PD-L1 and PD-L2 Mutations in Pediatric Hodgkin Lymphoma: Do They Have Any Prognostic Significance?

Background: Reed-Sternberg cells can escape from the immune system by enhancement of the expression of PD-L1 and PD-L2. Objectives: The aim of the present study was to investigate the significance PD-L1 and PD-L2 gene mutations in childhood Hodgkin Lymphoma's (HL). Methods: The study included 39 pediatric classical HL cases. PD-L1 and PD-L2 mutations were determined by Sanger sequencing. Clinicopathological parameters were obtained from patients' records. Results: Eight cases (20.5%) showed p.R260C mutations, and three (7.7%) p.R234L in the exome 5 of PD-L1 gene. None of the cases had PD-L2 mutations. p.R260C mutation exhibited a significant relationship with older age and nodular sclerosing (NS) histology and was associated with longer event free survival. Conclusions: Although PD-L1 mutational status did not show statistically significance with well-established prognostic factors, our preliminary data indicate that p.R260C mutation of PD-L1 gene may be associated with longer event free survival in older patients and NS histology in pediatric HL.