I-Mab Announces First Patient Dosed in Phase 1b Study of Plonmarlimab in Rheumatoid Arthritis in China

I-Mab (the “Company”) (Nasdaq: IMAB), a clinical stage biopharmaceutical company committed to the discovery, development and commercialization of novel biologics, today announced that the first patient has been dosed with plonmarlimab (also known as TJM2) in a Phase 1b study (CXSL1900100; NCT04457856) to evaluate its use in treating patients with rheumatoid arthritis (RA) in China.

Plonmarlimab is a humanized immunoglobulin G1 (IgG1) antibody that targets the cytokine granulocyte-macrophage colony-stimulating factor (GM-CSF), which plays a critical role in autoimmune and inflammatory disease. Neutralization of GM-CSF can dampen inflammatory responses and may provide clinical benefits to patients with autoimmune conditions such as RA.

“Studies have shown that GM-CSF has a profound role in modulating immune response and suppressing autoimmune diseases. We are eager to further investigate and characterize the safety and efficacy profile of plonmarlimab in treating patients with RA, a disease that continues to afflict five million people in China today[1],” said Prof. Zhan-Guo Li, lead investigator of the trial and Chief of the Department of Rheumatology and Immunology at Peking University Health Science Center.

The Phase 1b trial is a multi-center, double-blind, placebo-controlled study with 63 patients who will receive a single dose or multiple doses of the treatment for up to eight weeks. It is designed to evaluate the safety, tolerability, pharmacokinetics, pharmacodynamics and immunogenicity of plonmarlimab in patients with RA. I-Mab has successfully completed a first-in-human single ascending dose study of plonmarlimab in healthy volunteers in the United States (NCT03794180). A Phase 2 trial to treat patients with cytokine release syndrome associated with COVID-19 is currently in progress in the US.

“Plonmarlimab is the first antibody of its class entering clinical trials in China. We believe it has the great potential to become a new treatment option as a disease-modifying anti-rheumatic agent. Our intention is to achieve proof of concept in RA and expand to broad autoimmune diseases with unmet needs,” said Dr. Joan Shen, Chief Executive Officer, I-Mab.

[1] Wenhui Xie, X. Y. (2019). The plight and light of treating rheumatoid arthritis in China. The Lancet Rheumatology, 1(2), E81-E82.

Source: I-Mab