citybiz+ IDRx Raises $120M in Series B Led by RA Capital, Commodore and Blackstone

Plymouth, Mass.-based IDRx, a clinical-stage biopharmaceutical company developing cancer therapies with Merck as a strategic partner, said it has raised $120 million from a Series B funding round consisting of preferred stock.

The funding was led by Boston-based RA Capital Management, New York’s Commodore Capital, and Blackstone Multi-Asset Investing. New investors who joined the round included Baltimore-based Rock Springs Capital and an unidentified U.S.-based healthcare-focused fund.

Richly Funded

Founded in 2021, IDRx came out of stealth the next year with a $122 million Series A round led by Andreessen Horowitz’s a16z and Casdin Capital. So far, the startup has raised $242 million, with other backers including Nextech Invest, Forge Life Science Partners, co-founder Nick Lydon and strategic partner Merck.

IDRx said the new funding would help it accelerate the development of IDRX-42, its drug candidate to treat gastrointestinal stromal tumor, or GIST, one of the most common subtypes of soft tissue sarcoma.

IDRX-42 was designed to overcome the twin challenges of on-target treatment resistance and off-target-driven adverse events, which limit the clinical benefit of a targeted therapy called tyrosine kinase inhibitors, or TKIs, said IDRx CEO Tim Clackson, who earned a Ph.D. in biology from the University of Cambridge.

“We are extremely encouraged by the clinical data generated with IDRX-42 to date and are focused on rapidly advancing this potential new treatment option that could elevate the standard of care for GIST patients,” added Clackson, who led Theseus Pharmaceuticals before joining IDRx in February.

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Critical Study Ahead
IDRX-42 has been granted so-called orphan drug designation by the FDA for the treatment of GIST, and is being evaluated in StrateGIST 1, a first-in-human Phase 1/1b study. The company expects to use the latest funding round to support the ongoing Phase 1/1b StrateGIST 1 study, and to initiate a proposed pivotal study for IDRX-42 in patients with second-line GIST.

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Subsequent to the funding round, RA Capital partner Derek DiRocco, Ph.D., joined the IDRx board. “We have been extremely impressed by what the IDRx team has accomplished in a short time, and I look forward to contributing to IDRx’s future growth and success as the company prepares to execute on its late-stage clinical development activities for IDRX-42,” he said.

Earlier this year, IDRx named oncologist David P. Kerstein, M.D., as chief medical officer. Kerstein has experience in early- and late-stage oncology drug development, including multiple precision oncology medicines. IDRx’s founding R&D leadership team includes chief development operations officer Jessica Christo and chief product development officer Vivek Kadambi.