The present invention pertains to a pharmaceutical composition comprising a recombinant measles virus encoding a suicide gene for use in the treatment of malignant cells with primary or secondary resistances against an oncolytic measles virus without suicide gene activity. Further, the present invention pertains to a recombinant measles virus based on measles vaccine strain Schwarz encoding a suicide gene, which comprises a fusion of a cytosine deaminase, particularly yeast cytosine deaminase, and a uracil phosphoribosyltransferase, particularly yeast uracil phosphoribosyltransferase, to a method and a kit for preparing the recombinant measles virus as claimed herein.