Proteon Therapeutics Inc. has started its second phase 3 study of vonapanitase in patients with chronic kidney disease undergoing surgical creation of a radiocephalic arteriovenous fistula (AVF) for hemodialysis. Vonapanitase is an investigational drug designed to improve arteriovenous fistula patency, and reduce the failure of the hemodialysis vascular access.

The second phase 3 study complements the first Phase 3 study, which was initiated in July 2014 and is expected to complete enrollment by the end of 2015. Both phase 3 studies are evaluating the safety and efficacy of a single treatment of vonapanitase. Vonapanitase is a locally acting recombinant human elastase.

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The first patient in the second Phase 3 study was enrolled at Saint Luke’s Hospital of Kansas City, by Christie Wynette Gooden, MD, Clinical Assistant Professor, Department of Surgery at the University of Missouri-Kansas City School of Medicine.

“Radiocephalic AVFs are at risk of reduced blood flow and patency loss, which results in additional corrective procedures and reduced AVF survival,” said Gooden. “There are no approved therapies currently available to prolong AVF patency, which we will be evaluating in this clinical study.”

The randomized, double-blind, placebo-controlled Phase 3 clinical trial will enroll 300 patients at approximately 40 centers in the United States and Canada. Immediately after surgical creation of a radiocephalic AVF, each patient will receive either 30 micrograms of vonapanitase or placebo, delivered in a single, local administration to the external surface of the AVF. The primary efficacy endpoint, measured over 12 months, is primary patency, the time from AVF creation until a thrombosis or a procedure to restore or maintain patency.

The secondary efficacy endpoint, also measured over 12 months, is secondary patency, defined as the time from AVF creation until AVF abandonment.

Phase 2 study results

In April, Proteon released positive results from a long-term analysis of more than three years of follow-up data from a phase 2 study of vonapanitase. The study, presented at National Kidney Foundation’s 2015 Spring Clinical Meetings, demonstrated prolonged primary patency of an arteriovenous fistula and a statistically significant improvement in the rate of corrective procedures over more than three years of follow-up for the 30 mcg vonapanitase dose as compared to placebo.