Durable Response to PD1 Inhibitor Pembrolizumab in a Metastatic, Metaplastic Breast Cancer

Abstract

Metaplastic breast cancer (MBC) is a rare and aggressive subtype of breast cancer. Tumor characteristics typically feature estrogen receptor, progesterone receptor, and HER2-negative, triple-negative breast cancer (TNBC), with a poorer prognosis relative to pure invasive ductal or lobular disease. Resistance to chemotherapy often leads to local recurrence and distant metastasis. Genomic profiling has identified multiple molecular abnormalities that may translate to targetable therapies in MBC. These tumors are known to display higher PD-L1 expressivity than other subtypes of breast cancer, and disease control with pembrolizumab and chemotherapy has been documented. We identify a patient with metastatic, metaplastic TNBC, with mesenchymal components and osseous differentiation, who completed 2 years of pembrolizumab treatment and has remained without evidence of disease after 32 months of observation, while maintaining good quality of life. Future efforts should focus on immunotherapy response with respect to the various subtypes of MBC, and treatment should continue to be incorporated in clinical trials to maximize disease response.

Discrepancy between Tumor Size Assessed by Full-Field Digital Mammography or Ultrasonography (cT) and Pathology (pT) in a Multicenter Series of Breast Metaplastic Carcinoma Patients

“…Currently, BC-Mp is often considered to respond poorly to treatment [ 7 ]. However, other studies indicate higher HER2-positive status than in our cohort, increased programmed cell death ligand-1 (PDL1) positivity, and the presence of specific somatic tumor mutations and germline mutations like Breast Cancer susceptibility gen1 mutation [ 34 , 35 , 36 , 37 , 38 ]. This suggests the potential for targeted and possibly more effective systemic treatment, including neoadjuvant systemic approaches.…”

Complete Response of Triple-Negative Metaplastic Carcinoma of the Breast Using Pembrolizumab

“…chemotherapy, duration of immunotherapy, and neoadjuvant versus adjuvant treatment [6,7,12]. Furthermore, there is no consensus on the predictive nature of PD-L1 status in the response to checkpoint inhibitors [9,14].…”

“…Notably, rare cases of low-grade metaplastic carcinoma have been reported, and those may not respond as well to chemoimmunotherapy [ 5 ]. Cases of high-grade metastatic MpBC have been reported with partial or complete response to pembrolizumab with or without chemotherapy [ 6 , 7 ].…”

Correlation between the setting of gating window width and setup accuracy in left breast cancer radiotherapy based on deep inspiration breath hold

“…Breast cancer is one of the most common malignant tumors in women, posing a severe threat to their health 1–3 . Adjuvant radiotherapy after surgery remains a standard therapeutic regimen for achieving locoregional control and improving overall survival in breast cancer patients 4,5 . However, this treatment method significantly increases the incidence of cardiovascular disease 6–8 .…”

“…[1][2][3] Adjuvant radiotherapy after surgery remains a standard therapeutic regimen for achieving locoregional control and improving overall survival in breast cancer patients. 4,5 However, this treatment method significantly increases the incidence of cardiovascular disease. [6][7][8] The incidence of cardiovascular disease, the leading cause of death among breast cancer survivors, is greater in patients irradiated for left-sided breast cancer than in those receiving irradiation for right-sided breast cancer.…”