A newly approved triple-combination modulator to treat cystic fibrosis (CF) has raised expectations of a treatment turning point among patients and specialists. If the early results are sustained, elexacaftor/ivacaftor/tezacaftor (Trikafta) could prove to be the rare case of a much-touted new medicine that meets high expectations.
Courtesy Susan Millard, MD
Dr. Susan Millard
“CF even in infants causes inflammation, so we know that lung damage can start early and progress,” said Susan Millard, MD, FCCP, of Helen DeVos Children’s Hospital in Grand Rapids, Mich., and the local clinical research director for the pediatric pulmonary and sleep medicine section. “This oral drug therapy is actually treating the underlying problem, as opposed to many of the therapies we have that take hours to nebulize and only work locally in the airways.”
Dr. Millard is the recent past pediatric editor for Chest Physician and has been a local principal investigator at Helen DeVos Children’s Hospital for many Vertex-sponsored clinical studies.
The pivotal studies
The Food and Drug Administration approval of Trikafta rested on two pivotal phase 3, placebo-controlled studies, one in patients with two copies of the most common CF mutations, F508del, and the second in patients with one copy of F508del and a second mutation that was called a “minimal-function” mutation. The findings have ignited the hopes of many people with CF and their physicians. The drug was approved in October 2019 for patients aged 12 years and older who have at least one F508del mutation of the cystic fibrosis transmembrane conductance regulator gene. About 90% of patients in the United States have at least one copy of F508del. In the study looking at patients with one copy of F508del, the mean predicted forced expiratory volume in 1 second increased 13.8% in patients taking the drug versus placebo (N Engl J Med. 2019 Oct 31. doi: 10.1056/NEJMoa1908639). The number of pulmonary exacerbations decreased by 63% in the Trikafta group, compared with placebo. Pulmonary exacerbations were described as a change in specific symptoms that required treatment with a new oral, intravenous, or inhaled antibiotic. Serious adverse drug reactions that occurred more frequently in patients receiving Trikafta, compared with placebo, were rash and influenza events.
In the study that included patients with two copies of F508del, on average, the lung function increased 10% versus patients on ivacaftor/tezacaftor at 4 weeks. In addition, there was a 45.1 mmol/L on average decrease in the sweat chloride level in the Trikafta group, compared with ivacaftor/tezacaftor.
A hopeful start
Robert Giusti, MD, a pediatric pulmonologist at New York University Langone Health, is also hopeful. “This could be the kind of treatment that will make a revolution in terms of [cystic fibrosis] care if it can be started very early in life shortly after diagnosis. We anticipate that patients will be disease free for a longer period of time.”
Dr. Robert Giusti
The Cystic Fibrosis Foundation’s (CFF) “venture philanthropy” initiative played an important role in the development of the drug by Vertex Pharmaceuticals. The CFF has invested many millions of dollars in research by drug companies since the 1980s and was an early backer of Vertex. According to a statement on the CFF website, the Foundation sold its royalty rights for treatments developed by Vertex for $3.3 billion in 2014. The drug has a list price of about $311,000 a year. Payment issues may arise in the future, but for now, Vertex has stated that insurers and some Medicaid programs have begun paying claims for Trikafta
Specialists who treat CF now are watching to see how well patients tolerate this highly anticipated drug – and how well it meets expectations. The Therapeutic Development Network, the clinical research division of the CFF, is enrolling patients taking Trikafta in an observational study to follow for long-term follow-up.
Meeting expectations
“[Long-term efficacy is] something that we’re always concerned about. When the drug comes to market, is it going to be as effective as we thought it might be?” said Ryan Thomas, MD, director of the Cystic Fibrosis Center at Michigan State University, East Lansing. The MSU Cystic Fibrosis Center receives funding from the Cystic Fibrosis Foundation.
Dr. Ryan Thomas
Almost one in five patients could not tolerate treatment with Orkambi, most often because of adverse breathing events, according to a French study published in the American Journal of Respiratory and Critical Care Medicine. The investigators wrote: “Among the 845 patients (292 adolescents, 553 adults) who initiated lumacaftor/ivacaftor, 18.2% (154 patients) discontinued treatment, often due to respiratory (48.1%, 74 patients) or nonrespiratory (27.9%, 43 patients) adverse events” and that the discontinuation rate was considerably higher than previously reported in clinical trials.
“We thought [Orkambi] was going to be something that could have a big effect,” Dr. Thomas said. “It turned out that it was harder for people to tolerate than we thought and the improvements weren’t as sustained as we thought they might be. I really don’t think this will end up being the case with Trikafta.”
Longer-term data are starting to emerge, which may ease some of the concerns inherent in working with a newer medicine. “These [data] suggest that this is going to be a game changer,” Dr. Thomas said. “If Trikafta is this efficacious, well, we’re talking about having people with CF who will live full lifespans without a lung transplant, and that is so rare.”
The decrease in hospitalizations, improved CT scans, and lower rates of lung function decline suggest it could be “the Holy Grail,” Dr. Thomas said.
A different disease
Trikafta is the latest in a series of improvements of CF treatment in recent decades, recalled Dr. Giusti, who has been in this field for about 3 decades. “It used to be that I attended many funerals for children with CF. Now with patients living longer and healthier lives I am invited to attend their weddings and even their children’s baptisms and bris ceremonies. It is a very different disease than it used to be.”
The promise of Trikafta leaves behind the minority of patients for whom the drug won’t work. This is for the 10% of patients that have rare mutations. That can lead to difficult conversations with parents about why this new option is not a choice for their child, Dr. Millard said. “It just crushes you, but the Cystic Fibrosis Foundation is committing a lot of new research in that direction. Their mantra is ‘until it is done.’ ”
Realistic expectations
William (Randy) Hunt, MD, FAAP, FACP, assistant professor of medicine in the Division of Pulmonary, Allergy, Critical Care and Sleep, Emory University School of Medicine, Atlanta, agrees that Trikafta is an exciting development in CF treatment. He noted, “Starting this medication early in life may very well significantly attenuate the disease, but it is not a cure. For individuals who already have significant disease, we may not see the same level of improvements in lung function as what we saw in the studies. The studies generally excluded individuals with ppFEV1 < 40%. Nevertheless, I remain optimistic and have been prescribing it to nearly everyone that qualifies after a discussion.”
Dr. Hunt added, “Patients are asking if they can stop their current chronic CF therapies once they start Trikafta. The answer is “no, at least not right now.” While all the relatively short-term data around Trikafta are very promising, we do not yet know how sustained the long-term benefits will be. Still, safely removing therapeutic burden from our patient population is a real interest. There are plans underway by the CFF and other institutions to systematically research whether discontinuing chronic CF therapies is safe in the setting of Trikafta.”
He concluded that 10% of individuals with CF mutations still do not respond to the modulators currently available. “We will not leave that population behind, but treating these remaining mutations is going to take continued efforts and likely modulators that are therapeutically differently from the mechanism of actions of those that are currently available,” he said.
Therese Borden contributed to this article.
1/2/2020 - This story was updated.