Programmed Death Ligand 1; An Immunotarget for Renal Cell Carcinoma

In this era of developing targeted therapies and immunotherapies as a treatment for renal cell carcinoma (RCC), Programmed death ligand 1 (PDL1) as a novel biomarker for RCC is analysed in our study. About 90% of all renal cancers are Renal Cell Carcinoma. Most cases are diagnosed incidentally. 17% of cases are advanced at the time of diagnosis. PDL1 being a trans-membrane cell surface protein is expressed on the tumor cells and is found to have a chief role to inhibit the T cell immune response. It is essential to improve the host immunity by targeting the PD1/PDL1 pathway, thereby destroying the tumor progression.

The aim of this study was to evaluate the expression of PDL1 in tumor cells and adjacent normal tissue among the renal cell carcinoma patients and assess the relation between the PDL1 expression and the tumor characters.

This is a retrospective study. Ethical clearance was obtained from the institution. 150 histopathologically proven RCC cases were chosen. Immunohistochemistry using a PD-L1 rabbit monoclonal antibody was performed on paraffin embedded formalin fixed tissue blocks. Q scoring was done to calculate the expression of PDL1.

Chi square test was done to assess the comparison between the PDL1 expression in tumor cells and their characteristic features like histology, grade and stage. SPSS (version 20.0) was used for analysis. P value <0.05 was considered significant. It also explains the heterogenous nature of PDL1 as it expressed more in the aggressive pathologic characters like high grade.

Positive PD-L1 expression was seen in 44% of tumors. Significant association was observed between high WWHO ISUP grading and positive PDL1 expression (p=0.028). It was expressed in 75% of the sarcomatous type of RCC and 46.8% of clear cell RCCs.

Our study suggests that blocking PD1/PDL1 pathway may become an effective mode of treatment in cancer immunotherapy especially for Renal Cell Carcinomas. Our findings confirmed the significant association between expression of PDL1 and the high graded tumors which proves it to be an important prognostic factor.