I-Mab Biopharma Announces Dosing of First Subject in Phase 1 Clinical Trial of Anti-GM-CSF Monoclonal Antibody TJM2 in the United States

ROCKVILLE,Md.,March 19,2019 -- I-Mab Biopharma (I-Mab),a China-based clinical stage biopharmaceutical company exclusively focused on the development of innovative biologics in immuno-oncology and autoimmune diseases,today announced dosing of the first healthy subject in a Phase 1 trial in the U.S. of TJM2 (TJ003234,NCT Number: NCT03794180),a humanized immunoglobulin G1 (IgG1) antibody targeting granulocyte-macrophage colony-stimulating factor (GM-CSF). TJM2 is the first candidate from I-Mab's innovative proprietary pipeline entering clinical studies in the US.

Preclinical data have indicated that TJM2,with an acceptable safety profile,potently and specifically inhibits GM-CSF mediated GM-CSFR signaling both in vitro and in vivo. GM-CSF is an important cytokine that plays a critical role in tissue inflammation and destruction in autoimmune and inflammatory diseases. Blockade and neutralization of the bioactivity of GM-CSF can affect macrophage function and may provide clinical benefit for patients with autoimmune conditions such as rheumatoid arthritis.

The Phase 1 trial is a randomized,double blind,placebo-controlled study designed to evaluate the safety,tolerability,pharmacokinetics (PK),pharmacodynamics and immunogenicity of single ascending intravenous doses of TJM2 versus placebo in approximately 32 healthy volunteers,including Chinese subjects in the US (NCT # if available).

"It's gratifying to begin this first-in-human study in the U.S. following the promising preclinical findings,which demonstrates I-Mab's global clinical development and in-house research capability," said Dr. Joan Shen,M.D.,Ph. D,Head of R&D at I-Mab.

"Our Phase 1 I clinical trial is designed to rapidly advance TJM2 towards clinical studies in China," Shen added. "Using data from this trial,we plan to file Investigational New Drug (IND) application with China's National Medical Products Administration for clinical studies in Chinese patients with high unmet medical needs in autoimmune and inflammatory conditions."

Future studies in patients with rheumatoid arthritis will be conducted also according to the safety and tolerability data obtained from this Phase 1 study.

About I-Mab

I-Mab is a dynamic and fast-growing China-based global player exclusively focused on developing potential first-in-class and/or best-in-class biologics in the areas of immuno-oncology and autoimmune diseases through internal R&D capabilities and global partnerships. I-Mab's pipeline is driven by the company's development strategy to address unmet needs in China and to bring innovative assets to the world. The company is prepared to submit additional INDs in order to initiate clinical trials in China and the US,including multiple Phase 2 and Phase 3 studies. I-Mab is on a fast track toward becoming an end-to-end fully integrated biopharma company. The company has been well-recognized by capital markets by successfully raising approximately USD 370 million within 12 months,with its USD 220 million Series C financing in July 2018 representing one of the largest amounts ever raised by an innovative biotech company in China. www.i-mabbiopharma.com

Company contact:

Claire Xu

Head of US Site

claire.xu@i-mabbiopharma.com

Investor contact:

Jielun Zhu

CFO

jielun.zhu@i-mabbiopharma.com

Media contact:

Amanda Dai

Associate Director of Public Relation

+86-21-6057-5709

zhehua.dai@i-mabbiopharma.com

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