On July 12, 2023 AstraZeneca and Daiichi Sankyo’s reported that Enhertu (trastuzumab deruxtecan) has been approved in China as a monotherapy for the treatment of adult patients with unresectable or metastatic HER2-low (IHC 1+ or IHC 2+/ISH-) breast cancer who have received a prior systemic therapy in the metastatic setting or developed disease recurrence during or within six months of completing adjuvant chemotherapy (Press release, AstraZeneca, JUL 12, 2023, View Source [SID1234633201]).
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Enhertu is a specifically engineered HER2-directed antibody drug conjugate (ADC) being jointly developed and commercialised by AstraZeneca and Daiichi Sankyo.
The approval by China’s National Medical Products Administration (NMPA) is based on the results of the DESTINY-Breast04 Phase III trial, first presented at the American Society of Clinical Oncology (ASCO) (Free ASCO Whitepaper) 2022 Annual Meeting and published in The New England Journal of Medicine.1 It follows the approval granted by China’s NMPA for Enhertu in patients with previously treated unresectable or metastatic HER2-positive breast cancer in February 2023.
In China, breast cancer is the most common cancer in women, with more than 415,000 patients diagnosed in 2020.2 There were nearly 120,000 breast cancer deaths in China in 2020, representing around 18% of global breast cancer deaths.2 Approximately half of all breast cancers are considered HER2-low.3-5
Binghe Xu, MD, Director of the National Clinical Research Center for New Anticancer Drugs, Tenured Professor and Former Director, Department of Medical Oncology, Cancer Hospital Chinese Academy of Medical Sciences and Peking Union Medical College, said: "Historically, breast cancer tumours with low levels of HER2 expression have been classified as HER2-negative and have not been eligible for treatment with HER2-directed therapies. With this approval in China, based on the results of the DESTINY-Breast04 trial, clinicians will now be able to identify and potentially treat a distinct patient population based on HER2-low status."
Dave Fredrickson, Executive Vice President, Oncology Business Unit, AstraZeneca, said: "Patients with HR-positive or HR-negative, HER2-low metastatic breast cancer previously had few effective treatment options beyond chemotherapy. The results from the DESTINY-Breast04 trial show Enhertu provides a significant improvement in outcomes compared to chemotherapy for patients whose tumours are determined to be HER2-low via routine testing. This approval is an important advance in the way breast cancer is classified and treated in China and supports our vision to bring Enhertu to more patients worldwide."
Kiminori Nagao, Head of the Asia, South & Central America (ASCA) Business Unit, Daiichi Sankyo, said: "This approval of Enhertu for patients with HER2-low metastatic breast cancer, which comes shortly after the approval of Enhertu in patients with HER2-positive disease, marks the first time patients with HER2-low tumours will have the opportunity to be treated with a HER2-directed therapy. Enhertu now has the potential to become a new standard of care treatment option in China for a broad range of patients with HER2-expressing metastatic breast cancer."
In DESTINY-Breast04, Enhertu reduced the risk of disease progression or death by 50% versus physician’s choice of chemotherapy (median progression-free survival [PFS] 9.9 vs. 5.1 months; hazard ratio [HR] of 0.50; 95% confidence interval [CI] 0.40-0.63; p<0.0001) in all randomised patients with HER2-low metastatic breast cancer (either hormone receptor (HR)-positive or HR-negative disease). A 36% reduction in the risk of death (HR of 0.64; 95% CI 0.49-0.84; p=0.001) also was seen with Enhertu compared to chemotherapy with a median overall survival (OS) of 23.4 months in patients treated with Enhertu versus 16.8 months in those treated with chemotherapy.
The safety profile observed in patients treated with Enhertu in the DESTINY-Breast04 trial was consistent with that seen in other trials of Enhertu in breast cancer with no new safety signals identified.
Financial considerations
Sales of Enhertu in China are recognised by AstraZeneca and will be recorded as product sales on the profit and loss statement. Further details on the financial arrangements were set out in the March 2019 announcement of the collaboration.
