Ad5‐Δ24 (an E1A‐CR2‐deleted OAd) and ICOVIR‐5 (a derivative of Ad5‐Δ24 with restricted E1A expression) are designed to replicate in cancer cells with defective retinoblastoma (RB) pathway [64, 65, 66, 67]. The gene discussed is RB1; the disease is cancer.