Expression of programmed death-ligand 1 in myeloma predicts early relapse: Egyptian single-center pilot study

Background Multiple myeloma (MM) is a complicated hematologic malignancy marked by the clonal proliferation of plasma cells and a significantly immunosuppressive tumor microenvironment. The programmed death-ligand 1 (PD-L1)/programmed death-1 axis is crucial in tumor immune evasion; however, its specific significance in MM is still ambiguous. Aim This study sought to evaluate PD-L1 expression in neoplastic plasma cells of patients with MM and plasmacytoma, as well as to investigate its correlation with clinicopathological features, treatment results, and survival metrics. Patients and methods Upon receiving approval from the Institutional Review Board of the National Cancer Institute, a retrospective analysis was performed on formalin-fixed, paraffin-embedded tissue specimens collected from 71 patients diagnosed between 2018 and 2022. The examined specimens comprised extramedullary lesions, bone biopsies, and bone marrow core biopsies. Expression of PD-L1 was assessed using immunohistochemical labeling and analyzed based on the detection of membranous positivity in tumor cells. Extensive clinical and laboratory data were simultaneously gathered to examine correlations between PD-L1 expression and disease stage, therapy efficacy, relapse status, and survival outcomes. Results PD-L1 was expressed in a significant percentage of patients, with elevated expression markedly correlated with advanced disease stages and heightened relapse rates. While PD-L1 positive correlated with enhanced early treatment responses at 12 weeks, it also predicted diminished relapse-free and overall survival rates. The Kaplan–Meier analysis revealed a distinct survival disadvantage in patients positive for PD-L1. Significantly, PD-L1 expression had no substantial correlation with demographic characteristics or initial laboratory results. Conclusions PD-L1 expression seems to indicate a more aggressive disease profile in MM and may facilitate immune evasion and recurrence. These data substantiate the function of PD-L1 as a predictive biomarker and a prospective therapeutic target.