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Sihuan Pharmaceutical Holdings Group Ltd.

̬ᐑᔼᖹછٰණྠϞࠢʮ̡

(incorporated in Bermuda with limited liability)

(Stock Code: 0460)

VOLUNTARY ANNOUNCEMENT Patented Innovative Oncology Drug Birociclib Achieved Breakthrough in Phase I Clinical Trial

The board of directors (the "Board") of Sihuan Pharmaceutical Holdings Group Ltd. (the "Company" together with its subsidiaries, the "Group") is pleased to announce that Birociclib has achieved breakthrough progress in its Phase I clinical trial in China. The New Drug is one of the Group's independently developed Category 1 innovative drugs in China.

As an inhibitor of cyclin-dependent kinase 4/6 (CDK4/6), Birociclib has been patented in China, the United States, Europe, Japan and Korea. CDK4/6 inhibiors have shown significant clinical activity in the treatment of HR+ (Hormone Receptor positive)/HER2- (Human Epidermal Growth Factor Receptor 2 negative) ABC (Advanced Breast Cancer). CDK4/6 is a key factor that triggers cell cycle transition from G1 phase (the first growth period of the cell cycle) to S phase (DNA replication period). CDK4/6 inhibitors function within the G1 phase of the cell cycle, thereby inhibiting tumor cell proliferation.

The traditional standard treatment for HR+/HER2- ABC patients is Endocrine Therapy (ET) while Aromatase Inhibitors (AIs) has been preferred as the first line therapy among all the ETs. But most patients under ET will experience endocrine resistance and disease progression. CDK4/6 inhibitors can overcome and postpone the endocrine resistance, and prolong survival for late stage HR+/HER2- ABC patients. Furthermore, there are less toxic side effects when CDK4/6 inhibitors are combined with ET. Therefore, CDK4/6 inhibitors are expected to change the treatment landscape for HR+/HER2- ABC.

Birociclib also has several potential advantages, such as efficient penetration of Blood Brain Barrier and potential to be a potent agent for brain tumor and malignant brain metastasis. As a strong CDK4/6 inhibitor, Birociclib has shown good activity as a single-agent therapy method. Birociclib also has a good safety profile with lower myelosuppression rate when compared with other similar drugs of the same class. Birociclib is the first CDK4/6 inhibitor which has been developed in China as a monotherapy to treat HR+/HER2- ABC patients who failed from multi-line treatments.

Birociclib is now in Phase I clinical trial. POM (proof of mechanism) has been proved based on preliminary human data. The data of phase I study exhibits a typical dose-effect relationship which demonstrates the mechanism of CDK4/6 inhibitors' regulating activity on cell cycle. The inhibitory effect on bone marrow cell gradually increased along with increased of exposure. Further clinical research on patients for POC (proof of concept) will move forward to pivotal study afterwards.

According to Global Cancer Incidence, Mortality and Prevalence (GLOBOCAN), breast cancer is regarded as the most common malignancy in Chinese women with the Age-standardized Rate (ASR) of 21.6 per 100,000 people. Chinese IMS Health predicts that breast cancer therapeutic drug market will maintain its rapid expansion trend with the number of newly diagnosed patients reaching 400,000 in 2022. Based on the report published by GlobalData, therapeutic drugs market for HER2- ABC will keep its rapid growth at a CAGR of 15.5% during 2013 to 2023, the sales volume will reach USD6.12 billion by 2023. Besides, the market share of HR+ Breast Cancer (HR+ BC) and Triple Negative Breast Cancer (TNBC) will change, the HR+ BC will take approximately 80% of the market volume.

Global sales volume of three CDK4/6 inhibitors launched by foreign companies are USD3.2 billion in 2017 (the sales volume of Palbociclib, Ribociclib and Abemaciclib are USD3.126 billion, USD76 million and USD21 million, respectively). The combination of CDK4/6 inhibitors and AIs (Letrozole) or Estrogen Receptor Antagonist (Fulvestrant) have been approved in first-line/second-line ET for postmenopausal metastatic breast cancer, indicating a broad prospects for clinical treatment. It is expected that there will be a huge market potential in the anti-tumor area both in domestic and overseas markets if this new drug can be launched successfully.

Clinical trial of Birociclib is currently progressing well. The aim is to be one of the leading CDK4/6 inhibitors for the treatment of HR+/HER2- breast cancer in the domestic market and the Group is planning to broaden its therapeutic area after the new drug application. Birociclib, together with other anti-tumor drugs under development by the Group, such as EGFR inhibitors, will strengthen the Group's anti-tumor development platform.

This announcement is being made by the Company on a voluntary basis to let the investing public understand the Group's latest business development, and does not constitute, and is not intended to be, an advertisement regarding the use of any medicine, surgical appliance, treatment or orally consumed product.

By order of the Board

Sihuan Pharmaceutical Holdings Group Ltd.

Che Fengsheng

Chairman and Executive Director

Hong Kong, 20 March 2019

As at the date of this announcement, the executive directors of the Company are Dr. Che Fengsheng (Chairman), Dr. Guo Weicheng (Deputy Chairman and Chief Executive Officer), Mr. Choi Yiau Chong, Dr. Zhang Jionglong and Ms. Chen Yanling; the non-executive director of the Company is Mr. Kim Jin Ha; and the independent non-executive directors of the Company are Mr. Patrick Sun, Mr. Tsang Wah Kwong and Dr. Zhu Xun.

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Sihuan Pharmaceutical Holdings Group Ltd. published this content on 20 March 2019 and is solely responsible for the information contained herein. Distributed by Public, unedited and unaltered, on 19 March 2019 22:44:06 UTC