CStone, Pfizer Enter into Strategic Collaboration to Address Oncological Needs in China

• Pfizer to invest $200 million in CStone shares and license CStone's late-stage oncology asset sugemalimab (CS1001, PD-L1 antibody) in mainland China
• CStone to receive up to $280 million in milestone payments for sugemalimab, and additional royalties
• CStone and Pfizer to develop and commercialize additional late-stage oncology therapies in Greater China

CStone Pharmaceuticals (" CStone ", HKEX: 2616)] and Pfizer Investment Co. Ltd. (" Pfizer Investment ") and Pfizer Corporation Hong Kong Limited (" Pfizer Hong Kong ") (both of which are subsidiaries of Pfizer Inc. (NYSE: PFE)) announced today the formation of a strategic collaboration that encompasses a $200 million equity investment by Pfizer Hong Kong in CStone, collaboration between CStone and Pfizer Investment for the development and commercialization of CStone's sugemalimab (CS1001, PD-L1 antibody) in mainland China, and a framework between CStone and Pfizer Investment to bring additional oncology assets to the Greater China market.

This collaboration provides financing to support CStone's development of sugemalimab, a potential best-in-class PD-L1 antibody that is being developed for high-incidence cancer indications in China, including lung, gastric and esophageal cancers, among others. Pfizer will in-license and exclusively lead commercialization of sugemalimab in China, harnessing its industry-leading capabilities to help doctors and patients across a far wider range of regions gain greater access to this treatment. The collaboration positions CStone and Pfizer to develop and commercialize additional oncology assets for the Greater China market.

"Pfizer's investment in CStone is a statement of its confidence in the potential of our anti-PD-L1 treatment and recognition of our research and development capabilities," said Frank Jiang, M.D., Ph.D., Chairman and Chief Executive Officer of CStone. "By joining forces with Pfizer and leveraging its commercialization infrastructure, we will ensure that patients across a vastly expanded number of markets in China have quicker access to our highly differentiated PD-L1 treatment. In addition, we have advanced our transformation into a full-fledged biopharmaceutical company by forging a collaboration that will enable us to accelerate development and commercialization of globally innovative therapies for Chinese patients."

"Our company has an extensive and proud history of bringing innovative medicines to patients in China," said Pierre Gaudreault, Acting President of Pfizer Biopharmaceuticals Group China. "This collaboration with CStone builds on that history by helping to develop a potential best-in-class PD-L1 treatment that we can commercialize upon approval. It also fosters our collaboration with a partner that has exceptional clinical development capabilities that can help us meet the clear need for novel oncology treatments in China."

Key Components and Financial Terms of the Collaboration

• Pfizer obtains exclusive commercialization rights to sugemalimab in mainland China, while CStone continues to lead clinical development and regulatory strategy for five selected indications.
• CStone is entitled to receive up to $280 million in milestone payments for sugemalimab and additional tiered royalties.
• CStone retains all development and commercialization rights to sugemalimab outside mainland China.
• Pfizer will invest $200 million, consisting of 115,928,803 CStone shares at a price of US$1.725 per share (approximately HK$13.37 per share). As a result of its equity investment, Pfizer will hold a 9.90 percent stake in CStone.
• CStone and Pfizer will together select late-stage (post proof-of-concept) oncology assets for co-development in the Greater China market. These assets may come either from Pfizer's pipeline or through joint in-licensing.
• CStone and Pfizer may pursue on a selected basis joint in-licensing arrangements for additional oncology assets for the Greater China market.

The transaction has received the necessary internal approvals of both companies. Closing is not subject to approval by CStone's shareholders.

Goldman Sachs & Co. LLC is acting as financial advisor to CStone, and Cooley LLP served as legal advisor. Clifford Chance LLP served as Pfizer's legal advisor.

Investor Presentation Information

CStone will host a live webcast at 11:00am (Hong Kong time) on September 30 ^th , 2020. Please find the access information as below.

All other regions: https://event.webcasts.com/starthere.jsp?ei=1380037&tp_key=735ccdf3e4
Mainland China: https://event.gmwebcasts.cn/starthere.jsp?ei=1380037&tp_key=735ccdf3e4
Password (case sensitive): CStone

About Sugemalimab

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.

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

About Pfizer: Breakthroughs and innovations to change the lives of patients

At Pfizer, we apply science and our global resources to improve health and well-being at every stage of life. We strive to set the standard for quality, safety and value in the discovery, development and manufacturing of medical and health products (including innovative drugs and vaccines) for people. Every day, Pfizer colleagues from the developed and emerging markets work to advance wellness, prevention, treatments and cures that challenge the most feared diseases of our time. Consistent with our responsibility as the world's leading biopharmaceutical company, we also collaborate with healthcare providers, governments and local communities to support and expand access to reliable, affordable health care around the world. For more than 170 years, Pfizer has worked to make a difference for all who rely on us. For more information, please visit www.pfizer.com.cn .

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.

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CSTONE INVESTORS  
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