GSK has announced agreement to acquire the U.S. biotech firm IDRx for up to $1.15 billion

The deal involves an upfront payment of $1 billion, with the potential for an additional $150 million contingent upon regulatory approval milestones.

The acquisition includes IDRX-42, a selective tyrosine kinase inhibitor (TKI) being developed as a treatment for GIST in both first- and second-line settings. GIST primarily affects the gastrointestinal tract and is often driven by mutations in the KIT gene, which are responsible for tumor cell growth and survival. Approximately 90% of patients treated with first-line therapies develop new mutations that lead to treatment resistance and relapse, highlighting the need for effective options. Currently, no approved TKIs target the full spectrum of significant primary and secondary KIT mutations.

“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.

IDRX-42 has shown promise in addressing these challenges by demonstrating efficacy against all key KIT mutations, which may enhance patient outcomes. Its high selectivity could also improve tolerability, positioning it as a potential best-in-class treatment option.

 “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.

Updated clinical data from the ongoing StrateGIST 1 trial of IDRX-42 in patients with advanced gastrointestinal stromal tumors (GIST) were presented at the Connective Tissue Oncology Society (CTOS) 2024 Annual Meeting. The findings indicate that IDRX-42 shows encouraging anti-tumor activity and has a manageable safety profile.

Among patients who had received second-line treatment or more, the objective response rate (ORR) was 29% (n=87), which included one complete response (CR) and 24 partial responses (PRs). For those who had undergone one prior therapy, the ORR increased to 53% (n=15), with one CR and seven PRs.At the data cutoff, two of the PRs were pending confirmation, but both were later validated. The durability of the responses also appeared favorable. Overall, IDRX-42 was well tolerated, with most treatment-related adverse events being low grade at the recommended phase Ib dosage.

Financial Considerations

Under the terms of the agreement, GSK will acquire 100% of the outstanding equity interests in IDRx for a total cash consideration of up to $1.15 billion. This amount includes an upfront payment of $1 billion, with the potential for an additional $150 million tied to success-based regulatory approval milestones. GSK will also be responsible for milestone payments and tiered royalties related to IDRX-42 that are owed to Merck KGaA.

The transaction is contingent upon standard conditions, including necessary regulatory approvals under the Hart-Scott-Rodino Act in the United States.For IDRx, Centerview Partners LLC is acting as the exclusive financial advisor, and Goodwin Procter LLP is serving as legal counsel. For GSK, Leerink Partners LLC is the exclusive financial advisor.

About IDRX-42

IDRX-42 is a highly selective, investigational small molecule tyrosine kinase inhibitor (TKI) designed to target all key KIT mutations in GIST. The U.S. Food and Drug Administration (FDA) has granted IDRX-42 Fast Track designation for the treatment of patients with GIST after disease progression on or intolerance to imatinib, and Orphan Drug designations for the treatment of GIST.

“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,

About GSK

GSK is a global biopharma company committed to uniting science, technology, and talent to stay ahead of disease and improve health outcomes worldwide. Focused on innovation in vaccines and specialty medicines, GSK aims to positively impact the health of 2.5 billion people by the end of the decade. As a successful and growing organization, GSK fosters an environment where people can thrive while contributing to groundbreaking advancements in healthcare.

Aboout IDRx

IDRx is a biotechnology company focused on overcoming the limitations of current precision cancer medicines. By developing highly potent and selective targeted therapies, IDRx aims to stop key tumor escape mechanisms and extend patients’ response to treatment. The company’s primary goal is clear: to transform the lives of patients with Gastrointestinal Stromal Tumor (GIST). IDRx is advancing its lead clinical-stage program, IDRX-42, as a potential treatment for GIST, working towards innovative therapies that can significantly improve patient outcomes.

Further Reading:

IDRx Announces Updated Phase 1 Data from Ongoing Phase 1/1b StrateGIST 1 Trial of IDRX-42

GSK Announced Landmark Results from FIRST Trial in First-Line Advanced Ovarian Cancer