On November 12, 2020 Castle Biosciences, Inc. (Nasdaq: CSTL), a skin cancer diagnostics company providing personalized genomic information to improve cancer treatment decisions, reported the presentation of data on two of its skin cancer gene expression profile tests during the 57th Meeting of The American Society of Dermatopathology (ASDP) (Press release, Castle Biosciences, NOV 12, 2020, View Source [SID1234570826]).
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DecisionDx-Melanoma:
"Identifying predictors of sentinel lymph node metastasis in cutaneous melanoma patients using molecular and clinicopathologic high-risk features" was presented by Federico Monzon, M.D.
DecisionDx-Melanoma is Castle’s gene expression profile test that uses an individual patient’s tumor biology to predict individual risk of cutaneous melanoma metastasis or recurrence, as well as sentinel lymph node (SLN) positivity, independent of traditional staging factors.
"DecisionDx-Melanoma uses primary tumor biology to delineate patient metastatic risk, including the risk of SLN metastasis," said Monzon. "In this study, among all features evaluated, DecisionDx-Melanoma was the most significant factor in predicting rates of SLN positivity, justifying a role for the test alongside other commonly used features in considering the sentinel lymph node biopsy surgical procedure."
Study methods and findings:
Authors modeled decision trees using the statistical R package for a cohort of 3,093 patients with cutaneous melanoma to determine which molecular and clinicopathologic features could best stratify the risk of patients’ receiving a positive result from a sentinel lymph node biopsy (SLNB).
DecisionDx-Melanoma was the most significant factor in distinguishing between high and low SLN-positivity rates (p<0.001).
Patients with a Class 2 (high-risk) DecisionDx-Melanoma result under age 75 or with a very high mitotic rate (>10/mm2) had the highest SLN-positivity rates (>20%).
Conversely, patients with a Class 1A result over age 47 with tumors with no mitoses and those age 47 or younger with a Breslow thickness of 0.85mm or less had the lowest positivity rates (<5%), indicating they could potentially forego SLNB.
Patients of all ages and Breslow thicknesses with a Class 2 result had a greater than 10% risk of SLN positivity, indicating that a Class 2 DecisionDx-Melanoma result can be considered a high-risk factor when considering the SLNB procedure for individual patients.
DecisionDx DiffDx-Melanoma:
"Development and validation of a diagnostic gene expression profile test for ambiguous or difficult-to-diagnose pigmented skin lesions" was presented by Sarah Estrada, M.D., FCAP.
DecisionDx DiffDx-Melanoma is designed to aid dermatopathologists in characterizing difficult-to-diagnose melanocytic lesions.
"Approximately 300,000 melanocytic lesions biopsied each year cannot be confidently identified as either malignant or benign, so the nature of these lesions remains ambiguous with discordant rates of diagnoses ranging from 25-43%," said Estrada. "The accuracy metrics shown in the development and validation study suggest DecisionDx DiffDx-Melanoma could help alleviate uncertainty in difficult-to-diagnose lesions, leading to decreased unnecessary procedures while appropriately identifying at-risk patients."
Study methods and findings:
DecisionDx DiffDx-Melanoma was designed to refine diagnoses of melanocytic neoplasms by providing clinicians with an objective ancillary tool with high accuracy.
A total of 503 formalin-fixed paraffin-embedded (FFPE) tissue samples sourced from primary cutaneous melanoma tumors and melanocytic nevi were used, of which 273 were benign and 230 were malignant lesions. Samples underwent quantitative polymerase chain reaction (qPCR) to evaluate expression of 76 genes with potential diagnostic utility.
Artificial intelligence approaches were used to select and prioritize gene sets, ultimately identifying 32 differentially expressed genes that reliably classified benign versus malignant melanocytic lesions.
The resulting 35-gene expression profile (GEP) test, DecisionDx DiffDx-Melanoma, (32 discriminant genes and 3 control genes) accurately diagnosed malignant and benign cases with 99.1% sensitivity, 94.3% specificity, 93.6% positive predictive value (PPV) and 99.2% negative predictive value (NPV).
About DecisionDx-Melanoma
DecisionDx-Melanoma is a gene expression profile test that uses an individual patient’s tumor biology to predict individual risk of cutaneous melanoma metastasis or recurrence, as well as sentinel lymph node positivity, independent of traditional staging factors, and has been studied in more than 5,700 patient samples. Using tissue from the primary melanoma, the test measures the expression of 31 genes. The test has been validated in four archival risk of recurrence studies of 901 patients and six prospective risk of recurrence studies including more than 1,600 patients. Prediction of the likelihood of sentinel lymph node positivity has also been validated in two prospective multicenter studies that included more than 3,000 patients. Impact on patient management plans for one of every two patients tested has been demonstrated in four multicenter and single-center studies including more than 560 patients. The consistent performance and accuracy demonstrated in these studies provides confidence in disease management plans that incorporate DecisionDx-Melanoma test results. Through September 30, 2020, DecisionDx-Melanoma has been ordered more than 64,560 times for use in patients with cutaneous melanoma.
More information about the test and disease can be found at www.SkinMelanoma.com.
About DecisionDx DiffDx-Melanoma
DecisionDx DiffDx-Melanoma is designed to aid dermatopathologists in characterizing difficult-to-diagnose melanocytic lesions. Of the 2 million suspicious pigmented lesions biopsied annually in the U.S., Castle estimates that approximately 300,000 of those cannot be confidently classified as either benign or malignant through traditional histopathology methods. DecisionDx DiffDx-Melanoma classifies these lesions as: benign (gene expression profile suggestive of benign neoplasm); intermediate-risk (gene expression profile cannot exclude malignancy); or malignant (gene expression profile suggestive of melanoma). Interpreted in the context of other clinical, laboratory and histopathologic information, DecisionDx DiffDx-Melanoma is designed to add diagnostic clarity and confidence for dermatopathologists while helping dermatologists deliver more informed patient management plans.
More information about the test and disease can be found at www.CastleTestInfo.com.