Poster Presentation 35th Lorne Cancer Conference 2023

Evolving genomic complexity unveiled in ctDNA analysis of melanoma patients (#144)

Sandra Fitzgerald 1 , Cherie Blenkiron 1 , Tiffany Somers-Edgar 2 , Rosalie Stephens 2 , Jon A Mathy 3 , Richard Martin 4 , Christopher Jackson 5 , Michael Eccles 6 , Rob Day 6 , Parry Guilford 6 , Ben Lawrence 1 , Annette Lasham 1 , Cristin Print 1
  1. University of Auckland, Grafton, AUCKLAND, New Zealand
  2. Cancer and Blood Service, Auckland City Hospital, Auckland, New Zealand
  3. Counties Manukau Health, Auckland, New Zealand
  4. Waitemata District Health Board, Auckland, New Zealand
  5. Southern District Health Board, Dunedin, New Zealand
  6. University of Otago, Dunedin, New Zealand

There is an increasing global focus on integrating liquid biopsy into routine cancer care, with many commercial tests now available. These minimally invasive blood plasma-based genomic tests identify tumour-derived DNA mutations in blood samples. They can provide information to patients and their clinicians about tumour growth, optimal treatment, treatment response, and tumour relapse after surgery, which can facilitate more informed clinical decisions. We have been developing affordable and sensitive liquid biopsies for the detection and surveillance of patients with advanced-stage melanoma, focusing on potential use in remote clinics to address health system inequities. Circulating tumour (ct)DNA-derived mutations were identified in patients’ plasma samples utilising a multi-platform approach, including next-generation sequencing and droplet digital PCR, and then mutations were tracked over time. The plasma ctDNA analysis detected complex tumour mutational patterns for many advanced melanoma patients, and here we will present the benefits and reflect on the challenges of such testing, especially in light of tumour heterogeneity. Whilst we are validating and conducting longitudinal studies, we recognise there are significant budget constraint in the NZ public health system that could impact the implementation of companion diagnostic test such as these ones. The data we have collected can help inform NZ regulatory bodies to implement and regulate such tests.