-- JW Biotechnology (Shanghai) Co., Ltd will Leverage

Juno’s Immuno-oncology Expertise and Assets and WuXi AppTec’s R&D and Manufacturing Platform to Build Leading Chinese Cell Therapy Company --

SEATTLE and SHANGHAI– April 7, 2016 – Juno Therapeutics (NASDAQ: JUNO), a biopharmaceutical company focused on re-engaging the body's immune system to revolutionize the treatment of cancer, and WuXi AppTec, a leading open-access R&D capability and technology platform company serving the pharmaceutical, biotechnology, and medical device industries, today announced that they have started a new company in China. JW Biotechnology (Shanghai)Co., Ltd’s mission is to build China’s leading cell therapy company by leveraging Juno’s world-class chimeric antigen receptor (CAR) and T cell receptor (TCR) technologies together with WuXi AppTec’s R&D and manufacturing platform and local expertise to develop novel cell-based immunotherapies for patients with hematologic and solidorgan cancers. James Li, M.D., formerly a Kleiner Perkins partner and General Manager of Amgen China, and a JW Biotechnology (Shanghai)Co., Ltd co-founder, has been appointed Chief Executive Officer of JW Biotechnology (Shanghai)Co., Ltd.

“Juno’s goal is to create novel immuno-oncology therapies to treat cancer patients around the world across a range of cancer types. Over 2.5 million people in China die annually from cancer, making it imperative for us to find an effective structure to reach these patients,” said Hans Bishop, Juno’s President and CEO. “JW Biotechnology (Shanghai)Co., Ltd, with Dr. James Li as CEO,will be able to draw on a diverse set of expertise from our company. WuXi AppTec’s track record of leadership and excellence in the Chinese pharmaceutical R&D sectorwill be key to develop and commercialize Juno’s transformational technologies for patients in this important market.”

“WuXi is very delighted to work with Juno Therapeutics, a world leader in immuno-oncology, to bring highly innovative cell therapy products to patients in China through JW Biotechnology (Shanghai) Co., Ltd,” said Dr. Ge Li, Chairman and CEO of WuXi AppTec. “The Chinese government’s regulatory reforms are expected to drive growth and demand for quality medicines that target major unmet medical needs in China, and our mission is to enable the development and commercialization of therapeutics in China through WuXi’s open-access R&D and manufacturing platform, and strategic partnerships with leading organizations worldwide.”

”JW Biotechnology (Shanghai)Co., Ltd will leverage Juno’s expertise in cell therapy technologies and WuXi AppTec’s excellence in contract services, and collaborate broadly with Chinese medical communities and government regulators to develop cell therapies that will deliver cutting-edge cancer treatments to Chinese patients. These novel technologies offer a unique opportunity that holds the potential to save lives while transforming the treatment of cancer,” said Dr. James Li, CEO of JW Biotechnology (Shanghai)Co., Ltd.

Juno and WuXi AppTec have equal initial ownership in JW Biotechnology (Shanghai)Co., Ltd, which after meeting certain conditions will have access to licensing product candidates from Juno’s pipeline for development and commercialization in China. In exchange, Juno will receive an upfront payment in equity, milestone payments, and royalties on any net sales. Dr. Ge Li will serve as Chairman of the Board of JW Biotechnology (Shanghai) Co., Ltd, and the remainder of the Board of Directors will initially include Dr. James Li, Hans Bishop, Steve Harr, M.D., Juno’s Chief Financial Officer and Head of Corporate Development, and Edward Hu, WuXi AppTec’s Chief Financial Officer and Chief Investment Officer.

About Juno's Chimeric Antigen Receptor (CAR) and T Cell Receptor (TCR) Technologies

Juno's CAR and TCR technologies genetically engineer T cells to recognize and kill cancer cells. Juno's CAR T cell technology inserts a gene for a particular CAR into the T cell, enabling it to recognize cancer cells based on the expression of a specific protein located on the cell surface. Juno's TCR technology provides the T cells with a specific T cell receptor to recognize protein fragments derived from either the surface or inside the cell. When either type of engineered T cell engages the target protein on the cancer cell, it initiates a cell-killing response against the cancer cell.

