Proteon Therapeutics Plans Path Forward for Blood Vessel Drug

Xconomy Boston — 

Three months ago, Proteon Therapeutics’ experimental blood vessel drug for people with failing kidneys flunked a Phase 3 clinical trial. The company now hopes that a larger study with a modified goal can produce different results.

The Proteon (NASDAQ: PRTO) drug, vonapanitase, treats people whose chronic kidney disease has progressed to the point that they need dialysis. Waltham, MA-based Proteon developed the drug to improve the success of arteriovenous fistula (AVF), a surgical procedure that connects an artery and a vein in the patient’s arm. This connection boosts blood flow, which thickens the wall of the blood vessel and helps it hold up against the needle pricks from dialysis.

In December, Proteon said vonapanitase failed the study’s main goal—keeping blood flowing, without assistance, in patients getting an AVF. Despite that setback, Proteon pointed to addressing a secondary trial goal—increasing the length of time between when an AVF is created and it finally fails, a measure called secondary patency. Proteon said that in patients treated with its drug in the previous Phase 3 trial, the risk of this failure fell by 34 percent.

Proteon had already been studying its drug in a separate Phase 3 trial, however. After talks with the FDA, Proteon says it won’t have to run a brand new study. Instead, it will modify the remaining Phase 3 trial, and if it succeeds, file for FDA approval. The modified study now has two new primary goals: secondary patency, and the ability to use the fistula for hemodialysis for 90 days. Both of those measures showed improvement in the first Phase 3 trial.

Proteon will also enroll 500 patients in the study, instead of 300. As of Feb. 28, Proteon had enrolled 315 patients. The company expects to complete enrollment by the fourth quarter.