It has taken nearly 23 years, but a drug that targets the cause of cystic fibrosis will soon be available for patients. The drug, called Kalydeco and developed by Vertex Pharmaceuticals of Cambridge, Massachusetts, was approved yesterday by the US Food and Drug Administration (FDA) to treat patients with a specific mutation in the cystic fibrosis transmembrane regulatory (CFTR) gene.

A crack team of scientists, including the current NIH chief Francis Collins, announced the discovery of CFTR in 1989, amid much fanfare about the find’s imminent impact on medicine. But although the gene taught researchers much about the cell biology underlying cystic fibrosis, decades later patients were still waiting for a drug that capitalized on that knowledge (see ‘Human genetics: One gene, twenty years’).

After all of that time, the FDA acted quickly to approve the drug, and gave Kalydeco (formerly known as VX-770) the green light three months ahead of schedule — a fact that you can be sure will be touted by the FDA. The agency has lately been stressing its speedy approvals, particularly in the realm of genetically targeted therapies, and FDA commissioner Margaret Hamburg already mentioned the approval three times during a congressional hearing this morning.

Unfortunately, the drug is approved for use only in people with a specific CFTR mutation called G551D. That accounts for a mere 4% of cystic fibrosis patients in the United States, or about 1,200 people. The company is busy testing the drug in patients with other mutations, singly and in combination with other cystic fibrosis drugs in the company’s pipeline.

As is often the case, high efficacy and a small market have translated into an eye-popping pricetag: in this case, US$294,000 a year. In a conference with investors yesterday, the company spent more time detailing its programme to help needy patients pay for the drug than it did on the clinical evidence backing its approval. Vertex won’t be the only benefactor of the profits — the Cystic Fibrosis Foundation has long supported the work, and stands to collect royalties in return for its investment (see ‘Charities seek cut of drug royalties’). The foundation typically channels such royalties into fresh investment in cystic fibrosis research.