AR and adenocarcinoma: To avoid any experimental variations, we placed NEPC‐type (characterized by staining positive for SYP, CD56, and CgA, and staining negative for AR) PDX specimens and adenocarcinoma‐type (characterized by staining negative for SYP, CD56, and CgA, and staining positive for AR; supplementary material, Figure S5B) patient samples on the same slide and conducted immunostaining with antibodies against PHF8 and FOXA2.