Abstract: The present invention comprises a biochemically pure protein, termed antistasin, which exhibits both antimetastatic and anticoagulant properties. Methods of producing the protein and methods of using the protein to inhibit or reduce metastasis and/or coagulation of blood are disclosed. The complete amino acid sequences of antistasin and some variants have been determined from purified protein and cloned cDNAs.

Abstract: Method for treating a patient to inhibit metastasis of malignant cells by administering to the patient a therapeutically effective amount of a composition including a blood anticoagulant and a protease inhibitor. A composition apparently unique for this purpose is a leech salivary gland extract, the anticoagulant effect and protease inhibitory effect of which are believed to be significant. Other significant components may also be present in the leech salivary gland extract and these components may act synergistically in producing the observed antimetastatic effect.