LAM-001 in Lung Transplant Recipients With Bronchiolitis Obliterans Syndrome.

Chronic rejection, commonly denoted as bronchiolitis obliterans (BO), obliterative bronchiolitis (OB), or bronchiolitis obliterans syndrome (BOS), is the leading cause of death beyond the first year after lung transplantation. Whereas the development of BOS is rare within the first year after lung transplantation, annual increments of approximately 10% are recorded in subsequent years, resulting in a cumulative incidence range of 40-50% within the first five years and 70-80% within 10 years of transplantation. No current effective treatment for BOS exists. BOS represents the leading cause of morbidity and mortality after lung transplantation, limiting 5-year survival to well below other solid organ transplants. BOS is characterized by an inexorable lung function decline despite currently available immunomodulatory treatments. Sirolimus has been shown to block T-cell proliferative effects induced by cytokines, alloantigens, and mitogens in a dose-dependent manner(4, 5). Oral sirolimus has been shown in small studies to have a beneficial impact on rapidly progressive BOS; however, administration in this patient population has been challenged by a high degree of intolerance with the side effects. The development of LAM-001 for lung transplant related BOS, conceptually a T-cell driven process against transplanted alloantigen, is based on the principal hypothesis that administration of a sirolimus dose to the rejecting lung allograft(s) by inhalation will result in improved efficacy by depositing higher drug concentrations directly within the allograft by inhalation than would be achieved by oral administration due to systemic toxicities associated with oral sirolimus. Because of known reduced systemic bioavailability of LAM-001 compared to oral sirolimus dosing, amelioration of the substantial adverse event profile compared to oral drug is expected. LAM-001 is also expected to reduce serious complication risks by obviating requirements for maintenance and augmented immune drugs used to treat BOS.