Sensitization of chemotherapeutic agent resistant neoplastic cells with a virus

A method of treating ras-activated neoplastic cells in a subject, comprising:

• (a) infecting the neoplastic cells in the subject with a reovirus by administering an effective amount of the reovirus to the subject under conditions that result in infection of the neoplastic cells;
• and
• (b) administering an effective amount of a first chemotherapeutic agent to the subject, wherein the ras-activated neoplastic cells were previously determined to be refractory to the first chemotherapeutic agent in the absence of the reovirus.