Study highlights accuracy of DecisionDx-Melanoma prognostic test in patients with Stage II-IIIA melanoma

Castle Biosciences, Inc., the skin cancer diagnostics company providing molecular diagnostics to improve cancer management decisions, today announced the presentation of data highlighting how the accuracy of the DecisionDx^®-Melanoma gene expression profile (GEP) test in patients with Stage II and IIIA melanoma can improve adjuvant clinical trial design at the 2018 Society for Melanoma Research International Congress held in Manchester, England from October 24-27.

The study titled, "Implications of a 31-gene expression profile test for cutaneous melanoma on AJCC-based risk assessment and adjuvant therapy trial design," was presented as a poster at the meeting.

Study Background

• The adjuvant treatment setting for melanoma has experienced significant advances in recent years. While therapies provide clear benefits for a subset of melanoma patients, they also can be associated with significant adverse effects. Accurate assessment of individual patient risk is increasingly important to guide treatment decisions, especially for those with no evidence of disease.
• The analysis focused on the use of the DecisionDx-Melanoma test to inform which Stage II and IIIA melanoma patients are at high risk of recurrence and could benefit from adjuvant therapy. Adjuvant therapy trials are being considered or underway for Stage II and Stage IIIA patients, but recurrence rates in this population make trials in this population challenging.
• The study assessed whether the DecisionDx-Melanoma test could have a role in patient selection for future adjuvant therapy clinical trials, and evaluated the potential cost savings associated with patient enrollment based on risk assessment.

Study Details and Key Findings

• The DecisionDx-Melanoma test was previously validated in a cohort of 690 patients from 18 centers to accurately predict 5-year risk of recurrence for patients with melanoma (Class 1A lowest risk; Class 2B highest risk).
• This analysis included a subset of 173 patients who had Stage II or IIIA melanoma (restaged using American Joint Committee on Cancer [AJCC] 8^th edition).
• Patients in the Stage II-IIIA cohort who had a Class 1A DecisionDx-Melanoma test result had a 5-year melanoma-specific survival (MSS) rate of 100%, similar to the risk of patients with Stage 1A melanoma. Stage II-IIIA patients who had a Class 2B result had an MSS of 85%, similar to a Stage IIIB risk.
• Similarly, 5-year recurrence-free survival for patients in the Stage II-IIIA cohort who had a Class 2B DecisionDx-Melanoma test result was 39% and distant metastasis-free survival was 54%, significantly lower than those for patients with a Class 1A result.
• Study results showed that using the DecisionDx-Melanoma test to select patients for a clinical trial, sample size could be reduced by 36% with an overall reduction in trial costs if enrollment focused on patients with a high risk of recurrence as determined by a DecisionDx-Melanoma Class 2B result.

"Optimization of adjuvant clinical trial enrollment for melanoma is increasingly important given the adverse effects that are associated with current targeted and immune checkpoint therapies," said Sancy Leachman M.D., Ph.D., Professor and chair, Department of Dermatology and Director, Melanoma Research Program, Oregon Health & Science University. "These data support application of the DecisionDx-Melanoma test to identify Stage II-IIIA patients who are at higher risk for recurrence and metastasis and are therefore appropriate candidates for adjuvant therapy consideration in a clinical trial."