FDA approves new breakthrough therapy for cystic fibrosis

The US Food and Drug Administration approved Trikafta (elexacaftor/ivacaftor/tezacaftor), the first triple combination therapy available to treat patients with the most common cystic fibrosis mutation. Trikafta is approved for patients 12 years and older with cystic fibrosis who have at least one F508del mutation in the cystic fibrosis transmembrane conductance regulator (CFTR) gene, which is estimated to represent 90 per cent of the cystic fibrosis population.

The US FDA release specifies that patients with cystic fibrosis should speak with a health care professional and have tests performed to understand which gene mutations they have. The presence of at least one F508del mutation should be confirmed using an FDA-cleared genotyping assay prior to treatment. The safety and effectiveness of Trikafta in patients with cystic fibrosis younger than 12 years of age have not been established.

The FDA granted this application under multiple expedited programmes: the Priority Review process, in addition to Fast Track and Breakthrough Therapy Designation. Trikafta also received orphan drug designation, which provides incentives to assist and encourage the development of drugs for rare diseases.

Drugs approved under expedited programmes are held to the same approval standards as other FDA approvals. Because of Trikafta’s benefit to the cystic fibrosis community, the FDA reviewed and approved Trikafta in approximately three months, ahead of the March 19, 2020 review goal date. The approval of Trikafta was granted to Vertex Pharmaceuticals Incorporated, which will receive a Rare Pediatric Disease Priority Review Voucher for developing this therapy.

Commenting on the approval, acting FDA Commissioner Ned Sharpless, M.D. said,, “In the past few years, we have seen remarkable breakthroughs in therapies to treat cystic fibrosis and improve patients’ quality of life, yet many subgroups of cystic fibrosis patients did not have approved treatment options. That’s why we used all available programmes, including Priority Review, Fast Track, Breakthrough Therapy, and orphan drug designation, to help advance today’s approval in the most efficient manner possible, while also adhering to our high standards. The FDA remains committed to advancing novel treatment options for areas of unmet patient need, particularly for diseases affecting children.”

Cystic fibrosis, a rare, progressive, life-threatening disease, results in the formation of thick mucus that builds up in the lungs, digestive tract, and other parts of the body. It leads to severe respiratory and digestive problems as well as other complications such as infections and diabetes. Cystic fibrosis is caused by a defective protein that results from mutations in the CFTR gene. While there are approximately 2,000 known mutations of the CFTR gene, the most common mutation is the F508del mutation.

Trikafta is a combination of three drugs that target the defective CFTR protein. It helps the protein made by the CFTR gene mutation function more effectively. Currently available therapies that target the defective protein are treatment options for some patients with cystic fibrosis, but many patients have mutations that are ineligible for treatment. Trikafta is the first approved treatment that is effective for cystic fibrosis patients 12 years and older with at least one F508del mutation, which affects 90 per cent of the population with cystic fibrosis or roughly 27,000 people in the US.

The efficacy of Trikafta in patients with cystic fibrosis aged 12 years and older was demonstrated in two trials. The first trial was a 24-week, randomised, double-blind, placebo-controlled trial in 403 patients who had an F508del mutation and a mutation on the second allele that results in either no CFTR protein or a CFTR protein that is not responsive to ivacaftor or tezacaftor/ivacaftor alone. The second trial was a four-week, randomised, double-blind, active-controlled trial in 107 patients who had two identical F508del mutations.

In each trial, the primary analysis looked at increases in the percent predicted forced expiratory volume in one second, known as ppFEV1, which is an established marker of cystic fibrosis lung disease progression. Trikafta increased the ppFEV1 in both trials. In the first trial, it increased mean ppFEV1 13.8% from baseline compared to placebo. In the second trial, it increased mean ppFEV1 10 per cent from baseline compared to tezacaftor/ivacaftor. In the first trial, treatment with Trikafta also resulted in improvements in sweat chloride, number of pulmonary exacerbations (worsening respiratory symptoms and lung function), and body mass index (weight-to-height ratio) compared to placebo.

The safety profile of Trikafta is based on data from the 510 cystic fibrosis patients in the two trials. The safety profile was generally similar across all subgroups of patients. Serious adverse drug reactions that occurred more frequently in patients receiving Trikafta compared to placebo were rash and influenza (flu) events. The most common adverse drug reactions included headaches, upper respiratory tract infections, abdominal pains, diarrhoea, rashes, increased liver enzymes (alanine aminotransferase and aspartate aminotransferase), nasal congestion, increased blood creatine phosphokinase (an enzyme that can be associated with muscle damage), rhinorrhea (mucus in the nasal cavity), rhinitis (swelling of the mucous membrane of the nose), influenza, sinusitis and increased blood bilirubin (may be caused by problems involving the liver, gallbladder or red blood cells).

The prescribing information for Trikafta includes warnings related to elevated liver function tests (transaminases and bilirubin), use at the same time with other products that are inducers or inhibitors of another liver enzyme called Cytochrome P450 3A4 (CYP3A), and the risk of cataracts. Patients and their caregivers should speak with a health care professional about these risks and any medicines they take before starting treatment.