Catrix is an acidic mucopolysaccharide complex derived from bovine tracheal cartilage. The antitumor efficacy of Catrix has been evaluated in the human tumor stem cell assay system using three human tumor cell lines and fresh biopsy specimens from 22 patients with malignant tumors. In vitro efficacy has been demonstrated with high dose continuous exposure Catrix, particularly against the 8226 human myeloma cell line as well as ovarian, pancreatic, colon, testicular, and sarcoma biopsy specimens. The level of sensitivity was at less than or equal to 30% survival of colony growth in vitro. Since the in vitro concentrations may be achievable in vivo, the results justify more detailed in vitro evaluation as well as potential clinical trials.