Amunix Raises $73M to Bring Safer T Cell Engagers to Solid Tumors

Xconomy San Francisco — 

Cell therapies have helped treat some blood cancers, but toxic side effects are one limitation preventing their use in solid tumors.

Amunix has, since its 2006 launch, licensed to biopharmas technology developed by company co-founder Volker Schellenberger to extend the half-life of some drugs while avoiding triggering an unwanted immune response. Now that technology has paved the way for the company to raise a $73 million Series A financing round to develop its own cancer drugs—and it plans to target solid tumors.

“Everyone’s looking at solid tumors as the next frontier, in terms of figuring out a way to redirect T cells to tumors, and I think the real challenge has been the toxicity,” Amunix CEO Angie You says. “There have been hints of really exciting activity with other T cell engagers, but they’re also hitting toxicity ceilings, so we think we’ve the solution to enable a real therapeutic index where we can increase dose, maximize efficacy, and still be safe.”

T cell engagers are designed to redirect T cells against tumors by binding to a target on T cells and to an antigen on tumor cells. These drugs are intended to be available “off the shelf,” rather than be individually produced for each patient, as are approved CAR-T cell therapies.

Amunix is developing medicines known as prodrugs—treatments that guide active drugs to specific markers, such as those on certain cancer cells, before those compounds activate. Each Amunix candidate is being developed using its proprietary technology, which involves combining a therapeutic protein with a polymer that has been designed to increase its half-life and to hide, or “mask,” what the compound is up to until it reaches the desired target. The idea is to increase a therapy’s selectivity and efficiency.

What sets Amunix’s approach apart from other technologies that can extend the time a drug can circulate is its low immunogenicity, You says.

The company’s lead product candidate, AMX-818, is a T cell engager that it is developing to treat tumors that overexpress HER2, a protein closely associated with an aggressive subtype of breast cancer. (HER2 is also the target of the Roche drug trastuzumab (Herceptin), which was the first monoclonal antibody to target a cancer-causing protein.)

The company has three other T cell engager programs in discovery, as well as one cytokine program.

Progress that Amunix is making in its preclinical work creating safer, yet potent, T cell engagers is what gave the company the confidence to launch its cytokines program, You adds.

Amunix’s chief executive, who joined the company in January 2019, previously served as chief business and strategy officer and head of commercial at Sierra Oncology (NASDAQ: SRRA), a hematology and oncology drug development company. Prior she served as chief business officer of Aragon Pharmaceuticals, where she worked with then-top executive Rich Heyman, who joined the Amunix board as chairman when You joined the company as CEO. (Aragon which was acquired by Johnson & Johnson (NYSE: ticker:[[JNJ]]) for $650 million upfront.)

Since becoming chief executive, You has recruited others with development experience to its management team, including Maninder Hora, formerly with Nektar Therapeutics (NASDAQ: NKTR), as chief technical operations officer; Bryan Irving, most recently at Five Prime Therapeutics (NASDAQ: FPRX), as chief scientific officer; and Mika Derynck, formerly global head for cancer immunotherapy, GI/GU cancers, angiogenesis franchises, and China oncology development at Genentech, as Amunix’s chief medical officer.

“The past year I’ve been focused on building a phenomenal team that can take this all the way,” You said. “This team can take it as far as we want to, and for me I’d love to take a drug through approval and to patients … This technology can be applied to areas the industry has been working on for decades because of the promise, but has been struggling with the toxicity issues of these modalities.”

No drugs developed using Amunix’s technology have yet earned FDA approval. But 200 patients received an investigational drug designed by Versartis, to whom Amunix licensed its tech to make a long-lasting pediatric human growth hormone. However, it failed in a pivotal non-inferiority trial in comparison to a Pfizer (NYSE: PFE) treatment.

Amunix, which has about 40 employees, is based in Mountain View, CA, but plans to relocate to South San Francisco later this year.

Boston-based Omega Funds led the financing. Earlier investor Frazier Healthcare Partners joined in, as did new investors Longitude Capital, Redmile Group, Polaris Partners, Casdin Capital, Two River, Venrock, and Delian Capital.

It’s a big Series A for a company that has just identified a lead development candidate. CEO You says Amunix didn’t set out to raise $73 million, but its plan to advance drugs based on its technology platform, rather than a single asset, proved especially appealing to investors.

“I think given the level of interest in the company it just made sense that we could raise this money,” she says. “We brought together great investors, many of whom know the T cell engager space—a couple were investors in Micromet, which was acquired by Amgen for over $1 billionds, and they now have the first approved T cell engager.”

And, unlike many other biotechs, the company already has revenue, thanks to its licensing deals with biopharma, she adds.

Amunix says it will use the Series A proceeds—plus $40 million it received from Roche in January as an upfront payment in a licensing deal—to advance its lead development candidate into the clinic, to continue research on other T cell engager programs, and to begin research into cytokine drugs.

Under the deal terms, Omega managing director and founder Otello Stampacchia, Longitude Capital managing director and founder David Hirsch, and Frazier partner James Brush join Amunix’s board of directors.

Image: iStock/selvanegra