Ex vivo human pancreatic cancer avatars; an in-line personalised therapeutic response assessment platform

A paradigm shift in long-term survival rates for patients with Pancreatic Ductal Adenocarcinoma (PDAC) has yet to be witnessed. Long-term survival is only achieved in a small minority of patients. Systemic control of the disease can be secured with chemotherapy, however PDAC harbours high rates of chemotherapeutic resistance. Within current clinical practice, chemotherapeutic treatment strategies for PDAC are dictated by the patients’ level of fitness. There is no assessment of the individual’s tumour biology or acknowledgement of the significant heterogeneity that exists across tumours. Precision therapy incorporates individual tumour phenotype and biological characteristics and utilises this information to guide future management. Such an approach may improve the outcome for patients with PDAC. Whilst several different models for precision therapies have been reported, they all possess weaknesses that limit their use within a clinical setting. Within this thesis, I present the creation of patient derived cancer avatars as a method for delivering precision therapy for patients with PDAC. This approach allows for the creation of individual and miniature versions of a patient’s tumour for detailed cellular profiling in addition to an opportunity to perform a therapeutic drug screen. This approach overcomes several of the limitations of other models of precision therapy notably the preservation of the cellular diversity of the primary tumour and can be implemented within a clinically meaningful time frame. I further investigated as to whether long-term ex vivo culture of patient avatars can be achieved through utilising novel perfusion culture. To date, we are the first group to describe the use of perfusion culture of PDAC tissue slices. We demonstrated that perfusion culture is associated with a physiological benefit as we were able to maintain both glucose and lactate levels at a constant level during 12 days of ex vivo culture (p < 0.001 and p<0.0001 respectively). Native functional biological processes within the avatars were preserved ex vivo through the use of perfusion culture. Avatars that were cultured with perfusion culture ex vivo maintained a significantly higher proliferation rate (p < 0.01) and demonstrated reduced rates of cell death as per cleaved caspase 3 activation (p < 0.01). The metabolic activity of the avatars (mTOR) was preserved with perfusion culture (p < 0.01). Our model system also preserved native immune cells present within the tumour during ex vivo culture. Our initial experience with ex vivo chemotherapy treatment of avatars demonstrated a correlation with the patients’ clinical response to adjuvant therapy. Therefore, the avatar response to treatment may provide a unique opportunity and a window of insight into the future response of the patient to systemic treatment. This information can be harnessed and utilised to create individual, personalised treatment regimes for each patient. This in turn would change the historic approach to systemic therapy for PDAC, evolving from a generic, standardised treatment approach for all patients to establishing an individual, customisable regime for an individual tumour for each patient. Such an approach may finally translate into prolonging survival for patients with this lethal disease.

Keywords: pancreatic ductal adenocarcinoma
precision treatment
precision therapy
pancreatic cancer
tissue explants
PDAC
Advisor: O'Neill, E
Mukherjee, S
Soonawalla, Z