Bladder cancer rapid autopsy: A mechanism for collecting metastatic tumor tissue and establishing xenograft models of metastatic disease.

Abstract

478 Background: Patients with metastatic bladder cancer have a poor prognosis with a median survival of only 9-15 months. Understanding the biology of metastatic bladder cancer has been historically difficult due to a paucity of specimens and models that recapitulate human disease. We established a bladder cancer rapid autopsy program to systemically acquire metastases, and build patient-derived xenograft (PDX) and organoid models for biological studies. Methods: Patients with metastatic bladder cancer were consented and a rapid autopsy was performed 2-6 hours after death to allow acquisition of normal and metastasis specimens. Frozen and formalin-fixed and paraffin embedded specimens were collected and pathological evaluation was performed on each specimen. Additionally, tumors were implanted subcutaneously into SCID mice to establish PDXs. Once PDXs were developed, PDXs were dissociated for companion organoid culture. Clinical history and treatment information was documented for each patient. Results: We have performed 10 bladder cancer rapid autopsies to date, and have acquired 105 metastatic and 45 normal specimens. The pathological subtypes of patients include urothelial cell carcinoma (5/10), squamous cell carcinoma (3/10), and plasmacytoid variant of urothelial carcinoma (2/10). The cohort has been treated BCG only (1/10), chemotherapy (3/10), and chemotherapy and immune checkpoint inhibitors (6/10). The leading site of metastasis was the liver (7/10) and lung (7/10), followed by lymph node (5/10), bone (5/10), intestine (4/10), and omentum (2/10). Half (5/10) of the patients had extensive liver metastases that allow acquisition of multiple tumor foci. For the first time, PDX and organoids from two independent metastases (omentum – CoCaB 14.1 and liver –CoCaB 14.2) from the same patient were successfully developed. Conclusions: This bladder cancer rapid autopsy program provides an important volume of metastatic tumor specimens for study. Importantly, the first bladder cancer PDX derived from metastasis has been developed. The availability of metastatic bladder cancer specimens, PDXs, and organoids will allow biological studies of advanced disease.