CStone receives approval in China to initiate Phase 1 clinical trial for RET inhibitor BLU-667 (CS3009)

SUZHOU,China,March 21,2019 -- CStone Pharmaceuticals ("CStone"; HKEX: 2616) today announced that China's National Medical Products Administration (NMPA) has approved the clinical trial application to begin a Phase 1 trial in China for BLU-667 (CS3009),a highly selective and potent RET inhibitor discovered by CStone's partner Blueprint Medicines. The study is part of Blueprint Medicines' ongoing,global Phase 1 ARROW clinical trial for patients with RET-altered non-small cell lung cancer (NSCLC),medullary thyroid cancer (MTC) and other advanced solid tumors. Trial objectives include overall clinical response,duration of response,pharmacokinetics,pharmacodynamics and safety.

In June 2018,CStone and Blueprint Medicines entered into a license and collaboration agreement in which Blueprint Medicines granted CStone exclusive rights to develop and commercialize BLU-667 and two other drug candidates in Mainland China,Hong Kong,Macau and Taiwan.

Recently,BLU-667 was granted Breakthrough Therapy Designation by the U.S. Food and Drug Administration (FDA) for the treatment of RET-mutation-positive MTC that requires systemic treatment and for which there are no acceptable alternative treatments.

Based on the early clinical data and regulatory feedback,Blueprint Medicines has announced plans to submit a New Drug Application (NDA) to the U.S. FDA for BLU-667 in the first half of 2020.

"BLU-667 has already demonstrated its potential to produce clinical responses in several RET-altered tumor types,and there are currently no selective RET inhibitors approved globally," noted CStone Chairman and CEO Dr. Frank Jiang. "If the data generated in Chinese patients are consistent with global results,we plan to use the global and China data from the ARROW study to support NDA filings in China."

CStone's Chief Medical Officer Dr. Jason Yang commented: "Currently available data show that non-small cell lung cancer and medullary thyroid cancer patients with RET altered tumors may benefit from BLU-667,with the potential to advance standards of care in these genetically defined populations. We will move forward on development of BLU-667 in China and hope to make this drug candidate available to Chinese patients as quickly as possible."

About BLU-667

BLU-667 is an investigational,once-daily oral precision therapy specifically designed for highly potent and selective targeting of oncogenic RET alterations. In preclinical studies,BLU-667 consistently demonstrated sub-nanomolar potency against the most common RET fusions,activating mutations and predicted resistance mutations. In addition,BLU-667 demonstrated markedly improved selectivity for RET compared to approved multi-kinase inhibitors,including more than 80-fold improved potency for RET versus VEGFR2. By suppressing primary and secondary mutants,BLU-667 has the potential to overcome and prevent the emergence of clinical resistance. This approach is expected to enable durable clinical responses across the range of RET alterations,with a favorable safety profile.

BLU-667 was designed by Blueprint Medicines' research team,leveraging the company's proprietary compound library. Blueprint Medicines is developing BLU-667 for the treatment of people with RET-altered NSCLC,MTC and other solid tumors. The U.S. FDA has granted Breakthrough Therapy Designation to BLU-667 for the treatment of RET-mutation-positive MTC.

About CStone

CStone Pharmaceuticals (HKEX: 2616) is a biopharmaceutical company focused on developing and commercializing innovative immuno-oncology and precision medicineto address the unmet medical needs of cancer patients in China and worldwide. Established in 2015,CStone has assembled a world-class management team with extensive experience in innovative drug development,clinical research,and commercialization. The company has built an oncology-focused pipeline with a strategic emphasis on immune-oncology combination therapies. Currently,4 late-stage candidates are at or near pivotal trials. With an experienced team,a rich pipeline,a robust clinical development-driven business model,and substantial funding,CStone's vision is to become globally recognized as a leading Chinese biopharmaceutical company by bringing innovative oncology therapies to cancer patients worldwide.

For more information about CStone Pharmaceuticals,please visit: www.cstonepharma.com.

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