# ETX-19477

Source: https://onco.cc/drugs/etx-19477/  
OnCo record `etx-19477` (Treatment). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

ETX-19477 is an experimental small molecule from 858 Therapeutics, in phase 1 trials for advanced solid tumours, BRCA-mutated platinum-resistant ovarian cancer and BRCA-mutated HR-positive, HER2-negative unresectable or metastatic breast cancer.

## Summary

ETX-19477 is a small molecule (oral) from 858 Therapeutics. An oral, selective inhibitor of PARG (poly(ADP-ribose) glycohydrolase) that exploits cancer cell vulnerabilities related to replication stress and defects in replication fork protection. Its furthest stage is phase 1, for advanced solid tumours, BRCA-mutated platinum-resistant ovarian cancer and BRCA-mutated HR-positive, HER2-negative unresectable or metastatic breast cancer. ClinicalTrials.gov registers it in one study linked below. Phase 1/2 NCT06395519 recruiting per v2 API; FDA Fast Track designations January and August 2026 (company news page). 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
- Tags: pipeline; ctgov-ingest
- Code: ETX-19477
- Modality: Small molecule (oral)
- Mechanism: An oral, selective inhibitor of PARG (poly(ADP-ribose) glycohydrolase) that exploits cancer cell vulnerabilities related to replication stress and defects in replication fork protection.

## Sources

- 858 Therapeutics: 8five8tx.com: https://www.8five8tx.com/
- 858 Therapeutics: 8five8tx.com: https://8five8tx.com/news/
- 858 Therapeutics: 8five8tx.com: https://8five8tx.com/news/
- 858 Therapeutics: clinicaltrials.gov: https://clinicaltrials.gov/api/v2/studies/NCT06395519
- ClinicalTrials.gov: trials of ETX-19477: https://clinicaltrials.gov/search?intr=ETX-19477

## Connected records

- cancers: [Metastatic cancer (cancer that has spread)](https://onco.cc/cancers/metastatic-cancer/)
- targets: [PARG](https://onco.cc/targets/parg/)
- companies: [858 Therapeutics](https://onco.cc/companies/858-therapeutics/)
- trials: [A Study of PARG Inhibitor ETX-19477 in Patients With Advanced Solid Malignancies](https://onco.cc/trials/nct06395519/)

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JSON: https://onco.cc/api/v1/entities/etx-19477.json