A systematic review and meta-analysis of nab-paclitaxel mono-chemotherapy for metastatic breast cancer

Background Although various clinical trials and real-life studies have tried to explore the value of nab-paclitaxel mono-chemotherapy for metastatic breast cancer (MBC), the safety and efficacy of nab-paclitaxel remain unclear which need to be systematically evaluated. Methods Electronic searches for prospective clinical trials evaluating nab-paclitaxel monotherapy for MBC were performed. Requisite data were extracted, integrated and analysed from the included studies according to the different study designs using systematic review and meta-analysis. Meta-regression and subgroup analysis were further performed to explore the potential risk factors affecting each individual outcome of interest following nab-paclitaxel monotherapy. Results Twenty-two studies with 3287 MBC patients were included. A total of 1685 MBC patients received nab-paclitaxel as first-line therapy, 640 patients as further-line therapy, and 962 patients as mixed-line therapy. A total of 1966 MBC patients (60.40%) received nab-paclitaxel weekly, 1190 patients (36.56%) received nab-paclitaxel triweekly and 99 patients (3.04%) received nab-paclitaxel biweekly. The overall incidence rates of all-grade neutropenia, leukopenia, peripheral sensory neuropathy, and fatigue were 52% (95% CI, 38–66%, I 2 = 98.97%), 58% (95% CI, 43–73%, I 2 = 97.72%), 58% (95% CI, 48–68%, I 2 = 97.17%), and 49% (95% CI, 41–56%, I 2 = 94.39%), respectively. The overall response rate (ORR) was 40% (95% CI, 35–45%, I 2 = 98.97%), and the clinical benefit rate (CBR) was 66% (95% CI, 59–73%, I 2 = 98.97%) following nab-paclitaxel monotherapy. The median progression-free survival (PFS) was 7.64 months (95% CI, 6.89–8.40 months, I 2 = 92.3%), and the median overall survival (OS) was 24.51 months (95% CI, 21.25–27.78 months, I 2 = 92.7%). Treatment line, human epidermal growth factor receptor-2(Her-2)-negative status and dosage were found to be sources of heterogeneity among the included studies. According to the meta-regression and subgroup analysis, grade 3/4 neutropenia occurred less frequently in Her-2-negative patients than in the entire population ( P = 0.046). Patients who received first-line nab-paclitaxel monotherapy showed a higher ORR ( P = 0.006) and longer PFS ( P = 0.045). Efficacy outcomes were not affected by the administration schedule. However, within the same schedule, patients appeared to have a superior ORR ( P = 0.044) and longer PFS ( P = 0.03) with an increasing dosage of nab-paclitaxel administered. Conclusions The benefits brought by nab-paclitaxel mono-chemotherapy in the treatment of MBC are considerable while the harm is generally manageable. Further study and validation are needed to figure out the roles which the dosage, schedule and other factors play actually in nab-paclitaxel chemotherapy.