Immunotherapy for Drug‐Refractory Mucosal Leishmaniasis

Abstract

Pentavalent antimony (Sb(v)) is the mainstay therapy for mucosal leishmaniasis (ML), but it is toxic, and relapses are common. Immunotherapy using a mixture of killed parasites, with or without bacille Calmette-Guerin, is an alternative but is used sporadically because of inconsistent results. We developed a defined immunotherapeutic antigen preparation for use in an observational, open-label trial to treat 6 patients with ML with a history of Sb(v) therapy failure. All patients were treated with the antigens thiol-specific antioxidant, Leishmania major stress inducible protein 1, Leishmania elongation initiation factor, and Leishmania heat shock protein 83, plus granulocyte-macrophage colony-stimulating factor. Patients underwent clinical and pathological evaluations before the initiation of immunotherapy and at 3, 6, 9, 12, 18, 24, and 60 months after. One month after the third injection, 1 patient showed complete clinical remission (CC) and remained disease free for the duration of the study. At the 9-month follow-up examination, 5 patients showed CC, and all patients were asymptomatic at a subsequent 5-year follow-up examination. These data support the concept that vaccine therapy with a defined antigen combination, used with standard chemotherapy, is a safe and effective approach to treat drug-refractory ML.