Sitamaquine Overcomes ABC-Mediated Resistance to Miltefosine and Antimony inLeishmania

Abstract

Although oral miltefosine represented an important therapeutic advance in the treatment of leishmaniasis, the appearance of resistance remains a serious threat. LMDR1/LABCB4, a P-glycoprotein-like transporter included in the Leishmania ABC (ATP-binding cassette) family, was the first molecule shown to be involved in experimental miltefosine resistance. LMDR1 pumps drugs out of the parasite, thereby decreasing their intracellular accumulation. Sitamaquine, another promising oral drug for leishmaniasis, is currently in phase 2b clinical trials. The physicochemical features of this drug suggested to us that it could be considered for use as an LMDR1 inhibitor. Indeed, we report herein that nonleishmanicidal concentrations of sitamaquine reverse miltefosine resistance in a multidrug resistance Leishmania tropica line that overexpresses LMDR1. This reversal effect is due to modulation of the LMDR1-mediated efflux of miltefosine. In addition, sitamaquine is not a substrate of LMDR1, as this transporter does not affect sitamaquine accumulation or sensitivity in the parasite. Likewise, we show that ketoconazole, another oral leishmanicidal drug known to interact with ABC transporters, is also able to reverse LMDR1-mediated miltefosine resistance, although with a lower efficiency than sitamaquine. Molecular docking on a three-dimensional homology model of LMDR1 showed different preferential binding sites for each substrate-inhibitor pair, thus explaining this different behavior. Finally, we show that sitamaquine is also able to modulate the antimony resistance mediated by MRPA/LABCC3, another ABC transporter involved in experimental and clinical antimony resistance in this parasite. Taken together, these data suggest that the combination of sitamaquine with miltefosine or antimony could avoid the appearance of resistance mediated by these membrane transporters in Leishmania.

Antimony-resistant but not antimony-sensitiveLeishmania donovaniup-regulates host IL-10 to overexpress multidrug-resistant protein 1

“…Finally, it raises concern about the impact of such major molecular adaptations on the outcome of the few available drugs that are implemented in the Indian subcontinent. This is even more concerning, when one is reminded that both Sb and miltefosine exploit the same efflux pump (40). Further work is required to understand if the increasing treatment failure rate of miltefosine in the Indian subcontinent is the consequence of the heritage of the antimonials (41).…”

Apoptotic Marker Expression in the Absence of Cell Death in Staurosporine-Treated Leishmania donovani

“…Recently, miltefosine (hexadecylphosphocholine [HePC]), an alkylphosphocholine originally developed as an anticancer drug, was proven to be effective and safe for use against visceral leishmaniasis in India (1) and was successfully applied to treat patients infected with antimony-resistant parasites. However, the therapeutic window of this drug might be very short, given the appearance of drug resistance in vitro (2). Thus, in the absence of vaccination and given the limitations of current therapies in cost, efficacy, and safety, there is an urgent need for the identification of novel targets and new chemical entities with antileishmanial activity.…”

Imipramine Exploits Histone Deacetylase 11 To Increase the IL-12/IL-10 Ratio in Macrophages Infected with Antimony-Resistant Leishmania donovani and Clears Organ Parasites in Experimental Infection

“…New drugs such as miltefosine and amphotericin B are in use for the treatment of antimony-resistant (Sb R ) kala-azar cases, but relapse cases are also increasing (5,6). Because antimonials and miltefosine use the same efflux pump (7), this raises serious concern about the efficacy of miltefosine, either alone or in combination, in view of the rampant antimony resistance in the field. Recent studies from our group showed that ∼78% of the recent clinical isolates are resistant to antimonials although the drug has not been in use for more than a decade in Bihar (8).…”