Proteon Therapeutics Inc.'s phase 3 trial of vonapanitase, a treatment for chronic kidney disease, failed to meet the primary endpoint of improved primary unassisted blood flow versus placebo.

The trial evaluated the efficiency of the drug in patients with chronic kidney disease receiving or expecting to receive dialysis who underwent surgical creation of a radiocephalic arteriovenous fistula, a procedure that connects a vein to an artery to assist with dialysis.

The primary endpoint in the trial was the length of time from fistula surgical creation to the first occurrence of a fistula thrombosis or corrective procedure to restore or maintain blood flow. Vonapanitase-treated patients had a 17% reduction in the risk of primary unassisted blood flow loss over one year, compared to placebo.

While the trial failed to achieve its primary endpoint, the results for the secondary endpoint, which was the length of time from surgical creation until fistula abandonment or failure, suggested that patients treated with the drug had a 34% reduction in the risk of secondary blood flow loss over a year versus placebo.

Steven Burke, senior vice president and chief medical officer, said in a statement that the company was encouraged by the secondary blood flow and fistula use for dialysis findings and will investigate these findings in another ongoing phase 3 trial.

Proteon had cash, cash equivalents and available-for-sale investments of $43.3 million as of Nov. 30. It expects these financial resources will be sufficient to fund its operations into the third quarter of 2018 based on changes to its operating plan that it plans to implement.