Amunix Raises $117 Million Series B Financing to Fund its Oncology Pipeline

– Proceeds will fund advancement of the company’s pipeline of protease-activated T cell engagers and cytokines for the treatment of solid tumors

– Funding round supported by top-tier crossover investor syndicate, including Viking Global Investors, Bain Capital Life Sciences, BlackRock, Franklin Templeton, Janus Henderson Investors, Redmile Group, and other investors

SOUTH SAN FRANCISCO, CA – March 4, 2021 – Amunix Pharmaceuticals, Inc. (“Amunix”), a biopharmaceutical company focused on developing masked, protease-activated immune-oncology therapeutics to bring the promise of these potent therapies to patients with solid tumor cancers, today announced that it has raised $117 million Series B financing. The funding round was led by Viking Global Investors with participation from a premier syndicate of funds, including new investors Bain Capital Life Sciences, BlackRock, Franklin Templeton, Janus Henderson Investors, ArrowMark Partners, Avidity Partners, certain funds managed by Clough Capital Partners, and CaaS Capital Management. Also participating in the round were existing investors Redmile Group, Venrock, Casdin Capital, Omega Funds, Frazier Healthcare Partners, Longitude Capital, and Polaris Partners.

Proceeds from the financing will fund the advancement into the clinic of AMX-818, a masked, protease-activated T cell engager (XPAT®) targeting HER2-expressing solid tumors, as well as support Amunix’s robust pipeline of earlier stage XPATs® and masked, protease-activated cytokines (XPACs™).

“We are pleased to partner with investors who support our vision and our innovative approach as we strive to realize the potential of T cell engagers and cytokines and significantly improve outcomes for cancer patients,” said Angie You, Ph.D., chief executive officer of Amunix. “We are building on the promise of these potent drugs to target and attack solid tumors, while potentially reducing their toxicity. Although widely recognized as powerful anti-tumor agents, the on-target and off-tumor toxicity of non-masked T cell engager and cytokine therapeutics has limited their utility. Our XTEN® polymer technology with significant human validation is the foundation of our XPAT® and XPAC™ platforms, enabling XTEN® to serve as a universal mask that is protease releasable for preferential activation in the tumor microenvironment. Our platform offers a next generation, plug and play masking technology that we have leveraged to build out a robust pipeline and quickly advance new drug candidates through discovery and optimization.”

About Amunix’s Platform

Amunix is leveraging its proprietary Pro- XTEN® technology platform to create potent immune modulator drugs that are preferentially activated in the high protease milieu of the tumor microenvironment to drive tumor cell killing while minimizing toxicity elsewhere in the body. The technology comprises two proprietary components: 1) a mask, which is an unstructured polypeptide (XTEN®) clinically validated to have low immunogenicity, that functions via steric hindrance and confers half-life extension, and 2) a protease release site that enables release of the mask and hence drug activation, by tumor-associated proteases. Amunix’s proprietary molecules are called XTENylated Protease-Activated T cell engagers XPAT®) and XTENylated Protease-Activated masked Cytokines (XPACs™).

About Amunix Pharmaceuticals

Amunix Pharmaceuticals, based in South San Francisco, CA, is focused on developing masked T cell engagers and cytokines to bring the promise of these potent immune-activating biotherapeutics to patients with solid tumor cancers. The company is leveraging its proprietary XPAT® and XPAC™ platforms to advance a pipeline of novel drugs that are preferentially activated in the tumor microenvironment and designed to overcome toxicity challenges that have hindered other T cell and cytokine therapies. Amunix’s proprietary masking technology has been clinically validated to extend drug half-life with limited immunogenicity. The company’s pipeline includes AMX-818, an XPAT® T cell engager targeting a variety of HER2-expressing solid tumors, which is currently in IND-enabling studies. Along with several other T cell engager programs, Amunix is also applying its proprietary masking technology to its first masked, protease-activated cytokine program, IL12-XPAC™, which is in discovery stage.

For additional information about the company, please visit


Company Contact:
Jen Herbach
Director, Corporate Development

Media Contact:
Sylvia Wheeler

Investor Contact:
Zeeshan Merchant
Chief Financial Officer