. Author manuscript; available in PMC: 2024 Dec 1.

Published in final edited form as: Clin Breast Cancer. 2023 Apr 19;23(8):775–783. doi: 10.1016/j.clbc.2023.04.004

Table 2:

Reports of Exceptional Responses in Metaplastic Breast Cancer

Class	Novel Agent(s)	MBC Subtypes Described	Responses Described
Immunotherapy and immunotherapy combinations	Durvalumab, pembrolizumab, nivolumab, ipilimumab	Spindle cell (N=2), Chondromyxoid (N=1)⁵³; Mesenchymal components and osseous differentiation⁵⁵ Squamous cell subtype⁵⁶	Prolonged disease control in metastatic disease
PARP Inhibition with deleterious germline BRCA mutations	Talazoparib	Metaplastic chondrosarcomatous carcinoma⁵⁷	Pathologic complete response with single agent neoadjuvant therapy
Anti-angiogenesis	Apatinib	Spindle cell breast carcinoma⁵⁸	Prolonged disease control in metastatic disease
Pathway Inhibition	Buparlisib	Osteoid metaplastic breast cancer⁵⁹	Prolonged disease control in metastatic disease
BRAF inhibition/MEK inhibition combination	Dabrafenib and Trametinib	Metaplastic carcinoma with melanocytic differentiation; BRAF mutation present⁶⁰	Partial response and symptom control for one cycle in advanced disease

Abbreviations: MBC, metaplastic breast cancer; PARP, poly-ADP ribose polymerase