To enhance the transduction of cancer cells with low CAR expression, a cell-penetrating peptide, the protein transduction domain (PTD) from the Trans-Activator of Transcription (Tat) protein of human immunodeficiency virus (HIV)-1, was inserted in the hypervariable region (HVR)-5 of the OA hexon protein, resulting in CAR-independent and optimized transduction of cancer cells [51]. This evidence concerns the gene CXADR and cancer.