CStone announced new drug approval of China's first IDH1 inhibitor TIBSOVO® (ivosidenib tablets) as a new precision therapy for patients with acute myeloid leukemia

TIBSOVO®,a first-in-class drug,is approved for adult patients with relapsed/refractory acute myeloid leukemia (R/R AML) who have a susceptible IDH1 mutation

Clinical study data showed that TIBSOVO® had robust clinical efficacy and a well-tolerated and manageable safety profile in Chinese adult patients with R/R AML who have a susceptible IDH1 mutation

TIBSOVO® became CStone's fourth innovative drug approved within 12 months after two first-in-class precision therapies GAVRETO® and AYVAKIT®,and the immuno-oncology therapy CEJEMLY®

SUZHOU,China,Feb. 9,2022 --CStone Pharmaceuticals ("CStone",HKEX: 2616),a leading biopharmaceutical company focused on research,development,and commercialization of innovative immuno-oncology therapies and precision medicines,today announced that the National Medical Products Administration (NMPA) of China has approved the new drug application (NDA) of TIBSOVO® (ivosidenib tablets) for the treatment of adult patients with relapsed/refractory acute myeloid leukemia (R/R AML) who have a susceptible IDH1 mutation,providing a new precision therapy for this patient population.

Acute myeloid leukemia (AML) is the most common type of leukemia in adults. The disease progresses rapidly,and the vast majority of patients are the elderly. In the US,there are about 20,000 new cases of AML each year,and the 5-year survival rate is about 29%. With the aging of the population,the incidence of AML in China has been rising,and particularly the elderly and relapsed/refractory patients have a poorer prognosis. In China,there are about 75.3 thousand new cases of Leukemia each year and approximately 59% are AML patients,among whom about 6-10% have IDH1 mutations.

Dr. Frank Jiang,Chairman and CEO of CStone,said,"This marks another milestone for CStone Pharmaceuticals. TIBSOVO® is our fourth innovative drug successfully approved,and it only took6 months from NDA acceptance to NDA approval,demonstrating once again the 'CStone Speed'. Previously,CStone has successfully obtained regulatory approvals for the launch of two first-in-class precision medicines and a potential best-in-class immuno-oncology therapy. We will advance our broad and diversified pipeline of innovative products and aim to provide more high-quality innovative drugs for patients around the world."

Professor Wang Jianxiang from the Institute of Hematology & Blood Diseases Hospital,Chinese Academy of Medical Sciences,the Principal Investigator of registrational bridging study CS3010-101 in China,"For a long time,there have been limited treatment options for AML patients with IDH1 mutations,and patients had a low 5-year survival rate and poor quality of life. We are excited that TIBSOVO®,as the first IDH1 inhibitor approved in China,demonstrated superior efficacy and safety in AML patients with IDH1 mutations. I believe that the approval of TIBSOVO® will offer an innovative precision therapy to more AML patients,helping improve their quality of life and prolong their lives."

Dr. Jason Yang,Chief Medical Officer of CStone,"We are thrilled that TIBSOVO® has been approved in Mainland China for the treatment of patients with R/R AML. As the first and only IDH1 inhibitor approved in China,TIBSOVO® demonstrated proven efficacy and well-tolerated safety in Chinese patients with R/R AML who have a susceptible IDH1 mutation. At the 63rd American Society of Hematology Annual Meeting in 2021,the data were presented to show that TIBSOVO® in combination with azacitidine significantly improved the event-free survival and overall survival in patients with treatment-naïve IDH1-mutated AML. We plan to hold regulatory discussions with the NMPA to bring this innovative therapy in combination with azacitidine to more Chinese patients as early as possible."

In China,TIBSOVO® was selected in the list of the third batch of Overseas New Drugs Urgently Needed in Clinical Settings by the Center for Drug Evaluation,NMPA in China,and granted fast-track designation. As a potent and highly selective first-in-class oral IDH1 inhibitor,TIBSOVO® was also recommended by the 2020 edition of the CSCO Guidelines for Diagnosis and Treatment of Hematological Malignancies due to its proven clinical advantages.

The approval of TIBSOVO® was based on the China registrational bridging study CS3010-101,which aimed to evaluate the pharmacokinetic (PK),pharmacodynamics (PD),safety,and clinical efficacy of orally administered TIBSOVO® in Chinese adult patients with R/R AML who have a susceptible IDH1 mutation. TIBSOVO® demonstrated robust clinical efficacy and a well-tolerated,manageable safety profile in the treatment of Chinese adults with R/R AML with a susceptible IDH1 mutation. Among 30 evaluable patients,the primary efficacy endpoint of complete remission plus complete remission with partial hematologic recovery (CR+CRh) rate was 36.7% (11/30) with all 11 patients achieving CR. The median duration of CR+CRh is not reached,and the estimated 12-month CR+CRh duration rate is 90.9%. The data were presented in a proffered paper presentation at the 2021 European Society for Medical Oncology (ESMO) Congress.

About TIBSOVO® (ivosidenib tablets)

TIBSOVO®is an oral targeted IDH1 inhibitor. The NMPA of China has approved the NDA of TIBSOVO® for the treatment of adult patients with relapsed/refractory acute myeloid leukemia who have a susceptible IDH1 mutation.

TIBSOVO® is currently approved in the U.S. as monotherapy for the treatment for the treatment of adults with IDH1-mutant relapsed or refractory acute myeloid leukemia (AML),and for adults with newly-diagnosed AML with a susceptible isocitrate dehydrogenase-1 (IDH1) mutation as detected by an FDA-approved test in adult patients who are ≥ 75 years old or who have comorbidities that preclude use of intensive induction chemotherapy. In 2021,TIBSOVO® was the first and only targeted therapy approved for patients with previously treated locally advanced or metastatic cholangiocarcinoma with an IDH1-mutation as detected by an FDA-approved test.

In addition,data from the global phase 3 study AGILE demonstrated that TIBSOVO® in combination with the chemotherapy azacitidine significantly improved event-free survival (HR=0.33) and overall survival (HR=0.44) compared to azacitidine plus placebo in patients with previously untreated IDH1-mutated acute myeloid leukemia (AML) who are not candidates for intensive chemotherapy. The median overall survival (OS) of patients in the TIBSOVO® plus azacitidine arm was 24.0 months,compared with 7.9 months in the placebo plus azacitidine arm. There are very limited safe and effective treatment options for these newly diagnosed AML patients. The treatment of TIBSOVO® plus azacitidine has the potential to provide a new treatment option for treatment-naïve AML patients with IDH1 mutations who are not candidates for intensive chemotherapy.

The U.S. FDA has granted Breakthrough Therapy Designation for TIBSOVO® in combination with azacitidine for this supplemental indication and Breakthrough Therapy Designation for TIBSOVO® for the treatment of adult patients with relapsed or refractory myelodysplastic syndrome (MDS) with a susceptible IDH1 mutation.

Servier is the owner of TIBSOVO®'s rights and has granted an exclusive license to CStone to develop and commercialize the product in Mainland China,Taiwan,Hong Kong,Macau and Singapore.

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 six drug approvals in Greater China,including four in Mainland China,one in Hong Kong,and one in Taiwan. 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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