Tokyo - Daiichi Sankyo Company, Limited (hereafter, Daiichi Sankyo) today announced that ENHERTU, a HER2 directed antibody drug conjugate, is now available by prescription in the U.S.

ENHERTU was granted accelerated approval by the U.S. Food and Drug Administration (FDA) on December 20, 2019 for the treatment of adult patients with unresectable or metastatic HER2 positive breast cancer who have received two or more prior anti-HER2-based regimens in the metastatic setting. This indication is approved under accelerated approval based on tumor response rate and duration of response. Continued approval for this indication may be contingent upon verification and description of clinical benefit in a confirmatory trial.

'Many patients with this aggressive form of metastatic breast cancer continue to face tumor progression despite being treated with two or more HER2 directed treatment regimens,' said Ken Keller, President and CEO, Daiichi Sankyo, Inc. 'We are proud that ENHERTU is now available in the U.S. nearly four months ahead of our original goal. Physicians now have a new specifically engineered HER2 directed antibody drug conjugate with demonstrated durable efficacy that may change the way these patients are treated.'

In the single-arm, phase 2 DESTINY-Breast01 trial that included 184 female patients with HER2 positive metastatic breast cancer, ENHERTU (5.4 mg/kg) achieved a confirmed objective response rate of 60.3% (n=111; 95% CI: 52.9-67.4), including a 4.3% complete response rate (n=8) and a 56.0% partial response rate (n=103).[1] The median duration of response was 14.8 months (n=111; 95% CI: 13.8-16.9).

ENHERTU is approved with a Boxed WARNING for Interstitial Lung Disease (ILD)/pneumonitis and Embryo-Fetal Toxicity. The safety of ENHERTU has been evaluated in a pooled analysis of 234 patients with unresectable or metastatic HER2 positive breast cancer who received at least one dose of ENHERTU (5.4 mg/kg) in the DESTINY-Breast01 trial and a phase 1 trial. ILD occurred in 9% of patients. Fatal outcomes due to ILD and/or pneumonitis occurred in six patients (2.6%) - two deaths already reported from the phase 1 trial and four deaths already reported in the phase 2 DESTINY-Breast01 trial. Patients and physicians should be aware of ILD/pneumonitis and patients should be actively monitored for potential signs and symptoms. If ILD/pneumonitis is identified, it should be managed as per the FDA approved Prescribing Information. Management may require dose modification or treatment discontinuation and steroid treatment. ENHERTU can cause fetal harm when administered to a pregnant woman. The most common adverse reactions (frequency 20%) were nausea, fatigue, vomiting, alopecia, constipation, decreased appetite, anemia, neutropenia, diarrhea, leukopenia, cough and thrombocytopenia.

Daiichi Sankyo and AstraZeneca are committed to ensuring that patients in the U.S. who are prescribed ENHERTU can access the medication and receive necessary financial support. Provider and patient support, reimbursement and distribution for ENHERTU in the U.S. will be accessible by visiting www.ENHERTU4U.com or calling 1-833-ENHERTU (1-833-364-3788).

About ENHERTU

ENHERTU (fam-trastuzumab deruxtecan-nxki), formerly known as DS-8201, is the lead product in the ADC Franchise of the Daiichi Sankyo Cancer Enterprise and the most advanced program in AstraZeneca's ADC Scientific platform. ADCs are targeted cancer medicines 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.

Designed using Daiichi Sankyo's proprietary DXd ADC technology, ENHERTU is comprised of a HER2 monoclonal antibody attached to a novel topoisomerase I inhibitor payload by a tetrapeptide-based linker.

ENHERTU received Priority Review, Breakthrough Therapy Designation, and Fast Track Designation from the FDA for the treatment of select patients with HER2 positive metastatic breast cancer.

About the Collaboration between Daiichi Sankyo and AstraZeneca

In March 2019, Daiichi Sankyo and AstraZeneca entered into a global collaboration to jointly develop and commercialize fam-trastuzumab deruxtecan-nxki as a potential new medicine worldwide, except in Japan where Daiichi Sankyo will maintain exclusive rights. Daiichi Sankyo will be solely responsible for the manufacturing and supply.

About the Clinical Development Program

A comprehensive development program for fam-trastuzumab deruxtecan-nxki is underway globally with five pivotal trials in HER2 expressing metastatic breast and gastric cancer, including a trial in patients with metastatic breast cancer and low levels of HER2 expression (HER2 low). Phase 2 trials are underway for HER2 expressing advanced colorectal cancer as well as metastatic non-squamous HER2 overexpressing or HER2 mutated non-small cell lung cancer. Trials in combination with other anticancer treatments, such as immunotherapy, also are underway.

A regulatory submission also has been made to Japan's Ministry of Health, Labour and Welfare (MHLW) for the treatment of HER2 positive metastatic breast cancer, and it has previously received SAKIGAKE designation for the treatment of advanced HER2 positive gastric or gastroesophageal junction cancer by Japan's MHLW.

About Daiichi Sankyo

Daiichi Sankyo Group is dedicated to the creation and supply of innovative pharmaceutical therapies to improve standards of care and address diversified, unmet medical needs of people globally by leveraging our world-class science and technology. With more than 100 years of scientific expertise and a presence in more than 20 countries, Daiichi Sankyo and its 15,000 employees around the world draw upon a rich legacy of innovation and a robust pipeline of promising new medicines to help people. In addition to a strong portfolio of medicines for cardiovascular diseases, under the Group's 2025 Vision to become a 'Global Pharma Innovator with Competitive Advantage in Oncology,' Daiichi Sankyo is primarily focused on providing novel therapies in oncology, as well as other research areas centered around rare diseases and immune disorders.

Contact:

Jennifer Brennan

Tel: +1 908 992 6631

Email: jbrennan2@dsi.com

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