November 12, 2013 -- Considerable epidemiologic evidence links dietary habits and incidence of a variety of cancers. Consumption of high levels of soybeans has been associated with decreased incidence of cancer of the breast, colon, and prostate. Soybeans contain a number of compounds that have potential anticarcinogenic activity including isoflavones, phytic acid, saponins, and several protease inhibitors. Both epidemiologic and experimental data strongly suggest a broad role for protease inhibitors in providing a protective effect against cancer formation, and those with chymotrypsin inhibitory activity have been found to be the most potent.
The goal of the study was to assess whether administering Bowman Birk Inhibitor Concentrate (BBIC) to study subjects with oral leukoplakia would result in a change in lesion area. BBI is a serine protease inhibitor isolated from soybeans possessing domains with trypsin and chymotrypsin inhibitory activity. In vitro and in vivo studies show anticarcinogenic activity in a number of animal model systems, and BBIC has been shown to be non-toxic in humans. BBI Concentrate (BBIC) has the same anticarcinogenic profile as purified BBI, and it has been developed for human trials. In order to test the efficacy of BBIC in reducing lesion area, one hundred and thirty two subjects were randomized; and 89 subjects completed six months on study drug or placebo.
Both placebo and BBIC showed a statistically significant decrease in mean lesion area of 17.1% and 20.6%, respectively, and partial or greater clinical responses of 30% and 28% respectively. No significant difference between placebo and study drug arms was observed. Histologic review, review of photographs of lesions, and comparison of serum neu protein and oral mucosal cell protease activity also did not show significant differences between study arms. The authors discuss possible reasons for the negative results, and advise using caution when searching for “green” chemopreventions.
This multi-center study, “Bowman Birk Inhibitor Concentrate and Oral Leukoplakia: A Randomized Phase IIb Trial,” was published in Cancer Prevention Research. Dr. Alexander Ross Kerr, an investigator from the New York University College of Dentistry & Bluestone Center for Clinical Research, was principal investigator at the NYU site.