Poster Presentation ASDR Annual Scientific Meeting 2019

Identification and Validation of a Diagnostic Autoantibody Signature for Primary Cutaneous Melanoma (#62)

Pauline Zaenker 1 , J. Lo 2 , R. Thornton 3 , R. Pearce 4 , L. Cowell 5 , M. Lee 6 , C. Quirk 7 , H. Law 8 , E. Gray 1 , M. Ziman 9
  1. School of Medical and Health Sciences, Edith Cowan University, Joondalup, Perth, Western Australia, Australia
  2. School of Science, Edith Cowan University, Joondalup, Perth, Western Australia, Australia
  3. School of Medicine, University of Western Australia, Perth, Western Australia, Australia
  4. Hollywood Specialist Centre, Hollywood Private Hospital, Nedlands, Perth, Western Australia, Australia
  5. Level 1 Melanoma, Fremantle, Perth, Western Australia, Australia
  6. St John of God Hospital, Subiaco, Perth, Western Australia, Australia
  7. Dermatology Specialist Group, Ardross, Perth, Western Australia, Australia
  8. Skin Check WA, Inglewood, Perth, Western Australia, Australia
  9. Department of Pathology and Laboratory Medicine, The University of Western Australia, Crawley, Perth, Western Australia, Australia

Aim: Elevated levels of autoantibodies in the serum of cancer patients have been associated with the presence of various cancer types and may serve as biomarkers for cancer diagnosis. The aim of this study was to identify individual serologic autoantibody biomarkers as well as a combination of these to complement the routine diagnosis of cutaneous melanoma patients at early stages.

Methods: Peripheral blood and clinical data was collected from early stage melanoma patients (n=104) and healthy volunteers (n=105). Samples were screened against a functional protein microarray to measure IgG responses as potential melanoma autoantibody biomarkers. Extensive statistical analyses including machine learning based approaches were used to determine the reliability of individual and combinations of autoantibody biomarkers.

A validation immunoassay was optimised and test samples were diluted 1:20, incubated with the protein-bound beads, washed and then incubated with a R-Phycoerythrin-conjugated goat anti-human IgG secondary antibody. Fluorescence was read using the BioPlex200 platform and IgG titres assigned using the in-house standard reference sera. ROC analysis helped to establish cutoffs and evaluate autoantibody biomarker sensitivity, specificity, AUC for melanoma diagnosis.

Results: Out of 1627 recombinant proteins immobilised on the microarray, 139 proteins displayed increased seroreactivity in patients with melanoma compared to healthy volunteers, with sensitivity and specificity scores of individual autoantibody biomarkers of 18% and 100% respectively for melanoma diagnosis. To improve sensitivity, a panel of 10 autoantibodies was identified with a combined sensitivity of 79% at 84% specificity for primary melanoma.

Conclusion: This is one of the first studies identifying autoantibodies in an extensive cohort of melanoma patients relative to healthy volunteers. Sensitivity levels of identified individual melanoma autoantibodies are comparable to results obtained in similar studies in other cancers, whereas the preliminary data of the validation immunoassay shows value as complementary diagnostic tool for the detection of early stage melanomas.

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