Positive results from the TROPION-Breast02 Phase III trial showed Datroway (datopotamab deruxtecan) demonstrated a statistically significant and clinically meaningful improvement for the dual primary endpoints of overall survival (OS) and progression-free survival (PFS) compared to investigator's choice of chemotherapy as 1st-line treatment for patients with locally recurrent inoperable or metastatic triple-negative breast cancer (TNBC) for whom immunotherapy was not an option.

These late-breaking results will be presented today during a Proffered Paper session at the 2025 European Society for Medical Oncology (ESMO) Congress in Berlin, Germany (abstract #LBA21).

Datroway demonstrated a 5.0-month improvement in median OS compared to chemotherapy (hazard ratio [HR] 0.79; 95% confidence interval [CI] 0.64-0.98; p=0.0291). Median OS was 23.7 months for patients treated with Datroway versus 18.7 months for those treated with chemotherapy.

Datroway reduced the risk of disease progression or death by 43% compared to chemotherapy (HR 0.57; 95% CI 0.47-0.69; p<0.0001) as assessed by blinded independent central review (BICR). Median PFS was 10.8 months for patients treated with Datroway versus 5.6 months for those treated with chemotherapy.

In addition to patients whose tumours did not express PD-L1, TROPION-Breast02 enrolled patients with PD-L1 expressing tumours for whom immunotherapy was not an option due to other factors.

Rebecca Dent, MD, FRCP, Professor and Deputy Chief Executive Officer, National Cancer Centre Singapore, and principal investigator for the trial, said: "In TROPION-Breast02, datopotamab deruxtecan meaningfully extended patients' lives and nearly doubled their time without disease progression. These are significant outcomes for patients with metastatic triple-negative breast cancer who are not suitable candidates for immunotherapy, and remarkable results considering the trial included a subset of patients with highly aggressive disease who are often excluded from research in this setting."

Susan Galbraith, Executive Vice President, Oncology Haematology R&D, AstraZeneca, said: "The TROPION-Breast02 results show for the first time that these triple-negative breast cancer patients may have an alternative to chemotherapy in the 1st-line setting that can both delay the progression of their disease and prolong their lives. For Datroway to have so significantly improved patient outcomes in the 1st-line metastatic setting as monotherapy also gives us great confidence in its potential in combination with Imfinzi, and in the early-stage, potentially curative setting where our next studies are ongoing."

Ken Takeshita, Global Head, R&D, Daiichi Sankyo, said: "Patients with metastatic triple-negative breast cancer have one of the worst prognoses of any breast cancer subtype, and for those who are not candidates for immunotherapy, chemotherapy has long been the 1st-line standard of care. The TROPION-Breast02 results show Datroway has the potential to replace traditional chemotherapy in this setting and to meaningfully improve survival of patients."

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

Summary of efficacy results

As of 25 August 2025, data cut-off, 45 patients (14%) remained on Datroway and 8 patients (3%) on chemotherapy. BICR, blinded independent central review; ​CI, confidence interval; CR, complete response; DoR, duration of response; HR, hazard ratio; ICC, investigator's choice of chemotherapy; ORR, objective response rate; OS, overall survival; PFS, progression-free survival; PR, partial response

Patients receiving Datroway were on treatment more than twice as long as those receiving chemotherapy (median duration of treatment of 8.5 versus 4.1 months) and experienced a lower rate of treatment-related adverse events (TRAEs) associated with discontinuation (4% versus 7%). Grade 3 or higher TRAEs occurred in 33% and 29% of patients in the Datroway and chemotherapy arms, respectively. The most common Grade 3 or higher TRAEs were neutropenia (3%, 13%), stomatitis (8%, 0%), leukopenia (<1%, 4%), fatigue (3%, 3%), vomiting (1%, <1%), anaemia (2%, 3%), alopecia (0%, <1%), peripheral neuropathy (0%, 2%), dry eye (1%, 0%), nausea (<1%, <1%), decreased appetite (<1%, <1%) and constipation (<1%, 0%). There was one Grade 5 interstitial lung disease (ILD) event in the Datroway arm adjudicated as drug-related by an independent committee. This event was characterised as Grade 3 pneumonitis and cause of death was attributed to disease progression by the treating investigator.

