Therapeutic activity of maleic anhydride-vinyl ether copolymers against spontaneous, autochthonous murine mammary tumors.

We have tested a series of five maleic anhydride-vinyl ether copolymers of varying molecular weight for antitumor activity against spontaneous, autochthonous murine breast tumors (average initial tumor weight, approximately 200 mg). Four of the five compounds demonstrated statistically significant inhibition of tumor growth at nontoxic doses. (The fifth compound demonstrated antitumor activity only at toxic doses). To our knowledge, this is the first report of significant activity in a spontaneous solid tumor system in a truly therapeutic setting (ie, with systemic administration only after the autochthonous tumors are clinically evident) with immunologic treatment alone.