Eribulin mesylate (ERI) demonstrated a survival benefit in patients with locally recurrent or metastatic breast cancer who previously received 2 or more chemotherapy regimens. Recently, we conducted Phase II study about the efficacy of ERI with trastuzumab (ERI+TRA) as late-line therapy for locally advanced or metastatic HER2-positive breast cancer (UMIN000012350), and reported that objective response rate (ORR) and median progression-free survival (mPFS) were 17% and 4.6 months. However, some patients who received prior pertuzumab (PER) and/or T-DM1 were enrolled in that study, there are limited data on the efficacy of ERI+TRA in those patients. The aim of this study was to assess the efficacy of this combination therapy based on prior PER and/or T-DM1 use.
In primary phase II study, patients with locally advanced or metastatic HER2 positive breast cancer who previously received at least one chemotherapeutic regimen, received ERI at 1.4 mg/m2 intravenously (I.V.) on days 1 and 8 of each 21-day cycle with an initial TRA dose of 8 mg/kg I.V. on day 1, followed by 6 mg/kg of TRA on day 1 of each subsequent cycle. ORR, clinical benefit rate (CBR) and PFS were assessed in patients who had and had not received prior PER and/or T-DM1.
Thirty-six patients (median age: 60.5 years) received ERI+TRA. 69.4% (n = 25) had previously treated with prior PER and/or T-DM1, defined as ‘prior’ patients. Remaining 30.6% (n = 11) without both agents were defined as ‘non-prior’ patients. In prior patients compared with non-prior patients, median number of prior treatment regimens was 4 (range, 1‐8) versus 3 (range, 1-7), respectively; ORR was 12.0% versus 27.3%, respectively; CBR was 24.0% versus 54.5%, respectively; mPFS was 4.3 versus 9.7 months, respectively.
ERI+TRA demonstrated lower efficacy than in non-prior patients, but CBR and PFS were 24.0% and 4.3 months, which was considered to be a clinically relevant treatment option in patients who received prior PER and/or T-DM1.
Clinical trial identification
Legal entity responsible for the study
Nagoya Surgical Oncology Group
All authors have declared no conflicts of interest.