The present invention is the use of designed recombinant viruses for the treatment of various forms of malignant tumors. The recombinant viruses of the invention are those in which one or more regions of the wild type virus was exchanged with a synthetic recoded sequence that reduces the codon pair score relative to human codon pair bias, or that increase the number for CpG di-nucleotides, or that increases the number of UpA di-nucleotides. The method of the present invention is particularly useful for the treatment of malignant tumors in various organs, such as: breast, skin, colon, bronchial passage, epithelial lining of the gastrointestinal, upper respiratory and genito-urinary tracts, liver, prostate and the brain. Astounding remissions in experimental animals have been demonstrated for the treatment of malignant glioblastoma multiforme, as well as for the treatment of breast cancer and melanoma as well.

Provided is a method of treating a tumor in an individual by neoadjuvant therapy, wherein the individual has not previously undergone treatment to effectively reduce tumor burden, the method comprising administering an oncolytic chimeric poliovirus construct, or an oncolytic chimeric poliovirus construct and an immune checkpoint inhibitor, followed by reduction of the tumor. The method may further comprise administration of immune checkpoint inhibitor or oncolytic chimeric poliovirus construct following reduction of tumor. Kits for performing the methods are also provided.