CStone presents clinical results of sugemalimab in patients with relapsed or refractory extranodal natural killer/T-cell lymphoma via an oral abstract session at ASCO 2022

GEMSTONE-201 is the largest registrational clinical study of an anti-PD-(L)1 antibody reported so far in patients with relapsed or refractory extranodal natural killer/T-cell lymphoma (R/R ENKTL).

Results on the primary endpoint showed that sugemalimab significantly improved objective response rate (ORR) compared to historical controls. In 78 evaluable patients,ORR assessed by Independent Radiology Review Committee (IRRC) was 46.2% with a complete response (CR) rate of 37.2%. The investigator-assessed ORR was highly consistent with IRRC's evaluation.

Based on the encouraging preliminary efficacy results from this study,sugemalimab was granted the Orphan Drug Designation (ODD) and Breakthrough Therapy Designation (BTD) by the U.S. Food and Drug Administration (FDA) for the treatment of T-cell lymphoma and adults with R/R ENKTL respectively in 2020. BTD was also granted by the National Medical Products Administration (NMPA) of China for the treatment of R/R ENKTL in 2021.

SUZHOU,China,June,4,2022 -- CStone Pharmaceuticals ("CStone",HKEX: 2616),a leading biopharmaceutical company focused on the research,development,and commercialization of innovative immuno-oncology therapies and precision medicines,today announced that the company has reported primary results from the registrational GEMSTONE-201 study of anti-PD-L1 antibody sugemalimab treating patients with relapsed or refractory extranodal natural killer cell/T-cell lymphoma (R/R ENKTL) as an oral presentation at the 2022 American Society of Clinical Oncology (ASCO) Annual Meeting.

The GEMSTONE-201 study was designed to evaluate the efficacy and safety of sugemalimab as monotherapy for the treatment of adult patients with R/R ENKTL. As of November 10,2021,80 patients were enrolled in the GEMSTONE-201 study and received sugemalimab monotherapy. As of the data cutoff date,median follow-up duration was 13.4 months,and 23 patients remained on treatment with sugemalimab in this study. Key results of this study are the following:

Results on the primary endpoint showed that sugemalimab significantly improved objective response rate (ORR) compared to historical controls. In 78 evaluable patients,ORR assessed by Independent Radiology Review Committee (IRRC) was 46.2% and the complete response (CR) rate reached 37.2%.

Based on the evaluation by IRRC,durable objective response was observed in patients who responded to sugemalimab. Median duration of response (DoR) was not reached at the time of the analysis. The 6-month and 12-month DoR rates were 90.8% and 86.0%,respectively.

Investigator-assessed efficacy was found highly consistent with IRRC evaluations. The concordance rate between investigator- and IRRC-assessed ORR reached 97.1%.

The analysis of overall survival (OS) showed a signal of OS benefit with sugemalimab as monotherapy in patients with R/R ENKTL; the OS rates at 6 months,12 months and 24 months were 79.2%,68.6% and 54.6%,respectively.

Sugemalimab also demonstrated a well-tolerated safety profile in patients with R/R ENKTL,and no new safety signals were observed.

Professor Huiqiang Huang of Sun Yat-sen University Cancer Center,the Principal Investigator of the GEMSTONE-201 study,said,"It is my honor to present the full results of GEMSTONE-201 study for the first time to the international audience at ASCO on behalf of all the investigators in this trial. R/R ENKTL is highly malignant and aggressive. Current lack of effective therapies leads to a low cure rate and poor prognosis. Results from this study further demonstrated the robust antitumor activity,durability of response and well-tolerated safety of sugemalimab as a treatment of R/R ENKTL. I believe that sugemalimab will become a new standard treatment option to meet the urgent medical needs of this patient population."

