Researchers at the University of Missouri School of Medicine have developed a helium-based imaging technique to measure how well Kalydeco, which fights mucus build-up in the lungs, is able to help cystic fibrosis (CF) patients.
They discovered that it dramatically improved patients’ respiratory function.
Helium imaging also can identify CF characteristics that other diagnostic approaches miss, and help doctors measure the burden of the disease, the researchers said.
The findings grew out of a Phase 2 clinical trial (NCT01161537) of Kalydeco (ivacaftor). The article the team wrote about their helium-based measuring device, titled “Use of hyperpolarized helium-3 MRI to assess response to ivacaftor treatment in patients with cystic fibrosis,” was published in the Journal of Cystic Fibrosis.
CF stems from mutations of the gene that encodes a protein known as the CF transmembrane conductance regulator (CFTR). The gene governs salt and water transport in cells of the lungs, pancreas and other organs.
CFTR mutations impair the fluids’ mobility, leading to an accumulation of mucus in the lungs. The build-up can clog airways, resulting in dangerous infections and respiratory failure.
Kalydeco helps move fluids in tissue, maintaining the correct balance of salt and water in the lungs. It works with specific CFTR mutations, including G551D, G1244E, G1349D, G178R, G551S, S1251N, S1255P, S549N, S549R, and R117H.
Although the U.S. Food and Drug Administration approved the drug as a way of helping CF patients, how much it helped was unknown until the University of Missouri study.
“The drug ‘ivacaftor’ [Kalydeco] targets this [CFTR] defective protein, but to what extent it is successful is not well understood,” Talissa Altes, lead author of the study, said in a press release. “Our study sought to use a new way of imaging the lung to understand how well the drug is working in patients with a specific gene mutation known as G551D-CFTR.”
Spirometry is the standard technique doctors use to measure lung function. It involves patients blowing through a tube. One of its drawbacks is that it’s hard for children to perform.
The helium-based test the Missouri researchers developed, combined with magnetic resonance imaging (MRI), gives doctors a visual picture of lung function.
“On an MRI, a healthy lung should look completely white when helium-3 is used as a contrast agent,” Altes said. “Conversely, areas that are not white indicate poor ventilation. That’s the beauty of this technique — it’s very obvious if the drug is working or not.”
Researchers used both spirometry and helium-based tests to check the lung functioning of 17 CF patients receiving either Kalydeco or a placebo for a short time.
The new method gave researchers a better grasp of the disease burden than spirometry. It also showed that both short- and long-term treatment with Kalydeco dramatically increased the respiratory capacity of CF patients.
“The importance of this technique is that it may well be a cost-effective tool to aid in the development of [new] drugs. However, it also can help patients know which medications may work best for their unique conditions,” Altes said.
The team believes additional studies will show that doctors can use the helium-MRI method with babies and younger children who have impaired lung function or a respiratory disease.
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