For metastatic prostate cancer, some treatment plans include upfront chemotherapy or androgen receptor axis-targeting medicines. However, there are no practical indicators for choosing the right individuals who need these medicines right now.

Gene expression patterns were thoroughly examined, and new patient-derived xenograft (PDX) castration-sensitive and -resistant animals were developed. A gene that is overexpressed in castration-resistant models was used to assess the function of the gene in LNCaP prostate cancer cells. Immunohistochemistry and ELISA were used to assess protein expression in patient tumors and blood, and relationships with castration resistance were then studied.

Expression of the α2 chain of interleukin-13 receptor (IL13Rα2) was greater in castration-resistant PDX tumors. In vitro and in vivo, LNCaP cells overexpressing IL13Rα2 developed castration resistance. IL13Rα2 expression levels in tissue samples were strongly related to the course of castration-resistant disease (P<0.05). About 5 of 28 (18%) castration-resistant prostate cancer patients had blood samples where IL13Rα2 levels could be detected.

Castration resistance of prostate cancer cells was linked to IL13Rα2, which was strongly expressed in PDX models of castration-resistant prostate cancer. It could be a tissue and serum biomarker with the potential for detecting castration resistance in patients with prostate cancer.