83P - Development of a cell-free DNA scoring system from organoid culture medium to predict drug response in bladder cancer

Background

Bladder cancer is one of the most prevalent malignancies worldwide, with its incidence varying significantly across different regions. It is notably prevalent in developed countries, posing considerable challenges to healthcare systems. Organoid technology, which involves three-dimensional cultures, facilitates patient-specific investigations that capture tumor heterogeneity. Additionally, the exploration of cell-free DNA as a non-invasive biomarker has revolutionized the diagnosis and management of various diseases, including cancer. cfDNA comprises small DNA fragments released into the bloodstream from normal and tumor cells undergoing apoptosis or necrosis.

Methods

We engineered organoids from bladder tumor tissues. Fresh specimens from patients diagnosed with bladder cancer were transported promptly to our laboratory, where they were sectioned for primary culture initiation and subsequent analyses. To assess the impact of chemotherapy, bladder organoids were treated with cisplatin—a drug commonly used in clinical treatment of this cancer. cfDNA was extracted from the organoid medium and sequenced for analysis.

Results

In both bladder organoid lines, we observed an increase in total DNA yield on day 8, corresponding to day 4 post-treatment, compared to the untreated control group. On day 6, one organoid line (ORG45) exhibited a minor increase in the abundance of short cfDNA fragments, while the other line (ORG1) showed no significant changes. By day 8, a pronounced reduction in the length of long cfDNA fragments was observed in both lines following cisplatin treatment. With cisplatin treatment, the cfDNA size became shorter, and nucleosome footprinting patterns were significantly different compared to the control group.

Conclusions

Our data suggest that the size profile of cfDNA derived from organoid culture mediums correlates well with established chemotherapy treatment standards. This finding supports the potential utility of a cfDNA-guided patient-derived organoid (PDO) scoring system in the treatment of bladder cancer. Utilizing cfDNA from organoid culture mediums could establish a robust biomarker for assessing drug treatment outcomes.

Editorial acknowledgement

Clinical trial identification

Legal entity responsible for the study

The authors.

Funding

The Chinese University of Hong Kong.

Disclosure

All authors have declared no conflicts of interest.