Triple negative breast cancer (TNBC) account for about 30% of invasive breast cancers in the Indian population. TNBC is an inherently aggressive cancer with limited treatment options. Hence alternative lines of treatment are the urgent need of the day. Immune checkpoint inhibitors are a new class of drugs used in the treatment of various cancers, the advantage being long lasting response and reduced toxicity.PDL-1 is a ligand which is a part of this immunomodulating pathway.
Paraffin blocks of 201 triple negative breast cancer (TNBC) patients are tested for the expression of PDL-1 expression by immunohistochemistry. Clinicopathological features associated with PDL-1 expressing cancers were compared with PDL-1 negative cancers. 5-year Disease free survival (DFS)and pathological complete response (pCR) were compared between PDL-1 positive and negative TNBC patients.
201 blocks of TNBC patients were evaluated for expression of PDL-1 receptor with immunohistochemistry. 48.2% of patients were PDL-1 positive,51.7% were PDL-1 negative. The probability of 5-year disease free survival(DFS) of PDL-1 positive patients was 82% compared to 87.2% in PDL-1 negative patients. There was no statistical significant difference in 5-year DFS between PDL-1 positive and negative patients. There is no statistically significant association between PDL-1 positivity and clinicopathological factors like age, pathological tumor stage, pathological nodal status, grade, lymphovascular invasion and pathological complete response.
Expression of PDL-1 was approximately 50% in triple negative invasive breast cancers in the Indian population. Disease free survival is comparable between PDL-1 positive patients and PDL-1 negative patients. Factors like age, histological type, pathological tumor stage, pathological nodal status or lymphovascular invasion and response to chemotherapy were not significantly different between PDL-1 positive and negative patients.PDL-1 expression may serve as a predictive factor for response to treatment with immune check point inhibitors in the future.PDL-1 testing needs further standardization.
Scientific Review Committee, Regional Cancer Centre.
Regional Cancer Centre, Trivandrum, India.
All authors have declared no conflicts of interest.