SUZHOU, China, January 15, 2020 –The partner of CStone Pharmaceuticals (“CStone”, HKEX: 2616), Blueprint Medicines, announced on January 9, 2020 that the U.S. Food and Drug Administration (FDA) approved AYVAKIT™ (avapritinib) for the treatment of adults with unresectable or metastatic gastrointestinal stromal tumor (GIST) harboring a platelet-derived growth factor receptor alpha (PDGFRA) exon 18 mutation, including PDGFRA D842V mutations. AYVAKIT was discovered by Blueprint Medicines.

“I am very pleased that avapritinib, which we are developing in China through our partnership with Blueprint Medicines, has been approved in the U.S., making it the second drug candidate in CStone's pipeline that has received a U.S. FDA approval,” said Dr. Frank Jiang, Chairman and CEO of CStone. “In 2020, CStone plans to submit an NDA for the same indication to the China National Medical Products Administration (NMPA) to help address the unmet clinical needs of a genomically defined population of GIST patients in China.”

CStone Pharmaceuticals and Blueprint Medicines have an exclusive collaboration and license agreement for the development and commercialization of avapritinib and certain other drug candidates in Mainland China, Hong Kong, Macau and Taiwan. Blueprint Medicines retains development and commercial rights for these drug candidates in the rest of the world.

At present, two registrational trials of avapritinib for the treatment of GIST are being conducted in China. Of these trials, the Phase III VOYAGER trial of avapritinib in third-line GIST has completed its target enrollment of Chinese patients in less than four months. CStone plans to submit an NDA to the China NMPA for avapritinib for the treatment of third-line GIST in the second half of 2020.

For more details on the U.S. FDA approval for AYVAKIT, please refer to http://ir.blueprintmedicines.com/news-releases/news-release-details/blueprint-medicines-announces-fda-approval-ayvakittm-avapritinib

***

About CStone

CStone Pharmaceuticals (HKEX: 2616) 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 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, 5 late-stage candidates are at pivotal trials. 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.

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

Forward-looking Statement

The forward-looking statements made in this article relate only to the events or information as of the date on which the statements are made in this article. Except as required by law, we undertake no obligation to update or revise publicly any forward-looking statements, whether as a result of new information, future events or otherwise, after the date on which the statements are made or to reflect the occurrence of unanticipated events. You should read this article completely and with the understanding that our actual future results or performance may be materially different from what we expect. In this article, statements of, or references to, our intentions or those of any of our Directors or our Company are made as of the date of this article. Any of these intentions may alter in light of future development.