DecisionDx Test IDs High-Risk Among Low-Risk Melanoma Patients

The DecisionDx-Melanoma gene expression profile (GEP) test can identify high-risk patients who are likely to recur or die from melanoma within groups of patients often considered low risk based on traditional staging metrics, suggests a study published in Journal of the American Academy of Dermatology (JAAD).

Results from this multicenter study of 690 patients demonstrates that the DecisionDx-Melanoma test is an independent predictor of risk for recurrence, metastasis, and melanoma-specific death, explains a media release from Castle Biosciences Inc, a skin cancer diagnostics company providing molecular diagnostics to improve cancer management decisions.

“In this study of a large, contemporary melanoma population, the GEP test identified patients at high risk for recurrence and death from melanoma among groups that are deemed low risk by traditional staging metrics,” says study co-author John Vetto, MD, Professor of Surgery, Division of Surgical Oncology and Director of the Cutaneous Oncology Program at the Department of Surgery, Oregon Health & Science University.

“The 31-gene GEP test provides independent information that improves risk prediction and enables physicians to develop tailored care for their patients with melanoma.”

Patients from three previously published DecisionDx-Melanoma validation studies were combined to enable analysis of test performance in the following three clinically important subgroups that are traditionally considered low risk based on current national melanoma guidelines: (1) patients who had a negative sentinel lymph node (SLN) biopsy; (2) those with American Joint Committee on Cancer (AJCC) Stage I-IIA melanoma; and (3) those with thin (≤1 mm) tumors.

The DecisionDx-Melanoma test was performed to determine molecular class for each patient, with a Class 1A result indicating the lowest 5-year risk of metastasis and a Class 2B result indicating the highest risk. Study endpoints included recurrence-free survival (RFS; time to local, regional or distant recurrence), distant metastasis-free survival (DMFS; time to any distant metastasis) and melanoma-specific survival (MSS; time to documented death from melanoma).

In this population of 690 unique Stage I-III patients with at least 5 years of follow-up or a metastatic event, median age was 59 years and median Breslow thickness was 1.3 mm. Seventy percent of patients had Stage I or II melanoma, the release explains.

Key Study Findings:

  • In the pooled cohort, patients with Class 1A results had significantly higher RFS, DMFS and MSS rates compared to Class 2B (p<0.0001 for all comparisons).
  • Seventy percent of the patients who were SLN negative and experienced metastasis were identified as Class 2 by the DecisionDx-Melanoma test. Similarly, 79% of melanoma-specific deaths among those who were SLN negative were identified as having a Class 2 result.
  • Patients with Stage I-IIA melanoma who received a Class 2B DecisionDx-Melanoma test result had significantly worse RFS, DMFS and MSS rates compared to patients with a Class 1A DecisionDx-Melanoma result (p<0.0001 for all comparisons).
  • Based on Cox multivariate analysis in the Stage I-IIA subgroup that included tumor thickness, ulceration and mitotic rate, DecisionDx-Melanoma test class was found to be the only significant predictor of all three endpoints (RFS, DMFS and MSS; p<0.05 for all).
  • For patients with thin tumors (≤1 mm), although most patients were low risk Class 1, 15 patients had the highest risk Class 2B result. Those patients with a Class 2B test result had a significantly reduced RFS of 64.6% compared to those with a Class 1A result (96.8%; p<0.0001).

Results of the study extend previous findings of high prognostic accuracy of the DecisionDx-Melanoma GEP test to subgroups of patients at high risk, yet for whom current national melanoma guidelines recommend low intensity follow-up and surveillance. Additionally, the study’s authors suggest that the results could have an important impact on clinical trials evaluating adjuvant treatment of Stage II disease with immunomodulatory or targeted therapies, as the identification of high-risk Stage II patients may guide appropriate patient enrollment in such trials, the release continues.

[Source(s): Castle Biosciences Inc, Business Wire]