Safety and effectiveness of nab-paclitaxel in young and elderly patients with metastatic breast cancer: a prospective, multicenter non-interventional study

Nab-paclitaxel (Abraxane®, Celgene), a nanometer-sized albumin-bound paclitaxel, was developed to reduce the toxicities associated with conventional taxanes and is approved for the second-line treatment of metastatic breast cancer (mBC). This prospective, multicenter, non-interventional study was designed to characterize the treatment patterns, safety, and activity of nab-paclitaxel in young and elderly mBC patients (pts) in routine clinical practice. Safety and tolerability of nab-paclitaxel was defined as the primary study endpoint. Secondary endpoints were overall response rate (ORR) and assessment of real-life dosages. Pts with confirmed mBC who met the eligibility criteria were enrolled and prospectively observed for at least 6 treatment cycles or until disease progression or unacceptable toxicity. Between 5/2012 and 1/2016, 203 pts (median age: 58 years, range 33-91; 34 (17%) ≥70) were included at 16 sites. 81 pts (40%) had ≥3 metastatic lesions, 35 (17%) were triple-negative, and 93 (46%) had grade 3 disease. 44 pts (22%) received nab-paclitaxel as first-line, 54 (26%) as second-line, and 103 (50%) as third- to seventh-line therapy. A total of 1036 treatment cycles (median: 5; range: 1-19) were administered. In a preplanned interim outcome analysis conducted in 132 pts, the ORR was 39%, consisting of 4 complete (CR; 3%) and 47 partial responses (PR;36%). In addition, 43 patients (33%) had stable disease for a clinical benefit rate (CBR) of 72%. In the elderly cohort, 10 pts (30%) had PR and 3 pts (10%) had SD for a CBR of 40%.Overall, Nab-paclitaxel was well tolerated, with most adverse drug reactions (ADRs) mild or moderate in severity. The most common ADRs were peripheral neuropathy, neutro- and leukopenia. ADRs leading to the discontinuation of nab-paclitaxel occurred in 18 pts (9%). No new safety signals were identified and no significant differences in the reason for treatment discontinuation between pts <70 years and ≥70 were observed. In this real-life study safety and efficacy data are consistent with previous clinical trial data. Of note, nab-paclitaxel was active and also well tolerated in pts aged ≥70 years.