The new most expensive drug in the world is a drug for the therapy of metachromatic leukodystrophy

The U.S. Food and Drug Administration (FDA) has approved for use the gene-based drug "Lenmeldy" for the treatment of metachromatic leukodystrophy. According to MIT Technology Review, "Lenmeldy" has become the most expensive drug in the world: its manufacturer said that the wholesale cost of the drug will be 4.25 million dollars.

In metachromatic leukodystrophy, there is a deficiency of the enzyme arylsulfatase A, which leads to the accumulation of sulfatide in many tissues of the body and the destruction of the myelin sheath of nerve fibers. The disease is considered rare, with incidence rates ranging from 1 in 40000 to 1 in 160000 children who have motor and cognitive impairment and seizures since childhood (there are forms that manifest in adolescence and adulthood). The gene therapy developed adds the missing arylsulfatase A gene to bone marrow cells: many of the children who received the drug in trials in 2010 grew up quite healthy. Lenmeldy was previously approved in several European countries at a cost of $3.16 million. Before that, the most expensive drug was gene therapy for hemophilia B.