Monoclonal antibody therapy in sinonasal disease

Successful management of severe asthma in a young boy with eosinophilic chronic rhinosinusitis who received omalizumab: a case report

Background

The incidence of chronic rhinosinusitis with nasal polyps has recently increased in Japan and other East Asian countries, and this disease is called eosinophilic chronic sinusitis (ECRS) in Japan. ECRS usually occurs in adults and is frequently accompanied by refractory bronchial asthma. However, its occurrence in children under 10 years of age is rare. Here, we present an unusual case of ECRS complicated by intractable asthma in an 8-year-old boy.

Case presentation

Oral administration of prednisolone (10 mg/day) initially relieved the ECRS and bronchial asthma, but both returned during prednisolone dose reduction. Because nasal cavity-opening surgery was ineffective, oral administration prednisolone at 10 mg/day was continued. Pancytopenia was observed 16 months after the start of treatment, and the patient was admitted to our hospital. He was diagnosed with refractory cytopenia in childhood, but gradually improved after cyclosporine treatment. Although the dose of cyclosporine was therapeutic for asthma, it did not alleviate the asthma attacks, and the patient’s quality of life markedly decreased. We administered omalizumab even though its use was contraindicated by negative results in an inhalable antigen test. After the third administration of omalizumab, the asthma was better controlled and respiratory function improved; however, the nasal symptoms of ECRS persisted. Attempts to relieve these symptoms by increasing the therapeutic dose of omalizumab were only partially successful. We replaced omalizumab with mepolizumab; doing so slightly improved the sinusitis symptoms, but quality of life remained unsatisfactory. We repeated the nasal cavity-opening surgery. After surgery, the asthma and sinusitis were unchanged.

Conclusions

Omalizumab effectively treated the severe combined asthma in a young patient, but its effect on sinusitis was insufficient. More cases and long-term follow-up data are needed to better evaluate the effectiveness of mepolizumab for treatment of ECRS.

FcRn-Dependent Transcytosis of Monoclonal Antibody in Human Nasal Epithelial Cells In Vitro: A Prerequisite for a New Delivery Route for Therapy?

Monoclonal antibodies (mAbs) are promising therapies to treat airway chronic inflammatory disease (asthma or nasal polyps). To date, no study has specifically assessed, in vitro, the potential function of neonatal Fc receptor (FcRn) in IgG transcytosis through the human nasal airway epithelium. The objective of this study was to report the in vitro expression and function of FcRn in nasal human epithelium. FcRn expression was studied in an air–liquid interface (ALI) primary culture model of human nasal epithelial cells (HNEC) from polyps. FcRn expression was characterized by quantitative RT-PCR, western blot, and immunolabeling. The ability of HNECs to support mAb transcytosis via FcRn was assessed by transcytosis assay. This study demonstrates the expression of FcRn mRNA and protein in HNEC. We report a high expression of FcRn in the cytosol of ciliated, mucus, and basal cells by immunohistochemistry with a higher level of FcRn proteins in differentiated HNEC. We also proved in vitro transepithelial delivery of an IgG1 therapeutic mAb with a dose–response curve. This is the first time that FcRn expression and mAb transcytosis has been shown in a model of human nasal respiratory epithelium in vitro. This study is a prerequisite for FcRn-dependent nasal administration of mAbs.

Targeting the Interleukin-5 Pathway for Treatment of Eosinophilic Conditions Other than Asthma

Improved understanding of the contribution of eosinophils to various chronic inflammatory conditions, most notably allergic asthma, has encouraged development of monoclonal antibodies specifically targeting mediators and surface receptors involved in eosinophil expansion and activation. The pivotal role of interleukin-5 (IL-5) in eosinophil biology, its high specificity for this leukocyte subset, and its involvement in the majority of eosinophilic conditions make it a very enticing target for treatment of eosinophil-mediated disorders. Two types of antibodies have been developed to target eosinophils: antibodies against IL-5 (mepolizumab and reslizumab), and an antibody against the IL-5-receptor-alpha-chain (IL-5Rα) (benralizumab). Both types of antibodies prevent IL-5 from engaging its receptor and in addition, anti-IL-5Rα antibodies induce target-cell lysis. They have been shown to reduce circulating eosinophil counts rapidly in humans with various disorders. Herein, a brief overview of the role of IL-5 in eosinophil biology will be presented, followed by a description of the development and characteristics of antibodies targeting IL-5 or its receptor. Results of clinical trials evaluating the efficacy and safety of these new antibodies in diseases (other than eosinophilic asthma) with prominent tissue eosinophilia are reviewed, followed by safety considerations and potential future applications.