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Tyra-300 is an investigational oral drug (from Tyra Biosciences) that selectively blocks FGFR3, one member of the fibroblast growth factor receptor family. It is being studied in two very different settings: bladder (urothelial) cancers driven by FGFR3 changes, and achondroplasia (a common form of dwarfism), where an overactive FGFR3 stunts bone growth. Its selling point is precision; it aims to hit FGFR3 while leaving the related FGFR1, FGFR2, and FGFR4 mostly alone. It is still in clinical trials and not an approved medicine.
- Selective for FGFR3, sparing the other FGFRs
- Oral dosing
- Aims to dodge gatekeeper resistance mutations
- Dual promise in FGFR3 cancers and achondroplasia
Mechanism
Tyra-300 was designed with a structure-based approach to be a potent, FGFR3-selective inhibitor, meaning it blocks FGFR3's kinase activity while largely sparing FGFR1, FGFR2, and FGFR4; that selectivity is meant to avoid the off-target toxicities of broad pan-FGFR drugs and to stay effective against the gatekeeper resistance mutations that can blunt earlier inhibitors [1]. In cancer, quieting an overactive FGFR3 removes a key growth driver in FGFR3-altered tumors [1]. In achondroplasia the logic flips; because the disease comes from too much FGFR3 signaling braking the growth plates, easing that brake lets bone grow. In FGFR3-driven animal models, tyra-300 increased body and limb length, boosted growth-plate chondrocyte proliferation and maturation, and even improved skull and spine measures tied to real complications of the condition [2].
receptor fingerprint
FGFR3 (kinase)inhibitor
Growth-plate chondrocytessupports
FGFR1 / FGFR2 / FGFR4largely spares
Dosingtypical ranges, not medical advice
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Safetyrisks and cautions, not medical advice
Investigational compound still being evaluated in trials, so its full safety profile is not yet established. As an FGFR-targeting drug, effects on phosphate, eyes, nails, and skin are the kinds of things being watched. It is not approved or available as a consumer product.
History
TYRA-300, which carries the proposed international name dabogratinib, was designed by Tyra Biosciences using the company's in-house SNAP structure-based discovery platform as an orally available, FGFR3-selective inhibitor intended to spare the FGFR1, FGFR2, and FGFR4 isoforms and their associated toxicities. The molecule entered a first-in-human Phase 1/2 study, SURF301 (NCT05544552), in patients with metastatic urothelial cancer bearing FGFR3 alterations, with interim clinical proof-of-concept data reported in October 2024 at the EORTC-NCI-AACR symposium. In parallel, because its FGFR3 selectivity fits the biology of skeletal dysplasias, Tyra advanced it toward pediatric development in achondroplasia, supported by animal models showing increased long-bone growth. As of this writing TYRA-300 remains investigational, with no regulatory approval.
Subjective profileweighing the evidence above
Nothing to recommend or dismiss yet; it is in trials and its safety picture is not established. The FGFR3 selectivity is a good idea, and treating FGFR3-driven bladder cancer and achondroplasia with the same drug is an unusual bet worth following.
Resources
This entry is here for reference.
Research
- 1.Discovery of TYRA-300: First Oral Selective FGFR3 Inhibitor for the Treatment of Urothelial Cancers and Achondroplasia
- 2.TYRA-300, an FGFR3-selective inhibitor, promotes bone growth in two FGFR3-driven models of chondrodysplasia
2 listed here; entry last updated July 2026
Reviews
My notesprivate to this device
FAQ
Why does selectivity matter so much here?
Older FGFR drugs hit all four receptors, which brings more side effects. By focusing on FGFR3, tyra-300 tries to keep the benefit while leaving FGFR1, 2, and 4 alone, which should mean a cleaner profile.
How can one drug help both cancer and dwarfism?
Both trace back to FGFR3. In some bladder cancers FGFR3 is overactive and drives the tumor; in achondroplasia an overactive FGFR3 brakes bone growth. Dialing FGFR3 down helps in each case, just for opposite-seeming reasons.
Can I get it now?
No; it is investigational and only available through clinical trials. It has not been approved by regulators.
What are 'gatekeeper' mutations?
They are resistance mutations tumors pick up that block a drug from fitting its target. Tyra-300 was designed to stay effective even when those show up.
Limitations of the evidence
- Not yet fully established (investigational)
Notes and cautions
- FGFR-class effects on phosphate being monitored
- Possible eye, nail, and skin effects
- Trial-stage safety data only