Risk stratification using the Merlin Assay (CP-GEP) in an independent cohort of 930 patients with clinical stage I/II melanoma who did not undergo sentinel lymph node biopsy

PURPOSE: More than 80 % of patients with melanoma are diagnosed without nodal metastasis, but most of those who relapse or die from melanoma are initially diagnosed as low risk early-stage. Here we investigate the ability of the Merlin Assay to stratify patients who did not undergo sentinel lymph node biopsy (SLNB) for their risk of recurrence.

PATIENTS AND METHODS: 930 patients with clinical stage I/II primary cutaneous melanoma from the University of Tuebingen diagnosed between 2000 and 2020 were analyzed. None of the patients included underwent SLNB. The Merlin Assay combines patient age at diagnosis, Breslow thickness, and gene expression of eight specific genes from the primary tumor. Risk output labels are High Risk and Low Risk.

RESULTS: Clinicopathological gene expression profile (CP-GEP) identified 879 patients as Low Risk and 51 patients as High Risk. The 10-year RFS (HR 20.07; p < 0.001) and DMFS (HR 19.39; p < 0.001) were significantly higher in CP-GEP Low Risk versus High Risk patients. Similar results were observed in 10-year MSS (HR 35.85; p < 0.001). CP-GEP analysis of lentigo maligna melanoma and acral lentiginous melanoma showed that the performance of assay was independent of melanoma histological subtypes.

CONCLUSION: This study shows that CP-GEP has the potential to stratify patients with early-stage melanoma who did not undergo SLNB based on their risk of recurrence. Patients with CP-GEP Low Risk have a significantly better long-term survival. CP-GEP shows to be promising for guiding SLNB referral and may support melanoma care by optimizing personalized treatment plans and potential surveillance regimens.