SAN FRANCISCO— BioMarin Pharmaceutical Inc. is exploring pricing its experimental gene therapy for hemophilia patients between $2 million and $3 million if it is approved, which could make it the most expensive drug in the world.

The company hasn’t yet announced a price for the therapy, but Chief Executive Jean-Jacques Bienaimé said in an interview at the J.P. Morgan Healthcare Conference that the drugmaker has spoken to insurers, who have indicated they are comfortable with the range. In clinical trials, patients who received the injection saw their bleeding episodes drop from an average of 16.5 to an average of zero, an impact that was sustained for three years.

It would be the first gene therapy approved in the U.S. for an inherited type of hemophilia, which is marked by frequent bleeding due to the lack of or deficiency of an essential blood-clotting protein. There are two gene therapies approved in the U.S., including Zolgensma for spinal muscular atrophy from Novartis AG , which costs $2.1 million and is the most expensive drug in the world.

“Payers seem to be comfortable in the U.S. around $2 [million] to $3 million,” he said, saying that the overall cost of care of hemophilia patients will drop.

In December, the San Rafael, Calif.-based company filed for regulatory approval with the Food and Drug Administration for its therapy, valoctocogene roxaparvovec, known as valrox. The agency hasn’t told the company when it expects to make a decision, but barring any setbacks the earliest would probably be late August, said Mr. Bienaimé.