Targeted therapies for renal cell carcinoma: more gains from using them again.

The development of molecularly targeted agents that inhibit pathways critical to the development of renal cell carcinoma has significantly improved outcomes in patients with these cancers. Compelling scientific and phase iii data have made the use of molecularly targeted agents the standard of care in first-line treatment. Now, available data show that re-treating patients with other tyrosine kinase inhibitors after they progress on sunitinib or sorafenib, or both, is beneficial. A large phase iii trial recently showed that, as compared with placebo, treatment with everolimus, an inhibitor of the mammalian target of rapamycin (mTOR), almost halved the risk of progression (37% vs. 65%) and doubled the median progression-free survival (4 months vs. 2 months). Overall survival was not improved in that study, likely reflecting treatment crossover in the placebo arm, but these data position everolimus as the second-line standard of care. A consistent and growing body of literature also suggests that re-treatment with other kinase inhibitors that the patient has not previously encountered is a reasonable option. Outcomes of initial treatment with sunitinib or sorafenib (or both) should not deter the use of second-line targeted therapy, because the first-line use of targeted agents does not appear to be predictive of outcomes with second-line therapy. However, in view of poor absolute outcomes after second-line treatment and the benefits seen with rationally developed targeted agents in the first-line setting, enrolment of second- and subsequent-line patients in further trials would be preferable.