Suzhou, China; November 1, 2018 -- CStone Pharmaceuticals ("CStone") today announced that the first two patients have been successfully enrolled and dosed in CS1001 Phase III GEMSTONE-301 trial in China in October. CS1001 is China's first domestically developed, fully-human anti-programmed death-ligand 1 (PD-L1) monoclonal antibody. The trial will evaluate CS1001's efficacy and safety as a consolidation therapy in Chinese patients with locally advanced, unresectable stage III non-small cell lung cancer (NSCLC) who display no disease progression after concurrent/sequential chemoradiotherapy.

In China, lung cancer is the most commonly diagnosed malignant tumor,[ Chen W, Zheng R, Baade PD, et al. Cancer statistics in China, 2015. CA Cancer J Clin ,2016,66:115-32.] while NSCLC accounts for 80% of all lung cancer cases in the country.[ NCCN Guidelines Version 6.2018 Non-Small Cell Lung Cancer] Standard treatments for locally advanced stage III NSCLC are based on chemoradiotherapy,[中国临床肿瘤学会（CSCO）原发性肺癌诊疗指南（2018版）] however the disease can progress within 8-10 months of treatment.

"CS1001 is the first drug candidate in CStone's pipeline that enters Phase III clinical trial in China. We will spare no effort to make this new therapeutic option available to meet the unmet needs for stage III lung cancer patients as early as possible.“  noted Dr. Frank Jiang, chairman and CEO of CStone. “There are 3 additional assets among CStone’s broad oncology pipeline that are at late-stage or near registrational trials."

"CS1001 is the first PD-1 or PD-L1 inhibitor that is being evaluated in locally advanced and unresectable stage III NSCLC  to gain registrational approval in China."Dr. Jason Yang, CStone's Chief Medical Officer (CMO), commented. "Currently, CS1001 is progressing through a number of clinical trials, and we recently disclosed Phase I clinical data for the drug in advanced cancers at CSCO and ESMO conferences. CS1001 also received approval of investigational new drug (IND) application from United States Food and Drug Administration this month. We are fully confident in this drug's prospects and will continue to drive the development of this drug to maximize its value for patients in China and globally".

The Phase III clinical trial for CS1001 in NSCLC has set an enrolment target of 402 patients and will evaluate the drug's efficacy, safety, pharmacokinetic profile and immunogenicity. The randomized, double-blind, parallel-group study has been designed with a primary endpoint of progression-free survival (PFS) assessed according to the Solid Tumor Efficacy Evaluation Criteria (RECIST v1.1).

About NSCLC

According to China's National Central Cancer Registry annual report, the most common malignant tumor across the country is lung cancer, with 782,000 newly diagnosed cases in 2014.[ Chen et al. 2014 annual report of cancer in China, Chin J Cancer Res, 2018;30(1):1-12] World Health Organization (WHO) statistics show that over 1.7 million people die each year due to lung cancer.[ World Health Organization, International Agency for Research on Cancer, World Cancer Report 2014, Page 28, Estimated world cancer mortality proportions by major sites, in both sexes combined, in men, and in women, 2012] The NCCN's cancer treatment guidelines note that NSCLC is the most common type of lung cancer, making up 80% of cases.[ NCCN Guidelines Version 6.2018 Non-Small Cell Lung Cancer] Currently, standard care for late-stage/unresectable stage III NSCLC is based around chemoradiotherapy, with limited alternative treatment options and poor outcomes[中国临床肿瘤学会（CSCO）原发性肺癌诊疗指南（2018版）] meaning there is an urgent need for improved treatments that can delay disease progression and extend patients’ long-term survival.

About CS1001

CS1001 is an investigational monoclonal antibody directed against PD-L1 being developed by CStone Pharmaceuticals. Authorized by the U.S.-based Ligand Corporation, CS1001 is a monoclonal antibody developed by the OMT transgenic animal platform, which can generate 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 reduce the risk of immunogenicity and potential toxicities in patients, a unique advantage over similar drugs.

Currently, CS1001 has completed a Phase I dose-escalation study in China, which showed the drug to be well-tolerated and produced sustained clinical benefit during the Phase Ia stage of development. In addition, two pivotal Phase II studies have been initiated in China: for natural killer cell/T-cell lymphoma (CS1001-201) and classical Hodgkin's lymphoma (CS1001-202). Meanwhile, Phase III studies are under way or being prepared both in China and globally for various tumor indications.

About CSTONE

CStone Pharmaceuticals is a China-based innovative biopharmaceutical company devoted to meeting patient needs, focused on development of innovative tumor drugs and immunotherapies. Established at the end of 2015, CStone has built a world-class management team with experience ranging across the drug development life cycle from clinical development to commercialization. Our international-standard clinical research and development team gained experience developing some of the world's best-selling anti-tumor drugs. In terms of business model, CStone's approach combines independent research, clinical development capabilities, and commercial partnering. The company has built one of the largest anti-cancer drug pipelines in China, with 14 anti-tumor drugs under research including independently developed and internationally partnered products. Exclusive cooperation and licensing agreements have been reached with Blueprint Medicine and Agios. CStone's capabilities have been recognized by partners and investors in Series A and B financing rounds that were record-breaking within the biopharmaceutical field at that time, raising a combined total of USD 410 million. CStone aims to become a leading Chinese biopharmaceutical company with international prestige and serve as the cornerstone for the future health of patients.