Dr. Jason Yang,Chief Medical Officer of CStone,"We are very glad that the latest results from GEMSTONE-201 have been presented at the oral abstract session of ASCO Annual Meeting. This marks that the promising results of sugemalimab in R/R ENKTL have been recognized by the global academic community. Until now,no anti-PD-(L)1 monoclonal antibody has been approved for R/R ENKTL indication. We will work closely with the National Medical Products Administration of China and look forward to bringing this important immunotherapy to patients."

About ENKTL

Extranodal natural killer/T-cell lymphoma (ENKTL) is a subtype of mature T cell and NK cell lymphoma. In 2012,a multicenter pathological classification survey of 10,002 lymphoma patients from China showed that ENKTL accounted for approximately 6% of all lymphomas and 28% of mature T-cell and NK-cell lymphomas. The 5-year OS rate was only 60.3% in patients with primary ENKTL using a L-asparaginase-based standard regimen,and there is no existing approved effective salvage treatment for patients with R/R ENKTL. Patients also typically respond poorly to conventional treatments. Clinicians often have limited treatment options for such patients due to rapid disease progression and poor survival outcomes with a one-year survival rate of less than 20%. The median OS and PFS were 6.4 and 4.1 months,respectively. In China,the currently available targeted monotherapy for these patients has a complete response (CR) rate of approximately 6%. Thus,there are significant unmet medical needs in patient who did not respond to first-line treatment.

About Sugemalimab

The anti-PD-L1 monoclonal antibody sugemalimab was discovered by CStone using OmniRat® transgenic animal platform,which allows creation of fully human antibodies in one step. Sugemalimab is a fully human,full-length anti-PD-L1 immunoglobulin G4 (IgG4) monoclonal antibody,which may allow a reduced risk of immunogenicity and toxicity for patients,a unique advantage over similar drugs.

Currently,the National Medical Products Administration (NMPA) of China has approved sugemalimab (Cejemly®) in combination with pemetrexed and carboplatin as first-line treatment of patients with metastatic non-squamous NSCLC,lacking EGFR and ALK genomic tumor aberrations; and in combination with paclitaxel and carboplatin as first-line treatment of patients with metastatic squamous NSCLC.

In September 2021,the NMPA of China accepted the NDA for sugemalimab as a consolidation therapy in patients with unresectable stage III NSCLC without disease progression after concurrent or sequential chemoradiotherapy.

With its proven therapeutic advantages,sugemalimab is set to be recommended by the 2022 Chinese Society of Clinical Oncology (CSCO) clinical guidelines for the diagnosis and treatment of NSCLC,in combination with chemotherapy as the first-line treatment of patients with stage IV non-squamous/squamous NSCLC without driver alterations; or as a consolidation therapy in patients with stage III NSCLC after concurrent or sequential chemoradiotherapy.

CStone formed a strategic collaboration agreement with EQRx,under which EQRx licensed the exclusive rights to sugemalimab for development and commercialization outside of Greater China.

About the GEMSTONE-201 study

The GEMSTONE-201 study is a single-arm,multicenter,Phase 2 pivotal study designed to evaluate the efficacy and safety of sugemalimab as monotherapy for the treatment of adult patients with R/R ENKTL. Based on the encouraging preliminary efficacy results,sugemalimab has been granted Orphan Drug Designation and Breakthrough Therapy Designation by the U.S. FDA for the treatment of T-cell lymphoma and adults with R/R ENKTL respectively. It has also been granted BTD by the National Medical Products Administration of China. The study includes investigational sites in both China and the U.S. In January 2022,the GEMSTONE-201 study,as assessed by the Independent Radiology Review Committee,met its pre-specified primary endpoint.

About CStone

CStone Pharmaceuticals (HKEX: 2616) is a biopharmaceutical company focused on researching,developing,and commercializing innovative immuno-oncology and precision medicines 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 of 15 drug candidates with a strategic emphasis on immuno-oncology combination therapies. Currently,CStone has received eight drug approvals for four drugs. CStone's vision is to become globally recognized as a world-renowned biopharmaceutical company by bringing innovative oncology therapies to cancer patients worldwide.

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

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