MacroGenics and I-Mab Announce Exclusive Collaboration and License Agreement to Develop and Commercialize Enoblituzumab in Greater China

ROCKVILLE,Md. and SHANGHAI,July 11,2019 --MacroGenics,Inc. (NASDAQ: MGNX),a clinical-stage biopharmaceutical company focused on discovering and developing innovative monoclonal antibody-based therapeutics for the treatment of cancer,and I-Mab Biopharma (I-Mab),a China and U.S.-based clinical-stage biopharmaceutical company committed to the discovery and development of first-in-class and best-in-class biologics in immuno-oncology and autoimmune diseases,announced today that the companies have entered into an exclusive collaboration and license agreement to develop and commercialize enoblituzumab. This investigational drug is an immune-optimized,anti-B7-H3 monoclonal antibody that incorporates MacroGenics' proprietary Fc Optimization technology platform. Enoblituzumab represents one of the most advanced programs in development directed against B7-H3,a target for which no agent is currently approved. I-Mab obtains regional development and commercialization rights in mainland China,Hong Kong,Macau and Taiwan.

As part of the collaboration,I-Mab will both lead regional studies in its territories as well as participate in global studies conducted by MacroGenics. MacroGenics intends to initiate a Phase 2 study of enoblituzumab in combination with MGA012 (also known as INCMGA0012),an investigational anti-PD-1 antibody that MacroGenics licensed to Incyte Corporation,in first-line patients with head and neck cancer later this year.

"We are very pleased to be partnering with I-Mab to further accelerate and broaden the development of enoblituzumab and to support our mission of bringing innovative medicines to patients with high unmet medical needs," said Scott Koenig,M.D.,Ph.D.,President and Chief Executive Officer of MacroGenics. "We believe that I-Mab is an ideal partner given its track record of rapidly progressing innovative immuno-oncology programs and its ability to tap into the growing pharmaceutical market in this region."

"MacroGenics is recognized as a leader in the development of therapeutics targeting B7-H3 and we are committed to accelerating the development of enoblituzumab,a promising investigational drug which may represent a new treatment paradigm in immuno-oncology," said Jingwu Zang,Chief Executive Officer of I-Mab. "We believe that this program is an exciting addition to our innovative pipeline of clinical stage oncology assets."

MacroGenics expects to receive an upfront payment of $15 million in connection with the collaboration. MacroGenics will also be eligible to receive additional development and regulatory milestone payments of up to $135 million. In addition,I-Mab will pay tiered double-digit royalties (ranging from mid teens to twenty percent) based on annual net sales in the territories.

About Enoblituzumab Program

Enoblituzumab is an investigational Fc-optimized monoclonal antibody that targets B7-H3,a member of the B7 family of immune regulator proteins. B7-H3 is widely expressed by a number of different tumor types and may play a key role in regulating the immune response to various types of cancer. Encouraging data from the Phase 1 clinical study of enoblituzumab in combination with an anti-PD-1 antibody were presented at the Society for Immunotherapy of Cancer (SITC) Annual Meeting in November 2018. Based on these data,MacroGenics is planning to initiate a Phase 2 study of enoblituzumab in combination with MGA012 in patients with squamous cell carcinoma of the head and neck (SCCHN) in the second half of 2019.

About MacroGenics' Fc-Optimization Technology

MacroGenics' Fc-Optimization platform is designed to modulate an antibody's interaction with immune effector cells. The Fc region of certain antibodies binds activating and inhibitory receptors,referred to as FcγRs,on immune cells found within the innate immune system. Such interactions affect killing of cancer cells through antibody dependent cellular cytotoxicity (ADCC),among other Fc-dependent functions.

MacroGenics' optimized Fc region binds with increased affinity to the activating CD16A FcγR and unique to MacroGenics' technology,with reduced affinity to CD32B,the inhibitory FcγR. MacroGenics' optimized Fc mediates improved effector functions,such as ADCC. To date,MacroGenics has successfully incorporated its proprietary Fc Optimization technology in enoblituzumab,as well as margetuximab,an investigational anti-HER2 monoclonal antibody currently in Phase 3 development.

AboutMacroGenics,Inc.

MacroGenics is a clinical-stage biopharmaceutical company focused on discovering and developing innovative monoclonal antibody-based therapeutics for the treatment of cancer. The Company generates its pipeline of product candidates primarily from its proprietary suite of next-generation antibody-based technology platforms,which have applicability across broad therapeutic domains. For more information,please see the Company's website at www.macrogenics.com. MacroGenics and the MacroGenics logo are trademarks or registered trademarks of MacroGenics,Inc.

About I-Mab Biopharma

I-Mab is a dynamic and fast-growing global biotech company focusing on developing innovative biologics of first-in-class and best-in-class potential in the therapeutic areas of immuno-oncology and autoimmune diseases. I-Mab's pipeline of clinical and pre-clinical stage assets is driven by the company's Fast-to-Market and Fast-to-PoC development strategies through internal R&D capabilities and global partnerships. I-Mab's vision is to address unmet needs through drug innovation in the target therapeutic areas in China and the world. I-Mab is on track to become an end-to-end fully integrated biopharma company. The company is well-recognized by capital markets to have successfully raised approximately $370 million USD in the past three years,with the recent $220 million USD Series C financing representing one of the largest amounts ever raised by an innovative biotech company in China. For more information,please see the company's website at www.i-mabbiopharma.com.

MacroGenics' Cautionary Note on Forward-Looking Statements

Any statements in this press release about future expectations,plans and prospects for MacroGenics,including statements about the company's strategy,future operations,clinical development of the company's therapeutic candidates,milestone or opt-in payments from the company's collaborators,the company's anticipated milestones and future expectations and plans and prospects for the company and other statements containing the words "subject to","believe","anticipate","plan","expect","intend","estimate","project","may","will","should","would","could","can",the negatives thereof,variations thereon and similar expressions,or by discussions of strategy constitute forward-looking statements within the meaning of Section 27A of the Securities Act of 1933 and Section 21E of the Securities Exchange Act of 1934. Actual results may differ materially from those indicated by such forward-looking statements as a result of various important factors,including: the uncertainties inherent in the initiation and enrollment of future clinical trials,expectations of expanding ongoing clinical trials,availability and timing of data from ongoing clinical trials,expectations for regulatory approvals,other matters that could affect the availability or commercial potential of MacroGenics' product candidates and other risks described in the company's filings with the Securities and Exchange Commission. In addition,the forward-looking statements included in this press release represent MacroGenics' views only as of the date hereof. MacroGenics anticipates that subsequent events and developments will cause the company's views to change. However,while the company may elect to update these forward-looking statements at some point in the future,the company specifically disclaims any obligation to do so,except as may be required by law. These forward-looking statements should not be relied upon as representing MacroGenics' views as of any date subsequent to the date hereof.

MacroGenics Contacts:

Jim Karrels,Senior Vice President,CFO

Anna Krassowska,Vice President,Investor Relations & Corporate Communications

MacroGenics,Inc.

1-301-251-5172,info@macrogenics.com

I-Mab Biopharma Contacts:

Jielun Zhu,CFO

jielun.zhu@i-mabbiopharma.com

Amanda Dai,Associate Director of Public Relation

zhenhua.dai@i-mabbiopharma.com

Weimin Tang,EVP and Head of Global Business Development

Weimin.tang@i-mabbiopharma.com

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