AstraZeneca Closes $2 Billion Summit Therapeutics Equity Investment

AstraZeneca (AZN ) announced on October 5, 2026, the successful completion of its $2 billion equity investment in Summit Therapeutics (SMMT ). AstraZeneca said the investment will accelerate the development of ivonescimab, a bispecific antibody targeting PD-1 and VEGF, in combination with antibody drug conjugates (ADCs) across tumour types.

Summit Therapeutics confirmed the closing in its own announcement the same day. Under the Securities Purchase Agreement between the two companies, AstraZeneca purchased approximately 108,955 shares of Summit preferred stock that are convertible into shares of Summit common stock at a 1:1,000 ratio, for a total investment of $2.0 billion. At that conversion ratio, the investment represents a common stock price equal to $18.36, which Summit stated was a premium over the closing trading price of its shares on the day the investment was announced.

“This investment reflects AstraZeneca’s confidence in Summit and in ivonescimab’s potential to redefine cancer treatment,” said Robert W. Duggan, Chairman and Co-Chief Executive Officer of Summit Therapeutics. He added that the strategic relationship strengthens Summit’s ability to pursue that vision. Baker Hostetler LLP served as legal advisor to Summit on the transaction.

Summit stated that the additional funds will allow for the accelerated development of ivonescimab across a number of solid tumor settings, including combinations with ADCs.

Agreement Background

The transaction was first announced on September 28, 2026, when AstraZeneca agreed to invest $2 billion in newly issued Summit Therapeutics equity. AstraZeneca stated at the time that, following completion of the investment, it would hold rights equivalent to approximately 12.0% of Summit’s outstanding common stock, or approximately 10.6% on a fully diluted basis. The September announcement said closing was anticipated within one week and that any future conversion of AstraZeneca’s preferred stock into common stock would be subject to customary regulatory clearances. The two companies also executed a Memorandum of Understanding with the intent to enter into an agreement initiating a global development programme combining ivonescimab with AstraZeneca’s cancer medicines, including additional ADCs.

Ivonescimab and the ADC Combinations

Alongside the investment agreement, Summit and AstraZeneca entered into a clinical collaboration agreement to evaluate sonesitatug vedotin (Sone-Ve), a CLDN18.2-targeting ADC with a monomethyl auristatin E (MMAE) payload, in combination with ivonescimab. The companies said in the September announcement that they intended to initiate trials in gastrointestinal cancers under the collaboration imminently. Under the terms, each company contributes its own medicine to the planned combination trials, the companies jointly contribute to trial costs, and each retains development and commercial rights to its own medicine. AstraZeneca also recently reported positive high-level results from the CLARITY-Gastric01 trial of Sone-Ve in second-line and later CLDN18.2-positive advanced gastric cancers, which it said demonstrated a statistically significant and highly clinically meaningful improvement in overall survival versus investigator’s choice of therapy. AstraZeneca said the results will be presented at the European Society for Medical Oncology Congress 2026 in a Presidential Symposium.

On October 2, 2026, AstraZeneca and Daiichi Sankyo entered into a separate clinical collaboration with Summit to evaluate Datroway (datopotamab deruxtecan), a TROP2-directed DXd ADC discovered by Daiichi Sankyo and being jointly developed and commercialised by AstraZeneca and Daiichi Sankyo, in combination with ivonescimab across multiple tumour types including lung and breast cancers. The companies intend to begin with a Phase III trial in first-line triple-negative breast cancer (TNBC). Under that agreement, the combination trials will be sponsored by AstraZeneca or Daiichi Sankyo, all three companies will contribute to trial costs, and each company will retain development and commercial rights to its own medicine. Datroway is approved in more than 30 countries and regions for adult patients with unresectable or metastatic TNBC who are not candidates for PD-1/PD-L1 inhibitor therapy, according to the collaboration announcement.

Ivonescimab was engineered by Akeso Inc. Summit holds exclusive rights to develop and commercialise it in North America, South America, Europe, the Middle East, Africa, and Japan, where it is known as SMT112, while Akeso retains rights in China and other regions, where the drug is known as AK112. Summit describes ivonescimab as a potential first-in-class investigational bispecific antibody that combines the effects of immunotherapy through a blockade of PD-1 with the anti-angiogenesis effects associated with blocking VEGF in a single molecule. Ivonescimab was first approved for marketing authorization in China in May 2024 and remains investigational in Summit’s license territories, including the United States and Europe. A Biologics License Application seeking approval in EGFR-mutated non-small cell lung cancer was accepted for filing by the US Food and Drug Administration in January 2026, with a Prescription Drug User Fee Act goal date of November 14, 2026.

According to Summit, 16 Phase III studies of ivonescimab are announced, ongoing, or completed: five Summit-sponsored global studies, one multiregional study sponsored by the GORTEC cooperative group in head and neck cancer, and ten that are being or have been conducted in China by Akeso. Summit began enrolling patients in its first two multiregional Phase III trials in non-small cell lung cancer (NSCLC), HARMONi and HARMONi-3, in 2023. Summit stated that five Phase III trials of ivonescimab have read out to date, all with positive data. Four are in NSCLC: Summit’s HARMONi study and Akeso’s single-region China studies HARMONi-A, HARMONi-2, and HARMONi-6, with a statistically significant overall survival benefit reported in all three of the China studies. The fifth, Akeso’s HARMONi-GI1 trial in advanced biliary tract cancer, also showed a statistically significant overall survival benefit, according to Summit. More than 5,000 patients have been treated with ivonescimab in clinical studies globally, and more than 100,000 when including those treated in a commercial setting in China, as noted by Akeso, Summit said.