FDA Grants AstraZeneca and Daiichi Sankyo’s Breast Cancer Drug Its Fifth Breakthrough Label

AstraZeneca and Daiichi Sankyo secured another FDA Breakthrough Therapy Designation for Enhertu (trastuzumab deruxtecan), after the DESTINY-Breast04 trial demonstrated significantly improved survival in patients with HER2-low metastatic breast cancer.

The DESTINY-Breast04 is the first-ever Phase III HER2-directed therapy trial in patients with HER2-low metastatic breast cancer to show clinically meaningful benefit in progression-free and overall survival compared to standard treatment. While HER2-positive diagnosis takes up around 20% of breast cancer cases, about 55% of primary breast cancers are considered HER2-low (low-level expression of human epidermal growth factor receptor 2, immunohistochemically 1+ or 2+ and lack of HER2 gene amplification measured by in-situ hybridization).

A FDA breakthrough label means that a drug could offer remarkably better treatment for a serious condition and address a significant unmet medical need. Boasting this designation, novel therapeutics are fast-tracked by the FDA and benefit from advanced development with a six-month review period.

Related Article: Recent Advances in Breast Cancer Treatments: An Overview

An ADC Drug Targeting HER-2 Expressing Cells

Enhertu is a HER2-directed antibody-drug conjugate (ADC) for treating unresectable or metastatic HER2-positive breast cancer types, consisting of a HER2 monoclonal antibody attached to a potent topoisomerase I inhibitor payload connected by a tumor-selective cleavable linker. 

Susan Galbraith, Executive Vice President of AstraZeneca Oncology R&D said: “Today’s news is a significant validation of the potential we see for the historic DESTINY-Breast04 trial to enable a paradigm shift in how breast cancer is classified by targeting the full spectrum of HER2 expression.” 

Credit Suisse analysts said the expansion of Enhertu’s use for HER2-low cancers could increase sales by $3 billion, fulfilling the multibillion-dollar predictions that prompted AstraZeneca to pay $1.4 billion upfront to Japan’s Daiichi Sankyo for licensing rights to the drug in a deal that could value up to $6.9 billion.

Author

Fujie Tham