AstraZeneca has announced two Lancet Oncology publications of its Phase I dose-expansion results of DS-8201 (trastuzumab deruxtecan) in HER2-positive metastatic breast and gastric cancer.
The HER2-targeting antibody drug conjugate (ADC) and potential new medicine was evaluated in heavily-pretreated patients with HER2-positive metastatic breast cancer and gastric cancer.
The breast cancer trial found a confirmed objective response rate of 59.5% and a disease control rate of 93.7% at a recommended expansion dose of 5.4 or 6.4 mg/kg.
The second manuscript also reported a confirmed gastric cancer overall response rate of 43.2% and a disease control rate of 79.5%.
There was also a 20.7 months median duration of response in HER2-positive metastatic breast cancer patients previously treated with trastuzumab emtansine, and a 7.0 months median duration of response in HER2-positive metastatic gastric cancer patients previously treated with trastuzumab.
Patients enrolled in this part of the trial had a median of seven prior lines of treatment, including trastuzumab and trastuzumab emtansine, and in 86% of cases, pertuzumab.
“For patients with HER2-positive metastatic breast cancer that progresses after trastuzumab, pertuzumab, and trastuzumab emtansine, optimal treatment is not clearly defined and choices may be limited. These results demonstrate preliminary clinically-meaningful response rates with an impressive duration of response, supporting further development and suggesting a potential role for trastuzumab deruxtecan as a HER2-targeted therapy option in this setting,” said Kenji Tamura, department of breast and medical oncology National Cancer Center Hospital, Tokyo, Japan, and lead author on the manuscript.
Around one in five breast and gastric cancers are HER2-positive, meaning that there are several unmet treatment needs.
Currently, there are no approved HER2-targeting therapies for patients with HER2-positive advanced gastric cancer that progresses after treatment with a trastuzumab-containing regimen.