Abstract P4-13-21: A pilot study of pertuzumab, trastuzumab and eribulin for patients with advanced HER2 positive breast cancer
Authors: Ishihara M , Tamaru S , Oda H , Yamashita Y , Tono Y , Mizuno T , Katayama N 
Published: May 2016

[Introduction] The triple therapy of pertuzumab, trastuzumab and taxanes (docetaxel or paclitaxel) is coming into widespread use, because of the beneficial effects on HER2 positive breast cancer. However, we don't have enough information about the efficacy and safety of other agents with trastuzumab and pertuzumab (TP). We studied triple therapy of pertuzumab, trastuzumab and eribulin (PTE) for advanced HER2 positive breast cancer to assess the efficacy, safety and QOL prospectively (UMIN000012018).

[Patients and methods] Responses were assessed by RECIST criteria v1.1. Adverse events (AEs) were graded according to CTCAE v4.0. Patients with advanced HER2 positive breast cancer were treated with pertuzumab (840 mg loading then 420 mg, day 1), trastuzumab (8 mg/kg loading then 6 mg/kg, day 1), and eribulin (1.4 mg/m2, day 1 and 8) every 3 weeks. Dose reduction was allowed when patients developed febrile neutropenia, grade 3-5 non-hematologic toxicity or skipped day 8 eribulin administration because of neutrophil count &lt;1000/mm3. QOL was assessed using FACT-B at baseline and 3 months after initial treatment.

[Results] Ten patients were enrolled. Median age of patients was 60 years-old (35-75). Median number of prior chemoregimen for metastatic disease was 3 (0-5). Two patients had a history of docetaxel allergy. Median number of PTE cycle was 6 (3-12). Eight patients reduced eribulin doses 1.4 mg/m2 to 1.1 mg/m2 because of AEs (2 patients), skipped day 8 eribulin (4 patients), or physician's choice (2 patients). One complete response, 1 partial response and 5 stable disease were achieved at 3 months. Two patients (1 CR and 1 SD) stopped eribulin and received TP as maintenance therapy. At 3 months, all 3 patients with progressive disease developed brain metastasis. Two patients had extracranial progressive lesions, but 1 patient had partial response for extracranial disease.

The common treatment-related AEs were leukopenia, neutropenia, lymphopenia diarrhea, hypokalemia and stomatitis. Grade 3 AEs were leukopenia (7 patients), neutropenia (8 patients), lymphopenia (2 patients), febrile neutropenia (1 patient), hypokalemia (1 patient) and peripheral neuropathy (1 patient). Grade 4/5 AEs were not observed.

Nine patients could be assessed QOL. FACT-B TOI, FACT-G and FACT-B total score had a tendency to be improved at 3 months.

[Conclusion] The PTE therapy showed appropriate clinical effect for extracranial lesions and maintained QOL of patients with advanced HER2 positive breast cancer. It may be a choice for patients who have taxane-resistant diseases or a history of taxane allergy.

Many patients needed to reduce eribulin dosage. When the PTE therapy is referred to advanced HER2 positive breast cancer patients as a palliative chemotherapy, eribulin (1.1mg/m2) might be a reasonable dosage.

Citation Format: Ishihara M, Tamaru S, Oda H, Yamashita Y, Tono Y, Mizuno T, Katayama N. A pilot study of pertuzumab, trastuzumab and eribulin for patients with advanced HER2 positive breast cancer. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P4-13-21.