The utility of immunohistochemistry-based biomarkers in predicting the pathological complete response in early-stage triple-negative breast cancer

Triple-negative breast cancer (TNBC) is a highly aggressive subtype of BC. A pathological complete response (pCR) to neoadjuvant chemotherapy is strongly associated with a favorable TNBC prognosis; however, established predictors of pCR, including tumor-infiltrating lymphocytes (TILs), are often not adequately reliable in the clinic. This study evaluated the utility of immunohistochemistry (IHC)-based markers and TILs in predicting pCR in early-stage TNBC. This study enrolled 61 women with stage I-III TNBC who were treated at our institution between January 2013 and December 2019. Pathological data were collected from electronic medical records, while IHC data were obtained from preoperative biopsy specimens. Fisher's test, multivariable logistic regression, and correlation analyses were used to identify biomarker candidates and their interactions. The majority of the patients had stage II or III invasive ductal TNBC. The pCR rate was 31 % (19/61). High TIL frequencies (≥ 40 %) and high Ki-67 (≥ 40 %) levels were associated with pCR. Among the patients with high TIL frequencies, AR-negative patients had a higher pCR rate than AR-positive patients (55.0 % versus 16.7 %; p = 0.71). Vimentin negativity correlated with high TIL frequencies (p = 0.02). High TIL frequencies and high Ki-67 levels were independently associated with an increased likelihood of achieving a pCR. The combination of high TIL frequencies and high Ki-67 levels was predictive of pCR in patients with primary TNBC, while AR and vimentin represent candidate markers that require further validation. Further studies should evaluate the performance of these markers in combination with other biomarkers and in the context of immune-checkpoint blockade.