DESTINY-Breast03 data showed Enhertu demonstrated a similar benefit in patient subgroups, including those with stable brain metastases, when compared to T-DM1.- AstraZeneca + Daiichi Sankyo
Enhertu is a HER2-directed antibody drug conjugate (ADC) being jointly developed by AstraZeneca and Daiichi Sankyo Company, Limited.
A similar PFS and ORR benefit was observed in exploratory analyses in patients defined by stable brain metastases, hormone receptor status, number of prior lines of therapy, prior pertuzumab treatment, or status of visceral metastasis. In patients with stable brain metastases at baseline, treatment with Enhertu resulted in higher PFS compared to T-DM1 (PFS by blinded independent central review (BICR) hazard ratio [HR] 0.25; 95% confidence interval [CI] 0.13-0.45). Additionally, in this subgroup, Enhertu improved PFS to a median of 15 months versus 3 months for T-DM1.
Confirmed ORR for patients with stable brain metastases at baseline was 67.4% with Enhertu versus 20.5% with T-DM1. A retrospective, non-prespecified evaluation of intracranial response among patients with stable brain metastases who received scans at baseline provided preliminary evidence that treatment with Enhertu is associated with intracranial tumour response and reduction in Central Nervous System disease with 10 (27.8%) complete responses (CR) and 13 (36.1%) partial responses (PR) compared to one (2.8%) CR and 11 (30.6%) PRs in those treated with T-DM1.
The safety profile of the most common adverse events with Enhertu in DESTINY-Breast03 remains consistent with previous clinical trials of Enhertu in breast cancer with no new safety concerns identified. Results were presented in an oral presentation at the 2021 San Antonio Breast Cancer Symposium (SABCS).
Between 30 to 50% of patients with HER2-positive metastatic breast cancer will develop brain metastases, and while increased availability of HER2 therapies has improved systemic disease control, prognosis following the development of brain metastases remains poor.