High serum endostatin levels in Down syndrome: implications for improved treatment and prevention of solid tumours.

We report here a comparison of serum endostatin levels in Down syndrome patients to normal control subjects. We analysed serum samples from 35 patients with Down syndrome and 54 normal control subjects and found that although serum levels of endostatin vary widely in a normal human population, serum endostatin levels are significantly elevated in patients with Down syndrome. This result may explain the relative decrease in incidence of various solid tissue tumours observed in Down syndrome, given the role of endostatin as a potent inhibitor of tumour-induced angiogenesis in both human and animal models. Based upon these data, we propose that an increase of about one-third of normal endostatin serum levels may represent an effective therapeutic dose to significantly inhibit many solid tumours.