Validation Of A Multimarker Blood Assay For Postoperative Assessment Of Stage Iv Melanoma Patients In A Prospective International Phase Iii Trial

9045 Background: Currently there are no validated prognostic molecular biomarkers for assessment of outcome after complete resection of stage IV melanoma patients. To validate blood molecular biomarkers for prognostic value and monitoring of these patients, we evaluated the clinical utility of a multimarker quantitative reverse-transcription PCR (qRT-PCR) for detecting circulating tumor cells (CTC) of patients blood enrolled in a multicenter international (29 sites) phase III trial of postoperative adjuvant therapy. After complete metastasectomy, AJCC stage IV patients underwent immunotherapy with bacille Calmette-Guerin (BCG) plus placebo or BCG plus melanoma vaccine. Methods: Bleeds were taken before and during treatment in both randomized treatment arms. Pre- and during treatment bleeds from patients were assessed by an optimized qRT-PCR assay for MART1, MAGEA3, and PAX3 genes mRNA. Median clinical follow-up time was 21.8 and 24.2 mos. for disease-free survival (DFS) and overall survival (OS), respectively. Results: MART1, MAGEA3, and PAX3 were detected in 64 (26%), 56 (23%), 73 (29%) of 244 post-operative pretreatment patients, respectively. Multivariate Cox analysis showed that biomarker-negative patients had significantly higher DFS than biomarker- positive patients (risk ratio 1.56, 95% CI, 1.14 - 2.15; P=0.0062). In serial-bleeds (pretreatment, mos 1 and 3) analysis of 214 patients, biomarker-negative patients had significantly higher OS than patients with 1–2 positive- or 3 positive-biomarkers (risk ratio 2.37, 95% CI 1.14 - 4.94, P=0.021; and risk ratio 2.90, 95% CI 1.28 - 6.53, P=0.01, respectively). Multivariate analysis confirmed that 1–2 positive- and 3 positive-biomarkers were significant independent prognostic factors for poor OS (risk ratio 2.44, 95% CI 1.16 - 5.12, P=0.019; and risk ratio 3.08, 95% CI 1.36 to 6.98, P=0.007, respectively). Conclusions: This prospective multicenter blood biomarker validation study demonstrates that multimarker qRT-PCR analysis of CTC has significant clinical utility as a prognostic factor of disease outcome at pretreatment, and as a treatment monitoring prognostic factor in stage IV melanoma patients. No significant financial relationships to disclose.