Notes
Breast cancer and HER2 expression
Breast cancer is the most common cancer and is one of the leading causes of cancer-related deaths worldwide.6 More than two million patients were diagnosed with breast cancer in 2020, with nearly 685,000 deaths globally.6 In China, breast cancer is the most common cancer in women, with more than 415,000 patients diagnosed in 2020.2
HER2 is a tyrosine kinase receptor growth-promoting protein expressed on the surface of many types of tumours, and is one of many biomarkers expressed in breast cancer tumours.7
Historically, HER2-positive cancers have been defined as HER2 expression measured as immunohistochemistry [IHC] 3+ or IHC 2+/in-situ hybridisation [ISH]+, and HER2-negative cancers are defined as HER2 expression measured as IHC 0, IHC 1+ or IHC 2+/ISH-.4 However, approximately half of all breast cancers are HER2-low, defined as a HER2 score of IHC1+ or IHC 2+/ISH-.3-5 HER2-low occurs in both HR-positive and HR-negative disease.8
Previously, patients with HR-positive metastatic breast cancer and HER2-low disease have had limited effective treatment options following progression on endocrine (hormone) therapy.9 Additionally, few targeted options are available for those with HR-negative disease.10 With this approval of Enhertu, patients with HER2-low tumours may be eligible for HER2-directed therapy.
DESTINY-Breast04
DESTINY-Breast04 is a global, randomised, open-label, Phase III trial evaluating the efficacy and safety of Enhertu (5.4mg/kg) versus physician’s choice of chemotherapy (capecitabine, eribulin, gemcitabine, paclitaxel or nab-paclitaxel) in patients with HR-positive or HR-negative, HER2-low unresectable and/or metastatic breast cancer previously treated with one or two prior lines of chemotherapy. Patients were randomised 2:1 to receive either Enhertu or chemotherapy.
The primary endpoint of DESTINY-Breast04 is PFS in patients with HR-positive disease based on BICR. Key secondary endpoints include PFS based on BICR in all randomised patients (HR-positive and HR-negative disease), OS in patients with HR-positive disease and OS in all randomised patients (HR-positive and HR-negative disease). Other secondary endpoints include PFS based on investigator assessment, objective response rate based on BICR and on investigator assessment, duration of response based on BICR and safety.
DESTINY-Breast04 enrolled 557 patients at multiple sites in Asia, Europe and North America. For more information about the trial, visit ClinicalTrials.gov.
Enhertu
Enhertu is a HER2-directed ADC. Designed using Daiichi Sankyo’s proprietary DXd ADC technology, Enhertu is the lead ADC in the oncology portfolio of Daiichi Sankyo and the most advanced programme in AstraZeneca’s ADC scientific platform. Enhertu consists of a HER2 monoclonal antibody attached to a topoisomerase I inhibitor payload, an exatecan derivative, via a stable tetrapeptide-based cleavable linker.
Enhertu (5.4mg/kg) is approved in more than 50 countries for the treatment of adult patients with unresectable or metastatic HER2-positive breast cancer who have received a (or one or more) prior anti-HER2-based regimen, either in the metastatic setting or in the neoadjuvant or adjuvant setting, and have developed disease recurrence during or within six months of completing therapy based on the results from the DESTINY-Breast03 trial.
Enhertu (5.4mg/kg) is approved in more than 40 countries for the treatment of adult patients with unresectable or metastatic HER2-low (IHC 1+ or IHC 2+/ISH-) breast cancer who have received a prior systemic therapy in the metastatic setting or developed disease recurrence during or within six months of completing adjuvant chemotherapy based on the results from the DESTINY-Breast04 trial.
Enhertu (5.4 mg/kg) is approved in Israel and under accelerated approval in the US for the treatment of adult patients with unresectable or metastatic non-small cell lung cancer (NSCLC) whose tumours have activating HER2 (ERBB2) mutations, as detected by a locally or regionally approved test, and who have received a prior systemic therapy based on the results from the DESTINY-Lung02 trial. Continued approval for this indication in the US may be contingent upon verification and description of clinical benefit in a confirmatory trial.
Enhertu (6.4mg/kg) is approved in more than 30 countries for the treatment of adult patients with locally advanced or metastatic HER2-positive gastric or gastroesophageal junction adenocarcinoma who have received a prior trastuzumab-based regimen based on the results from the DESTINY-Gastric01 trial and/or DESTINY-Gastric02 trial.
Enhertu development programme
A comprehensive global development programme is underway evaluating the efficacy and safety of Enhertu monotherapy across multiple HER2-targetable cancers. Trials in combination with other anticancer treatments, such as immunotherapy, are also underway.