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FDA approves first drug for etiologic treatment of cystic fibrosis
Last reviewed: 01.07.2025
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The US Food and Drug Administration (FDA) has approved the first drug for the etiologic treatment of cystic fibrosis, AP reports.
Cystic fibrosis is a hereditary disease caused by a mutation in the cystic fibrosis transmembrane conductance regulator (CFTR) gene. This protein, being an ion channel, regulates the transport of water and chloride ions through the membranes of mucous membrane cells. Due to changes in the CFTR structure, the viscosity of mucus increases, which leads to its accumulation in the respiratory, digestive and genitourinary systems. This, in turn, is fraught with severe chronic infections of the corresponding organs, which is why many patients do not survive to adulthood.
Until now, there was no etiological (acting on the cause of the disease) treatment for cystic fibrosis; only symptomatic therapy was used for such patients.
The new drug Kalydeco (ivacaftor), developed by the American pharmaceutical company Vertex Pharmaceuticals, improves the function of CFTR, in which, due to a mutation, the amino acid glycine at position 155 is replaced by aspartic acid (this variant of the protein is designated G551D-CFTR). In particular, it increases the probability of opening this ion channel under the influence of cyclic adenosine monophosphate (cAMP) and increases the current of chlorine through membranes, which is impaired in cystic fibrosis.
The experimental course of ivacaftor improved the patients' lung function by an average of 10% and helped them gain weight (cystic fibrosis patients are usually underweight), and also significantly improved their well-being.
Kalydeco comes in tablet form, containing 150 milligrams of the active ingredient, and is taken twice daily. The FDA has approved it for use in adults and children over the age of six. The drug's effectiveness and safety in younger children is currently being studied.
The mutation that ivacaftor is active against is responsible for only 4 percent of CF cases, meaning that of the roughly 30,000 Americans with the disease, the drug would only help about 1,200 (the drug would only be prescribed if a patient was diagnosed with G551D-CFTR). Most cases of CF are caused by a mutation that lacks the amino acid phenylalanine at position 508 of the CFTR protein (a variant called CFTR-ΔF508). Vertex has developed VX-809, a drug currently undergoing clinical trials, for this form of the disease.
"Even though [ivacaftor] is not intended for most patients, it shows that you can find a mistake in the genes and rationally design a drug that corrects the problem," said Drucy Borowitz, director of the cystic fibrosis program at the State University of New York at Buffalo.
Ivacaftor cost Vertex hundreds of millions of dollars to develop. The Cystic Fibrosis Foundation donated $75 million. A year's worth of treatment with the drug would cost $294,000, making it one of the most expensive drugs.
"The price of the drug is set in accordance with its value for such a small group of patients," Nancy Wysenski, executive vice president of Vertex, explained to analysts. At the same time, she noted that the company will provide the drug for free to patients without health insurance or those whose family income does not exceed $150,000 a year. In addition, it will cover 30% of the price of Kalydeco for certain groups of insured patients.
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