A multi-national, randomised, open-label, parallel, phase III non-inferiority study comparing NK105 and paclitaxel in metastatic or recurrent breast cancer patients.

Background: NK105 is a novel nanoparticle drug delivery formulation that encapsulates paclitaxel (PTX) in polymeric micelles. We conducted an open-label phase III non-inferiority trial to compare the efficacy and safety of NK105 and PTX in metastatic or recurrent breast cancer.

Methods: Patients were randomly assigned in a 1:1 ratio to receive either NK105 (65 mg/m) or PTX (80 mg/m) on days 1, 8 and 15 of a 28-day cycle. The primary endpoint was progression-free survival (PFS), with a non-inferiority margin of 1.215.

Results: A total of 436 patients were randomised and 211 patients in each group were included in the efficacy analysis. The median PFS was 8.4 and 8.5 months for NK105 and PTX, respectively (adjusted hazard ratio: 1.255; 95% confidence interval: 0.989-1.592). The median overall survival and overall response rates were 31.2 vs. 36.2 months and 31.6% vs. 39.0%, respectively. The two groups exhibited similar safety profiles. The incidence of peripheral sensory neuropathy (PSN) was 1.4% vs. 7.5% (≥Grade 3) for NK105 and PTX, respectively. The patient-reported outcomes of PSN were significantly favourable for NK105 (P < 0.0001).

Conclusions: The primary endpoint was not met, but NK105 had a better PSN toxicity profile than PTX.

Clinical Trial Registration: ClinicalTrials.gov: NCT01644890.