It is not uncommon that at a late-stage of drug development (especially during the clinical testing) unforeseen toxicities and/or poor efficacy are observed. This is often, but not only, due to the limitations of the off-target screening used by pharma (the so-called secondary pharmacology). Although still useful for quickly screening a relatively high number of potential off-target hits, these screening studies, often used by pharmaceutical companies, are in the form of a proprietary set of in vitro methods biased and/or tailored for the specific molecule background of the drug candidate. Often, this does not allow evaluation in a clinical context and can contribute to the high rate of drug failures (attrition rate) at a later stage of the drug discovery process. This is a costly “Achilles heel” for the pharmaceutical industry[1].
