Treatment of Bolivian L Braziliensis Mucosal Leishmaniasis With Inhaled Pentamidine Plus Oral Miltefosine

The 3 major forms of leishmaniasis are visceral, cutaneous, and mucosal disease. Of these, mucosal leishmaniasis (ML) arguably poses the most difficult therapeutic problem. Although visceral disease (VL) occurs in perhaps 300,000 persons a year and is rapidly fatal since TH1 immunity is lacking, visceral disease is well-treated by drugs. Whereras cutaneous disease (CL) is the most prevalent major form occurring in perhaps 1,000,000 persons a year, TH1 Immunity is present and CL self-resolves in 3-18 months.

CL is treated to speed healing of the cutaneous lesion and, for certain species, to try to prevent dissemination of parasites to the oro-nasal mucosa resulting in mucosal leishmaniasis .

Mucosal leishmaniasis (ML) is estimated to occur as a late sequella in approximately 3% of L braziliensis CL. If there are approximately 130,000 cases per year of L braziliensis cutaneous disease, and 3% of these are succeeded by ML, the approximately 4,000 yearly cases of L braziliensis ML makes ML far less common than VL or CL. However, and in spite of more TH1 immunity than cutaneous disease, self-cure of ML is so rare as to be reportable. The patient with ML experiences inexorable erosion of the cartilage of the nose, pharynx, palate, and larynx. ML has been difficult to treat with classical agents (a cure rate of approximately 71%) Thus, of the 3 common forms of leishmaniasis, ML is the form that combines disease severity with poor response to chemotherapy.

Mucosal disease is perhaps the most chemotherapeutically challenging presentation of the leishmaniases. Unlike cutaneous disease, ML results in significant medical morbidity leading to marked psycho-social difficulty, and even mortality. Unlike visceral disease which although mortal quickly responds to therapy, ML is difficult to cure and relapses are common.

Drug combinations are now accepted approaches for many infectious diseases. Since 2 drugs already have the disadvantages of increased cost and potential increased toxicity, use of non-parenteral agents is an important consideration for any proposed combination. As the only recognized oral antileishmanial agent, miltefosine is the drug on which antileishmanial combinations have been based for visceral disease and for cutaneous disease [thermotherapy plus miltefosine: Soto personal communication].

The goal for a miltefosine-based combination for ML would be to raise the ML miltefosine cure rate for "mild" nasal disease to >90% and to raise the miltefosine cure rate for anatomically extensive disease to >58%. Inhaled pentamidine is a non-parenteral agent which in our pilot study was very successful for mild disease (86% cure) but unsuccessful for moderate or severe disease. The combination of oral miltefosine and inhaled pentamidine is a completely non-parenteral regimen that should lead to >90% cure of mild ML disease and could lead to an improved cure rate of moderate-severe disease. Although two drugs will be administered, adverse events should not be additive because miltefosine does not affect the respiratory tract and inhaled pentamidine is minimally absorbed.

This proof-of-concept phase 2 trial will enroll 20 moderate-to-severe ML patients. The primary endpoint is the cure rate for moderate-severe patients in comparison to literature values for miltefosine alone. If mild ML patients present, up to 10 will also be enrolled. The secondary endpoint is demonstrating that the cure rate for mild disease is 90%-100%.