according to results of a phase 1/2 clinical trial.
“One year of allergen immunotherapy [AIT] combined with tezepelumab was significantly more effective than SCIT alone in reducing the nasal response to allergen challenge both at the end of treatment and one year after stopping treatment,” lead study author Jonathan Corren, MD, of the University of California, Los Angeles, and his colleagues wrote in The Journal of Allergy and Clinical Immunology.
“This persistent improvement in clinical response was paralleled by reductions in nasal transcripts for multiple immunologic pathways, including mast cell activation.”
The study was cited in a news release from the National Institutes of Health that said that the approach may work in a similar way with other allergens.
The Food and Drug Administration recently approved tezepelumab for the treatment of severe asthma in people aged 12 years and older. Tezelumab, a monoclonal antibody, works by blocking the cytokine thymic stromal lymphopoietin (TSLP).
“Cells that cover the surface of organs like the skin and intestines or that line the inside of the nose and lungs rapidly secrete TSLP in response to signals of potential danger,” according to the NIH news release. “In allergic disease, TSLP helps initiate an overreactive immune response to otherwise harmless substances like cat dander, provoking airway inflammation that leads to the symptoms of allergic rhinitis.”
Testing an enhanced strategy
The double-blind CATNIP trial was conducted by Dr. Corren and colleagues at nine sites in the United States. The trial included patients aged 18-65 years who’d had moderate to severe cat-induced allergic rhinitis for at least 2 years from 2015 to 2019.
The researchers excluded patients with recurrent acute or chronic sinusitis. They excluded patients who had undergone SCIT with cat allergen within the past 10 years or seasonal or perennial allergen sensitivity during nasal challenges. They also excluded persons with a history of persistent asthma.
In the parallel-design study, 121 participants were randomly allocated into four groups: 32 patients were treated with intravenous tezepelumab plus cat SCIT, 31 received the allergy shots alone, 30 received tezepelumab alone, and 28 received placebo alone for 52 weeks, followed by 52 weeks of observation.
Participants received SCIT (10,000 bioequivalent allergy units per milliliter) or matched placebo via subcutaneous injections weekly in increasing doses for around 12 weeks, followed by monthly maintenance injections (4,000 BAU or maximum tolerated dose) until week 48.
They received tezepelumab (700 mg IV) or matched placebo 1-3 days prior to the SCIT or placebo SCIT injections once every 4 weeks through week 24, then before or on the same day as the SCIT or placebo injections through week 48.
Measures of effectiveness
Participants were also given nasal allergy challenges – one spritz of a nasal spray containing cat allergen extract in each nostril at screening, baseline, and weeks 26, 52, 78, and 104. The researchers recorded participants’ total nasal symptom score (TNSS) and peak nasal inspiratory flow at 5, 15, 30, and 60 minutes after being sprayed and hourly for up to 6 hours post challenge. Blood and nasal cell samples were also collected.
The research team performed skin prick tests using serial dilutions of cat extract and an intradermal skin test (IDST) using the concentration of allergen that produced an early response of at least 15 mm at baseline. They measured early-phase responses for the both tests at 15 minutes and late-phase response to the IDST at 6 hours.
They measured serum levels of cat dander–specific IgE, IgG4, and total IgE using fluoroenzyme immunoassay. They measured serum interleukin-5 and IL-13 using high-sensitivity single-molecule digital immunoassay and performed nasal brushing using a 3-mm cytology brush 6 hours after a nasal allergy challenge. They performed whole-genome transcriptional profiling on the extracted RNA.
Combination therapy worked better and longer
The combined therapy worked better while being administered. Although the allergy shots alone stopped working after they were discontinued, the combination continued to benefit participants 1 year after that therapy ended.
At week 52, statistically significant reductions in TNSS induced by nasal allergy challenges occurred in patients receiving tezepelumab plus SCIT compared with patients receiving SCIT alone.
