The present invention relates to hyperproliferative diseases. Specifically, the present invention encompasses pharmaceutical compositions comprising a modified Reoviridae virus, wherein the Reoviridae virus is conjugated to a hydroxylated hydrocarbon or a polycationic polymer to reduce the clearance of the composition and reduce the immunogenicity of the composition. Yet further, the invention relates to methods of treating a hyperproliferative disease by administering to a patient an effective amount of the modified Reoviridae virus.