Real-world data indicate the efficacy and safety profile of the biosimilar trastuzumab-dttb + pertuzumab was consistent with that previously reported for trastuzumab reference + pertuzumab in patients with HER2-positive breast cancer.
Dual inhibition with trastuzumab + pertuzumab in combination with chemotherapy is the standard of care for patients with human epidermal growth factor receptor 2 (HER2)-positive breast cancer and higher tumor stages. During the 2020 American Society of Clinical Oncology Virtual Scientific Program, the results of a study evaluating the safety and efficacy of the biosimilar trastuzumab-dttb in combination with pertuzumab and chemotherapy were reported.
This case series included 35 female patients with HER2-positive breast cancer who were treated with trastuzumab-dttb + pertuzumab at the Division of Oncology at the Medical University of Graz, Austria, between September 2018 and August 2019. Of the enrolled patients, 8 switched from trastuzumab reference to trastuzumab-dttb; 24 (69%) patients were treated with trastuzumab-dttb + pertuzumab in the neoadjuvant setting.
The study population received a median of 4 (range, 3-7) cycles of trastuzumab-dttb + pertuzumab, received a median cumulative trastuzumab-dttb dose of 1904 mg (range, 1560-2640 mg), and received a median cumulative pertuzumab dose of 2100 mg (range, 1680-3360 mg). Prior to receiving trastuzumab-dttb + pertuzumab therapy, all patients included in the study had a normal baseline left ventricular ejection fraction (LVEF; >50%); median LVEF was 60% (range, 60%-65%). At completion of trastuzumab-dttb + pertuzumab therapy or at last assessment, the median LVEF was 60.0% (range, 58%-62%).
A median absolute LVEF decline of 1% (range, –5%-0%) was observed in 21 patients, which corresponded to a median change of 1.7% (range, –7.7%-0%). LVEF reduction ≤50% was reported in 2 patients (5.7%). Decline in LVEF of ≥10% was not reported. Dose interruptions or terminations resulting from adverse events were reported in 2 patients (diarrhea and appetite loss); trastuzumab-dttb treatment continued on schedule. In the 22 patients evaluable for efficacy, 11 patients achieved a pathologic complete response.
Real-world data from this case series in an academic setting indicate the use of the biosimilar trastuzumab-dttb in combination with pertuzumab was associated with efficacy and safety profiles consistent with those previously reported for trastuzumab reference + pertuzumab in patients with HER2-positive breast cancer.
Suppan C, et al. ASCO 2020. Abstract e12520.