GSK Strikes Deal to Acquire IDRx for $1 Billion

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GSK announced that it has agreed to terms to acquire IDRx, a clinical-stage biopharmaceutical company focused on developing precision therapeutics for gastrointestinal stromal tumors (GIST). According to the company, the acquisition includes IDRX-42, a highly selective KIT tyrosine kinase inhibitor (TKI) designed to address both primary and secondary KIT mutations in patients with GIST. Early data from the StrateGIST 1 Phase I/Ib trial demonstrated promising antitumor activity, with an objective response rate (ORR) of 53% in patients treated after one prior line of therapy, along with a favorable safety profile.¹

“IDRX-42 complements our growing portfolio in gastrointestinal cancers. This acquisition is consistent with our approach of acquiring assets that address validated targets and where there is clear unmet medical need, despite existing approved products,” said Luke Miels, chief commercial officer, GSK, in a press release.

Under terms of the deal, GSK will acquire all outstanding shares of IDRx for up to $1.15 billion, including an upfront payment of $1 billion and a potential extra $150 million based on success-based regulatory approval milestones. The transaction is subject to customary conditions, such as applicable regulatory agency clearances under the Hart-Scott-Rodino Act.

Results from StrateGIST, which were presented at the Connective Tissue Oncology Society 2024 Annual Meeting, demonstrated a favorable safety profile. Additionally, a 29% ORR was achieved in patients with second-line or greater GIST and all KIT mutation subsets. This included one complete response and 24 partial responses. Further, the rate of treatment-related adverse events was reported to be low grade from the recommended dose.¹

“We are excited by the early data from IDRX-42 and its unique ability to target all clinically relevant KIT mutations present in GIST, a major gap in the current standard of care. We look forward to accelerating its development in 2025 to redefine treatment,” said Tony Wood, chief scientific officer, GSK, in the press release.

According to the American Cancer Society, GISTs are not common, with current estimates in the United States ranging from 4,000 to about 6,000 cases. While they are most common in people over 50 years of age, GISTs can develop at any age, albeit in rare cases.² Globally, an estimated 80,000 to 120,000 patients are diagnosed with GIST per year. Eighty percent of cases are pushed by mutations in the KIT gene that lead to the growth, proliferation, and survival of tumor cells. Further, around 90% of first-line treated patients will develop new KIT mutations that result in limited treatment options. Currently, no TKIs are approved for patients in this indication.¹

According to Yale Medicine, approximately 50% to 60% of all GISTs are located in the stomach, with 30% to 35% of all cases located in the small intestine and 5% in the colon and rectum. Only 1% of all GISTs are found in the esophagus.³

“We are looking forward to working with GSK to advance IDRX-42 for patients with GIST given there have been no major advances to the standard of care for almost 20 years. Combining our experience to date with GSK’s expertise in GI cancers, global clinical development capability, and strong commercial presence in oncology will help to accelerate the development of this novel medicine for patients,” said Tim Clackson, CEO, IDRx, in the press release.

GSK plans to accelerate IDRX-42’s development starting in 2025, aiming to redefine the treatment landscape for GIST.

References

1. GSK enters agreement to acquire IDRx, Inc. GSK. January 13, 2025. Accessed January 13, 2025. https://www.gsk.com/en-gb/media/press-releases/gsk-enters-agreement-to-acquire-idrx-inc/

2. Key Statistics for Gastrointestinal Stromal Tumors. American Cancer Society. Accessed January 13, 2025. https://www.cancer.org/cancer/types/gastrointestinal-stromal-tumor/about/key-statistics.html

3. Gastrointestinal Stromal Tumors (GIST). Yale Medicine. Accessed January 13, 2025. https://www.yalemedicine.org/conditions/gastrointestinal-stromal-tumors-gist