Novel Therapeutic Developments Other Than EGFR and VEGF Inhibition in Colorectal Cancer

Developments that may improve existing cytotoxic therapy for colorectal cancer (CRC) include alternatives to 5-fluorouracil (5-FU) such as the liposomal Thymidylate Synthase inhibitor OSI-7904L and the multitargeted antifolate pemetrexed. Studies have explored means of reformulating irinotecan, modulating its pharmacokinetics, and enhancing its activity by maximizing DNA damage through poly(ADP-ribose) polymerase inhibition. Cell cycle inhibitors may offer an alternative to combination with 5-FU. However, as standard regimens become more complex, so do the clinical trials needed to develop new agents, and the path to registration becomes ever more tortuous. It is therefore likely that several drugs with promise in CRC will not be developed for this indication.