combination drug therapy
Targeting Cystic Fibrosis: Are Two Drugs Better than One?
Posted on by Dr. Francis Collins
Caption: Doctor with a child with cystic fibrosis who is taking part in clinical research studies. Credit: Colorado Clinical and Translational Sciences Institute
To explain the many challenges involved in turning scientific discoveries into treatments and cures, I often say, “Research is not a 100-yard dash, it’s a marathon.” Perhaps there is no better example of this than cystic fibrosis (CF). Back in 1989, I co-led the team that identified the cystic fibrosis transmembrane conductance regulator (CFTR) gene—the gene responsible for this life-shortening, inherited disease that affects some 70,000 people worldwide [1]. Yet, it has taken more than 25 years of additional basic, translational, and clinical research to reach the point where we are today: seeing the emergence of precise combination drug therapy that may help about half of all people with CF.
CF is a recessive disease—that is, affected individuals have a misspelling of both copies of CFTR, one inherited from each parent; the parents are asymptomatic carriers. The first major advance in designer drug treatment for CF came in 2012, when the Food and Drug Administration (FDA) approved ivacaftor (Kalydeco™), the first drug to target specifically CF’s underlying molecular cause [2]. Exciting news, but the rub was that ivacaftor was expected to help only about 4 percent of CF patients—those who carry a copy of the relatively rare G551D mutation (that means a normal glycine at position 551 in the 1480 amino acid protein has been changed to aspartic acid) in CFTR. What could be done for the roughly 50 percent of CF patients who carry two copies of the far more common F508del mutation (that means a phenylalanine at position 508 is missing)? New findings show one answer may be to team ivacaftor with an experimental drug called lumacaftor.
