Eli Lilly has turned to a biotechnology startup for help building its pipeline of cancer drugs, agreeing on Monday to purchase an experimental cancer drug from privately held Scorpion Therapeutics for as much as $2.5 billion.As part of the deal, Scorpion will spin out a new, independent company that will hold its other assets as well as inherit its employees. Lilly will take a minority stake in the new company, which will be owned by Scorpions current shareholders, among them Atlas Venture, Vida Ventures and Omega Funds.Current Scorpion CEO Adam Friedman will lead the new company along with other members of the startups management.The acquisition hands Lilly a medicine, dubbed STX-678, that is aimed at tumors driven to growth by mutations to a gene called PI3Ka. So-called PI3Ka mutations are among the most common drivers of cancer, affecting more than 160,000 people diagnosed each year with breast, gynecological and head and neck cancers in the U.S., according to Scorpion.A handful of medicines already available, like Novartis Piqray and AstraZenecas Truqap, as well as others in clinical development also target PI3Ka mutations.Scorpion has claimed its drug could be more selective and potent than existing PI3Ka inhibitors, which block normal, or wild-type, PI3Ka and as a result are tough to tolerate. Existing drugs also dont readily reach the brain tissue into which many solid tumors spread. Scorpion says its drug might overcome these limitations and has advanced the treatment into a Phase 1/2 trial in multiple tumor types, among them a common form of breast cancer.Scorpion has been collaborating with Pfizer to study STX-678 together with a so-called CDK4 inhibitor. Lilly sells a drug, called Verzenio, that similarly targets CDK4 alongside a related protein.The deal will expand a cancer drug division Lilly has poured considerable resources into as a complement to its lucrative metabolic disease business. Lilly acquired Loxo Oncology in 2019 and, since then, has used deals to buy into other areas of precision oncology such as radiopharmaceuticals and antibody-drug conjugates.Verzenio, which Lilly discovered and developed internally, has become the top-selling drug of its class, though much of Lillys revenue is derived from its diabetes and weight loss treatments. Lilly also has in its pipeline an internally developed PI3Ka inhibitor thats in Phase 1 testing.Lillys deal with Scorpion adds to an upward trend in private biotech M&A. The increase has coincided with a weakening market for initial public offerings, which as forced many mature startups to explore strategic options.Scorpion was co-founded in 2020 by Gary Glick, who helped the company raise nearly $300 million in venture funding before departingin 2021. Prior to Scorpion, Glick led Lycera, which inked a 2015 deal with Celgene, and IFM Therapeutics, which has spun off multiple companies that were acquired by Bristol Myers Squibb and Novartis.Glicks latest company, Odyssey Therapeutics, is developing treatments for inflammatory diseases. '