PhD research unlocks less-invasive cancer testing
Only a decade ago, tracking cancer tumours with blood tests was the realm of science fiction. Now, MWC Affiliate Investigator Dr Sandra Fitzgerald has a whole technology for detecting circulating tumour DNA (ctDNA) in blood samples off the ground.
Sandra is a Research Fellow at the University of Auckland based in the laboratory of MWC Principal Investigator Cris Print. She is also a member of the MWC Early Career Steering Group.
After years in the private sector working in plant genomics, raising a family, and working as a senior technician in breast cancer research and a neuroendocrine cancer project, Sandra embarked on her PhD on ctDNA as a mature student.
Small fragments of ctDNA are released into the bloodstream as cancer cells undergo necrosis or apoptosis. The early stages of Sandra’s PhD focussed on developing technologies to show that blood tests for ctDNA are sensitive and specific. When the COVID-19 pandemic hit, Sandra halted her studies. Instead, she supported the national COVID response, transitioning to clinical laboratory SARS-CoV-2 testing, then a validation role, eventually becoming a fully qualified medical laboratory scientist.
MWC provided a three-month MWC COVID studentship grant that helped Sandra complete her PhD when she returned to her studies, and, along with Healthier Lives National Science Challenge funding, this laid the foundation for a paper1 in Molecular Diagnosis & Therapy (2023) involving several MWC investigators. They showed how minimally invasive blood tests could be used to accurately follow tumour evolution and responses to treatment in immunotherapy-treated melanoma patients.
Sandra says the presence of ctDNA in the bloodstream can allow more representative profiling of a patient’s tumour as it can capture information from multiple sites in a patient’s body.
“Nobody has really figured it out internationally. In New Zealand, we have strengths: very strong links to our hospitals and a single NHI number. With patients who have consented for access to clinical data, we can work very closely with clinicians, radiologists, nurses to really bring together a nice package of information.”
Using the new technologies, she tracked tumour response to checkpoint inhibitor immunotherapies in patients with advanced melanoma.
“We are getting a bigger picture of what is going on, starting to tease apart the biology behind it.”
“The goal is to reduce the dependency on CT imaging or biopsy needles going into places like lungs where they don’t sit very well – and to make something feasible for patients, affordable for the health system, and that will reduce the inequity in who can access these tests.”
On completing her PhD, Sandra secured a two-year Cancer Research Trust NZ postdoctoral fellowship and additional funding in collaboration with a range of scientists and clinicians to apply ctDNA technology to lung, pancreatic, and endometrial cancers and head and neck squamous cell carcinoma.
“Having developed these tests so they are robust and reproducible, the challenge that excites me now is to increase their sensitivity, to make them useful for early cancer diagnosis or for detecting early relapse following surgery.”
1. Fitzgerald S, Blenkiron C, Stephens R, Mathy J, Somers-Edgar T, Rolfe G, Martin R, Jackson C, Eccles M, Robb T, Rodger E, Lawrence B, Guilford P, Lasham A and Print C. Dynamic ctDNA mutational complexity in melanoma patients receiving immunotherapy. Molecular Diagnosis & Therapy, 2023, 27(4), 537-550