AstraZeneca and Daiichi Sankyo's Enhertu Achieves Breakthrough in Early-Stage Breast Cancer Treatment

Positive Results in Phase 3 Trial for High-Risk HER2-Positive Breast Cancer

AstraZeneca and Daiichi Sankyo have announced significant success in their latest phase 3 trial for the oncology drug Enhertu. The Destiny-Breast11 trial demonstrated that Enhertu, when used in combination with other treatments, provided a statistically significant and clinically meaningful improvement in pathologic complete response (pCR) for patients with high-risk, locally advanced HER2-positive early-stage breast cancer.

The trial compared Enhertu followed by paclitaxel, Herceptin, and Perjeta (THP) against the current standard of care (SOC) in pre-surgical treatment. The SOC typically includes chemotherapies doxorubicin and cyclophosphamide, followed by the THP regimen. This marks a crucial advancement in the treatment of early-stage breast cancer, where achieving pCR is associated with improved long-term outcomes.

Susan Galbraith, head of oncology hematology R&D for AstraZeneca, emphasized the potential impact of these results, stating, "Enhertu is already an important treatment option in the metastatic setting and these data have the potential to allow this medicine to move into early stages of disease where cure is possible."

Expanding Enhertu's Treatment Landscape

The success in early-stage breast cancer builds upon Enhertu's growing list of achievements. Less than three weeks prior to this announcement, AstraZeneca and Daiichi Sankyo reported positive results from the Destiny-Breast09 trial, where Enhertu and Roche's Perjeta outperformed the THP regimen in delaying tumor progression or death in patients with newly diagnosed HER2-positive metastatic breast cancer.

Since its initial FDA approval in 2019 for third-line use in HER2-positive unresectable or metastatic breast cancer, Enhertu has received six additional label expansions. Notable among these is the January endorsement for patients with HER2-low or HER2-ultralow metastatic breast cancer, further broadening its application across various breast cancer subtypes.

Ken Takeshita, Daiichi's R&D chief, highlighted the significance of these findings for high-risk patients, noting, "There are still many patients with early-stage breast cancer who do not achieve a pathologic complete response with treatment in the neoadjuvant setting, increasing the risk of disease recurrence."

Financial Implications and Future Outlook

The expanding treatment landscape for Enhertu is reflected in its robust sales figures. In Daiichi's 2024 fiscal year, which ended in March, Enhertu recorded sales of $3.75 billion. The company projects sales to reach 662 billion Japanese yen (approximately $4.6 billion) in the current fiscal year, underscoring the drug's growing importance in the oncology market.

As AstraZeneca and Daiichi Sankyo prepare to share the Destiny-Breast11 trial data with regulatory authorities and present them at future medical conferences, the pharmaceutical industry eagerly anticipates the potential for Enhertu to reshape early-stage breast cancer treatment protocols. The companies are also continuing to investigate Enhertu in several other ongoing breast cancer trials, including the Destiny-Breast05 study, which is evaluating the treatment in the high-risk adjuvant early HER2-positive setting.