At week 104, 1 year after treatment ended, the primary endpoint TNSS was not significantly different in the tezepelumab-plus-SCIT group than in the SCIT-alone group, but TNSS peak 0–1 hour was significantly lower in the combination treatment group than in the SCIT-alone group.
In analysis of gene expression from nasal epithelial samples, participants who had been treated with the combination but not with either therapy by itself showed persistent modulation of the nasal immunologic environment, including diminished mast cell function. This was explained in large part by decreased transcription of the gene TPSAB1 (tryptase). Tryptase protein in nasal fluid was also decreased in the combination group, compared with the SCIT-alone group.
Adverse and serious adverse events, including infections and infestations as well as respiratory, thoracic, mediastinal, gastrointestinal, immune system, and nervous system disorders, did not differ significantly between treatment groups.
Four independent experts welcome the results
Patricia Lynne Lugar, MD, associate professor of medicine in the division of pulmonology, allergy, and critical care medicine at Duke University, Durham, N.C., found the results, especially the 1-year posttreatment response durability, surprising.
“AIT is a very effective treatment that often provides prolonged symptom improvement and is ‘curative’ in many cases,” she said in an interview. “If further studies show that tezepelumab offers long-term results, more patients might opt for combination therapy.
“A significant strength of the study is its evaluation of responses of the combination therapy on cellular output and gene expression,” Dr. Lugar added. “The mechanism by which AIT modulates the allergic response is largely understood. Tezepelumab may augment this modulation to alter the Th2 response upon exposure to the allergens.”
Will payors cover the prohibitively costly biologic?
Scott Frank, MD, associate professor in the department of family medicine and community health at Case Western Reserve University, Cleveland, called the study well designed and rigorous.
“The practicality of the approach may be limited by the need for intravenous administration of tezepelumab in addition to the traditional allergy shot,” he noted by email, “and the cost of this therapeutic approach is not addressed.”
Christopher Brooks, MD, clinical assistant professor of allergy and immunology in the department of otolaryngology at Ohio State University Wexner Medical Center, Columbus, also pointed out the drug’s cost.
“Tezepelumab is currently an expensive biologic, so it remains to be seen whether patients and payors will be willing to pay for this add-on medication when AIT by itself still remains very effective,” he said by email.
“AIT is most effective when given for 5 years, so it also remains to be seen whether the results and conclusions of this study would still hold true if done for the typical 5-year treatment period,” he added.
Stokes Peebles, MD, professor of medicine in the division of allergy, pulmonary, and critical care medicine at Vanderbilt University Medical Center, Nashville, Tenn., called the study “very well designed by a highly respected group of investigators using well-matched study populations.
“Tezepelumab has been shown to work in asthma, and there is no reason to think it would not work in allergic rhinitis,” he said in an interview.
“However, while the results of the combined therapy were statistically significant, their clinical significance was not clear. Patients do not care about statistical significance. They want to know whether a drug will be clinically significant,” he added.
Many people avoid cat allergy symptoms by avoiding cats and, in some cases, by avoiding people who live with cats, he said. Medical therapy, usually involving nasal corticosteroids and antihistamines, helps most people avoid cat allergy symptoms.
“Patients with bad allergies who have not done well with SCIT may consider adding tezepelumab, but it incurs a major cost. If medical therapy doesn’t work, allergy shots are available at roughly $3,000 per year. Adding tezepelumab costs around $40,000 more per year,” he explained. “Does the slight clinical benefit justify the greatly increased cost?”
The authors and uninvolved experts recommend further related research.
The research was supported by the National Institute of Allergy and Infectious Diseases. AstraZeneca and Amgen donated the drug used in the study. Dr. Corren reported financial relationships with AstraZeneca, and one coauthor reported relevant financial relationships with Amgen and other pharmaceutical companies. The remaining coauthors reported no relevant financial relationships.
A version of this article first appeared on Medscape.com.