Abstract
BackgroundThe DecisionDx-Melanoma test provides prognostic information for patients with cutaneous melanoma (CM). Using formalin-fixed paraffin-embedded primary tumor tissue, the RT-PCR-based test classifies patients into a low- (Class 1) or high-risk (Class 2) category for recurrence based on expression of 31 genes. The current study was designed to assess the analytical validity of this test.MethodsInter-assay, inter-instrument, and inter-operator studies were performed to evaluate reliability of the 31-gene expression test results, sample stability and reagent stability. From March 2013 through June 2016, the gene expression test was performed on 8244 CM tumors. De-identified data from Pathology Reports were used to assess technical success.ResultsRobust sample and reagent stability was observed. Inter-assay concordance on 168 specimens run on 2 consecutive days was 99% and matched probability scores were significantly correlated (R2 = 0.96). Inter-instrument concordance was 95%, and probability scores had a correlation R2 of 0.99 (p < 0.001). From 8244 CM specimens submitted since 2013, 85% (7023) fulfilled pre-specified tumor content parameters. In these samples with sufficient tumor requirements, the technical success of the test was 98%.ConclusionDecisionDx-Melanoma is a robust gene expression profile test that demonstrates strong reproducibility between experiments and has high technical reliability on clinical samples.
Highlights
The DecisionDx-Melanoma test provides prognostic information for patients with cutaneous melanoma (CM)
We report the analytic validity of the gene expression profile (GEP) test, including reproducibility of molecular classification and technical reliability of clinical testing in accordance with published guidelines [10, 11], when performed in a College of American Pathologists (CAP)-accredited, Clinical Laboratory Improvement Act (CLIA)-certified laboratory setting
Comparison of probability score values showed high correlation (R2 = 0.99, p < 0.001), 100% concordance in binary risk classification (Class 1 or Class 2) and 90% concordance on subclass risk classification (Class 1A, 1B, 2A, or 2B) (18 of 21 cases; 95% confidence interval [Confidence interval (CI)] = 70–99%)
Summary
The DecisionDx-Melanoma test provides prognostic information for patients with cutaneous melanoma (CM). Using formalin-fixed paraffin-embedded primary tumor tissue, the RT-PCR-based test classifies patients into a low- (Class 1) or high-risk (Class 2) category for recurrence based on expression of 31 genes. We have developed and validated a gene expression profile (GEP) test that assesses melanoma tumor biology to improve the prediction of metastasis risk beyond traditional clinicopathologic factors [8, 9]. Cook et al Diagnostic Pathology (2018) 13:13 expression of 31 gene targets using primary tumor biopsy tissue and provides a binary classification of low risk (Class 1) or high risk (Class 2) of metastasis within 5 years. Molecular classification was shown to improve risk prediction when used in combination with SLNB, identifying as Class 2 more than 80% of SLN-negative patients who developed metastatic disease and died from melanoma [8]
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