Targeted anticancer therapies are often prescribed at the same dosage regimen in all patients. However, it is known that the marked interindividual variability in drug level may affect treatment outcomes. Several factors are known to modulate drug levels, such as weight, genetics host-drug and drug-drug interaction. The identification of these factors could give the possibility to propose better adjusted dosage regimens according to patient's individual characteristics. Moreover, the presence of high or low drug concentrations may partially explain toxicity or lack of efficacy of targeted anticancer drugs in some patients. The characterization of the relationship between drug levels and treatment response (efficacy and toxicity) would allow an optimized and a more individualized patient management with targeted anticancer drugs.

Oral targeted therapies must be taken on the long term and adherence issues have been shown to compromise treatment efficacy. Side effects and lifestyle management are among factors affecting treatment adherence. The characterization of adherence over time and the identification of factors susceptible to improve it will represent a great benefit for healthcare professionals and patients.