Subcutaneous administration of anticancer agents

In recent years, much has been discussed on the development of oral anticancer treatment in terms of practical aspects and convenience for the patient. Less has been devoted to the potential of subcutaneous administration as a parenteral alternative. However, recent approvals (bortezomib, omacetaxine, trastuzumab) seem to show a renewed interest in this route of administration. All anticancer agents given subcutaneously display a very high bioavailability (>80%) and are rapidly absorbed (except the monoclonal antibodies trastuzumab and alemtuzumab). Subcutaneous delivery does not impact on the rate of elimination when compared to the intravenous route (azacitidine, cladribine, bortezomib, trastuzumab). Some formulations may be self-administered in educated patients (methotrexate, cladribine) but others require hospitalization (omacetaxine). When available, comparative studies with intravenous administration showed comparable clinical issues with an advantage for subcutaneous bortezomib with regard to the occurrence of peripheral neurotoxicity. Subcutaneous formulations of trastuzumab and, in the future rituximab, may allow for ambulatory treatment and self-administration. From an economic point of view, subcutaneous formulations of monoclonal antibodies may lead to lower healthcare costs but will have to face the arrival of less expensive intravenous biologically similar agents ('biosimilars') that will reduce the cost of hospitalization.