Johnson & Johnson said Monday it will purchase Halda Therapeutics and its experimental prostate cancer drugs for $3.05 billion, marking the first major buyout for a startup built around a field that has attracted significant investment but not yet secured any drug approvals.

Over the last decade, the drug industry has been excited over so-called PROTACs: new two-handed molecules, capable of taking a cancer or other disease-causing protein and dragging it into the cellular garbage disposal.

The approach, also called targeted protein degradation, came out of the lab of Yale chemist Craig Crews. It has been widely used in academic labs and has led to the creation of numerous startups, including Arvinas, which has raised over $1 billion and signed a lucrative partnership with Pfizer.

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