Effect of neoadjuvant chemotherapy (NAC) on programmed cell death ligand (PD-L1) in patients of carcinoma breast: A prospective study in Indian tertiary care setting

CONTEXT: Several studies have reported that PD-L1 has shown therapeutic activity in various tumor types. However, its expression changes in a person on administration of NAC which is reported by very few studies. AIMS: To find out the difference in the expression of PD-L1 by tumor cells after the administration of NAC. SETTINGS AND DESIGN: This prospective study was conducted on 30 patients who were diagnosed with locally advanced breast carcinoma (LABC) between 2017 and 2019 and those who received NAC followed by surgery. METHODS AND MATERIAL: Breast cancer specimens were collected using core needle biopsy prior to administration of NAC and IHC was performed. Frequency and staining intensity of PD-L1 by tumor cells were analyzed. PD-L1 expression was dichotomized into two groups according to the frequency distributions of the H-scores. STATISTICAL ANALYSIS USED: The differences in expression of PD-L1 along with various parameters were analyzed using Chi-square test and Student's t test. RESULTS: The mean age of the patients in our study was 51.37 ± 11.37 years. The response of NAC according to the RECIST criteria showed that most of patients (83.3%) showed complete response. Of the 30 cases, 11 (36.7%) patients were PD-L1 positive before the administration of NAC. We found a significant change in expression from positive to negative status, i.e., seven patients changed from positive to negative (p = 0.036). Upon comparing the PD-L1 expression before NAC, significant association was observed between the primary tumor (T) and tumor stage with high PD-L1 expression (p = 0.020 and P = 0.034). After NAC, 18 (69.2%) patients who were ER positive and 18 (69.2%) patients who were PR positive showed negative PD-L1 expression while none of them were positive in PD-L1 positive patients (p = 0.018 and P = 0.018). CONCLUSION: PD-L1 expression in a same person changes upon administration of NAC which may indirectly be used as a predictor of response to NAC.