The world's most costly drug was approved with inaccurate data, the U.S. Food and Drug Administration said Tuesday.
The gene therapy Zolgensma was given the green light by the FDA in May at the price of $2.125 million for a one-time treatment for children with a severe form of spinal muscular atrophy, a leading genetic cause of infant mortality.
The FDA approved Zolgensma on May 24, only to learn a month later of a "data manipulation issue that impacts the accuracy of certain data from product testing performed in animals," the agency said in a statement.
The drug's manufacturer, AveXis, a unit of Novartis, discovered the data was faulty before its approval, but waited until after to inform the FDA, the agency added.
"The agency will use its full authorities to take action, if appropriate, which may include civil or criminal penalties," Peter Marks, an FDA official, stated.
Despite the problems, the FDA said it "remains confident that Zolgensma should remain on the market."
Novartis did not deny the allegations, but defended its product and handling of the situation overall.
"We maintain that the totality of the evidence demonstrating the product's effectiveness and its safety profile continue to provide compelling evidence supporting an overall favorable benefit-risk profile," the company said in an emailed statement. "At no time during the investigation did the findings indicate issues with product safety, efficacy or quality."
The company is working with the FDA to update its application and "address any quality gaps," Novartis added.
U.S.-traded shares of the Swiss drugmaker fell nearly 3% on Tuesday, while shares of competitor Biogen, which also makes a spinal muscular atrophy treatment, ended more than 2% higher.
In a tweet, acting FDA Commissioner Ned Sharpless said the agency depends "on truthful scientific data to make regulatory decisions, and we take the issue of data integrity very seriously."