To investigate whether treatment with ANP‐coupled HA‐GNPs influences the tumor growth of etoposide‐resistant RB cells, we used the in ovo chicken chorioallantoic membrane (CAM) assay as a 3R‐conform prescreening model system to strengthen our hypothesis prior to treatment approaches in a classical rodent in vivo animal model. Here, NPPA is linked to retinoblastoma.