AstraZeneca and Daiichi Sankyo will also present updated results from the BEGONIA Phase Ib/II trial at ESMO showing Datroway in combination with Imfinzi (durvalumab) continued to demonstrate robust anti-tumour activity as 1st-line treatment for patients with metastatic TNBC across PD-L1 expression levels and specifically in those with high PD-L1-expressing tumours. These results will be presented on Monday, 20 October (abstract #555MO).

AstraZeneca and Daiichi Sankyo are evaluating Datroway across stages and treatment settings of TNBC in three additional Phase III trials. TROPION-Breast03 is evaluating Datroway with or without Imfinzi in patients with Stage I-III TNBC with residual invasive disease after neoadjuvant systemic therapy. TROPION-Breast04 is evaluating neoadjuvant Datroway plus Imfinzi in patients with Stage II-III triple-negative or hormone receptor (HR)-low, HER2-low or -negative breast cancer. TROPION-Breast05 is evaluating 1st-line Datroway with or without Imfinzi in patients with metastatic TNBC whose tumours express PD-L1.

Notes

Triple-negative breast cancer
TNBC accounts for approximately 15% of all breast cancer cases, with an estimated 345,000 diagnoses globally each year.^1,2 TNBC is diagnosed more frequently in younger and premenopausal women, and is more prevalent in Black and Hispanic women.^3-5 Metastatic TNBC is the most aggressive type of breast cancer and has one of the worst prognoses, with median OS of just 12 to 18 months and only about 14% of patients living five years following diagnosis.^3,6,7

While some breast cancers may test positive for oestrogen receptors, progesterone receptors or overexpression of HER2, TNBC tests negative for all three.³ Due to its aggressive nature and absence of common breast cancer receptors, TNBC is characteristically difficult to treat.³ For patients with metastatic disease with PD-L1 expressing tumours, the addition of immunotherapy to chemotherapy has improved outcomes in the 1st-line setting.^8,9 However, for the approximately 70% of patients with metastatic TNBC who are not candidates for immunotherapy, chemotherapy remains the 1st-line standard of care.^10,11

TROP2 is a protein broadly expressed in several solid tumours including TNBC.¹² TROP2 is associated with increased tumour progression and poor survival in patients with breast cancer.^13,14

TROPION-Breast02
TROPION-Breast02 is a global, multicentre, randomised, open-label Phase III trial evaluating the efficacy and safety of Datroway versus investigator's choice of chemotherapy (paclitaxel, nab-paclitaxel, capecitabine, carboplatin or eribulin) in patients with previously untreated locally recurrent inoperable or metastatic TNBC for whom immunotherapy was not an option. This included patients whose tumours did not express PD-L1 as well as patients with PD-L1 expressing tumours who could not receive immunotherapy due to prior exposure in early-stage disease, comorbidities or immunotherapy not being accessible in their geography. Enrolment included patients with de novo or recurrent disease, regardless of disease-free interval, and those with poor prognostic factors such as stable brain metastases.

The dual primary endpoints of TROPION-Breast02 are PFS as assessed by BICR and OS. Key secondary endpoints include PFS as assessed by investigator, objective response rate, duration of response, disease control rate, pharmacokinetics and safety.

TROPION-Breast02 enrolled 644 patients at sites in Africa, Asia, Europe, North America and South America. For more information, visit ClinicalTrials.gov.

