West Nile virus treatment increases survival

Ascorbate, or vitamin C, is usually thought of as an antioxidant. The body tightly controls blood levels of orally ingested ascorbate, capping them at 0.2 mM. However, Qi Chen et al. show that injection can circumvent this limit, allowing pharmacological concentrations up to 30 mM, which exert an oxidative effect and slow tumor growth. A previous study suggested that ascorbate might be effective against terminal cancer, but a subsequent trial appeared to show that ascorbate had no effect. Later research revealed the tight constraints on orally ingested ascorbate and provided the rationale for the present work. The authors first tested a range of tumor and normal cell lines, showing that the ascorbate EC50 for most tumor lines was 10 mM, whereas normal cells easily tolerate 20 mM. The authors then demonstrated ascorbate’s protective effects in a mouse tumor model, showing that ascorbate slowed tumor growth by 43–51% in three types of aggressive tumors. Because clinical investigation revealed that plasma levels of ascorbate reached in human patients are similar to those achieved in the mice, the authors suggest that ascorbate may prove to be a useful component of an anticancer regimen. — K.M.