There are several different forms of chronic sinusitis. One form that is particularly difficult to treat is “chronic sinusitis with nasal polyps,” or CRSwNP. This form of chronic sinusitis is a different disease than straightforward chronic sinusitis.
Polyps are benign “growths” in the nasal cavity and sinuses. They are clear and have the consistency of the inside of a grape. They result in problems because they obstruct the sinus drainage pathways. When the block the passage of air through the nose, they can lead to decreased smell or a stuffy/congested nose that never improves. Traditional therapy includes steroids by mouth or in the solution of nasal sinus irrigation fluid. Surgery may also be done to remove obstructive polyps. It is common that patients with CRSNP often have multiple courses of oral steroids and several sinus surgeries.
However, even with aggressive therapy, nasal polyps often return. For these patients, a new therapy is available. Dupilumab (Dupixent) is an injectable biologic drug taken once every other week. Biologics are a class of drugs called “monoclonal antibodies.” Antibodies are naturally occurring proteins that have highly specific activities against a particular molecule. In the human body, antibodies are generated by immune cells against molecules specific to foreign invaders. These invaders become covered in antibodies which targets their for removal by other immune cells.
Dupilumab is a monoclonal antibody produced by animal cells in manufacturing laboratories. It is targeted against an immune signaling chemical, interleukin-4 (IL-4). Abnormal signaling of IL-4 is thought to be involved in those with allergic disease such as asthma, atopic dermatitis, and nasal polyps. Other biologic drugs in the pipeline include omalizumab and mepolizumab. These drugs target different signaling compounds than dupilumab.
“[On average] dupilumab improves symptoms from severe to moderate. Some people do not respond. ”
— Dr. Rodney Schlosser, Director of the Nose and Sinus Center at the Medical University of South Carolina
Two clinical trials have shown that dupilumab significantly improves polyp disease. A few patients do not respond. On average, polyp sizes were decreased, CT scans (a type of x-ray) improved, and patients reported improved symptoms. Many patients were continuing to improve as long as a year after starting the drug. The trials showed that lifelong treatment is necessary—polyps return after stopping the drug.
There were no serious side effects. The most common side effects were irritation of the mucous membranes in the eyes, nose, and throat. Headache, nosebleeds, and redness at the injection site were also noted.
At $37,000 per year, dupilumab isn’t cheap. Due to the expense, therapy is reserved for patients whose polyps have returned despite traditional therapy.
Unlike other biologics against the human immune system, dupilumab doesn’t suppress the immune system. Because long term safety is unknown, patients should carefully weigh the benefits and risks of the drug.