Shares of Summit Therapeutics SMMT rose 22% in pre-market trading on Tuesday after it announced that AstraZeneca AZN had agreed to invest $2 billion in the company to accelerate development of its lead pipeline drug, ivonescimab.

The deal is structured as a strategic equity investment, with AstraZeneca purchasing approximately 108,955 shares of preferred stock convertible into shares of Summit’s common stock at a 1:1,000 ratio. At the conversion ratio, the investment represents an effective common-stock price of $18.36 per share, roughly 19% above Summit’s closing price on Sept. 28.

Once completed, AstraZeneca will hold rights equivalent to about 12% of Summit’s outstanding common stock, or about 10.6% on a…