Current idea of an algorithm for drug treatment and optimal succession of using targeted drugs

The application of targeted and pathogenetically sound medicational approaches could considerably improve the results of therapy in patients with metastatic renal-cell carcinoma (mRCC). To date, VEGF/VEGFR inhibitors continue to remain a basic and most effective drug treatment in patients with mRCC and the choice of a drug for first-line therapy is based on the following factors: disease prognosis, a patient’s general somatic state, and the understanding of immediate therapy goals, anticipated toxicity and tolerability.
Most patients develop resistance to VEGFR inhibitors within 6–11 months after treatment initiation. The basis for resistance development may be the following mechanisms: activation of alternative proangiogenic signaling pathways, that of angiogenesis-independent progression pathways, a microenvironment-induced phenotypic change of tumor cells to form their resistance to targeted drugs, and pharmacokinetic and pharmacodynamic changes in the drug itself during therapy. To overcome resistance to VEGFR inhibitors, there are 2 possible options: 1) switching to a drug having another mechanism of action (the mTOR inhibitor everolimus); 2) that to a more selective and potent tyrosine kinase inhibitor (axitinib) that selectively affects and suppresses the activity
of the same targets – VEGFR (Vascular Endothelial Growth Factor Receptor) 1–3. As before, there is scanty convincing evidence for unique benefits in a particular succession of targeted drugs: a VEGFR inhibitor – a VEGFR inhibitor or a VEGFR inhibitor – an mТOR inhibitor. In a number of cases, the succession of prescribing of targeted drugs may be practically determined by clinical criteria, specifically by the possibility of controlling toxic complications that may be typical for VEFGR inhibitors and may accumulate in case of their successive use. It must be also remembered that VEGFR inhibitors may be successfully reused in patients who have received second- or more line therapy with targeted drugs in different succession.