An in vivo test to assess mefloquine 25 mg/kg for the treatment of uncomplicated falciparum malaria in Rondônia, Brazil

Combining Mefloquine with an Mcl-1 Inhibitor as a Novel Therapeutic Strategy for the Treatment of Nasopharyngeal Carcinoma

Considering the established pharmacokinetics and toxicity profiles, drug repurposing has emerged as an alternative therapeutic approach for treating cancer. Mefloquine has previously demonstrated inhibitory effects on multiple cancer types. This study aims to explore the impact of mefloquine on nasopharyngeal carcinoma (NPC). We found that mefloquine, at pharmacologically achievable concentrations, displayed anti-NPC activity while sparing normal counterparts. Mefloquine inhibits proliferation and induces death by reducing the levels of Cyclin A2, Bcl-2, and Bcl-xL. Intriguingly, we observed an increase in the levels of the anti-apoptotic protein Mcl-1. Mefloquine exerts its effects on NPC cells by inducing lysosomal-mediated ROS production, and the heightened expression of Mcl-1 is a consequence of ROS generation in mefloquine-treated NPC cells. The combination of an Mcl-1 inhibitor with mefloquine synergistically inhibits NPC growth in mice without causing substantial toxicity. These findings demonstrate the effectiveness and limited toxicity of mefloquine as a monotherapy and in combination with an Mcl-1 inhibitor. Our research underscores the promise of the mefloquine and Mcl-1 inhibitor combination as a potential treatment for NPC. Additionally, the elevation of Mcl-1 is a compensatory response in cells exposed to oxidative stress, offering a potential target to overcome resistance induced by pro-oxidant therapies.

Lysosome Inhibition by Mefloquine Preferentially Enhances the Cytotoxic Effects of Tyrosine Kinase Inhibitors in Blast Phase Chronic Myeloid Leukemia

Despite the efficacy of BCR-ABL tyrosine kinase inhibitors (TKIs) in chronic phase-chronic myeloid leukemia, the management of blast phase-chronic myeloid leukemia (BP-CML) remains a challenge. Therefore, there is an urgent need to identify alternative agents that act synergistically with BCR-ABL TKIs in BP-CML. Our results show that the anti-malarial agent, mefloquine augments the efficacy of TKIs in CML cell lines and primary CML cells in vitro, including those with the T315I mutation. This effect is selective as mefloquine is more effective in inducing apoptosis, inhibiting colony formation and self-renewal capacity of CD34⁺ cells derived from TKI-resistant BP-CML patients than normal cord blood (CB) CD34⁺ stem/progenitor cells. Notably, the combination of mefloquine and TKIs at sublethal concentrations leads to synergistic effects in CML CD34⁺ cells, while sparing normal CB CD34⁺ cells. We further demonstrate that the initial action of mefloquine in CML cells is to increase lysosomal biogenesis and activation, followed by oxidative stress, lysosomal lipid damage and functional impairment. Taken together, our work elucidates that mefloquine selectively augments the effects of TKIs in CML stem/progenitor cells by inducing lysosomal dysfunction.

Lysosomal disruption preferentially targets acute myeloid leukemia cells and progenitors

Despite efforts to understand and treat acute myeloid leukemia (AML), there remains a need for more comprehensive therapies to prevent AML-associated relapses. To identify new therapeutic strategies for AML, we screened a library of on- and off-patent drugs and identified the antimalarial agent mefloquine as a compound that selectively kills AML cells and AML stem cells in a panel of leukemia cell lines and in mice. Using a yeast genome-wide functional screen for mefloquine sensitizers, we identified genes associated with the yeast vacuole, the homolog of the mammalian lysosome. Consistent with this, we determined that mefloquine disrupts lysosomes, directly permeabilizes the lysosome membrane, and releases cathepsins into the cytosol. Knockdown of the lysosomal membrane proteins LAMP1 and LAMP2 resulted in decreased cell viability, as did treatment of AML cells with known lysosome disrupters. Highlighting a potential therapeutic rationale for this strategy, leukemic cells had significantly larger lysosomes compared with normal cells, and leukemia-initiating cells overexpressed lysosomal biogenesis genes. These results demonstrate that lysosomal disruption preferentially targets AML cells and AML progenitor cells, providing a rationale for testing lysosomal disruption as a novel therapeutic strategy for AML.

Antimalarials and the fight against malaria in Brazil

Malaria, known as the “fevers,” has been treated for over three thousand years in China with extracts of plants of the genus Artemisia (including Artemisia annua, A. opiacea, and A. lancea) from which the active compound is artemisin, a sesquiterpene that is highly effective in the treatment of the disease, especially against young forms of the parasite. South American Indians in the seventeenth century already used an extract of the bark of chinchona tree, commonly named “Jesuits’ powder.” Its active compound was isolated in 1820 and its use spread all over the world being used as a prophylactic drug during the construction of the Madeira–Mamoré railroad in the beginning of the twentieth century. During the 1920s to the 1940s, new antimalarial drugs were synthesized to increase the arsenal against this parasite. However, the parasite has presented systematic resistence to conventional antimalarial drugs, driving researchers to find new strategies to treat the disease. In the present review we discuss how Brazil treats Plasmodium-infected patients.