Kalydeco aids weight gain in infants and toddlers with CF, study suggests

'Favorable changes' with 12 weeks of use in weight and nutritional markers

Marisa Wexler, MS avatar

by Marisa Wexler, MS |

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Treatment with the CFTR modulator Kalydeco (ivacaftor) led to significant weight gain, suggesting better nutritional status, in  babies and toddlers with cystic fibrosis (CF) eligible for this therapy’s use, a study reports.

“Young children experienced favorable changes in weight gain and some nutritional biomarkers in the first 12 weeks of [Kalydeco] therapy,” the scientists wrote.

The study, “Changes in nutrition and growth status in young children in the first 12 weeks of ivacaftor therapy,” was published in the Journal of Cystic Fibrosis.

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Weight gain of importance to infants and young children with CF

Digestive problems are a common CF symptom, and as a result, many patients are unable to extract the normal amount of nutrition from the food they eat. This can make it difficult to get enough energy and put on weight, which is particularly of concern for young children who are growing.

CF is caused by mutations that disrupt the activity of the CFTR protein. A recently developed class of therapies called CFTR modulators can help to boost this protein’s functionality in people with specific types of disease-causing mutations.

Kalydeco, the first CFTR modulator to receive widespread approval, can treat CF patients in the U.S with eligible mutations starting at 1 month old. It is sold by Vertex Pharmaceuticals, which co-funded this study alongside the CF Foundation.

Previous studies in older children and adults suggested that Kalydeco can improve nutrient absorption and help patients to gain weight, but whether these effects can be seen in very young children remains unclear. Scientists at Children’s Hospital of Philadelphia evaluated how treatment with Kalydeco affects nutritional status for infants and toddlers.

“This study was designed to examine CFTR modulator associated changes in nutritional and other non-[lung] outcomes in children 4 to 24 months of age after the first 12 weeks of [Kalydeco] treatment,” the researchers wrote.

They enrolled 15 children with CF between 4 and 20 months of age, who were started on treatment with Kalydeco. All but three were followed through at least 12 weeks of treatment.

Researchers measured patients’ weight before and after treatment, with adjustments made to account for age differences. Results showed significant increases in weight-for-age scores after six or 12 weeks on Kalydeco.

Both before and after starting treatment, none of the babies were considered especially underweight or overweight, the researchers noted. Assessments of energy expenditure also were within normal ranges both before and after Kalydeco’s use. “This suggests infants growing normally prior to receiving [Kalydeco] should continue to grow normally,” they wrote.

Rise in red blood cells, digestive enzyme with Kalydeco’s use

Length-for-age scores also tended to increase after patients started on Kalydeco, but the change by 12 weeks did not reach statistical significance, meaning it might be attributable to chance. The researchers noted that, given the study’s short time frame, they weren’t expecting to detect a significant change in the children’s growth.

“It is likely that changes in … length growth patterns would occur with a longer period of observation,” they wrote.

Blood tests showed that the number and percentage of red blood cells, which carry oxygen through the bloodstream, increased significantly following 12 weeks on Kalydeco. Simultaneously, levels of carbon dioxide in the bloodstream decreased, which the researchers said is likely attributable to patients having better lung function with Kalydeco.

“Overall, there were favorable changes in laboratory values after 12 weeks of [Kalydeco] therapy,” the researchers wrote.

Treatment also led to a significant increase in levels of fecal elastase, a digestive enzyme that often is deficient in people with CF due to problems with the pancreas. Likewise, blood levels of some fatty molecules changed following Kalydeco, but given the study’s small number of patients and short duration, they cautioned that it’s difficult to draw definitive conclusions about how the therapy may affect fat digestion.

They stressed a need for further long-term studies to assess how Kalydeco and other CFTR modulators can affect nutritional outcomes.

Those limitations notwithstanding, the researchers concluded that, “in the context of the first 12 weeks of CFTR modulator treatment in children 4 to 20 months of age at enrollment, [Kalydeco] therapy supported significant weight gain and some clinically meaningful improvements in laboratory measures.”