Pieris Pharmaceuticals Announces Dosing of First Patient in Phase I Combination Trial

Pieris Pharmaceuticals, Inc. recently announced it has dosed the first patient in the company’s Phase 1 combination clinical trial of PRS-343, its lead proprietary immuno-oncology drug candidate targeting HER2 and 4-1BB, plus atezolizumab (Tecentriq), an approved PD-L1 inhibitor.

The trial, a multicenter, open-label, Phase 1 dose escalation study, is designed to determine the safety, tolerability, and potential synergistic anti-tumor effects of PRS-343 plus anti-PD-L1 immunotherapy in patients with advanced or metastatic HER2-positive solid tumors. Elevated HER2 expression is associated with multiple cancers, including gastroesophageal, bladder, breast, and a range of other tumor types. The trial is fully funded and sponsored by Pieris, while Roche is supplying atezolizumab.

“The initiation of the combination trial of PRS-343 with an anti-PD-L1 immunotherapy marks the beginning of Pieris’ investigation into the potential synergistic effects of its 4-1BB-targeted therapy with PD-1/L1 blockade,” said Louis Matis, MD, Senior Vice President and Chief Development Officer of Pieris. “Given evidence from multiple preclinical studies demonstrating synergistic anti-tumor activity from concurrent 4-1BB activation and PD-(L)1 pathway blockade, we believe that combination therapy with PRS-343 and atezolizumab has the potential to provide significant clinical benefit for patients. We are enthusiastic to be initiating this trial and look forward to reporting our findings from this combination study next year.”

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.

HER2 is a tyrosine kinase receptor growth-promoting protein found on the surface of some cancer cells and is associated with aggressive disease progression. Multiple tumor types can express HER2 including breast, gastroesophageal, bladder, biliary (cholangiocarcinoma), colorectal, endometrial, ovarian, non-small cell lung, pancreatic, head and neck, and other cancers.

Pieris is a clinical-stage biotechnology company that discovers and develops Anticalin protein-based drugs to target validated disease pathways in a unique and transformative way. Our pipeline includes immuno-oncology multi-specifics tailored for the tumor microenvironment, an inhaled Anticalin protein to treat uncontrolled asthma and a half-life-optimized Anticalin protein to treat anemia. Proprietary to Pieris, Anticalin proteins are a novel class of therapeutics validated in the clinic and by partnerships with leading pharmaceutical companies. For more information, visit www.pieris.com.