The role of PD-L1 in the prediction of treatment responses to neoadjuvant chemotherapy in breast carcinoma

Abstract

Aims: To assess programmed death ligand 1 (PD-L1) expression and its correlation with prediction of response to neoadjuvant chemotherapy (NACT) in invasive breast carcinoma (IBC). Introduction: NACT is being increasingly utilised in IBC management with pathologic complete response (pCR) strongly correlated with excellent disease-free and overall survival. PD-L1 has recently gained attention in breast carcinomas as a potential therapeutic target as well as a prognostic indicator. PD-L1 is expressed in response to inflammation and has been found to be expressed on a number of tumours. The presence of tumour infiltrating lymphocytes has been found to be strongly associated with pathological complete response (pCR) and a relationship between PD-L1 and pCR has been suggested in recent studies. Methods: Pretreatment core biopsies and their matched subsequent surgical excision from 74 consecutive patients with IBC from the PathWest pathology database, Fiona Stanley Hospital, in 2013–2016 were assessed for TILs and PD-L1 expression. Results: Eighteen cases achieved pCR while 56 cases did not. When comparing these groups, there was a greater likelihood of pCR in patients with higher TILs scores (p=0.006) and higher PD-L1 scores (p=0.018). Conclusion: Our study demonstrates a significant association between PD-L1 expression with pCR in NACT.