On 22 September, AstraZeneca announced positive interim data for the Phase III TROPION-Breast01 trial evaluating Daiichi Sankyo and AstraZeneca’s datopotomab deruxtecan (Dato-DXd) versus the investigator’s choice of chemotherapy in the second-line metastatic setting for patients with hormone receptor-positive (HR+), human epidermal growth factor receptor-2 (HER2) low or negative breast cancer.
The trial data demonstrated a statistically significant and clinically meaningful improvement in progression-free survival (PFS).
The dual primary endpoint of overall survival (OS) exhibited a trend in improvement; however, the data is immature, and the trial will continue pending full analysis.
Dato-DXd is an antibody-drug conjugate (ADC) based on Daiichi Sankyo’s proprietary DXd technology.
The drug consists of a trophoblast cell surface antigen 2 (TROP2) monoclonal antibody conjugated with potent topoisomerase I inhibitor payloads via a highly selective, serum-stable, cleavable linker.
TROP2 is a protein broadly expressed in HR+ and HER2 low or negative breast cancer.
The collaboration between AstraZeneca and Daiichi Sankyo has already resulted in the US Food and Drug Administration's approval of the anti-HER2 ADC Enhertu (trastuzumab deruxtecan) drug for patients with HR+ and HER2-low breast cancer in metastatic or advanced second-line settings.
Dato-DXd faces a major anti-TROP2 ADC competitor, Gilead’s Trodelvy (sacituzumab govitecan).
Trodelvy is approved for patients with HR+ and HER2 negative locally advanced or metastatic breast with prior endocrine-based therapy and at least two or more systemic therapies.
Trodelvy’s approval was based on the TROPICS-02 trial, which boasted statistically significant PFS and OS benefits.
Based on GlobalData’s analyst consensus forecast, the approval has contributed to predicted annual sales of $3.2bn by 2029.
However, Trodelvy exhibited an underwhelming 1.5-month median PFS benefit versus chemotherapy, allowing Dato-DXd to potentially compete in the PFS space.
Additionally, Trodelvy is approved in the third- to fifth-line setting. If a complete analysis of the TROPION-Breast01 trial confirms positive results, Dato-DXd will effectively dominate in the earlier HER2-negative second-line setting, boosting Dato-DXd’s projected annual sales of $2.4bn by 2029.
Regarding side effects, the announcement stated that there were low rates of all-grade interstitial lung disease without revealing the presence of high-grade events.
Daiichi and AstraZeneca display continued persistence in evaluating Dato-DXd across breast cancer subtypes in their Phase III programme with two additional trials in triple-negative breast cancer and expansion into other solid tumour indications, including non-small cell lung cancer.
