# Amunix Pharmaceuticals

Source: https://onco.cc/companies/amunix-pharmaceuticals/  
OnCo record `amunix-pharmaceuticals` (Company). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

Amunix developed T-cell engager and cytokine cancer drugs with a protective mask that is clipped off by enzymes found in tumours, so the drugs become active mainly at the cancer. Sanofi agreed to buy the company in December 2021 for about $1 billion upfront.

## Summary

Amunix Pharmaceuticals was an immuno-oncology company built on its clinically validated XTEN polypeptide technology and the Pro-XTEN universal protease-releasable masking platform, used to create conditionally activated T-cell engagers (XPAT) and cytokines (XPAC). Its lead candidate AMX-818 was a masked HER2-directed T-cell engager expected to enter the clinic in early 2022. On 21 December 2021 Sanofi announced an agreement to acquire Amunix for an upfront payment of approximately $1 billion plus up to $225 million on achievement of development milestones, citing a strategic fit with its immuno-oncology portfolio. Sanofi's fourth-quarter 2021 results reiterated the agreement. The Amunix website no longer resolves.

## Fields

- Kind: Company
- Last checked: 2026-09-10
- HQ: South San Francisco, CA
- Type: biotech

## Notes

- amunix.com is offline, so the Sanofi 6-K press release is given as the website. Deal completion (early 2022) not separately sourced. HQ taken from the user's hint and consistent with the company's known location, but not stated in the fetched release; the release dateline is Paris.

## Sources

- Official website: https://www.sec.gov/Archives/edgar/data/1121404/000119312521363409/d237650dex992.htm
- Sanofi Q4 2021 results referencing the agreement (6-K): https://www.sec.gov/Archives/edgar/data/1121404/000112140422000002/pressreleaseq42021english.htm
- SEC EDGAR filings: https://www.sec.gov/Archives/edgar/data/1121404/000119312521363409/d237650dex992.htm

## Connected records

- fronts: [Immunotherapy](https://onco.cc/fronts/immunotherapy/)
- technologies: [Bispecific antibodies](https://onco.cc/technologies/bispecific-antibody/), [Cytokines & engineered cytokines](https://onco.cc/technologies/cytokine-therapy/), [T-cell engagers (bispecific)](https://onco.cc/technologies/t-cell-engager/)
- targets: [HER2](https://onco.cc/targets/her2/)
- companies: [Sanofi](https://onco.cc/companies/sanofi/)

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JSON: https://onco.cc/api/v1/entities/amunix-pharmaceuticals.json