On November 17, 2020 Castle Biosciences, Inc. (Nasdaq: CSTL), a skin cancer diagnostics company providing personalized genomic information to improve cancer treatment decisions, reported the publication of two studies in SKIN: The Journal of Cutaneous Medicine, which demonstrated that DecisionDx DiffDx-Melanoma adds significant diagnostic clarity for physicians when characterizing difficult-to-diagnose melanocytic lesions and establishes clinical utility with the potential to improve patient care (Press release, Castle Biosciences, NOV 17, 2020, View Source [SID1234571280]).

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The development and validation study, authored by Dr. Sarah I. Estrada, et al., is titled, "Development and Validation of a Diagnostic 35-Gene Expression Profile Test for Ambiguous or Difficult-To-Diagnose Suspicious Pigmented Skin Lesions." This study describes the development and clinical validation of the DecisionDx DiffDx-Melanoma test, which is designed to refine the diagnoses of suspicious pigmented lesions.

The clinical utility study, authored by Dr. Aaron S. Farberg, et al., is titled, "A 35-Gene Expression Profile Test for Use in Suspicious Pigmented Lesions Impacts Clinical Management Decisions of Dermatopathologists and Dermatologists." This study documents the influence of DecisionDx DiffDx-Melanoma test results on subsequent clinical management decisions, potentially leading to decreased unnecessary procedures while correctly identifying at-risk patients.

Estrada et al. Study Background and Results:

The purpose of this study was to develop and validate DecisionDx DiffDx-Melanoma, including the test’s ability to accurately differentiate between benign and malignant pigmented lesions.
Discovery started with the assessment of 76 genes with quantitative reverse transcription polymerase chain reaction (RT-PCR); artificial intelligence methods were then employed for diagnostic gene selection and algorithm development using 200 benign nevi and 216 melanomas for training. The final algorithm included 32 discriminant and 3 control genes. To reflect the complex biology of melanocytic neoplasia, the DecisionDx DiffDx-Melanoma test was developed to include an intermediate-risk zone.
The results of the study showed that the DecisionDx DiffDx-Melanoma test:
Had a technical success rate of 97%, meaning that a test result was successfully generated;
Achieved accuracy statistics of: Sensitivity = 99.1%, Specificity = 94.3%, Positive Predictive Value = 93.6%, Negative Predictive Value = 99.2%; with an intermediate-risk result in 3.6% of the cases.
Conclusions: DecisionDx DiffDx-Melanoma was developed to refine diagnoses of melanocytic neoplasms by providing clinicians with an objective tool. A test with these accuracy metrics could alleviate uncertainty in difficult-to-diagnose lesions leading to decreased unnecessary procedures while appropriately identifying at-risk patients.
Farberg et al. Study Background and Results:

The purpose of this study was to evaluate DecisionDx DiffDx-Melanoma’s clinical utility.
Dermatopathologists and dermatologists were surveyed regarding diagnostic challenges and patient management strategies in 60 difficult-to-diagnose melanocytic neoplasms. Participants reviewed each lesion twice, once without a DecisionDx DiffDx-Melanoma result and once with. Responses were evaluated for consistent trends in the utilization of the DecisionDx DiffDx-Melanoma test result.
Dermatopathologists utilized the DecisionDx DiffDx-Melanoma result to refine their diagnoses in lesions receiving a benign vs. malignant result (82.3% diagnostic downgrade vs. 94.9% diagnostic upgrade, respectively).
Diagnostic confidence was increased (51%), while additional diagnostic work-up requests were decreased in cases with a benign DecisionDx DiffDx-Melanoma result (72.1%) and increased with a malignant DecisionDx DiffDx-Melanoma result (45.6%).
Conclusions: The diagnosis of challenging melanocytic neoplasms and subsequent clinical management decisions were influenced by DecisionDx DiffDx-Melanoma results in alignment with the test result. The utility of the test may provide the opportunity for clinicians to deliver more informed patient management plans.
About DecisionDx DiffDx-Melanoma

DecisionDx DiffDx-Melanoma is designed to aid dermatopathologists in characterizing difficult-to-diagnose melanocytic lesions. Of the approximately 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.