Scorpion Therapeutics
Scorpion Therapeutics was a Boston start-up that designed a cancer pill, STX-478, aimed only at the mutated form of a growth protein called PI3K-alpha, sparing the normal form. Eli Lilly bought the programme in 2025.
Overview
Scorpion Therapeutics was a Boston precision oncology company founded in 2020 whose lead asset, STX-478, is a mutant-selective, allosteric PI3K-alpha inhibitor intended to avoid the hyperglycaemia and other toxicities of wild-type PI3K-alpha inhibition. In January 2025 Eli Lilly agreed to acquire the STX-478 programme; Lilly's first-quarter 2025 results describe the acquisition as the main driver of a 1.57 billion US dollar acquired in-process research and development charge, and the Scorpion website now redirects to Lilly's announcement. SEC Form D filings show roughly 172 million US dollars sold in 2020 offerings and a further 125.7 million US dollars sold in a 2024 offering before the sale to Lilly.
Funding
All startupsInvestors not recorded; see the round sources.
| Round | Year | Amount | Source |
|---|---|---|---|
| Acquisition · Lilly's Q1 2025 results attribute most of a 1.57 billion US dollar acquired in-process R&D charge to the acquisition of Scorpion's PI3K-alpha inhibitor programme STX-478; headline deal value not verified | 2025 | undisclosed | sec.gov |
| Form D offering · Total sold of a 150 million US dollar offering per Form D filed July 2024 | 2024 | $126M | sec.gov |
| Form D offering · Total sold per Form D filed May 2020 | 2020 | $25M | sec.gov |
| Form D offering · Total sold per Form D filed December 2020 | 2020 | $147M | sec.gov |
Amounts only where the cited source states them. Rounds without a public source are not listed.
Notes
top- scorpiontx.com redirects to a Lilly investor page that returned HTTP 403, so the acquisition press release itself could not be fetched; the deal is confirmed via Lilly's SEC-filed earnings releases. Headline deal value (reported in press as up to 2.5 billion US dollars) and the reported spin-out of non-PI3K assets were not verified. Series labels for the Form D rounds are not stated in the filings.
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