Minority Patients Miss Out On Life-Saving Cystic Fibrosis Drugs Due to Genetic Test Limitations
There are many new drugs to treat cystic fibrosis (CF), but non-white patients are far less likely to receive the latest precision medicines, accord to a new study. These drugs were approved by the U.S. Food and Drug Administration (FDA) for people with specific mutations, but non-white patients are more likely to carry different CF mutations. Because these other mutations aren’t included in genetic tests to qualify for the drugs, doctors cannot prescribe these new treatments for non-white patients, and insurance carriers won’t cover the cost.
The findings were published February 1 in Pediatric Pulmonology by Susanna McColley, MD, scientific director for Interdisciplinary Research Partnerships at Stanley Manne Children’s Research Institute, professor of Pediatrics in the Division of Pulmonary and Sleep Medicine, and the associate director for Child Health at NUCATS, and Meghan McGarry, MD, MS, assistant professor of pediatrics at UC San Francisco.
“The new drugs are remarkable – they take people from almost needing a lung transplant to leaving the hospital within days,” says McGarry. “The problem is that these drugs are only approved for people with specific mutations, and everyone else gets left out. That is going to increase preexisting disparities.”
CF is a rare but devastating disease caused by genetic mutations in a single gene, called CFTR. This gene codes for a pore, or channel, in cell membranes that allows water and chloride ions to enter and exit cells. Mutations in the CFTR gene can compromise the function of these channel proteins, leading to thickening of mucus and ensuing infections in the lungs and intestines of affected individuals.
Decades ago, most CF sufferers died by the age of five, but thanks to medical advances, including recently approved drugs known as CFTR modulators – which improve the function of the faulty channel proteins that result from CFTR gene mutations – the average life expectancy in CF today is 44 years.
The new study confirms and expands upon these findings. Using the Cystic Fibrosis Foundation’s patient registry, which catalogs all the CF patients in the United States, McColley and McGarry analyzed how many patients had genetic mutations that confer eligibility for CFTR modulator drugs based on their U.S. Census-defined racial group. They found wide disparities in eligibility for the various groups, with about 94 percent of non-Hispanic white patients eligible for the drugs, but only about 75 percent of Hispanic patients and 70 percent of Black patients meeting current screening guidelines.
These numbers are not surprising considering that the clinical trials for CF modulators included almost exclusively non-Hispanic white participants. For example, in clinical trials for the drugs elexacaftor, tezacaftor and ivacaftor, the number of Black, Hispanic and Asian patients combined made up only around five percent of total trial participants.
“Drug companies sought approval for these drugs based solely on the most common CF mutations overall, because the bulk of CF patients are non-Hispanic white,” says McGarry. “But that’s not how we should be allocating drugs for rare, life-threatening diseases in children.”
Research reported in this publication was supported, in part, by the National Institutes of Health's National Center for Advancing Translational Sciences, Grant Number UL1TR001422. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.
This article was originally published by UCSF.
