Patient-derived Sialyl-Tn-positive Invasive Bladder Cancer Xenografts in Nude Mice: An Exploratory Model Study

Background: More than 70% of muscle invasive bladder cancers (MIBC) express the cell-surface antigen sialyl-Tn (sTn) that promotes motility and invasive potential of tumor cells. Effective drug testing models to optimize therapy against these tumors are warranted. Materials and Methods: Fragments of sTn-positive MIBC were subcutaneously engrafted into nude mice and expanded until the third passage. Histology and immunoexpression of tumor markers (p53, p63, Ki-67, CK20, sTn) were studied in order to evaluate tumor phenotype maintenance. Results: Tumor take rate was low in the first passage (119) but increased and became consistent, therefore suitable for drug testing, in the third passage (13113). Histology and immunoexpression patterns were similar between primary tumors and xenografts. However, p53 and ki-67 levels increased with passages suggesting a selection of more proliferative clones. STn expression, even though decreased, was preserved in xenografts. Conclusion: We describe the first patient-derived sTn-positive xenograft model to be used for drug testing and identification of prognostic biomarkers.