Pieris presents data from phase 1 dose-escalation monotherapy study of PRS-343
Pieris Pharmaceuticals announced the presentation of data from the phase 1 dose-escalation monotherapy study of PRS-343, a 4-1BB/HER2 bispecific for the treatment of HER2-positive solid tumors, in a late-breaking oral presentation at the Society for Immunotherapy of Cancer Annual Meeting. PRS-343 demonstrated single-agent anti-tumor activity, including partial responses, in heavily pre-treated patients across multiple HER2-positive tumors. Beyond demonstrating clinical benefit, PRS-343 showed a potent increase in CD8+ T cell numbers and proliferative index in the tumor microenvironment of responders, indicative of 4-1BB agonism on T cells. PRS-343 was safe and well tolerated at all doses and schedules tested. "The data presented today demonstrate PRS-343's potential to make a meaningful difference for patients with tumors that are difficult to treat with currently-available therapies," said Geoffrey Ku, medical oncologist at Memorial Sloan Kettering and the principal investigator for the PRS-343 monotherapy trial. "Beyond today's presentation, I look forward to sharing some of these case studies at Pieris' upcoming R&D day alongside emerging data from the study of PRS-343 in combination with atezolizumab."