Castle Biosciences Release: Study Demonstrates That Decisiondx-Melanoma Test Improves Identification Of High Risk Skin Melanoma When Used With AJCC Outcome Prediction Tool

Results published in Journal of the American Academy of Dermatology

FRIENDSWOOD, Texas--(BUSINESS WIRE)--Castle Biosciences, Inc., a provider of molecular diagnostics to improve cancer treatment decisions, today announced the publication of results from a study comparing and combining risk prediction using DecisionDx^®-Melanoma, the Company’s gene expression profile (GEP) test used to predict risk of metastasis in cutaneous melanoma (CM) patients, and the American Joint Committee on Cancer’s (AJCC’s) clinical staging system using the Individualized Melanoma Patient Outcome Prediction Tool. The AJCC online prognostic tool is used by clinicians to estimate survival rates for patients with Stage I and II melanoma based on tumor depth, ulceration status, location and patient age to determine appropriate patient management.

“For physicians and patients, the risk assessment provided by the GEP test may ultimately lead to earlier identification of metastatic disease when tumor burden is lower and the disease is potentially more treatable”

The paper, “Identification of High Risk Cutaneous Melanoma Tumors is Improved When Combining the Online AJCC Melanoma Patient Outcome Prediction Tool with a 31-Gene Expression Profile-Based Classification” was published today in the Journal of the American Academy of Dermatology (JAAD). In the study, researchers found that when used in combination with the AJCC clinical staging system, DecisionDx-Melanoma can significantly improve the identification of those Stage I and II melanoma patients who have a high risk for recurrence and/or developing metastatic disease.

“For physicians and patients, the risk assessment provided by the GEP test may ultimately lead to earlier identification of metastatic disease when tumor burden is lower and the disease is potentially more treatable,” said Laura Ferris, M.D., Ph.D., Associate Professor of Dermatology, University of Pittsburgh, and lead author of the study. “This information is vital in determining the best possible follow-up care plans for patients to ensure that their intensity of surveillance is appropriate for their individual risk of melanoma recurrence.”

Study Details

Study investigators determined survival predictions by examining records from 205 Stage I and Stage II melanoma patients collected from six U.S. centers. AJCC clinical staging factors (Breslow thickness, ulceration, site of lesion, age and sentinel lymph node biopsy status) were entered into the AJCC Individualized Melanoma Patient Outcome Prediction Tool to attain predicted 5-year survival rates for each patient. Patients also received the DecisionDx-Melanoma GEP test, which provides a binary prediction of risk (Class 1 or Class 2) for melanoma recurrence, with refinement into subclasses (1A, 1B, 2A and 2B) that reflect proximity of risk to the crossover point between Class 1 and Class 2.

The cohort included 109 Stage I and 96 Stage II cases. To compare risk prediction from the AJCC clinical staging system to the binary GEP prediction of risk, five-year survival rates of 79 percent and 68 percent were used as cutoff scores to separate patients into low risk and high risk groups. These cutoff scores reflect the 5-year survival rates for Stage IIA or IIB patients, respectively, and are used to identify cohorts of patients who can receive significantly different surveillance and therapeutic opportunities based upon national treatment guidelines and center-specific management strategies for Stage II patients.

In comparing the GEP test with the AJCC clinical staging system, researchers found that the GEP test accurately identified early stage, high risk disease at both cutoff scores, when analyzed for regional or distant recurrence, distant metastasis, and death (from all causes).

Multivariate Cox regression analysis to compare the binary GEP classification and AJCC predictions of risk (n=205)

Further analysis was conducted to compare outcomes from the GEP test and AJCC tool when risk prediction was not concordant. One in five results (21%) were not concordant. As seen in the table below, 13 patients with documented evidence of regional or distant metastasis were predicted as low risk (survival risk above 79%) by the AJCC clinical staging system but high risk (Class 2) by DecisionDx-Melanoma. Eleven had Stage I or IIA disease at diagnosis. For those patients, national management guidelines recommend low intensity surveillance. However this approach would not allow these patients to benefit from early detection of metastatic disease that can be achieved by appropriate high-intensity surveillance in high-risk patients.

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