A study presented at the annual meeting of the American Society for Clinical Oncology has shown that DecisionDx-Melanoma (Castle Biosciences), a commercially available gene expression-profile (GEP) test, can be a useful prognostic tool for patients with high-risk cutaneous melanoma who undergo sentinel lymph node (SLN) biopsy.
The results, presented by David H. Lawson, M.D., Professor of Hematology and Medical Oncology, Winship Cancer Institute, Emory University, showed that DecisionDx-Melanoma was capable of identifying primary cutaneous (skin) melanoma tumors that were sentinel lymph node biopsy negative but were at high risk of metastasis. Furthermore, the test successfully identified tumors that were unlikely to become metastatic, independent of nodal status.
DecisionDx-Melanoma consists of a signature of 31 genes, 28 of which identify particular targets while the remaining 3 act as controls. These genes can classify tumors into two groups (high or low) depending on their risk for metastatic potential.
In a previous clinical study, the GEP test was capable of efficiently predicting the five-year risk of metastasis for primary cutaneous melanomas.
Now, in a second study, researchers applied the test in 217 Stage I, II, or III cutaneous melanoma tumor samples from patients who also had SLN biopsies, with the predictive capacity of each method compared at year 5 for distant metastasis-free survival (DMFS) and overall survival (OS).
“These data show that GEP testing may provide clinically significant information for assessing risk in melanoma patients beyond what we are seeing with sentinel lymph node status alone,” Dr. Lawson commented in a press release. “Although the sentinel lymph node biopsy is our best tool for staging melanoma patients, many node-negative patients become metastatic. The results of this study indicate that this test may help further classify risk regardless of node status.”
Results demonstrated that both tests provided comparable predictions of distant metastasis (GEP=50% vs SLNB=55%), however, the GEP test showed a better prediction (82%) of low risk distant metastasis, when compared with SLNB (67%).
Overall, GEP testing of SLNB eligible patients proved to be a better prognostic tool, independent of SLNB status, highlighting its possible use as an additional test to improve patient management.
“Although SLNB has been shown to be the most valuable tool for staging high risk melanoma patients, twice as many node-negative as positive patients will develop advanced disease,” Derek Maetzold, President and CEO of Castle Biosciences added in the press release. “It is known that many melanomas spread through non-lymphatic mechanisms or are biologically cleared from the lymphatic system prior to SLNB, underscoring the need for prognostic methods that are independent of the lymphatic system to more accurately assess metastatic risk and determine the most appropriate follow-up care.”