Eli Lilly and Company has announced a definitive agreement to acquire Scorpion Therapeutics' PI3Kα inhibitor program, including the investigational drug STX-478, for a potential total consideration of $2.5 billion. This strategic move aims to bolster Lilly's oncology pipeline with a differentiated, mutant-selective PI3Kα inhibitor currently undergoing Phase 1/2 clinical trials for breast cancer and other advanced solid tumors.
STX-478: A Next-Generation PI3Kα Inhibitor
STX-478 is designed as a once-daily oral therapy that selectively targets the PI3Kα pathway in cancerous cells while sparing healthy cells. This approach seeks to overcome the limitations of existing PI3Kα inhibitors, potentially leading to better disease control and improved tolerability. Interim Phase I/II data released by Scorpion in September showed a monotherapy overall response rate (ORR) of 23% in breast cancer and 21% in all tumors, with tumor reductions observed in 72% of patients as a monotherapy. Mutant PIK3CA circulating tumor DNA (ctDNA) declined in 86% of patients.
Addressing Unmet Needs in Breast Cancer
"PI3Kα mutations occur in a meaningful proportion of hormone-positive breast cancers, and there is significant unmet need for new treatment options that effectively and safely target this pathway," said Jacob Van Naarden, executive vice president and president of Lilly Oncology. He added that the selectivity profile of STX-478 allows for potential combination use with standard-of-care therapies, offering a meaningful impact in earlier treatment settings.
The acquisition aligns with Lilly's commitment to advancing scientific breakthroughs in difficult-to-treat cancers. STX-478 could potentially address 30-40% of people with hormone-positive breast cancer.
Deal Structure and Future Plans
Under the terms of the agreement, Scorpion shareholders could receive up to $2.5 billion in cash, including an upfront payment and subsequent payments upon achievement of regulatory and sales milestones. Scorpion will spin out a new entity to hold its employees and non-PI3Kα pipeline assets, with Lilly retaining a minority equity interest. The new company will focus on discovering and delivering precision medicines, led by Dr. Adam Friedman and the current Scorpion management team.
"Lilly has advanced scientific breakthroughs for some of the most difficult-to-treat cancers," said Dr. Friedman, president and chief executive officer of Scorpion. "We believe Lilly's global capabilities and strategic commitment to patients with breast cancer will accelerate our goal of developing STX-478 to improve outcomes for the many patients with solid tumors driven by PI3Kα mutations."
The transaction is subject to customary closing conditions.
