Suzhou, China; September 17, 2018 -- CStone Pharmaceuticals (CStone) today announced that the global Phase III (AGILE) clinical trial for ivosidenib (TIBSOVO^®) has been approved by China's National Medical Products Administration (NMPA). The study will evaluate ivosidenib in combination with azacitidine in patients with newly diagnosed IDH1-mutated acute myeloid leukemia (AML) who are not eligible for standard-of-care chemotherapy. CStone is responsible for ivosidenib's development in China under a license agreement with Agios Pharmaceuticals, Inc., (NASDAQ:AGIO) and aims to make the product accessible to Chinese AML patients as soon as possible.

As an innovative biotechnology company focused in oncology, CStone plans to bring a new generation of transformative drugs to Chinese patients through both in-house drug discovery and external partnerships.

In June 2018, CStone and Agios announced the exclusive collaboration and license agreement for the development and commercialization of ivosidenib in Mainland China, Hong Kong, Macau and Taiwan ("Greater China"). In July 2018, ivosidenib achieved a critical milestone with its market approval from the U.S. Food and Drug Administration (FDA) for the treatment for adult patients with relapsed or refractory AML with an 1DH1 mutation. Today's approval of the Phase III AGILE trial in China represents a significant milestone in the collaboration between the two companies.

CStone's chairman and CEO Dr. Frank Jiang commented: "CStone is thrilled to initiate the AGILE study in China. Ivosidenib is a first-in-class, orally available targeted therapy against the IDH1 mutation that has the potential to bring significant benefits for patients with acute myeloid leukemia in China. CStone is committed to rapidly and efficiently carry out clinical development to ensure early access of cutting-edge therapies for Chinese patients."

About AML

AML is the most common form of acute leukemia affecting adults and is marked by rapid disease progression. There are an estimated 20,000 new cases in the United States each year, while China has over 30,000 newly diagnosed AML sufferers annually. The majority of patients with AML eventually relapse. Relapsed or refractory AML has a poor prognosis, with a five-year survival rate of approximately 27%.

IDH1 mutation affects a proportion of AML sufferers, contributing to an abnormal accumulation of metabolites, blocking normal blood stem cell differentiation, and acting as one of the mechanisms behind the genesis of acute leukemia. Blocking the activity of mutated IDH1 enzyme promotes differentiation of AML cells, thereby exerting an anti-tumor effect. In China, CStone estimates that IDH1m is associated with 6%-10% of AML cases.

About Ivosidenib (TIBSOVO^®)

Ivosidenib is an investigational first-in-class, orally available, selective, potent inhibitor of the mutated IDH1 protein and is a highly targeted investigational medicine for the treatment of patients with cancers that harbor an IDH1 mutation. IDH1 is a metabolic enzyme that is mutated in a wide range of cancers, including AML, cholangiocarcinoma and glioma. Ivosidenib was approved as a treatment for IDH1m relapsed or refractory AML by the U.S. FDA on July 20, 2018. The following global Phase III global clinical trials of ivosidenib are ongoing:

Phase III AGILE trial of ivosidenib in combination with azacitidine in patients with newly diagnosed IDH1m AML who are not eligible for standard-of-care chemotherapy

Phase III ClarIDHy trial of ivosidenib in advanced IDH1m cholangiocarcinoma

About CStone Pharmaceuticals

CStone Pharmaceuticals is an innovation-driven biopharmaceutical company devoted to the development of immuno-oncology therapeutics and combination therapies. The company has a broad pipeline consisting of 14 molecules currently, 8 of which are in clinical-stage development while 3 products have been approved for registrational studies in China and overseas markets. All members of the management team are seasoned executives from top multinational pharmaceutical companies. CStone has successfully built up its core competency in clinical development and translational medicine. The company is backed by prestigious VC/PE funds via two financing rounds to date, raising $150 million in a Series A round in July 2016, followed by $260 million in a Series B round in May 2018. With an experienced team, a rich pipeline, a robust R&D model, and substantial funding, CStone is well positioned as the partner of choice for multinational pharmaceutical and biotech companies to develop drugs in China and the Asia-Pacific region.

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