AstraZeneca commits $2 billion to Summit Therapeutics as part of new equity stake and cancer research alliance centered on antibody drug conjugate combinations

Under a new clinical partnership, the companies will test sonesitatug vedotin, an experimental antibody drug conjugate targeting Claudin-18.2, alongside ivonescimab, a bispecific antibody blocking both PD-1 and VEGF, in patients with gastrointestinal cancers. A wider collaboration is also planned that would pair ivonescimab with additional cancer treatments from AstraZeneca’s broader portfolio.

AstraZeneca has agreed to purchase $2 billion worth of newly issued shares in Summit Therapeutics Inc., with the funding intended to speed up work on ivonescimab, described as a first-in-class bispecific antibody that targets both the PD-1 and VEGF pathways, used alongside antibody drug conjugates across a range of tumor types.

Alongside the investment, the two companies signed a separate clinical trial agreement to study sonesitatug vedotin, known by the shorthand Sone-Ve, together with ivonescimab. Sone-Ve targets CLDN18.2 and delivers a monomethyl auristatin E payload; it is potentially the first medicine of its kind worldwide and is already being tested in a number of ongoing gastrointestinal cancer trials. Trials combining the two drugs in gastrointestinal cancer are expected to begin shortly under this new arrangement.

Per the agreement’s terms, each company will supply its own drug for the planned trials and split the associated costs, while each retains full development and commercialization rights over its own product.

Summit and AstraZeneca additionally signed a Memorandum of Understanding laying the groundwork for a future, more extensive agreement: a global development program pairing ivonescimab with other cancer medicines from AstraZeneca’s pipeline, including additional antibody drug conjugates beyond Sone-Ve.

Susan Galbraith, who leads oncology and haematology R&D as executive vice president at AstraZeneca, described extending the reach of the company’s antibody drug conjugate portfolio, paired with newer immunotherapies, as central to its oncology strategy. She noted that bispecific antibodies targeting PD-1 and VEGF together are moving quickly through development and could outperform existing immunotherapy options, particularly for lung, breast, and gastrointestinal cancers. Pairing ivonescimab with AstraZeneca’s antibody drug conjugates, Sone-Ve included, she said, could produce new treatment regimens capable of raising standards across the broader cancer care landscape.

Dr. Maky Zanganeh, Summit Therapeutics’ president and co-chief executive officer, called the agreement with AstraZeneca the start of an exciting new phase for ivonescimab’s development. Citing mounting evidence behind the drug’s distinctive dual-targeting approach, she said Summit is eager to broaden its development plans further and begin new trials exploring combinations with promising cancer compounds, including antibody drug conjugates, in order to attack tumors through multiple complementary mechanisms at once, spanning direct tumor-cell killing, immune activation against the tumor, and the surrounding tumor environment.

AstraZeneca also recently shared encouraging top-line data from its CLARITY-Gastric01 trial, which tested Sone-Ve in patients with advanced, Claudin18.2-positive gastric cancer who had already received at least one prior line of treatment. The trial found a statistically significant, clinically important improvement in overall survival compared with whatever therapy the treating physician would otherwise have chosen. These findings will be presented during a Presidential Symposium session at the European Society for Medical Oncology Congress 2026.

Ivonescimab works by combining two mechanisms into a single molecule: blocking PD-1 to activate the immune system’s anti-cancer response, and blocking VEGF to starve tumors of blood supply. Akeso Inc. originally developed the molecule. Summit controls exclusive development and commercial rights to ivonescimab in major markets outside China, while Akeso retains those rights within China and select other territories.

The drug already holds approval in China for certain non-small cell lung cancer patients, and a Biologics License Application covering EGFR-mutated non-small cell lung cancer is currently under FDA review in the U.S. Beyond lung cancer, ivonescimab is being tested in Phase III trials spanning small cell lung cancer, biliary tract cancer, bladder cancer, triple-negative breast cancer, head and neck squamous cell carcinoma, colorectal cancer, and pancreatic cancer.

---

---

Related Topics and Keywords

antibody drug conjugate, AstraZeneca, cancer research, Summit Therapeutics