Evaluating the Efficacy of Omalizumab in Severe Cedar Seasonal Allergic Rhinitis in Japan

Background: Traditional treatments for cedar seasonal allergic rhinitis include second-generation antihistamines, nasal corticosteroids, and sublingual immunotherapy (SLIT). Omalizumab (Xolair®), an anti-immunoglobulin E (IgE) monoclonal antibody, is an additional option for severe cases unresponsive to existing therapies. Numerous studies have demonstrated the therapeutic effectiveness of omalizumab for cedar seasonal allergic rhinitis; however, most reported results after only up to four weeks of follow-up. Therefore, this study evaluates the clinical efficacy of omalizumab throughout one whole cedar pollen season. Subjects and methods: This study included patients from our department and the Otorhinolaryngology Department of Minami Osaka Hospital between 2021 and 2023 who were ≥ 12 years old and had serum total IgE levels of 30-1,500 IU/mL, a baseline weight of 30-150 kg, and persistent severe nasal symptoms despite conventional treatments. Patients taking oral steroids at the time of enrollment or had fewer than two omalizumab doses were excluded. Forty-six patients (26 males, 20 females; mean age, 19.1 ± 11.2 years) met these criteria and received subcutaneous omalizumab every 2 or 4 weeks based on their IgE levels and weight. Symptoms were assessed at baseline and 4, 8, and 12 weeks post-administration using the Total Nasal Symptom Score (TNSS) and the Japanese Standard Quality of Life Questionnaire (JRQLQ No. 1) for allergic rhinitis. Results: Thirty-six patients were followed up for 8 weeks and 13 for 12 weeks. TNSS significantly improved from 6.6 to 4.5 at 4 weeks, 4.2 at 8 weeks, and 4.1 at 12 weeks (p<0.05). Nasal discharge, sneezing, nasal obstruction, itchy eyes, and tearfulness showed significant improvements (p<0.05). Quality of life scores improved in daily activities, sleep, and physical health from week 4 to week 12. Discussion: Consistent with previous findings, omalizumab significantly improved nasal and ocular symptoms and quality of life in patients with severe cedar seasonal allergic rhinitis. Despite many patients discontinuing the drug after eight weeks due to high costs, the drug's effectiveness in preventing symptom recurrence suggests potential long-term benefits. Combining omalizumab with SLIT showed no significant differences in outcomes; however, further pharmacoeconomic studies are warranted to evaluate cost-effectiveness. Conclusion: Omalizumab proved to be an effective treatment for severe cedar seasonal allergic rhinitis, providing significant symptom relief and quality of life improvements. Further studies should investigate its long-term efficacy and safety, including potential adverse effects and the development of anti-omalizumab antibodies.