Association of a novel mutation in the plasmodium falciparum chloroquine resistance transporter with decreased piperaquine sensitivity

Background. Amplified copy number in the plasmepsin II/III genes within Plasmodium falciparum has been associated with decreased sensitivity to piperaquine. To examine this association and test whether additional loci might also contribute, we performed a genome-wide association study of ex vivo P. falciparum susceptibility to piperaquine. Methods. Plasmodium falciparum DNA from 183 samples collected primarily from Cambodia was genotyped at 33 716 genomewide single nucleotide polymorphisms (SNPs). Linear mixed models and random forests were used to estimate associations between parasite genotypes and piperaquine susceptibility. Candidate polymorphisms were evaluated for their association with dihydroartemisinin- piperaquine treatment outcomes in an independent dataset. Results. Single nucleotide polymorphisms on multiple chromosomes were associated with piperaquine 90% inhibitory concentrations (IC90) in a genome-wide analysis. Fine-mapping of genomic regions implicated in genome-wide analyses identified multiple SNPs in linkage disequilibrium with each other that were significantly associated with piperaquine IC90, including a novel mutation within the gene encoding the P. falciparum chloroquine resistance transporter, PfCRT. This mutation (F145I) was associated with dihydroartemisinin-piperaquine treatment failure after adjusting for the presence of amplified plasmepsin II/III, which was also associated with decreased piperaquine sensitivity. Conclusions. Our data suggest that, in addition to plasmepsin II/III copy number, other loci, including pfcrt, may also be involved in piperaquine resistance

Roles for the Trypanosoma brucei P2 transporter in DB75 uptake and resistance

A novel trypanocide, 2,5-bis(4-amidinophenyl)furan (DB75), in its prodrug amidoxime-derivative form, 2,5-bis(4-amidinophenyl)furan-bis-O-methylamidoxime (DB289), is in trials as the first orally administered drug for human African trypanosomiasis. DB75 is a diamidine. Resistance to some diamidines correlates to loss of uptake via the P2 aminopurine transporter. We show here that uptake of DB75 into Trypanosoma brucei also occurs principally via the P2 transporter. Uptake of tritiated DB75 occurred via a high-affinity (Km app, 3.2 μM) carriermediated route that was inhibited by adenosine, adenine, and pentamidine, all known substrates of the P2 transporter. Trypanosomes lacking the TbAT1 gene that encodes the P2 transporter demonstrated an 11-fold reduction in sensitivity to DB75 when measured under controlled in vitro conditions. These knockout cells were also less sensitive to DB75 than wild-type cells in mice. Initial uptake rates of DB75 into the Δtbat1 knockout cell line were greatly reduced compared with rates in wild-type cells. A trypanosome cell line selected in vitro for DB75 resistance was shown to have lost P2-mediated DB75 uptake. The TbAT1 gene was mapped to chromosome V of the T. brucei genome and the DB75-resistant parasites were shown to have deleted both alleles of this gene. Fluorescence microscopy of DB75-treated trypanosomes revealed that DB75 fluorescence localizes rapidly within the DNA-containing organelles of wild-type trypanosomes, whereas no fluorescence was observed in Δtbat1-null parasites or in the parasites selected for resistance to DB75

Treatment for neuropathic pain in patients with cancer: comparative analysis of recommendations in national clinical practice guidelines from European countries

INTRODUCTION: Neuropathic pain is a common symptom, present in 39% of the patients with cancer pain. Treating this type of pain is challenging, as this patient group is often frail and has comorbidities which increase the risk of side events and hence influences their quality of life. Clinical practice guidelines (CPGs) can be helpful for clinicians, especially when scientific evidence is uncertain or weak. In this study, we focused on the quality of the review of the literature used in treatment recommendations in the selected European CPGs. METHODS: In a previous study, 9 CPGs from European countries that contained at least one paragraph on treatment for neuropathic pain in cancer were included. Recommendations with their grade (according SIGN 55 classification) and supporting literature (first author, patients' population, year and type of publication) were compared between CPGs. RESULTS: In all CPGs, amitriptylin was mentioned as the drug of first choice. Six guidelines proposed also gabapentinoids. Only 30 of the 163 citations (18%) were based on studies in patients with cancer. Seven CPGs did not argue the indirect evidence due to extrapolation of study results from non-cancer to patients with cancer. CONCLUSION: The majority of guideline development groups extrapolated their results from non-cancer publications to formulate recommendations. Consequently, these guidelines fail to address important issues such as altered kinetics and side effect profiles in these patients. We recommend creating specific recommendations by an international expert group for the treatment for neuropathic pain in patients with cancer supported by targeted research in patients with cancer