About Juno

Juno Therapeutics is building a fully integrated biopharmaceutical company focused on re-engaging the body’s immune system to revolutionize the treatment of cancer. Founded on the vision that the use of human cells as therapeutic entities will drive one of the next important phases in medicine, Juno is developing cell-based cancer immunotherapies based on chimeric antigen receptor and high-affinity T cell receptor technologies to genetically engineer T cells to recognize and kill cancer. Juno is developing multiple cell-based product candidates to treat a variety of B-cell malignancies as well as solid tumors. Several product candidates have shown compelling clinical responses in clinical trials in refractory leukemia and lymphoma conducted to date. Juno’s long-term aim is to leverage its cell-based platform to develop new product candidates that address a broader range of cancers and human diseases. Juno brings together innovative technologies from some of the world’s leading research institutions, including the Fred Hutchinson Cancer Research Center, Memorial Sloan Kettering Cancer Center, Seattle Children’s Research Institute, and The National Cancer Institute. Juno Therapeutics has an exclusive license to the St. Jude Children’s Research Hospital patented technology for CD19-directed product candidates that use 4-1BB, which was developed by Dario Campana, Chihaya Imai, and St. Jude Children’s Research Hospital.

About WuXi AppTec

WuXi AppTec is a leading pharmaceutical, biotechnology, and medical device R&D platform company with global operations. As a research-driven and customer-focused company, WuXi AppTec provides a broad and integrated portfolio of laboratory and manufacturing services throughout the drug and medical device R&D process. WuXi AppTec's services are designed to assist its global partners in shortening the cycle and lowering the cost of drug and medical device R&D. WuXi AppTec is also building a platform to provide clinical diagnostic services directly to physicians and their patients globally. For more information, please visit: http://www.wuxiapptec.com.

Juno’s Forward-Looking Statements

This press release contains “forward-looking statements”within the meaning of the Private Securities Litigation Reform Act of 1995, Section 27A of the Securities Act of 1933, and Section 21E of the Securities Exchange Act of 1934, including statements regarding Juno’s mission, business focus, business plans, and IP position, and the objectives and potential of JW Biotechnology (Shanghai) Co., Ltd, including the possibility of developing and commercialized CAR and TCR technologies in China and the possibility of collaborating with Chinese medical communities and government regulators. Forward-looking statements are subject to risks and uncertainties that could cause actual results to differ materially from such forward-looking statements, and reported results should not be considered as an indication of future performance. These risks and uncertainties include, but are not limited to, risks associated with: the success, cost, and timing of Juno's product development activities and clinical trials; Juno's ability to obtain regulatory approval for and to commercialize its product candidates; Juno's ability to establish a commercially-viable manufacturing process and manufacturing infrastructure; regulatory requirements and regulatory developments; success of Juno's competitors with respect to competing treatments and technologies; Juno's dependence on third-party collaborators and other contractors in Juno's research and development activities, including for the conduct of clinical trials and the manufacture of Juno's product candidates; Juno's dependence on Celgene for the development and commercialization outside of North America and China of product candidates for which Celgene exercises an option; Juno’s dependence on JW Biotechnology (Shanghai) Co., Ltd, over which Juno does not exercise complete control,for the development and commercialization of product candidates in China; Juno's ability to obtain, maintain, or protect intellectual property rights related to its product candidates; amongst others. For a further description of the risks and uncertainties that could cause actual results to differ from those expressed in these forward-looking statements, as well as risks relating to Juno's business in general, see Juno's Annual Report on Form 10-K filed with the Securities and Exchange Commission on February 29, 2016 and Juno’s other periodic reports filed with the Securities and Exchange Commission. These forward-looking statements speak only as of the date hereof. Juno disclaims any obligation to update these forward-looking statements.

Juno Contacts:

Investor Relations

Nicole Keith

206-566-5521, nikki.keith@junotherapeutics.com

Media

Julie Normart, W2O Group

415-946-1087, jnormart@w2ogroup.com

WuXi AppTec Contact:

Aaron Shi

+86-21-5046-4362, aaron_shi@wuxiapptec.com