Evaluation of the Clinical Benefits of Nanoparticle Albumin-Bound Paclitaxel in Women with Metastatic Breast Cancer in British Columbia

Background: Altered formulations of taxanes may lack cross-resistance with standardly used solvent-based taxanes. The primary objective of the present study was to assess the clinical benefit of nanoparticle albumin-bound (nab)–paclitaxel in women with metastatic breast cancer previously treated with and without adjuvant taxane in British Columbia. Methods: The BC Cancer Agency Pharmacy data repository and Breast Cancer Outcomes Unit database were linked to identify all patients who received nab-paclitaxel in British Columbia since its introduction in 2007. Hormone receptor status, demographic characteristics, number of cycles prescribed, and time to treatment failure were extracted and analyzed. Results: From 2007 to 2011, 138 patients in British Columbia received nab-paclitaxel, with 122 patients available for analysis. Most (70.5%) received adjuvant chemotherapy; about a quarter (24.6%) received an adjuvant taxane. Patients who received adjuvant taxane were more likely to have node-positive (86.7% vs. 48.9%, p = 0.007), estrogen receptor–negative (46.7% vs. 13.0% p < 0.001) disease and to receive initial adjuvant radiotherapy (76.7% vs. 51.1%, p < 0.001). For the entire cohort, the median number of nab-paclitaxel cycles prescribed was 4.4 (range: 0.3–13). The median number of nab-paclitaxel cycles was greater when that agent was given as first- or second-line therapy than as third-line or greater therapy (5.0 cycles vs. 3.7 cycles respectively). The median time to treatment failure was 96 days in the prior adjuvant taxane group (range: 0–361) and 73.5 days in the no prior adjuvant taxane group (range: 0–1176). Conclusions: This retrospective study demonstrates potential clinical activity of nab-paclitaxel in metastatic breast cancer regardless of whether patients had prior exposure to adjuvant taxanes.