Aspergillus, angiogenesis, and obesity: the story behind beloranib.

Fumagillin, an antimicrobial compound first isolated in 1949 from the fungus Aspergillus fumigatus, four decades later was unexpectedly found to inhibit angiogenesis. Interest in developing angiogenesis inhibitor drugs as possible treatments for cancer led to the synthesis of analogs of fumagillin. Preclinical studies of various analog drugs confirmed that they inhibited angiogenesis, but they also were associated with weight loss as an adverse effect. Because adipose tissue can grow and regress throughout adulthood, is highly vascularized, and has angiogenic properties, interest in investigating anti-angiogenic agents in animal models of obesity found that fumagillin analogs caused dose-dependent reversible weight reduction and adipose tissue loss. Beloranib, a fumagillin analog that is an angiogenesis inhibitor and associated with decreased adiposity in animals, has been studied in phase I clinical trials for cancer. It is currently being investigated for the treatment of obesity and related conditions. Three phase I and three phase II studies found significant degrees of weight loss and acceptable tolerability for beloranib compared to placebo, justifying further clinical development of the drug for obesity.