AstraZeneca is making a $2 billion bet on combining two of oncology’s most closely watched drug classes. On September 28, the company announced an agreement to invest $2 billion in newly issued equity in Summit Therapeutics. The goal is to speed up development of ivonescimab, a PD-1/VEGF bispecific antibody, alongside antibody-drug conjugates (ADCs) across tumor types.
The first step is a clinical collaboration pairing ivonescimab with AstraZeneca’s sonesitatug vedotin (Sone-Ve) in gastrointestinal (GI) cancers. Sone-Ve is an ADC that targets Claudin-18.2 (CLDN18.2). The companies said they plan to start trials imminently.
How the Collaboration Works
Each company will contribute its own medicine to the combination trials, and both will share the trial costs. Neither gives up its drug: each keeps development and commercial rights to its own product.
The deal may also go further. The companies signed a Memorandum of Understanding (MOU) stating their intent to enter an agreement on a global development program. It would pair ivonescimab with AstraZeneca’s cancer medicines, including additional ADCs. The MOU expresses intent and is not a final agreement.
The Numbers
AstraZeneca will buy approximately 109 thousand shares of Summit preferred stock, convertible into common stock at a ratio of 1:1,000. Once the investment closes, it will hold rights equivalent to about 12.0% of Summit’s outstanding common stock, or about 10.6% on a fully diluted basis. Closing is expected within one week. Any later conversion to common stock would need customary regulatory clearances.
Why These Two Drugs
Ivonescimab packs two mechanisms into one molecule: PD-1 blockade for immunotherapy and VEGF blockade for anti-angiogenesis. It was engineered by Akeso, and Summit holds exclusive rights to develop and commercialize it in major territories outside China. Akeso retains rights in China and other regions.
The drug is approved for certain patients with non-small cell lung cancer (NSCLC) in China, and a Biologics License Application for EGFR-mutated NSCLC is under review by the U.S. Food and Drug Administration. Phase 3 trials are ongoing in NSCLC, small cell lung cancer, biliary tract cancer, bladder cancer, triple-negative breast cancer, head and neck squamous cell carcinoma, colorectal cancer, and pancreatic cancer.
Sone-Ve links an anti-CLDN18.2 antibody to an MMAE cytotoxic payload through a protease-degradable linker. CLDN18.2 is a protein found in the stomach lining and a validated target in GI cancers. AstraZeneca licensed the drug from KYM Biosciences in March 2023.
Sone-Ve Data Coming at ESMO 2026
The timing overlaps with a major data readout. AstraZeneca recently reported positive high-level results from the Phase 3 CLARITY-Gastric01 trial. The trial tested Sone-Ve in second-line and later CLDN18.2-positive advanced gastric cancer. The company reported a statistically significant improvement in overall survival versus investigator’s choice of therapy, and described it as highly clinically meaningful. Full results will be presented in a Presidential Symposium at the ESMO Congress 2026.
Sone-Ve is also being tested in the Phase 3 CLARITY-Gastric02 trial. It is combined with capecitabine, with or without rilvegostomig, as first-line treatment for advanced or metastatic gastric, gastroesophageal junction, and esophageal adenocarcinoma. Phase 2 studies cover advanced solid tumors, including CLDN18.2-positive pancreatic and biliary tract cancers.
What the Companies Are Saying
Susan Galbraith, Executive Vice President of Oncology Haematology R&D at AstraZeneca, said that broadening the reach of the company’s ADC portfolio is a core pillar of its oncology strategy. She described the aim as making ADCs the treatment backbone across tumor types, in combination with next-generation immunotherapies.
Galbraith noted that PD-1/VEGF bispecifics are advancing rapidly and could improve on current immunotherapies, particularly in lung, breast, and gastrointestinal cancers. She said combining ivonescimab with AstraZeneca’s ADCs, including Sone-Ve, could enable new regimens across the treatment landscape.
Dr. Maky Zanganeh, President and Co-Chief Executive Officer of Summit Therapeutics, said the developments announced with AstraZeneca “open an exciting new chapter in the advancement of ivonescimab.” She pointed to a growing body of evidence supporting the drug’s differentiated approach.
Zanganeh said Summit plans to broaden ivonescimab’s development plan and start new trials combining it with novel anti-cancer compounds, including ADCs. She described the aim as bringing together complementary approaches to tumor-cell killing, antitumor immunity, and the tumor microenvironment.
What to Watch
The GI trials are expected to start first, so the next update will likely come on trial initiation. A final agreement following the MOU would show how far the partnership extends. The full CLARITY-Gastric01 data at ESMO 2026 will give the first detailed look at Sone-Ve’s survival benefit. Stay tuned with OncoDaily so you don’t miss anything from ESMO 2026.
Read further on OncoDaily: Merck Enters $2.13 Billion License Agreement for SciBrunch’s Investigational Oral KRAS G12D (ON) Inhibitor SPR2015
