I-Mab Reports Positive Interim Analysis of Phase 2/3 Study of Its GM-CSF Plonmarlimab (TJM2) Antibody to Treat Patients with Severe COVID-19



SHANGHAI and GAITHERSBURG, MD., August 11, 2021 / PRNewswire / – I-Mab (the “Company”) (Nasdaq: IMAB), a clinical-stage biopharmaceutical company engaged in the discovery, development and commercialization of new biologics, today announced positive interim data of its phase 2 in the United States / 3 study (NCT04341116) plonmarlimab (also known as TJM2 or TJ003234) for the treatment of cytokine release syndrome (CRS) in patients with severe COVID-19. Plonmarlimab was discovered and developed by I-Mab to target Granulocyte and Macrophage Colony Stimulating Factor (GM-CSF), a cytokine that plays an essential role in acute and chronic inflammation.

The COVID-19 virus (SARS-CoV-2), particularly the Delta variant, is known to cause a pathological surge of circulating inflammatory cytokines called cytokine release syndrome (CRS) or cytokine storm, which is responsible for complications and higher mortality associated with the disease. Plonmarlimab plays an essential therapeutic role in CRS by inhibiting GM-CSF which acts upstream of the pathological inflammatory cascade and is expected to be more effective in the prevention and treatment of CRS.

“We are very excited about the data and plonmarlimab could be a very promising treatment for hospital patients with COVID-19,” said Deepa gotur, MD, associate professor of clinical medicine at Houston Methodist.

The ongoing Phase 2/3 study in the United States is one of the first randomized, placebo-controlled, double-blind studies to assess the therapeutic role of GM-CSF antibodies in patients with severe COVID-19. The study aimed to determine the safety, efficacy and effects on cytokine levels after a single 6 mg / kg dose of plonmarlimab or placebo in patients with severe COVID-19.

The current interim analysis showed positive preliminary results in patients who were without mechanical ventilation (MVF) at baseline (N = 91). Plonmarlimab treatment resulted in higher FMV rate (83.6% vs. 76.7%) on day 30, lower mortality rate (4.9% vs. 13.3%) on day 30, higher recovery (68.9% vs. 56.7% on day 14 and 80.3% vs. 70.0% on day 30), as well as reduced recovery time and hospital stay, compared to placebo . The magnitudes of clinical improvements are comparable to those seen with lenzilumab in a similar patient population.[1] Biomarker the results were consistent with the clinical results observed and indicated that patients treated with plonmarlimab exhibited a reduction in plasma levels of pro-inflammatory cytokines and chemokines strongly involved in CRS, including TARC, IP10, GCSF, IL10, IL6, MCP1, IL1RA, TNF-alpha but not gamma interferon. A transient increase in the neutrophil-to-lymphocyte ratio (NLR) which is commonly associated with an exacerbation of the disease has only been observed with placebo. Plonmarlimab was well tolerated in all patients without any significant safety concerns.

“Plonmarlimab has shown very promising results from the analysis of interim data in our Phase 2/3 trial, and we intend to continue advancing the study in the United States at this critical stage of the pandemic. COVID-19 and continue to explore other clinical opportunities associated with CRS, said Dr. Joan shen, CEO of I-Mab.

About Plonmarlimab

Plonmarlimab (or TJM2) is an internally discovered neutralizing antibody against human GM-CSF, an important cytokine that plays an essential role in chronic inflammation and destruction in autoimmune diseases such as RA. GM-CSF can polarize macrophages in the pro-inflammatory M1 phenotype and is known to induce an inflammatory cascade involving other pro-inflammatory cytokines such as tumor necrosis factor (TNF), interleukin-1 (IL- 1), IL-6, IL-12 and IL-23. It is evident that GM-CSF plays a crucial role in the pathogenesis and disease progression of multiple autoimmune diseases.

Plonmarlimab binds specifically to human GM-CSF with high affinity and can prevent GM-CSF from binding to its receptor, thereby preventing downstream signaling and activation of target cells. As a result, it can effectively inhibit inflammatory responses mediated by macrophages, neutrophils, and dendritic cells, resulting in reduced inflammation and tissue damage.

About I-Mab

I-Mab (Nasdaq: IMAB) is a dynamic global biotechnology company focused exclusively on the discovery, development and soon to commercialize new or highly differentiated biologics in the therapeutic areas of immuno-oncology and autoimmune diseases. . The Company’s mission is to bring transformational medicines to patients around the world through innovation. I-Mab’s innovative pipeline of more than 10 clinical and preclinical drug candidates is guided by the Company’s Fast-to-PoC (Proof-of-Concept) and Fast-to-Market development strategies via the Internal R&D and global partnerships. The company is on track to grow from a clinical-stage biotechnology company to a fully integrated global biopharmaceutical company with cutting-edge R&D capabilities, world-class GMP manufacturing facilities and commercial capabilities. I-Mab has offices at Beijing, Shanghai, Hangzhou, Hong Kong, and Maryland, United States. For more information, please visit http://ir.i-mabbiopharma.com and follow I-Mab on LinkedIn, Twitter, and WeChat.

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 plonmarlimab Phase 2/3 trial data, potential implications of clinical data for patients, and I – Advancement and anticipated clinical development of Mab, regulatory milestones and commercialization of plonmarlimab. Actual results may differ materially from those shown in forward-looking statements due to 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 of its drug candidates, which may not support further development or NDA / BLA approval; the content and timing of decisions made by relevant regulatory authorities regarding the regulatory approval of I-Mab drug candidates; I-Mab’s ability to achieve commercial success for its drug candidates, if approved; I-Mab’s ability to obtain and maintain intellectual property protection for its technology and drugs; I-Mab’s dependence on third parties to conduct drug development, manufacturing and other services; I-Mab’s limited operating history and I-Mab’s ability to secure additional funding for its operations and complete the development and commercialization of its drug candidates; and the impact of the COVID-19 pandemic on the Company’s clinical development, business and other operations, as well as the risks discussed in more detail in the “Risk Factors” section of I -Mab on Form 20-F, as well as discussions of potential risks, uncertainties, and other important factors in I-Mab’s subsequent filings with the United States Securities and Exchange Commission. All forward-looking statements are based on information currently available to I-Mab, and I-Mab assumes no obligation to publicly update or revise any forward-looking statements, whether as a result of new information, events future or otherwise, unless may be required by law.

For more information please contact:


Jielun Zhu, Chief Financial Officer
E-mail: [email protected]
Office line: +86 21 6057 8000

Gigi feng, responsible for the communication
E-mail: [email protected]
Office line: +86 21 6057 5709

Investor surveys:

The Piacente Group, Inc.
Emilie wu
E-mail: [email protected]
Office line: + 86 21 6039 8363


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