Protein S-100β serum levels predicts clinical outcome of high-risk melanoma patients treated with high-dose adjuvant interferon alfa2b

Abstract

8543 Background: S-100β serum levels have been shown to be useful to monitor response to therapy in metastatic melanoma patients. We have recently reported that S-100β levels could also be useful in the adjuvant context. In this study we analyze the clinical relevance of S-100β serum levels in an homogeneuos stage IIB-III group of patients treated with high-dose interferon. Methods: Patients with melanoma diagnosis were prospectively tested for serum S-100β protein by luminoimmunometric assay (LIA) before starting interferon (baseline) and every 3 months thereafter (on.therapy), until treatment was completed. Median time to progression and overall survival were assessed. Multivariate analysis using the Cox proportional hazards model with covariable dependent on time was perfomed since S-100β under therapy changes during time. Results: Ninety-seven patients were included. Median follow-up was 62.9 months (range 32.7–87.4). Median baseline S-100β levels were 0.06μg/l (range 0.06–0.53). S-100 was considered high (=0.15 μg/l) in 20.6% of the patients. High baseline S-100β levels were associated with positive lymph-node status (p=0.02). High S-100β levels (while on therapy) showed relation with positive lymph-node status (p=0.014), number of positive lymph-nodes (p=0.01), macroscopic lymph-node involvement (p=0.002) and second melanoma diagnosis at study entry (p=0.001). By univariate analysis, high baseline S-100β levels were associated with disease free survival (DFS) (p=0.004) and overall survival (OS) (p=0.0007). Similarly, high on therapy S-100β levels were associated with DFS (p<0.0001) and OS (p<0.0001). In the multivariate analysis, high on therapy S-100β levels (HR 1.029, CI95% 1.015–1.042; p<0.0001) was an independent prognostic factor for DFS. High on therapy S-100β levels (HR 1.017, CI 95% 1.10–1.026; p<0.0001) and high baseline S-100β levels (HR 3.31, CI 95% 1.10–9.89; p=0.032) were independent prognostic factors for OS. Conclusions: These results provide novel evidence of the clinical usefulness of serum S-100β levels determination for monitoring the clinical outcome of high-risk melanoma patients treated with adjuvant therapy. No significant financial relationships to disclose.