Albumin-bound paclitaxel (ab-pac) versus docetaxel for first-line treatment of metastatic breast cancer (MBC): Final overall survival (OS) analysis of a randomized phase II trial.

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275 Background: We previously reported the results of a phase II study evaluating the efficacy and safety of three different dosing regimens of ab-pac and docetaxel for the first-line treatment of MBC (Gradishar et al. J Clin Oncol. 2009;27:3611-3619). Here we report final OS outcomes. Methods: Patients (N = 300) with previously untreated MBC were randomized to 1 of 4 treatment arms (arms A–D listed in table). A step-down statistical approach was used for pairwise comparisons of treatment groups. Results: Patients (N = 300) with previously untreated MBC were randomized to 1 of 4 treatment arms (arms A–D listed in table). A step-down statistical approach was used for pairwise comparisons of treatment groups. These OS data were consistent with the investigator assessment of overall response rates (ORR) and progression-free survival (PFS) that were previously published. Rates of grade (gr) 3 sensory neuropathy (SN) were 21%, 9%, 22% and 12%, respectively in arms A, B,C, and D (p= 0.082). There were no cases of gr 4 SN. The median times to improvement to ≤ gr 2 SN were 22, 22, and 20 days for arms A, B, and C and 37 days for arm D. Gr 3/4 neutropenia occurred less frequently with ab-pac vs docetaxel (gr 3: 39, 20, 35, and 19% in arms A,B,C, and D, respectively; gr 4: 5, 5, 9, and 75%, p < .001 for gr 4). Conclusions: Ab-pac qw 3/4 at 150 mg/m2 resulted in a 33.8 mo OS, a longer OS than historically achieved with taxane monotherapy in MBC. The 150 mg/m2 qw 3/4 dosing regimen provided the best clinical outcome in this phase II trial in patients with MBC. [Table: see text]