IGF1R and osteosarcoma: Several antibodies aimed at inhibiting key pediatric cancer-associated signaling pathways have also been studied in an array of pediatric tumors but have not been nearly as effective as rituximab and dinutuximab; these include the IGF1R (insulin-like growth factor 1 receptor)-targeting antibodies cixutumumab and teprotumumab (R1507) (Malempati et al. 2019; Pappo et al. 2011, 2014; Wagner et al. 2015; Weigel et al. 2014) and the HER2-targeting antibody trastuzumab in osteosarcoma (Ebb et al. 2012).