Kalydeco: A New Drug That Treats the Cause of Cystic Fibrosis
What Is Cystic Fibrosis?
Cystic fibrosis is an inherited, life-threatening disorder characterized by the build-up of thick fluid in the lungs and digestive system. According to the Cystic Fibrosis Foundation, more than 70% of patients are diagnosed by the age of two. However, the disease can also occur in adolescents and adults. Symptoms include salty-tasting skin, persistent coughing, frequent lung infections, poor growth and weight gain and shortness of breath. Cystic fibrosis affects about 30,000 children and adults in the United States, and the median life expectancy for people who have it is somewhere in the late 30s.
Cystic fibrosis is caused by a defect (called the G551D mutation) in the gene that codes for the protein that regulates the flow of chloride ion and water into and out of the cells of the body. This means that when the body makes this important protein, errors occur in the synthesis process. The improperly prepared protein does not control the flow of chloride ion and water in the way that it should. Without the correct amount of water and chloride ion flowing into and out of the cells, a thick fluid accumulates in the lungs and in the gastrointestinal system. This fluid impairs lung function and digestion, and is a perfect breeding ground for bacteria. This is why people with cystic fibrosis get frequent infections.
Previous Drug Therapy for Cystic Fibrosis
Up until this time, cystic fibrosis patients have been treated with drugs that address the symptoms of the disease. These drugs fall into three classes:
Antibiotics-Tobramycin, an inhaled antibiotic, and azithromycin, an antibiotic that also reduces inflammation, have been used to attack the bacterial infections that patients with cystic fibrosis frequently get.
Mucus-Thinning Drugs-Drugs like dornase alfa, administered by inhalation, and acetylcysteine with saline help to thin out accumulated fluid so that it can more easily be coughed up.
Bronchodilators-These drugs keep bronchial tubes (airways) in the lungs open. One example is albuterol which the patient gets by inhalation.
Kalydeco was approved by the U.S. Food and Drug Administration (FDA) as a New Molecular Entity on January 31, 2012. The drug is the product of the research and development of Vertex Pharmaceuticals, Inc. headquartered in Cambridge, Massachusetts. The review and approval were accomplished in three months under the FDA's priority review program. This program is reserved for new medications that represent a significant advance over existing therapy for a given condition. Kalydeco is a small organic molecule classified as a quinolinone, and is administered orally as a tablet. It is intended for cystic fibrosis patients over the age of six who have the G551D mutation in the gene that codes for the preparation of the protein that regulates chloride ion and water flow into and out of the cell. It is an example of personalized medicine because it is targeted for patients with a specific genetic profile. Kalydeco is the first medication to treat the cause of cystic fibrosis because it acts to help the improperly-prepared protein work to regulate chloride ion and water flow.
In clinical trials before it came to market, kalydeco significantly improved lung function as measured by the Forced Expiratory Volume in the First Second (FEV1) assay. In this assay, the clinicians measure the volume of air that can be forced out in one second after taking a deep breath. Patients on kayldeco also experienced fewer lung infections, and children on the drug were able to gain weight in a manner more consistent with normal growth and development. Common side effects included headache, sore throat, sinus congestion, runny nose, abdominal pain, diarrhea, rash, nausea and dizziness.
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