Merlin CP-GEP Test Accurately Stratifies Melanoma Patients by Sentinel Node Metastasis Risk in Landmark Study

The MERLIN_001 trial, the largest prospective evaluation of a genomic test in cutaneous melanoma, has demonstrated that the Merlin CP-GEP Test accurately stratifies patients by sentinel lymph node metastasis risk, showing a greater than three-fold difference between High-Risk and Low-Risk groups. Published in the October 2025 issue of JAMA Surgery, the study enrolled 1,761 patients across leading U.S. academic cancer centers including the Mayo Clinic, University of Michigan, Memorial Sloan Kettering Cancer Center, and Moffitt Cancer Center, providing quantitative guidance for clinicians regarding the clinical utility of Merlin CP-GEP testing in guiding sentinel lymph node biopsy decision-making.

Across the study population, the Merlin CP-GEP Test stratified melanomas into two distinct risk groups: High-Risk patients had greater than a three-fold likelihood of SLN metastasis (23.8%) compared to Low-Risk patients (7.1%). Overall, 37.0% of patients were classified as Low-Risk while 63.0% were High-Risk, with the test achieving a 97.7% success rate in submitted samples. The study represents the first and only prospective blinded data confirming the test's ability to accurately stratify melanoma patients by sentinel node metastasis risk.

Vernon Sondak, MD, MERLIN_001 Principal Investigator and chair of the Cutaneous Oncology Department at Moffitt Cancer Center, emphasized the study's significance, stating that the test adds a level of accuracy above current clinical factors alone, even when factors like mitotic rate and histologic subtype are considered. This knowledge ultimately allows patients and surgeons to make better decisions about when sentinel node biopsy should be part of the management of clinically localized melanoma, particularly valuable for shared decision-making in appropriately selected patients.

The test demonstrated particular utility in challenging patient populations. In patients aged 65 and older, where comorbidities can be more prevalent, the test identified 57.9% as High-Risk with a positive SLNB rate of 20.3%, versus a 6.6% positive SLNB rate for Low-Risk cases. For head and neck melanomas, where SLNB can be technically difficult and carry higher morbidity, the Merlin CP-GEP test identified High-Risk cases with a 26.7% SLN rate and Low-Risk cases with a 4.9% SLN rate, representing a five-fold risk increase in the High-Risk versus Low-Risk groups.

Across all ages and primary sites, cases with clinical Stage IB melanoma were classified as Low-Risk 49.3% of the time, with a 6.5% positive SLNB rate compared with an 18.3% rate for High-Risk cases. The complete MERLIN_001 trial results published in JAMA Surgery can be accessed at https://doi.org/10.1001/jamasurg.2025.4399. The CP-GEP model represents the only commercially available gene expression profiling test that combines clinicopathologic variables with gene expression profiling into a single integrated algorithm, providing binary stratification of all patients based on metastasis risk.