Suzhou, China, October 19, 2020 - CStone Pharmaceuticals (Suzhou) Co., Ltd. (“CStone”, HKEX: 2616) today announced that the U.S. Food and Drug Administration (FDA) has granted Orphan Drug Designation (ODD) to its anti-PD-L1 antibody sugemalimab (CS1001) for the treatment of T-cell lymphoma. This marks another important milestone for CStone Pharmaceutical’s immunotherapy pipeline after the U.S. FDA granted Orphan Drug Designation (ODD) to its anti-PD-1 monoclonal antibody CS1003 for the treatment of hepatocellular carcinoma in July 2020.

Provided by the Orphan Drug Act (ODA), an Orphan Drug Designation is an incentive created by the U.S. FDA to promote the development of innovative drugs for the treatment of rare diseases and conditions. Orphan designation can qualify the sponsor of an orphan drug for 7 years of market exclusivity, along with a series of benefits provided by the FDA, including tax credits, reduction of or exemption from prescription drug user fees, R&D funding support, protocol assistance, and accelerated approval.

Dr. Jason Yang, Chief Medical Officer of CStone, said, “T-cell lymphoma encompasses different subtypes, and extra-nodal natural killer cell/T-cell lymphoma (ENKTL) is a subtype with a particularly poor prognosis. The Orphan Drug Designation granted by the U.S. FDA recognizes the clinical value of sugemalimab and the benefits it can bring for ENKTL patients, who currently have considerable unmet medical needs. The efficacy data for sugemalimab, compared with data from other existing drugs, represent a remarkable breakthrough. We are committed to advancing the development of sugemalimab, including by working closely with the U.S. FDA and the National Medical Products Administration (NMPA) of China, and will bring sugemalimab to patients across the globe as soon as possible.”

In China, ENKTL accounts for approximately 6% of all lymphomas1. Relapsed or refractory ENKTL (R/R ENKTL) is highly malignant and aggressive with a poor prognosis. The 1-year survival rate was less than 20%2 . In China, the current approved targeted monotherapy for these patients has a complete response (CR) rate of approximately 6%^3,4. An oral presentation of data from the CS1001-201 study, in which sugemalimab monotherapy was evaluated in patients with R/R ENKTL, was presented at the 2020 annual meeting of the Chinese Society of Clinical Oncology (CSCO). As of July 1st ,2020, the objective response rate (ORR) of 38 evaluable patients was 44.7%, with a CR rate of 31.6%; the median duration of response (mDoR) was 16.8 months and 1-year DoR rate is 67.8%. Median overall survival (mOS) of the 43 patients who received study treatment was 19.7 months, and the 1-year overall survival (OS) rate was 55.5%.

CS1001-201 Study

CS1001-201 is a single-arm, multicenter, Phase II pivotal study designed to evaluate the efficacy and safety of sugemalimab as monotherapy for the treatment of R/R ENKTL. The primary endpoint of this study is ORR as assessed by the Independent Radiology Review Committee (IRRC). On August 31st,2020, it has received clearance from the U.S. FDA for the Investigational New Drug (IND) application, and a Study May Proceed (SMP) letter.

About Sugemalimab（CS1001）

Sugemalimab is an investigational anti-PD-L1 monoclonal antibody discovered by CStone. Authorized by a company based in the U.S., Ligand Pharmaceuticals Inc. (NASDAQ: LGND), sugemalimab is developed using the OmniRat® transgenic animal platform, which can generate fully human antibodies in one stop. As a fully human, full-length anti-PD-L1 monoclonal antibody, sugemalimab mirrors the natural G-type immunoglobulin 4 (“IgG4”) human antibody, which may reduce the risk of immunogenicity and toxicities in patients, a potentially unique advantage over similar drugs.

Sugemalimab has completed a Phase I dose-escalation study in China. During Phase 1a and 1b stages of the study, sugemalimab showed antitumor activity in multiple tumor types and was well-tolerated.

Currently, sugemalimab is being investigated in a number of ongoing clinical trials. In addition to a Phase I bridging study in the U.S., the clinical programs in China include one multi-arm Phase Ib study for several tumor types, one Phase II registrational study for lymphoma, and four Phase III registrational studies, respectively, for stage III/IV non-small cell lung cancer, gastric cancer, and esophageal cancer. The phase III clinical trial of sugemalimab in patients with stage IV non-small cell lung cancer has reached its primary endpoint. CStone plans to submit a new drug application (NDA) to the National Medical Products Administration (NMPA) of China soon.

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.

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