Zolgensma, Novartis' gene therapy drug for spinal muscular atrophy, totaled $186 million in fourth quarter sales, according to Stat.
Total sales for 2019 were $361 million, with the FDA only approving the drug for infants under the age of 2 in June.
About 200 patients have been treated with Zolgensma since its approval.
Priced at $2.1 million, Zolgensma provides a one-time treatment for the rare neurological disease and is the most expensive drug on the market.
Reimbursement agreements have been established with payers to cover 97 percent of patients with commercial plans and 50 percent of patients covered by Medicaid, according to Stat.