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AstraZeneca’s AZN stock rose more than 5% on Monday after it presented some key cancer data at the European Society for Medical Oncology (ESMO) Congress over the weekend.
Detailed data from the head-to-head DESTINY-Breast03 phase III study showed that AstraZeneca and partner Daiichi Sankyo's breast cancer drug, Enhertu reduced the risk of death or tumor progression by 72% in patients with HER2-positive metastatic breast cancer previously treated with Roche’s RHHBY Kadcyla (trastuzumab emtansine (T-DM1)) and a taxane. Kadcyla, also HER2-directed antibody drug conjugate (ADC) like Enhertu, is the current standard of treatment for previously treated HER2-positive metastatic breast cancer.
In the study, progression free survival (PFE - a key secondary endpoint), as assessed by investigators, in patients treated with Enhertu was 25.1 months, almost three times of 7.2 months for Kadcyla. In the previously treated HER2-positive metastatic breast cancer population, patients usually experience disease progression in less than a year when treated with current available HER2-directed treatments. Enhertu almost tripled PFS and provided a disease control rate exceeding 95% (compared to 77% for Kadcyla). AstraZeneca believes that this data on Enhertu is “groundbreaking” and shows that the drug has the potential to become the new standard of care for previously treated HER2-positive metastatic breast cancer.
Though the overall survival (OS - a key secondary endpoint) data are still immature and not statistically significant, the study indicated a strong trend toward improved OS compared to T-DM1.
The confirmed objective response rate (ORR) was 79.7% in the Enhertu arm versus 34.2% in the Kadcyla arm
Please note that Enhertu is already approved to treat unresectable or metastatic HER2-positive breast cancer in patients who have received two or more prior anti-HER2-based regimens in the metastatic setting based on data from the DESTINY-Breast01 study. AstraZeneca also presented updated data from DESTINY-Breast01 study at ESMO. The data showed an impressive median OS of 29.1 months in HER2-positive patients following two or more HER2-based regimens.
This year so far, AstraZeneca’s shares are up 17% compared with an increase of 8.5% for the industry.
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AstraZeneca had acquired joint development and commercialization rights to Enhertu from Japan’s Daiichi Sankyo in April 2019. Sales of Enhertu in the United States are recognized by Daiichi Sankyo while AstraZeneca records its share of profit from the sales of the drug in the United States as collaboration revenues. Enhertu was approved for its second indication, HER2+, metastatic gastric cancer in January 2021 while it is also being evaluated for other cancer types.