AstraZeneca says Enhertu combo showed PFS improvement over THP in trial

Results from the DESTINY-Breast09 Phase III trial showed Enhertu plus pertuzumab demonstrated a highly statistically significant and clinically meaningful improvement in progression-free survival compared to a taxane, trastuzumab and pertuzumab as a first-line treatment for patients with HER2-positive metastatic breast cancer, AstraZeneca announced. Results will be presented today during a special late-breaking oral session at the 2025 American Society of Clinical Oncology Annual Meeting in Chicago, the company noted. In a prespecified interim analysis, Enhertu plus pertuzumab reduced the risk of disease progression or death by 44% versus THP. Median PFS was 40.7 months with Enhertu plus pertuzumab compared to 26.9 months for THP, as assessed by blinded independent central review. The PFS benefit for Enhertu plus pertuzumab versus THP was consistent across subgroups, including for the prespecified stratification factors of de novo or recurrent disease, hormone receptor status and PIK3CA mutation status. Investigator-assessed PFS demonstrated a median PFS of 40.7 months for Enhertu plus pertuzumab compared to 20.7 months for THP, the company noted. Overall survival was not mature at the time of the interim analysis; however, interim OS data showed an early trend favouring the Enhertu combination compared to THP, the company added. Susan Galbraith, Executive Vice President, Oncology Haematology R&D, AstraZeneca (AZN), said: “Bringing Enhertu earlier in the treatment of HER2-positive metastatic breast cancer may represent an important advancement for patients. The DESTINY-Breast09 trial showed the combination of Enhertu and pertuzumab in the first-line setting substantially increased the amount of time before a patient’s cancer progressed compared to standard of care and nearly doubled the number of patients showing no signs of disease on imaging. Establishing a strong therapeutic response as soon as metastatic disease is diagnosed is critical given that about one in three patients do not receive further treatment after progressing in the first-line setting.” Ken Takeshita, Global Head, R&D, Daiichi Sankyo (DSNKY), said: “Enhertu continues to transform the treatment of metastatic breast cancer with the first new data in more than a decade to demonstrate improved outcomes for a broad population of patients with HER2-positive disease compared to THP in the first-line setting. DESTINY-Breast09 shows that initiating treatment with Enhertu in combination with pertuzumab at the time of metastatic diagnosis can delay disease progression.”