Final Results of Phase III SYMMETRY Study: Randomized, Double-Blind Trial of Elesclomol Plus Paclitaxel Versus Paclitaxel Alone As Treatment for Chemotherapy-Naive Patients With Advanced Melanoma

Abstract

Purpose Elesclomol, an investigational first-in-class compound, induces oxidative stress, triggers mitochondrial-induced apoptosis in cancer cells, and shows synergy with taxanes in tumor models. Following completion of a phase II trial of elesclomol in combination with paclitaxel that met its primary end point of progression-free survival (PFS), this randomized, double-blind, controlled phase III study was conducted to confirm the efficacy and tolerability of elesclomol in combination with paclitaxel versus paclitaxel alone in patients with advanced melanoma. Patients and Methods Patients with stage IV chemotherapy-naive melanoma (n = 651) were randomly assigned 1:1 to paclitaxel 80 mg/m2 either alone or in combination with elesclomol 213 mg/m2 administered weekly for 3 weeks of a 4-week cycle. Patients were stratified by prior systemic treatment, M1 subclass, and baseline lactate dehydrogenase (LDH) levels. The primary end point was PFS. Results The study did not achieve its PFS end point (hazard ratio, 0.89; P = .23). The study was stopped when an early overall survival data analysis indicated an imbalance in total deaths favoring paclitaxel, predominantly in patients with high LDH levels. A prospectively defined subgroup analysis revealed a statistically significant improvement in median PFS for the combination in patients with normal baseline LDH. Conclusion The addition of elesclomol to paclitaxel did not significantly improve PFS in unselected patients with advanced melanoma. The association between baseline LDH and clinical outcomes suggests that LDH may be a predictive factor for treatment with this combination, consistent with recent findings on the association between elesclomol anticancer activity and cellular metabolic state.