第一三共与阿斯利康联合Summit开展Datroway联合依沃西单抗跨瘤种临床合作，拟启动一线三阴性乳腺癌III期试验

Daiichi Sankyo and AstraZeneca Enter into Clinical Trial Collaboration with
Summit Therapeutics to Evaluate Datroway® in Combination with
Ivonescimab Across Multiple Tumor Types

Tokyo – (October 2, 2026) – Daiichi Sankyo (TSE: 4568) and AstraZeneca (LSE/STO/NYSE: AZN) have entered
into a clinical trial collaboration agreement with Summit Therapeutics Inc. (Nasdaq: SMMT) to evaluate Datroway®
(datopotamab deruxtecan) in combination with ivonescimab across multiple tumor types including lung and breast
cancers. The companies intend to begin with a phase 3 trial in first-line triple negative breast cancer (TNBC).

Datroway is a specifically engineered TROP2 directed DXd antibody drug conjugate (ADC) discovered by Daiichi
Sankyo and being jointly developed and commercialized by Daiichi Sankyo and AstraZeneca.

“At Daiichi Sankyo, we are focused on maximizing the potential of our DXd antibody drug conjugate portfolio
through innovative combinations and strategic collaborations that support the continued advancement of our
pipeline,” said John Tsai, MD, Global Head, R&D, Daiichi Sankyo. “We are encouraged by the opportunity to
explore ivonescimab in combination with Datroway to potentially deliver clinically meaningful benefit to patients.”

“Central to our strategy to transform cancer outcomes is harnessing the power of immunotherapy and antibody
drug conjugate combinations to drive deeper, more durable responses,” said Susan Galbraith, Executive Vice
President, Oncology Hematology R&D, AstraZeneca. “We believe the combination of Datroway and ivonescimab
has the potential to make a meaningful difference in multiple tumor types including lung and breast cancers.”

“We believe this collaboration with Daiichi Sankyo and AstraZeneca reflects increasing conviction in ivonescimab’s
potential as a foundational next-generation immunotherapy and advances our ambition for ivonescimab to become
the global PD-1/VEGF partner of choice for novel combinations,” said Maky Zanganeh, President and Co-Chief
Executive Officer, Summit Therapeutics. “Beginning with a phase 3 study in first-line triple negative breast cancer,
this collaboration represents an important expansion of Summit’s global development program into breast cancer
and a path for additional solid tumor settings.”

Under the terms of the agreement, each company will contribute their respective compound for the planned
combination trials, which will be sponsored by AstraZeneca or Daiichi Sankyo. AstraZeneca, Daiichi Sankyo and
Summit will each contribute to trial costs, and each company will retain development and commercial rights to their
respective medicines.

Ivonescimab is a novel, potential first-in-class bispecific antibody combining the effects of immunotherapy via a
blockade of PD-1 with the anti-angiogenesis effects associated with blocking VEGF into a single molecule.

About Datroway
Datroway (datopotamab deruxtecan; datopotamab deruxtecan -dlnk in the U.S. only) is a TROP2 directed ADC.
Designed using the proprietary DXd ADC Technology of Daiichi Sankyo, Datroway is one of seven DXd ADCs in
the oncology pipeline of Daiichi Sankyo, and one of the most advanced programs in AstraZeneca’s ADC scientific
platform. Datroway is comprised of a humanized anti-TROP2 IgG1 monoclonal antibody, developed in
collaboration with Sapporo Medical University, attached to a number of topoisomerase I inhibitor payloads (an
exatecan derivative, DXd) via tetrapeptide-based cleavable linkers.

Datroway (6 mg/kg) is approved in more than 30 countries/regions worldwide for the treatment of adult patients
with unresectable or metastatic TNBC who are not candidates for PD-1/PD-L1 inhibitor therapy based on the
results from the TROPION-Breast02 trial.
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Datroway (6 mg/kg) is approved in more than 45 countries/regions worldwide for the treatment of adult patients
with unresectable or metastatic HR positive, HER2 negative (IHC 0, IHC 1+ or IHC 2+/ISH-) breast cancer who
have received prior endocrine-based therapy and chemotherapy for unresectable or metastatic disease based on
the results from the TROPION-Breast01 trial.

