AstraZeneca has completed a $2bn investment in US biotech Summit Therapeutics, taking a stake of about 12% and opening a route to test its cancer drug conjugates alongside Summit’s ivonescimab.
AstraZeneca (LON: AZN), the UK-listed drugmaker, announced today that it has completed its $2 billion equity investment in Summit Therapeutics. The investment was first announced on Tuesday 29 September, with closing then anticipated within one week.
The money bought newly issued convertible preferred stock, shares that can later be converted into common stock. There are approximately 109,000 of them, each convertible into 1,000 common shares, and they carry rights equal to about 12.0% of Summit’s outstanding common stock, or about 10.6% fully diluted, which counts all convertible securities. Conversion remains subject to customary regulatory clearances.
The deal comes with a clinical collaboration pairing AstraZeneca’s Sone-Ve with Summit’s ivonescimab in gastrointestinal cancers. Sone-Ve is an antibody-drug conjugate (ADC, an antibody that carries a cancer-killing drug) aimed at a protein called CLDN18.2. Each company contributes its own medicine, trial costs are shared and each keeps its development and commercial rights.
A memorandum of understanding signals intent to build a broader global programme, including additional ADCs. Susan Galbraith, Executive Vice President, Oncology Haematology R&D at AstraZeneca, said when the deal was announced:
A core pillar of our oncology strategy is to broaden the reach of our ADC portfolio as the backbone of treatment across tumour types with combinations alongside next-generation immunotherapies.
Susan Galbraith, AstraZeneca
Dr. Maky Zanganeh, President and Co-CEO of Summit, said at the same time:
The developments announced today with AstraZeneca open an exciting new chapter in the advancement of ivonescimab.
Dr. Maky Zanganeh, Summit Therapeutics
The first combination trials will be in gastrointestinal cancers. Separately, AstraZeneca’s CLARITY-Gastric01 trial of Sone-Ve in second and later-line CLDN18.2-positive advanced gastric cancer met its overall survival endpoint, with results due at the ESMO 2026 Presidential Symposium.
Ivonescimab is already approved in China for certain patients with non-small cell lung cancer, and a Biologics License Application for EGFR-mutated disease of that type is under review by the US Food and Drug Administration.
