Polyphor Shares Plunge After it Halts Enrollment in Two Pneumonia Trials Due to Safety Concerns

Shares of Switzerland-based Polyphor have plunged more than 20 percent on the Swiss exchange after the company announced it temporarily halted enrollment for two Phase III trials evaluating its pneumonia treatment candidate due to safety concerns.

In a brief announcement today, Polyphor said it halted enrollment in PRISM-MDR and PRISM-UDR, two late-stage trials that are evaluating the company’s experimental drug murepavadin in patients with nosocomial pneumonia. Polyphor noted that enrollment was halted due to “higher than expected acute kidney injury incidences” in the murepavadin arm of the PRISM-MDR trial. Polyphor said that the kidney alteration incidences were observed in 56 percent of patients who were treated in the Phase III study. The company said that it was anticipating incidences of 25 to 40 percent due to the existing literature, as well as the comparator arm in the trial.

Murepavadin is Polyphor's most advanced product candidate. Murepavadin is a pathogen-specific antibiotic functioning through a novel mechanism of action involving binding to an outer membrane protein of Pseudomonas aeruginosa. In contrast to commonly used broad-spectrum antibiotics, murepavadin is a precision medicine and as such it supports the growing practice known as "antibiotic stewardship" which, among other things, seeks to reduce the excessive use of broad-spectrum products to avoid the buildup of resistance and to preserve the microbiome of the patients, the company said.

“While proactively halting the Phase III trials for murepavadin is disappointing, patient safety is of utmost importance to Polyphor,” Frank Weber, Polyphor’s director and chief medical and development officer, said in a statement. “We are trying to better understand the reasons for these events and are exploring ideas on how to tackle them for the future, as we remain convinced that murepavadin could still represent a valuable drug to help patients fighting pseudomonas infections.”

Polyphor said the decision to temporarily halt enrollment in the trial was made in conjunction with the independent Data Monitoring Committee. The company said it will provide an update on the continuation of both Phase III trials in July, once all available data has been reviewed. The decision to temporarily halt enrollment applies only to the PRISM-MDR and PRISM-UDR studies. It will not impact additional development of the murepavadin inhaled program, nor the advancement of the OMPTA program. Polyphor also noted that its Phase III trial evaluating the development of its immuno-oncology candidate balixafortide for treatment of metastatic breast cancer will proceed as planned.