An object of the present invention is to find a new
oncolytic virus and to utilize it for treatment of cancers. The present invention relates to a pharmaceutical composition for treatment of cancers containing
Sindbis virus as an
active ingredient, a method for treatment of cancers, which comprises administering a therapeutically effective amount of
Sindbis virus to a
mammal having cancers, a method for identifying cancers, which comprises introducing
Sindbis virus into an animal, thereby detecting a Sindbis
virus protein or Sindbis
virus RNA in vital tissues of the above animal, a method of identifying cancers, which comprises introducing into an animal Sindbis
virus having a
reporter gene incorporated therein, thereby, detecting the product of said
reporter gene in vital tissues of said animal, and a method of identifying cancers, which comprises detecting a increase in
antibody titer to the Sindbis
virus protein or the product of the
reporter gene in the aforementioned animals. It is confirmed that Sindbis virus has cytopathic effects upon various
cancer cell lines
in vitro, and that reduction in
tumor size or disappearance of tumor takes place
in vivo. Therefore, Sindbis virus is effective for treatment of cancers. In addition, Sindbis virus shows selective proliferation in a tumor, and is effective for identification or diagnosis for cancers within the
living body.