Interim analysis of survival outcomes in a prospective cohort evaluating a prognostic 31-gene expression profile (GEP) test for melanoma.

Abstract

9573 Background: DecisionDx-Melanoma has been validated as an accurate prognosticator of cutaneous melanoma (CM) metastasis risk. The GEP test classifies CM pts as Class 1 (low risk) or Class 2 (high risk). Interim survival analysis from two clinical registry studies (NCT02355574/NCT02355587) designed to prospectively evaluate outcomes in pts for whom the GEP test was performed is described. Methods: Eleven US dermatologic and surgical centers participated in the IRB-approved protocols. Physicians enrolled CM pts who were ≥16 years old and had successful GEP test results. Endpoints of recurrence-free (RFS), distant metastasis-free (DMFS) and melanoma-specific survival (MSS) were assessed using Kaplan-Meier and Cox regression analysis. As an interim analysis at year 3 of an expected 5-year study, the critical alpha level (p-value) was 0.01. Results: At the time of data extraction, 322 pts were accrued and completed at least one follow-up visit. Median age was 58 years (range 18-87), median Breslow thickness (BT) was 1.2mm, 55% were male, 20% (58/296) were ulcerated, and 15% (36/237 biopsied) had a positive sentinel lymph node (SLN). Median follow-up time was 1.5 years for pts without a recurrence. Of 25 recurrent cases, 80% (20/25) were Class 2 and 40% (10/25) were SLN-positive. Two percent of Class 1 pts had a recurrence compared to 6% (12/201 biopsied) of SLN-negative pts. Of the SLN-negative pts who recurred, 75% (9/12) were called Class 2. Combined GEP and SLN risk prediction identified 88% (21/24) of recurrences. Kaplan-Meier event rates for each class are shown in the table. In Cox multivariate analysis, BT and GEP Class 2 were significant predictors of recurrence (p<0.01 for each). Conclusions: Results of this analysis show that the GEP test provides prognostic information that complements conventional staging and significantly enhances identification of high risk CM pts, consistent with reported validation studies.The results support use of the test for guiding surveillance decisions and enrollment of CM pts in clinical trials. Clinical trial information: NCT02355574, NCT02355587. [Table: see text]