Lilly agrees to buy Scorpion Therapeutics' PI3K-alpha cancer drug program for up to $2.5 billion

Eli Lilly and Company announced on Jan. 13, 2025, that it has a definitive agreement to acquire Scorpion Therapeutics' PI3K-alpha inhibitor program, led by an experimental cancer drug called STX-478, for up to $2.5 billion in cash ^[1].

STX-478 is a once-daily oral drug that is designed to target the PI3K-alpha pathway in cancer cells while avoiding healthy cells, according to the two companies. It is currently being tested in a Phase 1/2 clinical trial for breast cancer and other advanced solid tumors ^[1]. Lilly said the drug could potentially address 30 to 40 percent of people with hormone-positive breast cancer ^[1].

The payment structure includes an upfront payment plus later payments that depend on hitting certain regulatory and sales milestones, with a total of up to $2.5 billion in cash ^[1]. The companies did not disclose how the money is split between the upfront amount and the milestone payments, and they did not give a date for when the deal is expected to close. The transaction is subject to customary closing conditions, and Lilly said it will decide how to account for the deal under GAAP once it closes ^[1].

As part of the deal, Scorpion will spin out a new, independent company that will hold its employees and its pipeline assets outside of PI3K-alpha. That new company would be owned by Scorpion's current shareholders, with Lilly holding a minority equity interest, and would be led by Scorpion president and chief executive officer Adam Friedman along with members of the current management team ^[1]. Scorpion describes its pipeline as three internally discovered clinical product candidates plus multiple discovery-stage programs ^[1].

Jacob Van Naarden, executive vice president and president of Lilly Oncology, said PI3K-alpha mutations occur in a meaningful share of hormone-positive breast cancers and that there is significant unmet need for treatments that safely target the pathway. He said the selectivity of STX-478 has led to a different clinical profile that could allow it to be used in combinations with standard-of-care therapies in earlier treatment settings ^[1]. Friedman said Lilly's global reach and commitment to breast cancer patients should speed development of STX-478 ^[1].

The deal does not report any clinical results for STX-478. How well the drug works, what side effects it causes, how many patients have been enrolled in the trial and when data might be released have not been disclosed ^[1].

Why it matters for patients

This is an oncology deal, not a weight-loss or diabetes one. No change to any GLP-1 medicine, including semaglutide and tirzepatide products, was announced as part of this transaction ^[1]. Nothing in the announcement changes the price, insurance coverage, supply or availability of any GLP-1 drug. Lilly describes its own work as spanning diabetes care, obesity, Alzheimer's disease, immune system disorders and hard-to-treat cancers, so the company's spending across those areas runs in parallel ^[1].

For people with hormone-positive breast cancer, the news concerns a drug still in early testing. Phase 1/2 trials are mainly designed to look at safety, dosing and early signs of activity, so whether STX-478 becomes a treatment option, and for whom, is not yet known ^[1]. The 30 to 40 percent figure refers to the share of hormone-positive breast cancers that could potentially be addressed by this approach, not to how well the drug performs ^[1].

What happens next

The acquisition still needs to clear customary closing conditions before it is complete ^[1]. No expected closing date was given. Once the deal closes, milestone payments to Scorpion shareholders would follow only if the drug reaches specified regulatory and sales targets ^[1]. Trial results, regulatory filings and any timeline for either have not been reported ^[1].