IDRx Secures $120M Series B to Advance New GIST Treatment

IDRx, Inc., a biopharmaceutical company in the clinical stage, has announced the successful completion of a $120 million Series B Preferred Stock financing. This financing round was led by RA Capital Management, Commodore Capital, and Blackstone Multi-Asset Investing, with significant contributions from new investors such as Rock Springs Capital and a U.S.-based healthcare fund. Existing investors, including Andreessen Horowitz (a16z) Bio + Health, Casdin Capital, Nextech Invest Ltd., Forge Life Science Partners, co-founder Nick Lydon, Ph.D., and strategic partner Merck KGaA, Darmstadt, Germany, also participated. As part of the financing deal, Derek DiRocco, Ph.D., Partner at RA Capital Management, has joined the IDRx Board of Directors.

The funds secured will primarily support the ongoing Phase 1/1b StrateGIST 1 study of IDRx’s leading product candidate, IDRX-42. IDRX-42 is a highly selective, potent, oral KIT inhibitor aimed at addressing major categories of activating and resistance mutations in patients with KIT-mutant GIST (Gastrointestinal Stromal Tumors). The financing will also aid in the planned initiation of the first pivotal study for IDRX-42 in patients requiring second-line treatment for GIST.

During the 2024 American Society of Clinical Oncology (ASCO) annual meeting, IDRx presented preliminary data from the Phase 1/1b StrateGIST 1 trial, supporting the potential of IDRX-42. The data revealed a 23% objective response rate (ORR) across all patients and a 43% ORR in second-line patients, showing promise for those with ATP binding site and activation loop mutations. The treatment was noted to have a favorable tolerability profile, fitting for both front-line and second-line settings. The company is currently enrolling patients for the Phase 1b portion of the trial. Moreover, the FDA has granted Fast Track designation to IDRX-42 for treating GIST in patients who have shown disease progression on or intolerance to imatinib.

Tim Clackson, Ph.D., CEO of IDRx, expressed enthusiasm about the financing, noting that the support from top-tier investors positions the company to accelerate the development of IDRX-42. He highlighted that IDRX-42 is designed to overcome challenges related to on-target treatment resistance and off-target adverse effects, which are limitations of current TKIs (tyrosine kinase inhibitors). Clackson emphasized the encouraging clinical data for IDRX-42 and the company's focus on advancing this potential new treatment to elevate the standard of care for GIST patients.

Derek DiRocco, Ph.D., from RA Capital Management, expressed his excitement about co-leading the financing round to support IDRX-42’s advancement as a new treatment for GIST. He praised the accomplishments of the IDRx team and looked forward to contributing to the company’s future success as it prepares for late-stage clinical developments of IDRX-42.

GIST is the most common subtype of soft tissue sarcoma, with approximately 80% of cases resulting from gain-of-function mutations in the KIT receptor tyrosine kinase. These mutations drive malignancy through aberrant signaling. In about 90% of patients treated with imatinib, resistance mutations in KIT develop. The existing treatments for unresectable or metastatic GIST show varied clinical benefits depending on mutation types.

The StrateGIST 1 study is an ongoing, open-label, first-in-human Phase 1/1b trial that evaluates the safety, tolerability, pharmacokinetics, and preliminary antitumor activity of IDRX-42 in patients with metastatic and/or surgically unresectable GIST. The study is enrolling patients with documented pathogenic mutations in KIT or certain PDGFRA mutations across several countries, including the U.S., U.K., Belgium, Netherlands, France, Germany, Italy, Spain, and South Korea. The Phase 1b portion consists of four expanded exploratory cohorts based on prior TKI therapy lines.

IDRX-42 has shown superior antitumor activity in preclinical studies compared to imatinib and sunitinib, the current standards of care for first-line and second-line GIST treatments, respectively. The FDA has granted Orphan Drug designation to IDRX-42 for the treatment of GIST.

IDRx, founded in 2021, aims to transform cancer care with precision therapies. The company’s expertise in drug development is evident from its leadership team’s involvement in the discovery and commercialization of over ten approved medicines.