Daiichi Sankyo will present new clinical research across its oncology portfolio with more than 25 abstracts in multiple cancers at the 2026 American Society of Clinical Oncology Annual Meeting. Data at ASCO will highlight the company?s progress toward advancing new standards of care for patients with cancer, including new analyses from five landmark trials in breast and gastric cancer, including the DESTINY-Breast05, DESTINY-Breast06, DESTINY-Breast09 and DESTINY-Gastric04 phase 3 trials of Enhertu (trastuzumab deruxtecan), and the TROPION-Breast02 phase 3 trial of Datroway (datopotamab deruxtecan). Additional results from earlier phase trials as well as trials-in-progress across new medicines being developed through the company?s breakthrough generating technology, a platform-based drug discovery model designed to deliver innovative medicines to patients faster, will be highlighted.

Data from DESTINY-Breast05 formed the basis of one of two new Enhertu indications recently approved in the U.S. for certain patients with early-stage HER2 positive breast cancer and data from DESTINY-Gastric04 was included as part of a label update to expand the use of Enhertu in Japan and China to include the second-line treatment of patients with HER2 positive metastatic gastric cancer. Additionally, results from TROPION-Breast02 formed the basis of the recent U.S. approval of Datroway in patients with metastatic triple negative breast cancer who are not candidates for PD-1/PD-L1 inhibitor therapy, the first antibody drug conjugate to be approved in this setting of triple negative breast cancer. Additional research updates across several additional HER2 expressing cancers include oral and poster sessions highlighting the preliminary safety run-in results from the DESTINY-Ovarian01 phase 3 trial evaluating Enhertu in combination with bevacizumab compared to bevacizumab monotherapy as a first-line maintenance therapy in patients with HER2 expressing ovarian cancer; the primary analysis from part 1 of the DESTINY-PanTumor03 phase 2 trial evaluating Enhertu in pretreated patients in China with HER2 positive (IHC 3+) solid tumors (excluding breast and gastric cancer); and, findings from the MYTHOS phase 2 trial evaluating Enhertu in patients with HER2-low recurrent or metastatic salivary gland cancer.

Additional breast and gastric cancer data for Enhertu include an oral presentation from one arm of the DESTINY-Breast07 phase 1b/2 trial evaluating Enhertu in combination with durvalumab as a first-line treatment in patients with HER2 positive metastatic breast cancer and a poster presentation highlighting a safety analysis from the DESTINY-Gastric03 phase 1b/2 trial evaluating Enhertu in combination with chemotherapy and immunotherapy as a first-line treatment in patients with HER2 expressing metastatic gastric cancer, gastroesophageal junction adenocarcinoma or esophageal adenocarcinoma. Results from cohort two of the EPOC2203 phase 1b/2 trial evaluating Enhertu in combination with nivolumab and capecitabine and oxaliplatin in patients with HER2 low gastroesophageal adenocarcinoma and an exploratory analysis of translational data from the EPOC2003 phase 2 trial evaluating neoadjuvant chemotherapy in combination with Enhertu in patients with HER2 positive gastric cancer will be highlighted as poster presentations. Poster presentations will include a trial-in-progress update of REJOICE-Ovarian01 for the phase 3 part of a phase 2/3 trial evaluating raludotatug deruxtecan (R-DXd) compared to treatment of physician?s choice in patients with platinum-resistant ovarian cancer.

Two additional poster presentations will highlight an exposure-response analysis and a population pharmacokinetic analysis of data from both the REJOICE-Ovarian01 phase 2/3 trial and the phase 1 trial evaluating raludotatug deruxtecan in patients with advanced ovarian cancer or renal cell carcinoma. An oral presentation will highlight results from a phase 1/2 trial of Vanflyta (quizartinib) plus decitabine and venetoclax in patients with newly diagnosed or relapsed/refractory FLT3-ITD acute myeloid leukemia. Trials-in-progress poster presentations across the DXd ADC portfolio include the TROPION-Urothelial03 phase 2/3 trial evaluating Datroway and platinum chemotherapy compared to gemcitabine plus platinum chemotherapy in patients with locally advanced or metastatic urothelial carcinoma; the HERTHENA-Breast04 phase 3 trial evaluating patritumab deruxtecan (HER3-DXd) compared to treatment of physician?s choice in patients with HR positive, HER2 negative unresectable locally advanced or metastatic breast cancer; and the DESTINY-PanTumor04 hybrid observational trial evaluating Enhertu in patients with HER2 positive (IHC 3+) solid tumors.

Trials-in-progress poster presentations featuring three potential new medicines include DS3610, a STING (stimulator of interferon genes) ADC, in patients with advanced or metastatic solid tumors; DS5361, a small-molecule, nonsense-mediated mRNA decay inhibitor, in patients with advanced or metastatic solid tumors; and, DS9051, a novel targeted protein degradation molecule, in patients with advanced or metastatic adrenocortical carcinoma or metastatic castration-resistant prostate cancer. The Daiichi Sankyo ADC portfolio consists of eight 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. An additional ADC being developed by Daiichi Sankyo is DS3610, which consists of an antibody attached to a novel payload that acts as an agonist of STING.

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