Toxicity of dual HER2-blockade with pertuzumab added to anthracycline versus non-anthracycline containing chemotherapy as neoadjuvant treatment in HER2-positive breast cancer: The TRAIN-2 study.

The TRAIN-2 study is a neoadjuvant randomized controlled trial in stage II and III HER2-positive breast cancer (NCT01996267). Patients are randomly assigned to receive either three cycles of FEC-T plus pertuzumab or three cycles of PTC plus pertuzumab, followed by six cycles of PTC plus pertuzumab in both arms. Toxicities are described per treatment arm according to the Common Toxicity Criteria for Adverse Events version 4.03.

Pertuzumab in combination with FEC-T mostly causes neutropenia, and when added to PTC mostly causes diarrhea. Significant cardiac toxicity is rare with both regimens, and toxicity is overall well manageable.

This analysis includes 110 patients balanced over both treatment arms. Neutropenia was the most common hematologic toxicity, with grade 3-4 occurring in 53% in the FEC-T-arm and in 51% in the PTC-arm. Febrile neutropenia occurred in 9% in the FEC-T arm and did not occur in the PTC-arm. Secondary G-CSF prophylaxis was used in 35-40% of patients. Asymptomatic ejection fraction decrease grade 2 was observed in 24% in the FEC-T-arm and 11% in the PTC-arm. The most common grade 3-4 non-hematologic toxicity was diarrhea (5% in the FEC-T-arm and 18% in the PTC-arm).

The addition of pertuzumab to neoadjuvant trastuzumab-based chemotherapy improves pathologic complete response rates in HER2-positive breast cancer. However, increased toxicity has been reported with the addition of pertuzumab, and this may differ between various chemotherapy backbone regimens. We evaluated toxicities of pertuzumab when added to either FEC-T (5-fluorouracil, epirubicin, cyclophosphamide, trastuzumab) or weekly paclitaxel, trastuzumab, carboplatin (PTC).