Pieris Pharmaceuticals Announces Dosing of First Patient in Phase I Trial for Fully Proprietary Lead IO Program, PRS-343

Pieris Pharmaceuticals (NASDAQ:PIRS) has announced that the first patient has been does in its Phase 1 clinical trial of PRS-343, its lead proprietary immuno-oncology drug candidate.
As quoted in the press release:

PRS-343 is a first-in-class bispecific antibody-Anticalin fusion protein and functions as a tumor-targeted immune costimulatory 4-1BB agonist. The trial, a multicenter, open-label, Phase I dose escalation study that will include expansion cohorts, is designed to determine the safety, tolerability and potential anti-cancer activity of PRS-343 in patients with advanced or metastatic HER2-positive solid tumors for which standard treatment options are not available, are no longer effective, are not tolerated, or the patient has refused standard therapy. Elevated HER2 expression is associated with multiple cancers, including gastroesophageal, bladder, breast and a range of other tumor types.
“We are very pleased to have commenced dosing PRS-343 in this Phase I trial,” said Louis Matis, M.D., Senior Vice President and Chief Development Officer of Pieris. “PRS-343 has been designed to selectively activate 4-1BB-expressing T cells within the tumor microenvironment, thus diminishing the likelihood of toxicity from systemic immune activation. PRS-343 has also exhibited HER2 inhibitory activity in preclinical studies, thereby demonstrating the potential to mediate dual anti-tumor effects.”
About PRS-343:
PRS-343 is a bispecific monoclonal antibody-Anticalin fusion protein comprised of a HER2 tumor-targeting antibody 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 bispecific 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, 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.

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