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# Pieris Pharma Study of Cancer Drug on Hold
- URL: https://www.fdaweb.com/pieris-pharma-study-of-cancer-drug-on-hold/
- Published: 2020-07-21T12:00:00.000Z
- Updated: 2026-09-14T16:21:57.000Z
- Author: David McFarland
- Tags: Drugs, #legacy-id-D5147240

FDA has placed a Pieris Pharmaceuticals Phase 1 study of PRS-343 on partial clinical hold while the company conducts an additional in-use and compatibility study requested by the agency. Currently-enrolled patients may continue to receive treatment, the company says, but no new patients can be enrolled until the hold is resolved. PRS-343 is currently being evaluated for treating HER2-positive solid tumors.

The company says the partial hold follows discussions with FDA about the 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,” it says. “In its telephonic communication, the agency did not cite any adverse events in connection with its request. In-use and compatibility studies are laboratory-based studies typically conducted to evaluate the impact of product handling on a drug candidate's behavior, including effects of dilution media, hold times, and adsorption to materials such as tubing and infusion bags before administration to patients.”

Pieris describes PRS-343 as a 4-1BB/HER2 fusion protein comprising a 4-1BB-targeting Anticalin protein and a HER2-targeting antibody. Ongoing Phase 1 studies of PRS-343 include a monotherapy study and a combination study with atezolizumab. Based on encouraging initial results from both studies, the company says it is actively working towards initiating a Phase 2 study in combination with ramucirumab and paclitaxel for treating HER2-positive gastric cancer in a second line setting later this year.