Trastuzumab and
pertuzumab with
taxane-based
chemotherapy are considered the first-line standard
therapy for
human epidermal growth factor receptor 2 (HER2)-positive metastatic
breast cancer (mBC).
Pertuzumab is also a later-line
therapy for mBC in Switzerland, although limited safety and efficacy data are available. The present study assessed the therapeutic regimens, toxicities and clinical outcomes after second- or later-line
pertuzumab therapy in patients with mBC who did not receive
pertuzumab as a first-line
therapy. Physicians from nine major Swiss oncology centers retrospectively completed a questionnaire for each
pertuzumab-naive patient who was treated with
pertuzumab as a second- or later-line
therapy. Of 35 patients with HER2-positive mBC (median age, 49 years; range, 35-87 years), 14 received
pertuzumab as a second-line
therapy, 6 as a third-line
therapy, and 15 as a fourth- or later-line
therapy. A total of 20 patients (57%) died during the study period. The median overall survival was 74.2 months (95% confidence interval, 47.6-139.8 months). Grade (G) 3/4 adverse events (AEs) were reported in 14% of patients, with only 1 patient discontinuing
therapy due to
pertuzumab-related toxicities. The most common AE was
fatigue (overall, 46%; G3, 11%). Overall, congestive
heart disease occurred in 14% of patients (G3, 6%),
nausea in 14% of patients (all G1), and myelosuppression in 12% of patients (G3, 6%). In conclusion, the median overall survival of patients who underwent second- or later-line
pertuzumab treatment was similar to that reported for patients who underwent first-line
pertuzumab treatment, and the safety profile was acceptable. These data support the use of
pertuzumab for second- or later-line
therapy when it was not administered as first-line
therapy.