Anti-HER2 therapy for HER2-positive metastatic breast cancer: regimens and treatment outcomes

Abstract

Background: To date, trastuzumab (Tr) has been the main treatment for HER2-positive metastatic breast cancer, with combination therapy with a taxane being the standard treatment. In patients with disease progression, combination with chemotherapeutic agents continued beyond PD is recommended; however, the relative merits of use with lapatinib (TKB) remain to be clarified. The approval of pertuzumab (Per) and T-DM1 has, however, made the choice of treatment more complicated. Aim: To analyze the current clinical conditions with regard to anti-HER2 therapy and examine future treatment guidelines. Methods: We analyzed the regimen treatment line, clinical benefit rate and time to treatment failure (TTF) for treatment with chemotherapy (CT) using Tr, TKB, Per or T-DM1 or with endocrine therapy (ET). Subjects: Subjects included 75 patients who underwent anti-HER2 therapy at our institution . Patient age ranged from 34 to 86 years (median 58), with follow-up ranging from 0 to 115 months (median 29). Results: The number of patients receiving each regimen ranged from 1 to 10 (median 4), with 16 combinations of Tr ± CT/ET, TKB ± CT/ET, Per + Tr + CT, T-DM1 and FEC giving a total of 218 regimens. First-line treatment consisted of Tr + taxane for 34 (45.3%), Tr alone for 16 (21.3%) and Per + Tr + taxane for 13 (22.2%) patients. The most common second-line treatment was Tr + Vinorelbine (VNR) for 15 (33.3%) and TKB + Capecitabine (CAPE) for 10 (22.2%) patients. The clinical benefit rate by line was 74.7%, 51.1%, 37.5% and 27.3% for 1st, 2nd, 3rd and 4th line, respectively, with late-line treatment also beneficial. When examined by treatment regimen, the clinical benefit rates were particularly high for Tr + taxane (76.6%), Per + Tr + taxane (83.3%) and T-DM1 (85.7%). Conclusions: Our results showed that long-term treatment was possible with even late-line treatment being effective. The response rates for Per and T-DM1 were high, and further extension of treatment period can be expected.