On September 26, 2016 Pieris Pharmaceuticals, Inc. (NASDAQ: PIRS), a biotechnology company advancing novel biotherapeutics through its proprietary Anticalin technology platform, reported that it has today presented new preclinical data demonstrating in vivo efficacy of its lead 4-1BB (CD137)-based bispecific cancer immunotherapeutic drug candidate, PRS-343, at the 2016 CRI-CIMT-AACR International Cancer Immunotherapy Conference (CIMT) (Free CIMT Whitepaper) – Translating Science into Survival, taking place in New York City (Press release, Pieris, SEP 26, 2016, View Source [SID:SID1234515414]).

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The in vivo data show that treatment of HER2-positive tumor-bearing animals with PRS-343 provided dose-dependent, dual anti-tumor activity by increasing the frequency of tumor-infiltrating lymphocytes via bispecific targeting of 4-1BB and HER2, as well as mediating tumor growth inhibition by direct antagonism of HER2 on tumor cells. In contrast, an agonistic anti-4-1BB benchmark monoclonal antibody (mAb) displayed neither tumor growth inhibition nor enhanced lymphocyte infiltration into tumors compared to an isotype control mAb, but preferentially activated T cells systemically, resulting in significant toxicity. A copy of the poster can be viewed and downloaded by clicking View Source

Louis Matis, M.D., Pieris SVP and Chief Development Officer, commented, "These new data support a differentiated mode of action for PRS-343 and demonstrate the potential benefits of tumor microenvironment-localized costimulatory T cell activation for both reduced systemic toxicity and higher efficacy in comparison to conventional agonistic anti-4-1BB mAbs. We look forward to the initiation of our phase 1 clinical trial of PRS-343 for the treatment of cancer patients planned for the first half of 2017."

About PRS-343
PRS-343 is a bispecific monoclonal antibody/Anticalin fusion protein comprised of a HER2 tumor-targeting mAb genetically linked to a potent anticalin specific for the immune costimulatory TNF family receptor 4-1BB (CD137). PRS-343 is being developed as the first 4-1BB based therapeutic to mediate the activation of tumor-specific T lymphocytes selectively within the tumor microenvironment (TME). 4-1BB is a potent costimulatory immunoreceptor and an established marker for tumor-specific infiltrating T lymphocytes (TILs), and is therefore, an attractive target for cancer immunotherapy. In in vivo preclinical tumor models, PRS-343 has demonstrated potent T lymphocyte activation localized to the TME of established HER2-positive tumors, indicating the potential for both enhanced safety and efficacy.