Tumor infiltrating lymphocytes profile and response in neoadjuvant chemotherapy-treated triple-negative breast carcinoma patients

Background: Triple negative breast carcinoma (TNBC) has the highest mortality among all the breast carcinoma subtypes, but paradoxically, it shows the best response to neoadjuvant chemotherapy (NACT). Tumor infiltrating lymphocytes (TIL) density has been shown to have prognostic significance in TNBC. However, there are limited data on TIL subpopulation and their association with response to NACT in TNBC. Materials and Methods: The study included 80 consecutive patients with TNBC prospectively diagnosed for two and half years, who underwent tru-cut biopsy before NACT, followed by subsequent definite surgical procedures. Global TIL profile and immunohistochemistry (IHC) analysis of CD3, CD4, CD8, CD20, and CD56 were done on all baseline tru-cut biopsies and post-NACT surgical specimens. Results: Almost half the patients were postmenopausal with a mean age of 45.89 ± 4.62 years. The majority had low CD3, low CD4, low CD56, low CD20, and high CD8 positivity in both pre- and post-NACT specimens. On multivariate analysis, low CD3, CD4, CD56 and CD 20 were established as independent predictor of poor pathologic response (PR). Low CD4 (adjusted odds ratio [OR]: 228.46) was associated with the highest OR for poor PR. Low CD8 was associated with significantly decreased odds of poor PR on univariate analysis (OR: 0.26), but it was not been established as an independent predictor of PR on multivariate logistic regression. NACT did not significantly alter the profile of TILs. Conclusions: TIL profile with low CD3, CD4, CD20, and CD56 expression predicts PR to NACT in TNBC and may thus help in prognostication of these patients.