Efficacy of an Anti-TSLP Monoclonal Antibody in the Management of Chronic Bronchial Disease Induced by Bronchiolitis Obliterans Syndrome in Allogeneic Hematopoietic Stem Cells Transplantation Recipients

Allogeneic hematopoietic stem cell transplantation (HSCT) is burdened with a high morbidity and mortality rates. Graft versus host disease (GVHD) is the clinical manifestation of an immune conflict. The expression of GVHD in the bronchioles is responsible for bronchiolitis obliterans syndrome (BOS), defined by the appearance of an obstructive ventilatory disorder. BOS may affect up to 10% of allogeneic transplant recipients. Repeated aggression-repair phenomena of the bronchial epithelium lead to an irreversible fibrous remodeling. The management of BOS remains a therapeutic challenge. A number of patients worsen their ventilatory disorder despite the available treatments and progress to obstructive respiratory failure complicated by repeated bronchial exacerbations. When the patient is far from the allograft and in the absence of any sign of active extrathoracic GVHD, the mechanisms of aggravation of the ventilatory disorder are equivocal. It seems more likely that the bronchial disease evolves on its own due to a persistent local inflammation without any immunological conflict. In this case, it would be reasonable to model the management on that of severe bronchial diseases for which the logic of cortisone sparing is now permitted by the arrival of targeted biotherapies. Since 2006, the therapeutic arsenal of bronchial inflammatory pathologies, mainly asthma, has been enriched with the class of targeted biotherapies. These therapies, targeting IgE (omalizumab), Th2 cytokines IL-5, IL-4, IL-13 (mepolizumab, benralizumab, dupilumab) and more recently the cytokine derived from the bronchial epithelium TSLP (tezepelumab), have shown effectiveness in reducing bronchial exacerbations, improving quality of life and reducing dependence on corticosteroids. TSLP is an alarmin that reflects bronchial epithelial involvement. The objective of this study is to test the performance of an anti-TSLP biotherapy (tezepelumab) in the reduction of bronchial exacerbations in alloHSCT recipients suffering from obstructive bronchial disorders not supposed to be still related to an active GVHD.