I-Mab, a clinical stage biopharmaceutical company committed to the discovery, development and commercialization of novel biologics, today announced that an abstract detailing clinical data from its U.S. phase 1 study of uliledlimab in combination with atezolizumab (TECENTRIQ?) in patients with advanced cancer will be presented at the 2021 American Society of Clinical Oncology (ASCO) Annual Meeting, taking place June 4-8, 2021. The abstract has been selected as one of the Top 12 abstracts for poster discussion during the Developmental Therapeutics – Immunotherapy session.

Uliledlimab is a humanized CD73 antibody and is designed to counter the adenosine-mediated immunosuppressive tumor microenvironment, rendering anti-tumor immune cells to act more effectively in response to checkpoint immunotherapies. Preclinical studies have shown that when combined with a PD-(L)1 antibody, uliledlimab exhibited a superior and synergistic inhibitory effect on tumor growth versus PD-(L)1 mono-therapy. Uliledlimab is a highly differentiated CD73 antibody that binds to a unique epitope of CD73 to confer pharmacological advantages by avoiding the "hook effect" commonly seen with other CD73 antibodies.

The U.S. phase 1 dose escalation study of uliledlimab in combination with atezolizumab showed that the treatment is safe and well tolerated with no dose-limiting toxicity. All treatment related adverse events were either grade 1 or grade 2. Uliledlimab demonstrated a linear pharmacokinetic (PK) profile and reached full receptor occupancy on B cells at the middle and high dose levels with no "hook effect." Patients who participated in the study had advanced cancers and exhausted other cancer therapies. Among the 13 efficacy-evaluable patients dosed at ≥ 10 mg/kg, three patients had complete or partial responses (objective response rate = 23%) and three had stable disease (disease control rate = 46%). The clinical activity was observed in both PD-(L)1 treatment na?ve and refractory cancer patients, including one partial response patient who previously failed nivolumab. Tumor types of patients who had complete or partial responses or stable disease included ovarian clear cell carcinoma, non-small cell lung cancer and a few other cancers. The three responders were identified as the only patients who exhibited higher co-expression of tumor CD73 and PD-L1 as compared to non-responders, indicating a correlation between higher CD73 expression and clinical activity of uliledlimab and a potential role of CD73 as a predictive biomarker to warrant further investigation.

"Despite recent breakthroughs with PD-1/PD-L1 therapies, clinical non-response rates to such treatments remain high in cancer patients. Uliledlimab, through its unique mechanism of action, has shown its promise to address this unmet medical need by breaking tumor resistance to immunotherapies through combination therapy," said Dr. Joan Shen, CEO of I-Mab. "The results from this phase 1 study are very encouraging in terms of potential therapeutic role of uliledlimab to treat multiple cancers, especially in patients who do not respond to PD-1/PD-L1 therapies. The differentiated properties of uliledlimab may provide additional pharmacological and treatment advantages, and we look forward to advancing the development of uliledlimab both globally and in China."

In parallel development, I-Mab has made significant progress in clinical trials in China to evaluate uliledlimab in combination with toripalimab (TUOYI?) in patients with advanced or metastatic cancers, including non-small cell lung cancer, who are refractory to or intolerant of available therapies.

About Uliledlimab (TJD5)

Uliledlimab (TJD5) is a differentiated, humanized antibody against CD73, an ecto-enzyme expressed on stromal cells and tumors that converts extracellular adenosine monophosphate (AMP) to adenosine.  Adenosine in turn binds to adenosine receptors on relevant immune cells and inhibits anti-tumor immune responses in tumor microenvironment.  Uliledlimab is expected to offer clinical benefit by suppressing tumor growth in concert with checkpoint therapies such as PD-(L)1 antibodies. Uliledlimab is effective in anti-tumor activities through a unique intra-dimer binding, leading to differentiated and favorable functional properties as evident in preclinical studies.

About I-Mab

I-Mab (Nasdaq: IMAB) is an innovation-driven global biotech company focusing on discovery, development and soon commercialization of novel and highly differentiated biologics in immuno-oncology therapeutic area. The Company's mission is to bring transformational medicines to patients around the world through drug innovation. I-Mab's globally competitive pipeline of more than 15 clinical and pre-clinical stage drug candidates is driven by its internal R&D capability and global licensing partnerships, based on the Company's unique Fast-to-Proof-of-Concept and Fast-to-Market pipeline development strategies. The Company is now rapidly progressing from a clinical stage biotech company to a fully integrated global biopharmaceutical company with cutting-edge global R&D capabilities, a world-class GMP manufacturing facility and commercialization capability. I-Mab has established its global footprint in Shanghai (headquarters), Beijing, Hangzhou and Hong Kong, S.A.R., China in China, and Maryland and San Diego in the United States.