Generating human prostate cancer organoids from leukapheresis enriched circulating tumour cells.

Abstract

BACKGROUND\nCirculating tumour cell (CTC)-derived organoids have the potential to provide a powerful tool for personalised cancer therapy\xa0but are restrained by low CTC numbers provided by blood samples. Here, we used diagnostic leukapheresis (DLA) to enrich CTCs from patients with metastatic prostate cancer (mPCa) and explored whether organoids provide a platform for ex\xa0vivo treatment modelling.\n\n\nMETHODS\nWe prospectively screened 102 patients with mPCa and performed DLA in 40 patients with ≥5 CTCs/7.5\xa0mL blood. We enriched CTCs from DLA using white blood cell (WBC) depletion alone or combined with EpCAM selection. The enriched CTC samples were cultured in 3D to obtain organoids and used for downstream analyses.\n\n\nRESULTS\nThe DLA procedure resulted in a median yield of 5312 CTCs as compared with 22 CTCs in 7.5\xa0mL of blood. Using WBC depletion, we recovered 46% of the CTCs, which reduced to 12% with subsequent EpCAM selection. From the isolated and enriched CTC samples, organoid expansion succeeded in 35%. Successful organoid cultures contained significantly higher CTC numbers at initiation. Moreover, we performed treatment modelling in one organoid cell line and identified substantial tumour heterogeneity in CTCs using single cell DNA sequencing.\n\n\nCONCLUSIONS\nDLA is an efficient method to enrich CTCs, although the modest success rate of culturing CTCs precludes large scale clinical application. Our data do suggest that DLA and subsequent processing provides a rich source of viable tumour cells. Therefore, DLA offers a promising alternative to biopsy procedures to obtain sufficient number of tumour cells to study sequential samples in patients with mPCa.\n\n\nTRIAL REGISTRATION NUMBER\nNL6019.