Castle Biosciences Inc. announced that data from studies of its DecisionDx-Melanoma test are being presented today at the Summer Academy Meeting of the American Academy of Dermatology (AAD). The validation data confirm previous studies showing that the gene expression profile test is a strong independent predictor for classifying which Stage I or II non-metastatic cutaneous melanoma patients will likely recur. The results were presented by Pedram Gerami, M.D., Associate Professor of Dermatology, Director of Melanoma Research at the Northwestern Skin Cancer Institute, Northwestern University.
"Up to one-third of Stage II melanoma patients, and 10% of Stage I patients, are at risk for developing future metastatic disease," commented Dr. Gerami. "The challenge for dermatologists has been in accurately identifying which earlier stage melanoma patients are at high risk and require more aggressive approaches to follow-up care. The availability of a tool that helps predict future cancer behavior based on the tumor's biology, independent of and additive to current staging methods, is a welcomed advance that will help guide physicians in prescribing the most appropriate care and treatment for their patients."
Approximately 60,000 patients are diagnosed annually in the U.S. with Stage I or II cutaneous melanoma (non-metastatic, lymph-node negative skin melanoma that can appear cured with tumor removal). Of these, approximately 8,500 will see their disease return within 5 years, metastasizing to a distant location in the skin, brain or lungs. There are limitations for predicting metastasis using the traditional AJCC staging system, based on Breslow's depth (tumor thickness), mitotic rate and ulceration.
The DecisionDx-Melanoma test is designed to predict metastasis by measuring the expression levels of 31 genes in the patient's tumor. The new test stratifies patients as Class 1 (low risk of metastasis), or Class 2 (high risk of metastasis), based on which tumor genes are turned on and off. To date, the test has analyzed archived tumor samples from more than 400 Stage I and II melanoma patients in prospectively designed studies. More information about the test and disease can be found at www.skinmelanoma.com.
Study Results
The multi-institutional validation study included archived tumors from 78 Stage I and II melanoma patients. Gene expression profiles were measured from formalin-fixed, paraffin-embedded biopsies or wide excisions of primary melanoma tumors.
Kaplan-Meier analysis for 5-year metastasis free survival rates were 98% for Class 1 (low risk) and 37% for Class 2 (high risk) [P<0.0001]. Accuracy = 85%, sensitivity = 86%. Cox proportional multi-variate analysis found the test to be independent of Breslow, mitosis and ulceration as well as AJCC stage (p<0.01). These data confirm the results of previous studies demonstrating that the gene expression profile test accurately stratifies metastatic risk in Stage I and II melanoma patients.
"Our studies involving more than 400 Stage I and Stage II melanoma patients demonstrate that DecisionDx-Melanoma performs well where it is needed most—in non-metastatic patients whose risk for recurrence is unclear or unknown," said Derek Maetzold, President and CEO of Castle Biosciences. "Insight into a tumor's genes, in combination with traditional staging methods, gives doctors and patients the ability to individualize follow-up care that matches metastatic risk with treatment planning."
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