Methods for improving therapeutic effectiveness of agents for the

Abstract

The present invention is directed to the use of an inhibitor of NO activity, such as a nitric oxide scavenger or an NO synthase inhibitor, as an antitumor therapy to reduce tumor blood flow and oxygenation. The invention is also directed to administration of a nitric oxide scavenger or a nitric oxide synthase inhibitor to enhance the effectiveness of tumor therapy with hypoxic or acidic chemotherapeutic agents or hyperthermia. The invention is also directed to the administration of a nitric oxide synthase substrate to a subject previously administered a nitric oxide synthase inhibitor, in order to selectively inhibit tumor perfusion. In a specific example, administration of cell free hemoglobin, a nitric oxide scavenger, in conjunction with mitomycin C, a hypoxic cytotoxin, results in a significant delay in tumor growth of a human tumor xenograft in a mouse compared to mitomycin C alone. In another example, the administration of an inhibitor of nitric oxide synthase followed by the administration of a substrate of the enzyme causes a specific irreversible reduction of tumor blood flow, while normal blood flow is restored.