AstraZeneca will invest $2 billion in newly issued equity of Summit Therapeutics Inc. and has entered a clinical collaboration to test ivonescimab, Summit's first-in-class programmed cell death protein 1 (PD-1)/vascular endothelial growth factor (VEGF) bispecific antibody, in combination with AstraZeneca's antibody-drug conjugates (ADCs) across multiple tumor types, the companies announced September 28, 2026.¹
Key facts
- Companies: AstraZeneca; Summit Therapeutics
- Drug: Ivonescimab (Akeso; Summit holds ex-China rights)
- Class: PD-1/VEGF bispecific antibody
- Partner drug: Sonesitatug vedotin (Sone-Ve; AstraZeneca), a claudin-18.2-targeted ADC with an MMAE payload
- Collaboration focus: Combination trials in gastrointestinal cancers, to begin imminently
- Regulatory status: BLA for ivonescimab plus chemotherapy in EGFR-mutated NSCLC under FDA review; PDUFA date November 14, 2026
- Current approval: Ivonescimab approved in China for certain NSCLC patients
- Trial data: Sone-Ve met its overall survival endpoint in the phase 3 CLARITY-Gastric01 gastric/GEJ cancer trial
- Closing: Equity investment expected to close within 1 week
What does the equity investment involve?
AstraZeneca will purchase approximately 109,000 shares of Summit preferred stock, convertible into common stock at a 1:1,000 ratio.¹ Once complete, AstraZeneca will hold rights equivalent to approximately 12.0% of Summit's outstanding common stock, or about 10.6% on a fully diluted basis.¹ Closing is expected within 1 week. Converting the shares into common stock will require regulatory clearances, AstraZeneca said in a company press release.¹
"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," said Susan Galbraith, PhD, AstraZeneca's executive vice president of oncology hematology R&D, in the release.¹ "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."
What will the sonesitatug vedotin-ivonescimab collaboration study?
AstraZeneca and Summit also signed a clinical collaboration agreement to evaluate sonesitatug vedotin (Sone-Ve), an investigational claudin-18.2 (CLDN18.2)-targeted ADC carrying a monomethyl auristatin E payload, in combination with ivonescimab. The companies intend to initiate trials in gastrointestinal cancers under the agreement imminently, contributing their own medicines and sharing trial costs while retaining commercial rights to each.¹
The companies also signed a memorandum of understanding outlining intent to launch a broader global development program pairing ivonescimab with additional AstraZeneca cancer medicines, including other ADCs. Maky Zanganeh, DDS, Summit's president and co-CEO, said in the release that the agreements broaden ivonescimab's development plan and open trials combining it with novel anti-cancer compounds, including ADCs.¹
What clinical evidence supports pairing the 2 drugs?
AstraZeneca has reported that sonesitatug vedotin met its primary endpoint in the phase 3 CLARITY-Gastric01 trial, showing a statistically significant and clinically meaningful overall survival improvement among patients with 2nd- and later-line claudin18.2-positive advanced gastric or gastroesophageal junction cancer, versus investigator's choice of therapy. Full results are expected at the European Society for Medical Oncology Congress 2026.¹ A fuller company update on that trial specified dual primary endpoints were met, though progression-free survival by independent central review did not reach statistical significance.²