Datroway (6 mg/kg) is approved in Brazil, Russia, Singapore and the U.S. for the treatment of adult patients with
locally advanced or metastatic EGFR-mutated non-small cell lung cancer (NSCLC) who have received prior
EGFR-directed therapy and platinum-based chemotherapy based on the results from TROPION-Lung05 and
TROPION-Lung01 trials. Continued approval for this indication in the U.S. may be contingent upon verification and
description of clinical benefit in a confirmatory trial.

About the Datroway Clinical Development Program
A comprehensive global clinical development program is underway with more than 20 trials evaluating the efficacy
and safety of Datroway across multiple cancers, including non-small cell lung cancer (NSCLC), TNBC and
urothelial cancer. The program includes eight phase 3 trials in lung cancer, five phase 3 trials in breast cancer and
one phase 3 and one phase 2/3 trial in urothelial cancer evaluating Datroway as a monotherapy and in
combination with other cancer treatments in various settings.

About the Daiichi Sankyo and AstraZeneca Collaboration
Daiichi Sankyo and AstraZeneca entered into a global collaboration to jointly develop and commercialize Enhertu ®
in March 2019 and Datroway in July 2020, except in Japan where Daiichi Sankyo maintains exclusive rights for
each ADC. Daiichi Sankyo is responsible for the manufacturing and supply of Enhertu and Datroway.

About the ADC Portfolio of Daiichi Sankyo
The Daiichi Sankyo ADC portfolio consists of nine ADCs in clinical development crafted from ADC technology
discovered in-house by Daiichi Sankyo.

The DXd ADC Technology platform of Daiichi Sankyo consists of seven ADCs in clinical development where each
ADC is comprised of a monoclonal antibody attached to a number of topoisomerase I inhibitor payloads (an
exatecan derivative, DXd) via tetrapeptide-based cleavable linkers. The DXd ADCs include Enhertu and Datroway,
which are being jointly developed and commercialized globally with AstraZeneca, and ifinatamab deruxtecan
(I-DXd), raludotatug deruxtecan (R-DXd) and patritumab deruxtecan (HER3-DXd), which are being jointly
developed and commercialized globally with Merck & Co., Inc, Rahway, NJ, USA. DS-3939 and DS3790 are being
developed by Daiichi Sankyo.

Additional ADCs being developed by Daiichi Sankyo include DS3610, which consists of an antibody attached to a
novel payload that acts as an agonist of STING, and DS1025, which consists of a CD25 directed antibody
attached to an immuno-oncology optimized cytotoxic payload.

Ifinatamab deruxtecan, raludotatug deruxtecan, patritumab deruxtecan, DS-3939, DS3610, DS3790 and DS1025
are investigational medicines that have not been approved for any indication in any country. Safety and efficacy
have not been established.

About Daiichi Sankyo
Daiichi Sankyo (TSE: 4568) is a global healthcare company committed to becoming a trusted healthcare innovator,
transforming the lives of people through its strength in science and technology. The company discovers and
develops new standards of care to address diverse medical needs to fulfill its purpose of contributing to the
enrichment of quality of life around the world. With a strategic focus on oncology, Daiichi Sankyo is advancing an
industry-leading antibody drug conjugate portfolio along with identifying new breakthrough generating technologies

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to deliver practice-changing medicines to patients, healthcare professionals and society. For more information,
please visit www.daiichisankyo.com.

MEDIA CONTACTS: INVESTOR RELATIONS CONTACT:
Global: [email protected]
Jennifer Brennan
[email protected]
+ 1 908 900 3183 (mobile)

Japan:
[email protected]

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