Off-label use of targeted therapies in oncology.

Off-label use is defined by the prescription of a marketed drug outside the conditions described in the summary of product characteristics. In oncology, off-label prescribing of targeted therapies may occur in patients with other tumor types expressing the same target. Agents associated to phenotypic approaches such as therapies against the tumoral vasculature (anti-angiogenic drugs) and new immunotherapies (checkpoint inhibitors) also carry the potential of alternative indications or combinations. Off-label use of targeted therapies is little documented and appears to be in the same range than that regarding older drugs with wide variations among agents. When compared with older agents, off-label use of targeted therapies is probably more rational through tumoral genotyping but is faced with a limited clinical support, reimbursement challenges related to the very high pricing and the cost of genotyping or molecular profiling, when applicable.