Journal of the Egyptian National Cancer Institute · Published 2026-06-17 · DOI 10.1186/s43046-026-00379-2
Shimaa El-Garf, Reham Hammad, Eman Kandeel, Ahmed Rabea, Mona Alrayes
Abstract Background The bone marrow microenvironment in multiple myeloma (MM) is characterized by complex immune dysregulation involving multiple inhibitory pathways. Among these, the programmed cell death protein 1 (PD-1)/programmed cell death ligand 1 (PD-L1) axis contributes to T-cell dysfunction; However, its isolated role within this multifactorial network remains incompletely defined. Methods This prospective observational study performed a cross-sectional immunophenotypic analysis of 39 newly diagnosed MM (NDMM) patients. PD-1 expression on T cells and PD-L1 expression on bone marrow (BM) plasma cells (PCs) were assessed using flow cytometry. Associations with clinical and laboratory parameters were analyzed using correlation analysis. Results PD-L1 mean fluorescence intensity (MFI) on PCs showed a positive correlation with BM T-cell percentage (r = 0.350, p = 0.029). PD-1 MFI on T cells correlated with total leukocytic count (TLC) (r = 0.326, p = 0.043). In International Staging System (ISS) stage III patients, PD-L1 expression on PC correlated with T cells% (r = 0.501, p = 0.018) and TLC (r = 0.427, p = 0.047), while PD-1 expression showed a strong positive correlation with TLC (r = 0.676, p = 0.001) and a negative correlation with age (r = − 0.492, p = 0.020). No significant association was observed with treatment response. Conclusion These findings provide an exploratory description of PD-1/PD-L1 expression patterns within the BM microenvironment in MM. Only in advanced cases according to ISS, PD-L1 expression on PC was linked to BM T cells frequency. PD-1/PD-L1 expression patterns were not linked to treatment response.
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El-Garf, S., Hammad, R., Kandeel, E., et al. (2026). Programmed cell death protein 1 (PD-1) / programmed cell death ligand 1 (PD-L1) in multiple myeloma. Journal of the Egyptian National Cancer Institute. https://doi.org/10.1186/s43046-026-00379-2