines' avapritinib (Ayvakit), also a KIT D816V inhibitor, has been FDA-approved for AdvSM since June 2021. Bezuclastinib's filing makes it a second-in-class challenger in that indication, on top of the drug's two other pending indications.