AstraZeneca is investing $2 billion in Summit Therapeutics as the drugmakers join forces to test a next-generation cancer combination that pairs antibody-drug conjugates with a dual-action immunotherapy.

 

AstraZeneca will take a roughly 12% stake in Summit Therapeutics under a deal aimed at accelerating development of ivonescimab, a bispecific antibody targeting both PD-1 and VEGF, the companies announced on September 28.

 

The agreement also launches a clinical collaboration to evaluate sonesitatug vedotin (Sone-Ve), AstraZeneca’s Claudin-18.2-targeting antibody-drug conjugate (ADC), in combination with ivonescimab in gastrointestinal cancers.

 

The companies plan to begin clinical trials in gastrointestinal cancers imminently, with each contributing its respective drug and sharing trial costs. Both will retain development and commercial rights to their own medicines.

 

The partnership could also expand beyond Sone-Ve. AstraZeneca and Summit have signed a memorandum of understanding with the intention of establishing a global development programme combining ivonescimab with AstraZeneca’s wider oncology portfolio, including additional ADCs.

 

Susan Galbraith, Executive Vice President, Oncology Haematology R&D, AstraZeneca, said: “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. Bispecifics targeting PD-1 and VEGF are rapidly advancing in development and have the potential to improve on current immunotherapies, particularly in lung, breast and gastrointestinal cancers. This opportunity to combine ivonescimab with AstraZeneca’s ADC portfolio, including with Sone-Ve, could enable new regimens that raise the bar for patients with cancer across the treatment landscape."

 

Summit President and Co-Chief Executive Officer Maky Zanganeh said: “The developments announced today with AstraZeneca open an exciting new chapter in the advancement of ivonescimab. 

 

"With a growing body of evidence supporting ivonescimab’s differentiated PD-1 / VEGF bispecific approach, we look forward to further broadening the development plan of ivonescimab and initiating new clinical trials exploring the potential to combine ivonescimab with promising novel anti-cancer compounds, including ADCs, to bring together complementary approaches to tumour-cell killing, antitumour immunity, and the tumour microenvironment.”

 

 

The deal comes after AstraZeneca reported positive high-level results from the CLARITY-Gastric01 trial of Sone-Ve in patients with Claudin18.2-positive advanced gastric cancer who had received two or more previous lines of treatment.

 

The company said the trial demonstrated a statistically significant and clinically meaningful improvement in overall survival compared with investigator’s choice of therapy.

 

Detailed results are due to be presented at the European Society for Medical Oncology Congress 2026 in a Presidential Symposium.

 

Sone-Ve is an ADC designed to target CLDN18.2, a protein found in the stomach lining and a validated target in gastrointestinal oncology. The drug combines a CLDN18.2-targeting antibody with a degradable linker and the cytotoxic payload monomethyl auristatin E (MMAE).

 

AstraZeneca licensed global exclusive rights to develop and commercialise Sone-Ve from KYM Biosciences in March 2023.

 

The drug is also being studied in the Phase III CLARITY-Gastric02 trial as a first-line treatment for advanced or metastatic gastric, gastroesophageal junction and oesophageal adenocarcinoma. Phase II studies are evaluating Sone-Ve in advanced solid tumours, including pancreatic and biliary tract cancers.

 

 

Ivonescimab is designed to combine two mechanisms in a single antibody: blocking PD-1 to stimulate an immune response while inhibiting VEGF, a pathway involved in tumour blood-vessel formation.

 

The drug was engineered by Akeso Inc. Summit holds exclusive rights to develop and commercialise ivonescimab in major markets outside China, while Akeso retains rights in China and other territories.

 

Ivonescimab is already approved for certain patients with non-small cell lung cancer in China. A US Biologics License Application seeking approval in EGFR-mutated NSCLC is under review by the US Food and Drug Administration.

 

The drug is also being tested in Phase III trials across a broad range of cancers, including non-small cell and small cell lung cancer, bladder cancer, triple-negative breast cancer, head and neck cancer, colorectal cancer, pancreatic cancer and biliary tract cancer.

 

 

Under the financial terms, AstraZeneca will invest $2 billion in newly issued Summit preferred stock.

 

The preferred shares are convertible into common stock at a 1:1,000 ratio. Following completion, AstraZeneca will hold rights equivalent to approximately 12% of Summit’s outstanding common stock, or about 10.6% on a fully diluted basis.

 

The investment is expected to close within one week. Any future conversion of the preferred stock into common shares will be subject to customary regulatory clearances.

 

The transaction gives AstraZeneca a significant equity position in Summit while tying the companies together on a broader strategy: combining ADCs, which deliver targeted cancer-killing payloads, with a bispecific antibody designed to attack both tumour immune evasion and angiogenesis.

 

The immediate focus will be gastrointestinal cancers, but the planned collaboration could ultimately extend across multiple tumour types and incorporate additional drugs from AstraZeneca’s oncology portfolio.