Discussing mechanism(s) of drug resistance, scientists should differentiate between two conditions: in vivo drug sensitivity and in vitro parasite susceptibility. In a report, the reviewers [3] claimed that definite scheduled dose and assessment of drug pharmacokinetics and pharmacogenetics in relation to host immune system are conducted in the in vivo studies. Unfortunately, these results are difficult to interpret due to loss of data regarding drug pharmacokinetics and pharmacogenetics. Although in vitro parasite susceptibility studies are expensive and consume much time and labor, results pointed to validated resistance markers if associated with bioinformatics (i.e. transcriptomic, metabolomic and genomic studies). Accordingly, the reviewers concluded that drug resistance is not attributed