FDA Grants Breakthrough Therapy Designation to DS-8201

Daiichi Sankyo Company announced the U.S. Food and Drug Administration (FDA) has granted Breakthrough Therapy designation to DS-8201, an investigational HER2-targeting antibody drug conjugate (ADC), for the treatment of patients with HER2-positive, locally advanced or metastatic breast cancer who have been treated with trastuzumab and pertuzumab and have disease progression after ado-trastuzumab emtansine (T-DM1).

Breakthrough Therapy designation is designed to expedite the development and review of medicines that may demonstrate substantial benefit over currently available treatments in order to ensure that patients with serious diseases have access to new treatments as soon as possible. Currently, there is no FDA-approved therapy for patients with HER2-positive metastatic breast cancer with disease progression following treatment with other HER2-targeting agents trastuzumab, pertuzumab and T-DM1.

"The Breakthrough Therapy designation for DS-8201 in HER2-positive metastatic breast cancer acknowledges the unmet medical need these patients face when currently approved treatments no longer control their disease," said Antoine Yver, MD, MSc, Executive Vice President and Global Head, Oncology Research and Development, Daiichi Sankyo. "We remain committed to rapidly progressing the development of DS-8201 and look forward to working closely with the FDA to potentially bring this new treatment option to patients with metastatic breast cancer as quickly as possible."

The Breakthrough Therapy designation was granted based on the results of the ongoing phase 1 study assessing the safety, tolerability and preliminary efficacy of DS-8201. In the phase 1 study, no dose limiting toxicities were observed, and the maximum tolerated dose was not reached. Preliminary results of DS-8201 from a subgroup analysis of HER2-expressing metastatic breast cancer pre-treated with trastuzumab, pertuzumab and T-DM1 were recently presented at the 2017 American Society of Clinical Oncology (ASCO) annual meeting.1

DS-8201 is the lead product in the ADC Franchise of the Daiichi Sankyo Cancer Enterprise. ADCs are a type of targeted cancer medicine that deliver cytotoxic chemotherapy (payload) to cancer cells via a linker attached to a monoclonal antibody that binds to a specific target expressed on cancer cells. Using Daiichi Sankyo's proprietary ADC technology, DS-8201 is a smart chemotherapy comprised of a humanized HER2 antibody attached to a novel topoisomerase I inhibitor (DXd) payload by a tetrapeptide linker. It is designed to deliver enhanced cell destruction upon release inside the cell and reduce systemic exposure to the cytotoxic payload (or chemotherapy) compared to the way chemotherapy is commonly delivered.

In addition to Breakthrough Therapy designation, the FDA has granted Fast Track designation to DS-8201 for the treatment of HER2-positive unresectable and/or metastatic breast cancer in patients who have progressed after prior treatment with HER2-targeted therapies including T-DM1. DS-8201 is currently in phase 1 clinical development for HER2-positive advanced or metastatic breast cancer and gastric cancer, HER2 low-expressing breast cancer and other HER2-expressing solid tumors. DS-8201 is an investigational agent that has not been approved for any indication in any country. Safety and efficacy have not been established, and there is no guarantee DS-8201 will become commercially available.

About one in five patients with breast cancer overexpress HER2, a tyrosine kinase receptor growth-promoting protein found on the surface of some cancer cells, which is associated with aggressive disease.  Many tumors advance to the point where no currently approved HER2-targeting treatment continues to control the disease. Furthermore, there is no standard of care for HER2-positive tumors following treatment with trastuzumab, pertuzumab and T-DM1.