On April 12, 2021 PharmAbcine Inc. (KOSDAQ: 208340ks), a clinical-stage biotech company focusing on the development of antibody therapeutics, reported that the company presented an e-poster featuring the non-clinical data of PMC-309 at American Association for Cancer Research (AACR) (Free AACR Whitepaper) 2021 Annual Meeting taking place virtually (Press release, PharmAbcine, APR 12, 2021, View Source [SID1234577940]).

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PMC-309, one of the company’s first immuno-oncology drug candidates, is a monoclonal IgG (Immunoglobulin G) that targets human VISTA (V-domain Ig Suppressor of T cell Activation), an immune checkpoint regulator. VISTA is found overexpressed on MDSC (Myeloid-Derived Suppressor Cells) and M2 macrophages both of which are immunosuppressive cells found abundantly around TME (Tumor Microenvironment).

The presentation highlighted that PMC-309 inhibits VISTA pathway on immunosuppressive cells and increases T cell activities in in vitro settings and shows potent anti-tumor effects in in vivo studies.

The in vitro studies confirmed that PMC-309 inhibits VISTA interaction and promotes T cell activation. PMC-309 blocked the VISTA pathway with its partner molecules such as VSIG3 (V-Set and Immunoglobulin domain containing 3), PSGL1 (P-selectin glycoprotein ligand-1) and other VISTA. In addition, there was a rise in the level of IFN-y, a pro-inflammatory cytokine, which indicates that PMC-309 enhanced T cell activities.

In in vivo studies, the test subjects administered with PMC-309 in both hPBMC (human Peripheral Blood Mononuclear Cell) engrafted mouse model and human VISTA Knock-In mouse model showed notable tumor growth inhibition. PMC-309 also showed a possible synergistic effect when used in combo with an anti-PD1 antibody because the combination of two antibodies demonstrated significantly improved tumor growth inhibition.

"Our non-clinical studies revealed PMC-309’s unique binding mechanism and its anti-tumor effect," said Dr. Jin-San Yoo, CEO of PharmAbcine. "The study results add to our confidence that PMC-309 can be a promising immunotherapeutic strategy in both mono and combo therapies for patients who do not respond to other immuno-oncology drugs."

Dr. Yoo also added, "We plan to initiate the IND (Investigational New Drug)-enabling studies and evaluate the potential toxicity risk this year. We expect PMC-309 to enter a clinical stage in 2022."

The e-poster presentation is currently available on the AACR (Free AACR Whitepaper) website. The details of the presentation are as follows:

Title: PMC309, a highly selective anti-VISTA antibody enhances T cell activation through blocking the interaction of T cells and myeloid derived suppressor cells (MDSC)
Session category/title: Immunology/Immune Checkpoints
Abstract number: 1116
Poster number: 1626
Presentation Type: E-poster with audio presentation