Effect of maleic anhydride-divinyl ether copolymers on experimental M109 metastases and macrophage tumoricidal function.

Pyran copolymer (NSC-46015) was compared with five maleic anhydride-divinyl ether copolymers (MVEs) of narrow molecular weight range both for the ability to render macrophages nonspecifically tumoricidal and to retard the development of artificially induced metastases. All MVEs were found effective at activating macrophages in vivo, although the optimal dose for each varied. No correlation was obtained between intrinsic viscosity and degree of activation. Pyran was found to strikingly inhibit M109 pulmonary metastases formation when given over a period of 5 days prior to, or 1 day after, iv tumor inoculation. Histologically, tumor inhibition appeared to result from macrophage accumulations and histiocytic granulomas in the lung. Generally, when MVEs were compared in the artificial metastasis model, polymers with the lower molecular weights were the most active.