CStone initiates a bridging Phase I clinical trial for PD-1 antibody CS1003 with first patient dosed in China

SUZHOU,China,Nov.19,2018 -- CStone Pharmaceuticals (CStone) today announced that a first patient has been enrolled and dosed in a Phase I clinical trial in China for the recombinant humanized anti-programmed death-1 (PD-1) monoclonal antibody (mAb) CS1003. This multi-center Phase I clinical trial is assessing the safety,tolerability and preliminary anti-tumor activity of CS1003 in Chinese patients with advanced cancers,led by the Beijing Cancer Hospital.

"CS1003 is an important IO backbone in CStone's pipeline and together with our PD-L1 monoclonal antibody (CS1001),is essential to our combination therapy strategy,"said Dr. Frank Jiang,Chairman and CEO of CStone,"We are happy to see Phase I trial get under wayin China. We plan to carry out global development for this promising drugcandidate as monotherapy and in combination with internal and external therapies to benefit cancer patients in China and globally."

CStone'sChief Medical Officer Dr. Jason Yang commented,"CS1003 is a humanized,IgG4 monoclonal antibody that has already generated strong preclinical data,with the unique advantage ofrecognizing both human and murine PD-1.A Phase I trialfor the drug candidateis currently ongoing in Australia,whileinvestigational new drug (IND)approvalwasreceivedin the United States in recent weeks.Wewill continueourworldwide efforts to developCS1003 in orderto maximize its value forcancerpatientsworldwide."

About CS1003 and the PD-1/PD-L1 pathway

PD-1,or programmed death-1,is an inhibitory checkpoint receptor expressed on T cells. Under normal circumstances,it binds with its ligands,programmed death ligand-1 or ligand 2 (PD-L1/PD-L2),inhibiting T cell and cytokine activation,serving to dampen the immune response in order to prevent damage to healthy tissues. However,studies have shown that PD-L1 can be abundantly expressed on the surface of many solid tumors as well as hematological malignancies. Cancer cells can therefore make use of the PD-1/PD-L1 pathway to successfully avoid immune system recognition. Targeting of the PD-1/PD-L1 checkpoint by anti-tumor drugs can block this "tumor immune evasion mechanism" and restore anti-cancer immune ability in patients.

Unlike other anti-PD-1 mAbs,CS1003 recognizes both human and murine PD-1,providing a unique competitive advantage during efficacy testing in syngeneic mouse tumor models,particularly for development of effective combination therapies.

AboutCStone

CStone Pharmaceuticals is a biotechnology company focused on developing and commercializing innovative immuno-oncology and molecularly targeted drugs to address significant unmet medical needs for cancer patients. Founded in December of 2015,CStone has assembled a world-class management team that has a full spectrum of complementary skillsets from preclinical research to clinical development and commercialization. Through a dual source of innovation,comprised of internal research and external partnership,the company has built a rich oncology pipeline of 14 drug candidates with significant mono-and combination-therapy potential and synergies. CStone's business model has a clear focus on clinical development,while at the same time the company is rapidly developing its commercial and manufacturing capabilities. The company is backed by prestigious VC/PE funds with record-breaking amounts of equity investment,raising a combined total ofUSD 412 million in two financing rounds to date. With an experienced team,a rich pipeline,a robust R&D model,and substantial funding,CStone's vision is to become globally recognized as a leading Chinese biotechnology company by bringing innovative and differentiated oncology therapies to cancer patients worldwide.

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

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