FDA puts partial clinical hold on Pieris trial

US clinical-stage biotech Pieris Pharmaceuticals (Nasdaq: PIS) saw its shares fall more than 11% to $2.91 in after-hours trading on Monday, after it announced that its Phase I studies of PRS-343 have been placed on partial clinical hold by the US Food and Drug Administration while Pieris conducts an additional in-use and compatibility study requested by the agency.

Currently-enrolled patients may continue to receive treatment, although no new patients can be enrolled until resolution of this partial hold. The drug candidate is currently in development for the treatment of HER2-positive solid tumors.

The partial hold follows discussions with FDA regarding the company's in-use study supporting the technical setup for clinical administration of PRS-343. Specifically, FDA has requested that Pieris conduct an additional in-use and compatibility study of PRS-343 with various infusion materials under specific conditions to confirm suitability of PRS-343 for administration in clinical settings. In its telephonic communication, the agency did not cite any adverse events in connection with its request.