Treatment with nanosomal paclitaxel lipid suspension versus conventional paclitaxel in metastatic breast cancer patients - a multicenter, randomized, comparative, phase II/III clinical study

Background: A novel nanosomal paclitaxel lipid suspension (NPLS), free from Cremophor EL (CrEL) and ethanol, was developed to address the solvent-related toxicities associated with conventional paclitaxel formulation. Objective: To evaluate the efficacy and safety of NPLS versus CrEL-based paclitaxel (conventional paclitaxel) in patients with metastatic breast cancer (MBC). Design: A prospective, open-label, randomized, multiple-dose, parallel, phase II/III study. Methods: Adult (18-65 years) female patients with MBC who had previously failed at least one line of chemotherapy were randomized (2:2:1) to NPLS 175 mg/m(2) every 3 weeks (Q3W, n = 48, arm A), NPLS 80 mg/m(2) every week (QW, n = 45, arm B) without premedication or conventional paclitaxel (Taxol (R), manufactured by Bristol-Myers Squibb, Princeton, NJ, USA) 175 mg/m(2) Q3W (n = 27, arm C) with premedication. In the extension study, an additional 54 patients were randomized (2:1) to arm A (n = 37) or arm C (n = 17). Results: Pooled data from the primary study and its extension phase included 174 patients. The primary endpoint was the overall response rate (ORR). As per intent-to-treat analysis, ORR was significantly better in the NPLS QW arm as compared to conventional paclitaxel [44.4% (20/45) versus 22.7% (10/44), (p = 0.04)]. An improvement in ORR with NPLS Q3W versus conventional paclitaxel arm [29.4% (25/85) versus 22.7% (10/44)] (p = 0.53) was observed. Disease control rates observed were improved with NPLS Q3W versus conventional paclitaxel Q3W (77.7% versus 72.7%, p = 0.66) and with NPLS QW versus conventional paclitaxel Q3W (84.4% versus 72.7%, p = 0.20), although not significant. A lower incidence of grade III/IV peripheral sensory neuropathy, vomiting, and dyspnea was reported with NPLS Q3W versus conventional paclitaxel Q3W arms. Conclusion: NPLS demonstrated an improved tumor response rate and a favorable safety profile versus conventional paclitaxel. NPLS 80 mg/m(2) QW demonstrated a significantly better response versus conventional paclitaxel 175 mg/m(2) Q3W.