# PFL-721

Source: https://onco.cc/drugs/pfl-721/  
OnCo record `pfl-721` (Treatment). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

PFL-721 is an experimental small molecule kinase inhibitor from Antares Therapeutics, in phase 1 trials for non-small cell lung cancer with EGFR or HER2 exon 20 insertion mutations.

## Summary

PFL-721 (STX-721) is a small molecule kinase inhibitor from Antares Therapeutics, with Pierre Fabre Laboratories as licensee and Scorpion Therapeutics as partner. A mutant-specific inhibitor of EGFR exon 20 and HER2 exon 20 insertion mutations. Its furthest stage is phase 1, for non-small cell lung cancer with EGFR or HER2 exon 20 insertion mutations. ClinicalTrials.gov registers it in one study linked below. First-in-human phase 1/2 NCT06043817 recruiting, sponsored by Pierre Fabre Medicament. Whether it works in people has not been established unless a trial below reports it.

## Fields

- Kind: Treatment
- Status: phase-1
- Last checked: 2026-11-03
- Also known as: STX-721
- Tags: pipeline; ctgov-ingest
- Code: PFL-721
- Modality: Small molecule kinase inhibitor
- Mechanism: A mutant-specific inhibitor of EGFR exon 20 and HER2 exon 20 insertion mutations.

## Sources

- Antares Therapeutics: biospace.com: https://www.biospace.com/press-releases/pierre-fabre-laboratories-strengthen-r-d-portfolio-and-announce-the-acquisition-of-the-worldwide-rights-for-pfl-721-and-pfl-241
- Antares Therapeutics: biospace.com: https://www.biospace.com/press-releases/pierre-fabre-laboratories-strengthen-r-d-portfolio-and-announce-the-acquisition-of-the-worldwide-rights-for-pfl-721-and-pfl-241
- Antares Therapeutics: antaresrx.com: https://antaresrx.com/
- Antares Therapeutics: clinicaltrials.gov: https://clinicaltrials.gov/api/v2/studies/NCT06043817
- ClinicalTrials.gov: trials of PFL-721: https://clinicaltrials.gov/search?intr=PFL-721

## Connected records

- cancers: [Non-small-cell lung cancer](https://onco.cc/cancers/nsclc/)
- targets: [EGFR](https://onco.cc/targets/egfr/), [HER2](https://onco.cc/targets/her2/)
- companies: [Antares Therapeutics](https://onco.cc/companies/antares-therapeutics/), [Pierre Fabre](https://onco.cc/companies/pierre-fabre/)
- trials: [First-In-Human Study of STX-721/PFL-721 in Participants With Locally Advanced or Metastatic Non-Small Cell Lung Cancer Harboring EGFR or HER2 Exon 20 Insertion Mutations](https://onco.cc/trials/nct06043817/)

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JSON: https://onco.cc/api/v1/entities/pfl-721.json