Phase II Study of Weekly Albumin-Bound Paclitaxel for Patients with Metastatic Breast Cancer Heavily Pretreated with Taxanes

PurposeNanoparticle albumin-bound paclitaxel, a solvent-free, albumin-bound paclitaxel, demonstrated antitumor activity in patients with taxane-naive metastatic breast cancer (MBC). We examined albumin-bound paclitaxel (100 mg/m2 or 125 mg/m2 administered weekly) to determine the antitumor activity in patients with MBC whose disease progressed despite conventional taxane therapy.Patients and MethodsWomen with MBC that was previously treated with taxanes were eligible for participation. Taxane failure was defined as metastatic disease progression during taxane therapy or relapse within 12 months of adjuvant taxane therapy. Primary objectives were response rates (RRs) and the safety/tolerability of albumin-bound paclitaxel.ResultsWomen were treated with albumin-bound paclitaxel 100 mg/m2 (n = 106) or 125 mg/m2 (n = 75) on days 1, 8, and 15 of a 28-day cycle. Response rates were 14% and 16% for the 100-mg/m2 and 125-mg/m2 cohorts, respectively; an additional 12% and 21% of patients, respectively, had stable disease (SD) ≥ 16 weeks. Median progression-free survival times were 3 months at 100 mg/m2 and 3.5 months at 125 mg/m2; median survival times were 9.2 months and 9.1 months, respectively. Survival was similar for responding patients and those with SD. No severe hypersensitivity reactions were reported. Patients who developed treatment-limiting peripheral neuropathy typically could be restarted on a reduced dose of albumin-bound paclitaxel after a 1-2–week delay. Grade 4 neutropenia occurred in < 5% of patients.ConclusionAlbumin-bound paclitaxel 100 mg/m2 given weekly demonstrated the same antitumor activity as albumin-bound paclitaxel 125 mg/m2 weekly and a more favorable safety profile in patients with MBC that had progressed with previous taxane therapy. Survival of patients with SD ≥ 16 weeks was similar to that of responders.