U.S. health regulators turned down an application to approve Novartis' (NAR) experimental heart failure drug due to insufficient evidence that it improves symptoms, the Swiss drugmaker said on Friday.
Novartis said in a statement the Food and Drug Administration (FDA) had asked for further evidence to determine the efficacy of serelaxin, also known as RLX030.
The decision follows a unanimous recommendation from a panel of advisers in March against approving the drug.
Serelaxin is one of several potential "blockbuster" drugs the Basel-based pharmaceutical company is looking to as it bets on cancer, heart and respiratory treatments to fill the gaps left by patent expiries on drugs such as Diovan, which lost U.S. patent rights and faces generic competition.
Tim Wright, global head of development at Novartis, said Novartis still believed serelaxin had the potential to become "an important treatment" for acute heart failure.
Novartis is continuing with its clinical trial program in order to build up a further body of evidence and plans to enroll over 6,300 patients in a second late-stage trial, the company said.
About five million people in the United States are living with chronic heart failure, a progressive weakening of the heart, according to Novartis. About one million are hospitalized with episodes of acute heart failure, and about 22 percent of patients who are hospitalized die within a year.