I-Mab Announces IND Approval from China NMPA for Phase 2 Clinical Trial of Enoblituzumab in Combination with Pembrolizumab in Solid Tumors

SHANGHAI and GAITHERSBURG,Md.,Dec. 27,2021 -- I-Mab (the "Company") (Nasdaq: IMAB),a clinical-stage biopharmaceutical company committed to the discovery,development,and commercialization of novel biologics,announced that the Center for Drug Evaluation (CDE) of China's National Medical Products Administration (NMPA) has approved I-Mab's IND submission for the initiation of a phase 2 trial in China for enoblituzumab (also known as TJ271) in combination with pembrolizumab (Keytruda®) in patients with solid tumors,including non-small cell lung cancer (NSCLC),urothelial carcinoma (UC),and other selected cancers. I-Mab has acquired exclusive rights to develop and commercialize enoblituzumab in Greater China from MacroGenics (Nasdaq: MGNX).

Enoblituzumab is a highly differentiated humanized monoclonal antibody directed against the immune regulator B7-H3,which plays a key role in regulating immune response against cancers and is widely expressed in multiple cancers. The presence of B7-H3 in tumors is associated with the poor efficacy of neoadjuvant therapies. Enoblituzumab enhances the antibody-dependent killing of cancer cells and has demonstrated strong anti-tumor activity in preclinical studies. Additional preclinical data generated by I-Mab and preliminary clinical evidence from MacroGenics support increased efficacy for the combination of enoblituzumab and a PD-1 antibody against cancers.

The phase 2 clinical trial in China will evaluate the efficacy of the combination of enoblituzumab and pembrolizumab. The trial is designed as a "basket" clinical trial in patients with NSCLC,UC,and other selected cancer types based on previous studies conducted by MacroGenics. These previous studieshave indicated that combination therapy resulted in anti-tumor activity in recurrent or metastatic NSCLC and squamous cell carcinoma of the head and neck (SCCHN).

"The initiation of the phase 2 clinical trial will accelerate the clinical development of enoblituzumab in China," said Dr. Andrew Zhu,President of I-Mab. "Enoblituzumab has become a key player against various advanced cancers and one of the Company's core clinical assets. We are excited about the initiation of this clinical study and expect to bring this valuable compound to cancer patients with critical unmet medical needs."

Currently,MacroGenics is conducting a phase 2 study of enoblituzumab in combination with retifanlimab (PD-1 antibody) or tebotelimab (PD-1 & LAG-3 bispecific DART® molecule) for first-line treatment of patients with recurrent or metastatic SCCHN.

About Enoblituzumab

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 many different tumor types and may play a key role in regulating the immune response to various types of cancer. Enoblituzumab has been or is currently being evaluated in clinical trials as a monotherapy or in combination with anti-PD-1-based therapies in patients with B7-H3-expressing cancers. I-Mab acquired the development and commercial rights from MacroGenics for Greater China.

About I-Mab

I-Mab (Nasdaq: IMAB) is an innovation-driven global biopharma company focused on the discovery,and commercialization of novel and highly differentiated biologics for immuno-oncology and autoimmune diseases. The Company's mission is to bring transformational medicines to patients around the world through innovation. I-Mab's globally competitive pipeline of more than 20 clinical and preclinical-stage drug candidates is driven by its internal discovery and global partnerships for in-licensing,based on the Company's Fast-to-Proof-of-Concept and Fast-to-Market development strategies. The Company is progressing from a clinical-stage biotech company into a fully integrated global biopharmaceutical company with cutting-edge R&D capabilities,a world-class GMP manufacturing facility,and commercial capability. I-Mab has established its global footprint in Shanghai (headquarters),Beijing,Hangzhou,Guangzhou,Lishui and Hong Kong in China,and Maryland and San Diego in the United States. For more information,please visithttp://ir.i-mabbiopharma.comand follow I-Mab onLinkedIn,Twitter,andWeChat.

I-Mab Forward-Looking Statements

This press release contains forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995 and other federal securities laws,including statements regarding data from the enoblituzumab preclinical studies,the potential implications of clinical data for patients,and I-Mab's advancement of and anticipated clinical development,regulatory milestones,and commercialization of enoblituzumab. Actual results may differ materially from those indicated in the forward-looking statements as a result of various important factors,including but not limited to I-Mab's ability to demonstrate the safety and efficacy of its drug candidates; the clinical results for its drug candidates,which may not support further development or NDA/BLA approval; the content and timing of decisions made by the relevant regulatory authorities regarding regulatory approval of I-Mab's drug candidates; I-Mab's ability to achieve commercial success for its drug candidates,if approved; I-Mab's ability to obtain and maintain protection of intellectual property for its technology and drugs; I-Mab's reliance on third parties to conduct drug development,manufacturing and other services; I-Mab's limited operating history and I-Mab's ability to obtain additional funding for operations and to complete the development and commercialization of its drug candidates; and the impact of the COVID-19 pandemic on the Company's clinical development,commercial and other operations,as well as those risks more fully discussed in the "Risk Factors" section in I-Mab's most recent annual report on Form 20-F,as well as discussions of potential risks,uncertainties,and other important factors in I-Mab's subsequent filings with the U.S. Securities and Exchange Commission. All forward-looking statements are based on information currently available to I-Mab,and I-Mab undertakes no obligation to publicly update or revise any forward-looking statements,whether as a result of new information,future events or otherwise,except as may be required by law.

I-Mab Contacts

John Long

Chief Financial Officer

john.long@i-mabbiopharma.com

+86 21 6057 8000

Gigi Feng

Chief Communications Officer

gigi.feng@i-mabbiopharma.com

+86 21 6057 8000

Investor Inquiries

The Piacente Group,Inc.

Emilie Wu

E-mail: emilie@thepiacentegroup.com

Office line: +86 21 6039 8363

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