Combination of eribulin with trastuzumab and pertuzumab for HER2 positive advanced or recurrent breast cancer: JBCRGM03.
Authors: Yamashita Toshinari , Kawaguchi Hidetoshi , Masuda Norikazu , Kitada Masahiro , Narui Kazutaka , Hattori Masaya , Yoshinami Tetsuhiro , Matsunami Nobuki , Yanagihara Kazuhiro , Nagashima Takeshi , Bando Hiroko , Yano Hiroshi , Hasegawa Yoshie , Nakamura Rikiya , Kashiwaba Masahiro , Morita Satoshi , Ohno Shinji , Toi Masakazu 
Published: June 2023

e13031 Background: Pertuzumab (P) was an effective first-line treatment for HER2 positive metastatic breast cancer (MBC) in the CLEOPATRA study, improving both overall and progression-free survival (PFS). However, it is challenging to provide intravenous docetaxel to MBC patients over long term at a dosage of 75 mg/m2 every three weeks. Eribulin (E) is a well tolerated cytotoxic agent. In a multicenter, open-label phase II research (UMIN000012232), we have shown the effectiveness and safety of E combined with trastuzumab (T) with P as first- and second-line treatment for metastatic or advanced BC. Methods: The study included HER2 positive MBC patients with no or one previous treatment, including advanced or recurrent chemotherapy. All patients were administered with T and taxane as perioperative or first-line chemotherapy. E (1.4 mg/m2) along with T (8 mg/kg loading dosage > 6 mg/kg), and P (840 mg loading dose > 420 mg) was administered intravenously on days 1 and 8 of a 21-day cycle, once every three weeks. The primary end point was PFS and the secondary endpoints were the response rate (RR) based on RECIST ver1.1. Overall patient survival effectiveness following P administration, E compliance, and success of follow-up therapies were observed. Results: A total of 50 patients were enrolled, with 49 of them qualifying for the safety analysis. However, the full analysis set (FAS) consisted of 46 individuals. The average patient age was 56 years old (range 23–70), and 9 (18%) and 40 (82%) patients received care in first- and second-line settings, respectively. The median PFS for patients who received main therapy was 20.5 months, whereas the median PFS for patients who received subsequent treatment was 8.6 months. Thirty-five patients (76.1%) were able to receive concomitant E until the end of protocol treatment. The overall RR was 56.5% among the 46 patients in the FAS. Nine patients (19.5%) responded completely, whereas 17 patients (37.0%) responded partially. There were 13 cases of stable disease (28.2%), six cases of progressing disease (13.0%), and one case was not evaluable (1.2%). The median survival of the primary treatment population was not reached; however, the median survival of the secondary treatment population was 42.4 months. Twenty three patients received T-DM1 as a follow-up treatment, 13 patients received TP plus chemotherapy, and five patients received additional therapies. The average duration of treatment with T-DM1 as a consequent therapy was approximately four months, whereas the average duration of treatment with HP plus chemotherapy was 11 months. Conclusions: For HER2positive MBC, E in combination with T plus P was well tolerated and may be an alternative to docetaxel-based combination therapy. Results from the JBCRG M06 trial research, which compares taxanes combination with T plus P with E combined with T plus P in first-line therapy, are still pending. Clinical trial information: UMIN000012232 .