The bacterial polysaccharide tecogalan blocks growth of breast cancer cells in vivo

The growth of supportive tissue during the progression of solid tumors is a n absolute requirement for the nourishment of the tumor. The blockade of th is proliferative response of normal tissues to the growing tumor should hen ce inhibit tumor progression. We have shown earlier, that the heparinoid pe ntosanpolysulfate (PPS) can block tumor growth and neoangiogenesis induced by Kaposi's FGF as well as by other heparin-binding growth factors (HBGFs). We now report on the effects of a bacterial polysaccharide, tecogalan, on tumor xenografts of human breast cancer cells. Tecogalan inhibited FGF-depe ndent SW-13 cells in. vitro very similarly to PPS. Growth factor-independen t MDA-MB 231 cells were used in animal studies to assess the in vivo potent ial of tecogalan. Subcutaneous growth of tumors was inhibited by once weekl y i.v. administration of tecogalan. PPS single weekly administration showed a similar effect. No gross side effects were observed. Based on our previo us studies with these models, we conclude, that tecogalan acts by blocking HBGFs released from tumor cells, interestingly, single weekly dosing of eit her PPS or tecogalan appears to be strikingly more efficacious than spreadi ng the dose over several administrations. These findings with a novel compo und, tecogalan, and a novel treatment regimen, PPS, suggests a different ap proach to planning of therapies with these types of drugs.