CStone and Bayer announce global collaboration to evaluate PD-L1 monoclonal antibody CS1001 in combination with regorafenib

SUZHOU,China,June9,2019 --CStone Pharmaceuticals ("CStone"; HKEX: 2616) today announced that the company has entered into a global clinical collaboration with China focus with Bayer HealthCare LLC to evaluate the safety,tolerability,pharmacokinetics (PK) and antitumor activity of its PD-L1 monoclonal antibody CS1001 in combination with Bayer's regorafenib,an oral multi-kinase inhibitor (targeting VEGFR,FGFR,CSF1R,etc.),as a treatment for multiple cancers including gastric cancer. This is the first global proof of concept study carried out as a collaboration between the two companies. CStone will be the study sponsor and Bayer will provide regorafenib throughout the clinical trial program.

Professor Lin Shen,Vice President at the Peking University Cancer Hospital,commented: "At present,patients with advanced gastric cancer lack safe and effective therapies. Preclinical and clinical evidence suggest that the combination of PD-1/PD-L1 antibodies with multi-kinase inhibitors that target VEGFR can induce significant synergistic anti-tumor effects. We hope this combination therapy can provide a new treatment option for patients suffering from gastric cancer and other serious malignancies."

CS1001 is one of CStone's backbone immuno-oncology pipeline candidates,having demonstrated that it is well-tolerated and has promising anti-tumor activities across a variety of tumor types in clinical studies. Currently,CS1001 is being evaluated in 7 clinical trials,including 5 pivotal trials. Regorafenib is approved in over 90 countries for the treatment of metastatic colorectal cancer (mCRC) and metastatic gastrointestinal stromal tumors (GIST) and in more than 80 countries for the second-line treatment of advanced hepatocellular (HCC).

Dr. Frank Jiang,CStone Chairman and CEO,commented: "We are very pleased that Bayer has chosen CStone as its partner and recognizes CS1001's potential. We hope,by complementing our two companies' pipelines via this combination therapy,that we can develop better cancer treatments for patients. In addition,this collaboration will be a big step forward for CStone's global strategy when we generate positive data."

Scott Z. Fields,M.D.,Senior Vice President and Head of Oncology Development at Bayer's Pharmaceutical Division said: "Combining multi-kinase inhibitors,such as regorafenib,with checkpoint inhibitors is a rising trend in cancer therapy in order to find new solutions for the many treatment gaps that still remain for patients. We look forward to collaborating with CStone,an innovative biopharmaceutical company,and exploring regorafenib's potential."

About CS1001

CS1001 is an investigational anti-PD-L1 monoclonal antibody being developed by CStone. Authorized by the U.S.-based Ligand Corporation,CS1001 was generated by the OMT transgenic animal platform,which can produce fully human antibodies in one step. As a fully human,full-length anti-PD-L1 monoclonal antibody,CS1001 mirrors natural G-type immune globulin 4 (IgG4) human antibody,which can potentially reduce the risk of immunogenicity and toxicities in patients,a unique advantage over similar drugs.

CS1001 has completed a Phase I dose-escalation study in China and has demonstrated promising anticancer activity and good tolerance. CS1001 is currently being evaluated in multiple clinical trials including a bridging phase I trial in the USA,a multi-arm phase Ib study,two pivotal Phase II studies and three Phase III studies in China in various cancer types,respectively. It has not been approved by any health authority for marketing.

About Regorafenib (Stivarga®)

Regorafenib is an oral multi-kinase inhibitor that potently blocks multiple protein kinases involved in tumor angiogenesis (VEGFR1,-2,-3,TIE2),oncogenesis (KIT,RET,RAF-1,BRAF),metastasis (VEGFR3,PDGFR,FGFR) and tumor immunity (CSF1R).

Regorafenib is approved under the brand name Stivarga® in more than 90 countries worldwide,including the U.S.,countries of the EU,China and Japan for the treatment of metastatic colorectal cancer (mCRC) and metastatic gastrointestinal stromal tumors (GIST). The product is also approved in more than 80 countries including the U.S.,Japan,countries of the EU as well as China for the second-line treatment of advanced hepatocellular (HCC).

Regorafenib is a compound developed by Bayer. In 2011,Bayer entered into an agreement with Onyx,now an Amgen subsidiary,under which Onyx receives a royalty on all global net sales of regorafenib in oncology.

About CStone

CStone Pharmaceuticals (HKEX:2616) is a biopharmaceutical company focused on developing and commercializing innovative immuno-oncology and precision medicine to 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 immuno-oncology combination therapies. Currently,5 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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