Correlation between drug sensitivity profiles ofcirculating tumour cell-derived organoids and clinicaltreatment response in patients with pancreatic ductaladenocarcinoma

European Journal of Cancer 166 (2022) 208e218. https://doi.org/10.1016/j.ejca.2022.01.030

Abstract

Introduction: Pancreatic ductal adenocarcinoma (PDAC) is highly aggressive and has poor prognosis. There are few biomarkers to inform treatment decisions, and collecting tumour samples for testing is challenging.

Methods: Circulating tumour cells (CTCs) from patients with PDAC liquid biopsies were expanded ex vivo to form CTC-derived organoid cultures, using a laboratory-developed biomimetic cell culture system. CTC-derived organoids were tested for sensitivity to a PDAC panel of nine drugs, with tests conducted in triplicate, and a weighted cytotoxicity score (CTS) was calculated from the results. Clinical response to treatment in patients was evaluated using Response Evaluation Criteria in Solid Tumours (RECIST) version 1.1 criteria at the time of blood sampling and 3 months later. The correlation between CTS and clinical response was then assessed.

Results: A total of 41 liquid biopsies (87.8% from patients with Stage 4 disease) were collected from 31 patients. The CTC-derived organoid expansion was achieved in 3 weeks, with 87.8% culture efficiency. CTC-derived organoid cultures were positive for EpCAM staining and negative for CD45 staining in the surface marker analysis. All patients had received a median of two lines of treatment prior to enrolment and prospective utility analysis indicated significant correlation of CTS with clinical treatment response. Two representative case studies are also presented to illustrate the relevant clinical contexts.

Conclusions: CTCs were expanded from patients with PDAC liquid biopsies with a high success rate. Drug sensitivity profiles from CTC-derived organoid cultures correlated meaningfully with treatment response. Further studies are warranted to validate the predictive potential for this approach.

Fig. 1 Flowchart of experimental procedures conducted for enrolled patients. CTCs were isolated and expanded ex vivo from patient liquid biopsies to form CTC-derived organoid cultures, which were then tested for sensitivity to a panel of PDAC-specific drugs. Drug sensitivity results were compared with clinical response to treatment(s) received for a minimum of 6 weeks in the 3-month period after liquid biopsy (prospective utility analysis) or before liquid biopsy (retrospective futility analysis). PDAC, pancreatic ductal adenocarcinoma.

Fig. 2 CTC-derived organoids expanded ex vivo from patients with PDAC CTCs. (A) Representative bright field images of CTC-derived organoids. Scale bar: 100 μm. (B) Representative images of organoid cultures at Week 0 and Week 4 (scale bar: 100 μm), with white arrows indicating organoids. A magnified view of organoids (scale bar: 50 μm) is also provided. CTC, circulating tumour cell; PDAC, pancreatic ductal adenocarcinoma.

Fig. 3 Immunofluorescence staining to confirm the presence of PDAC CTCs. (A) Representative EpCam, CD45 and Hoechst staining results from three patients to confirm the presence of CTCs. Scale bar: 20 μm. (B) Representative cytokeratin 7 and DAPI staining to confirm the presence of PDAC cells. Scale bar: 75 μm. CTC, circulating tumour cell; DAPI, 4′,6-diamidino-2-phenylindole; PDAC, pancreatic ductal adenocarcinoma.

Fig. 4 overview of patient enrolment and CTC extraction and expansion from liquid biopsies.