# VIR-5818

Source: https://onco.cc/drugs/amx-818/  
OnCo record `amx-818` (Treatment). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

VIR-5818 is an experimental masked T-cell engager from Amunix Pharmaceuticals, in phase 1 trials for HER2-expressing locally advanced or metastatic solid tumours.

## Summary

VIR-5818 (AMX-818, SAR446309) is a masked T-cell engager (PRO-XTEN dual-masked TCE) from Amunix Pharmaceuticals, with Sanofi as acquirer, Vir Biotechnology as licensee and Merck Sharp & Dohme as partner. A HER2-targeted T-cell engager with PRO-XTEN masks that are removed by proteases in tumours. Its furthest stage is phase 1, for HER2-expressing locally advanced or metastatic solid tumours. ClinicalTrials.gov registers it in one study linked below. Phase 1/2 NCT05356741 recruiting under Vir; updated dose-escalation data expected 2H 2026 (Vir Q2 2026 release). 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: AMX-818; SAR446309
- Tags: pipeline; ctgov-ingest
- Code: AMX-818
- Modality: Masked T-cell engager (PRO-XTEN dual-masked TCE)
- Mechanism: A HER2-targeted T-cell engager with PRO-XTEN masks that are removed by proteases in tumours.

## Sources

- Amunix Pharmaceuticals: clinicaltrials.gov: https://clinicaltrials.gov/api/v2/studies/NCT05356741
- Amunix Pharmaceuticals: sec.gov: https://www.sec.gov/Archives/edgar/data/1706431/000162828024039948/vir-20240906.htm
- Amunix Pharmaceuticals: sec.gov: https://www.sec.gov/Archives/edgar/data/1706431/000162828026053351/a20260805-q2ex991earningsr.htm
- ClinicalTrials.gov: trials of AMX-818: https://clinicaltrials.gov/search?intr=AMX-818

## Connected records

- cancers: [Metastatic cancer (cancer that has spread)](https://onco.cc/cancers/metastatic-cancer/)
- targets: [HER2](https://onco.cc/targets/her2/)
- companies: [Amunix Pharmaceuticals](https://onco.cc/companies/amunix-pharmaceuticals/), [Merck KGaA (EMD Serono)](https://onco.cc/companies/merck-kgaa/), [Sanofi](https://onco.cc/companies/sanofi/)
- trials: [To Access the Safety and Effects of Intravenous Administration of VIR-5818 Alone and in Combination With Pembrolizumab in Adult Participants With Locally Advanced or Metastatic HER2-Expressing Cancers](https://onco.cc/trials/nct05356741/)

---
JSON: https://onco.cc/api/v1/entities/amx-818.json