The invention relates to transgene expressing Newcastle Disease Viruses (NDV), which have been demonstrated to possess significant oncolytic activity against mammalian cancers and/or an improved safety profile. The invention provides novel oncolytic viruses through the use of genetic engineering, including the transfer of foreign genes or parts thereof, such as genes encoding Atezolizumab or Bevacizumab. The present invention also provides nucleic acids encoding a reverse genetically engineered (rg-)NDV comprising one or more of these foreign genes and having a mutation in the HN gene, said mutation allowing replication of said rgNDV in a cancer cell to a higher level than replication of an otherwise identical rgNDV not having said mutation in the HN gene.