Generation and Characterisation of PDX-derived Head and Neck Squamous Cell Carcinoma Tumour Organoids

Abstract

Purpose

Head and Neck Squamous Cell Carcinomas (HNSCC) are a class of malignant tumours that affect the squamous epithelial cells in the head and neck, and represent the 7th most-commonly occurring cancer type globally. As such, a need has arisen for the development of novel in vitro and in vivo models to determine the suitability of new potential therapies for treating HNSCC. This project aims to develop and characterise one such model: organoid models derived from patient-derived xenograft (PDX) tumours.

Experimental Design

Fourteen different PDX tumours for HNSCC were dissociated and seeded onto tissue culture plates to grow PDX-derived organoid models, with growth being monitored over a period of 1-2 months for each organoid line. The models that grew most successfully were harvested after short-term growth for histological analysis using haematoxylin and eosin (H+E), as well as characterisation for hypoxia using pimonidazole. The organoids were subjected to drug treatment, using a therapy that has been studied in the source PDX models: the hypoxia-activated prodrug evofosfamide, in order to assess the utility of the organoids for evaluating drug therapies In addition, RNA was extracted from these models in anticipation of downstream sequencing.

Results

Four organoid models were successfully established following short-term culture after two passages, allowing additional downstream characterisation experiments to be carried out. Histological analysis identified that the organoids recapitulate the squamous epithelial cell morphology present in the HNSCC PDX models, while pimonidazole staining did not show any presence of hypoxia in the organoids. When treated with evofosfamide, the organoids appear to reflect the variability in observed sensitivities that was reported in the matched PDX tumours .However, the extracted RNA was not of sufficient quality for RNA sequencing.

Conclusion

This thesis is the first published record of PDX-derived organoids being developed for HNSCC. These organoids appeared to recapitulate the histology and evofosfamide drug sensitivity of the source PDX tumours following short-term organoid cultures. However, further optimisation is required to ensure that these organoid models can be perpetuated over the longer term, as well as confirm that they recapitulate the genomic status of HNSCC tumours and therefore possess sufficient clinical utility for the testing of novel HNSCC therapies.