GEP Assays in Melanoma: Comparing the Evidence and NCCN Risk Thresholds

This episode of Expert Perspectives, "GEP Assays in Melanoma: Comparing the Evidence and NCCN Risk Thresholds," takes up the question of which gene expression profile tests are available and how strongly the data support each one.

Dr. Singh explains that two gene expression profiling tools are currently available for cutaneous melanoma: DecisionDx-Melanoma and Merlin. He says DecisionDx-Melanoma has been shown to accurately stratify patients into low-risk and high-risk cohorts. It also provides an exact percentage risk of recurrence, metastasis, and nodal involvement, which he notes has been shown to be accurate.

By contrast, he points out that the Merlin test is based on the MERLIN_001 study, which did not meet its primary endpoint. For that reason, he says it has not been shown to identify low-risk patients as truly low risk. He anchors his interpretation in NCCN guidance, which defines low risk as a less than 5% likelihood of melanoma in the lymph nodes.

Dr. Singh adds that DecisionDx-Melanoma has demonstrated a survival benefit in a large SEER database study spanning thousands of patients across multiple stages. Tested patients showed an absolute mortality difference of greater than 1%, and he says a survival benefit is always something he looks for in a test. He also highlights prospective evidence from the DECIDE trial, in which management changes based on test results were associated with improved survival. He describes the field as quickly evolving and says he would like to see additional data on Merlin in the future.

On guidelines, Dr. Singh says he always follows NCCN but notes that clinicians sometimes move ahead of them. He compares the situation to breast cancer prognostic assays, which took years to enter guidelines before becoming standard of care. He closes by stressing that offering cutting-edge precision medicine tools helps ensure patients receive the best possible outcomes.

Our next episode, "Using GEP Results to Guide SLNB and Imaging in Stage I-II Melanoma," moves into the clinic as Dr. Singh shares how test results change biopsy, imaging, and surveillance decisions for stage I and II patients.