Datroway
Datroway (datopotamab deruxtecan; datopotamab deruxtecan-dlnk in the US only) is a TROP2-directed ADC. Designed using Daiichi Sankyo's proprietary DXd ADC Technology, Datroway is one of six DXd ADCs in the oncology pipeline of Daiichi Sankyo, and one of the most advanced programmes in AstraZeneca's ADC scientific platform. Datroway is comprised of a humanised 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 is approved in more than 35 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 results from the TROPION-Breast01 trial.

Datroway is available in the US under accelerated approval 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 results from the TROPION-Lung05 and TROPION-Lung01 trials. Continued approval for this indication in the US may be contingent upon verification and description of clinical benefit in a confirmatory trial. Datroway is approved in Russia for the same population.

Datroway clinical development programme
A comprehensive global clinical development programme is underway with more than 20 trials evaluating the efficacy and safety of Datroway across multiple cancers, including NSCLC, TNBC and urothelial cancer. The programme includes eight Phase III trials in lung cancer and five Phase III trials in breast cancer evaluating Datroway as a monotherapy and in combination with other anticancer treatments in various settings.

Daiichi Sankyo collaboration
AstraZeneca and Daiichi Sankyo entered into a global collaboration to jointly develop and commercialise 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.

AstraZeneca in breast cancer 
Driven by a growing understanding of breast cancer biology, AstraZeneca is challenging, and redefining, the current clinical paradigm for how breast cancer is classified and treated to deliver even more effective treatments to patients in need - with the bold ambition to one day eliminate breast cancer as a cause of death.

AstraZeneca has a comprehensive portfolio of approved and promising compounds in development that leverage different mechanisms of action to address the biologically diverse breast cancer tumour environment.

With Enhertu, AstraZeneca and Daiichi Sankyo are aiming to improve outcomes in previously treated HER2-positive, HER2-low and HER2-ultralow metastatic breast cancer, and are exploring its potential in earlier lines of treatment and in new breast cancer settings.

In HR-positive breast cancer, AstraZeneca continues to improve outcomes with foundational medicines Faslodex (fulvestrant) and Zoladex (goserelin) and aims to reshape the HR-positive space with first-in-class AKT inhibitor, Truqap (capivasertib), the TROP2-directed ADC, Datroway, and next-generation oral SERD and potential new medicine camizestrant.

PARP inhibitor Lynparza (olaparib) is a targeted treatment option that has been studied in early and metastatic breast cancer patients with an inherited BRCA mutation. AstraZeneca with MSD (Merck & Co., Inc. in the US and Canada) continue to research Lynparza in these settings. AstraZeneca is also exploring the potential of saruparib, a potent and selective inhibitor of PARP1, in combination with camizestrant in BRCA-mutated, HR-positive, HER2-negative advanced breast cancer.

To bring much-needed treatment options to patients with triple-negative breast cancer, an aggressive form of breast cancer, AstraZeneca is collaborating with Daiichi Sankyo to evaluate the potential of Datroway alone and in combination with immunotherapy Imfinzi. 

AstraZeneca in oncology
AstraZeneca is leading a revolution in oncology with the ambition to provide cures for cancer in every form, following the science to understand cancer and all its complexities to discover, develop and deliver life-changing medicines to patients.

The Company's focus is on some of the most challenging cancers. It is through persistent innovation that AstraZeneca has built one of the most diverse portfolios and pipelines in the industry, with the potential to catalyse changes in the practice of medicine and transform the patient experience.

AstraZeneca has the vision to redefine cancer care and, one day, eliminate cancer as a cause of death.

AstraZeneca
AstraZeneca (LSE/STO/Nasdaq: AZN) is a global, science-led biopharmaceutical company that focuses on the discovery, development, and commercialisation of prescription medicines in Oncology, Rare Diseases, and BioPharmaceuticals, including Cardiovascular, Renal & Metabolism, and Respiratory & Immunology. Based in Cambridge, UK, AstraZeneca's innovative medicines are sold in more than 125 countries and used by millions of patients worldwide. Please visit astrazeneca.com and follow the Company on Social Media @AstraZeneca.

Contacts
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