While these models require clinical access and host lower engraftment rates than xenografts, they have shown promising results - work by Zhou et al. in an orthotopic pancreatic PDX showed comparable collagen and fibroblast-activated protein levels to the native tumor and, when treated with either IGF1R-targeted IONP-doxorubicin or free doxorubicin, showed increased tumor growth regression and apoptotic cell death in the nanoformulation treatment arm 141. Here, IGF1R is linked to neoplasm.