CStone and LegoChem Biosciences Enter Global Licensing Agreement for New Antibody Drug Conjugate

CStone to acquire exclusive rights for development and commercialization outside South Korea for LCB71,an ROR1 antibody drug conjugate

Agreement adds to CStone's pipeline a potential first-in-class/best-in-class drug candidate with monotherapy and combination applications for a range of cancer indications

LCB71 has demonstrated preclinical efficacy and reduced toxicity

SUZHOU,China,Oct. 29,2020 -- CStone Pharmaceuticals ("CStone",HKEX: 2616) announced today a licensing agreement with LegoChem Biosciences,Inc. ("LCB",KOSDAQ:141080),for the development and commercialization of LCB71,a potential first-in-class/best-in-class antibody drug conjugate ("ADC").

Under the agreement,CStone obtains the exclusive global right to lead development and commercialization of LCB71 outside the Republic of Korea. LCB will receive an upfront payment of US$10 million,and up to US$353.5 million in cumulative milestone payments,plus tiered royalties.

Frank Jiang,M.D.,Ph.D.,Chairman and Chief Executive Officer of CStone,said: "We are very pleased to form this partnership with LCB,a leading ADC platform company,to obtain global rights to an asset with highly differentiated attributes in an exciting new field of oncology. The agreement adds the first ADC to CStone's development pipeline,and bolsters our precision medicine franchise with a new modality. We look forward to harnessing its full potential and bringing it to patients around the world."

LCB71 is a pre-clinical ADC entering into Investigational New Drug ("IND") enabling studies. It targets ROR1 (receptor tyrosine kinase-like orphan receptor 1),a high-potential ADC target for multiple solid and hematological malignancies. ROR1 protein expression is prevalent in a variety of cancers including various forms of leukemia,non-Hodgkin lymphoma,and breast,lung,and ovarian cancers.

LCB71 has a proprietary tumor-activated pyrrolobenzodiazepine ("PBD") prodrug toxin that addresses the typical toxicity problem associated with traditional PBD payloads. It has demonstrated complete tumor inhibition across several preclinical cancer models,which may translate into a wide therapeutic index for a range of solid and hematologic malignancies. Additionally,it utilizes site-specific conjugation for a precise drug antibody ratio. This supports serum half-life and improves its pharmacokinetic profile,and also enables homogeneous production and large-scale manufacturing.

Dr. Yong-Zu Kim,CEO and President of LCB,said: "We are pleased to have reached this agreement with CStone,which has demonstrated extensive oncology expertise,especially in global clinical development. This partnership puts LCB71 on a path to development and commercialization for patients worldwide. We are convinced that CStone is the right partner to secure the future of this important drug."

About CStone

CStone is a biopharmaceutical company focused on developing and commercializing innovative immuno-oncology and precision medicines to address the unmet medical needs of cancer patients in China and worldwide. Established at the end of 2015,CStone has assembled a world-class management team with extensive experience in innovative drug development,clinical research,and commercialization. With a strategic emphasis on immuno-oncology combination therapies,the Company has built an oncology-focused pipeline of 15 drug candidates,including five late-stage candidates at pivotal trials or registration stages. 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,please visit: www.cstonepharma.com.

About LegoChem Biosciences

LegoChem Biosciences (LCB) is a clinical-stage biopharmaceutical company focusing on the development of next-generation novel therapeutics utilizing its proprietary medicinal drug discovery technology LegoChemistry and ADC platform technology ConjuAll. Since its foundation in 2006,LCB has focused on the research and development of Antibody-Drug-Conjugates (ADCs),antibiotics,anti-fibrotic and anticancer therapeutics based on proprietary platform technologies. For more information on LCB's robust pipeline,visit www.legochembio.com.

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CSTONE INVESTOR CONTACT

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