الفهرس 
IntroductionOnly 14 pages are availabe for public view
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Abstract
Multiple myeloma (MM) is a heterogenous disease and despite advanced therapeutic strategies, it is still considered incurable. The outcome of patients remains very poor especially those with relapsed refractory disease. Aim of the Work : This study aimed to evaluate the expression of PD-L1 and PD-1 by IHC in MM, to compare (PD-L1/PD-1) expression between therapy naïve and post therapy myeloma BMBs and to investigate a possible prognostic and/or predictive role for the (PD-L1/PD-1) axis. Material and methods: This retrospective study was conducted on 70 BMB of 35 MM patients. H & E stained slides were reviewed. IHC staining for staining of pre and post therapy MM BMBs was carried out with PDL-1, PD-1, CD3 and CD20 anti bodies together with CD138 and CD56 retrieved from their archived slides. Then evaluation of their relationship with different clinical, laboratory, histopathological prognostic variables in MM and with disease outcome was done using statistical analysis. Results : The results showed that PD-L1 appeared on the cells of multiple myeloma and megakaryocytes and as for PD-1, it appeared on the lymphocytes associated with the tumor. Statistical analysis showed a strong statistical relationship between the appearance of PD-L1 on tumor cells before and after treatment, as well as its appearance on megakaryocytes, with patients’ relapse and lack of response to conventional treatment. The results also showed that the appearance of PD-L1 on multiple myeloma cells varied and was affected by the type of treatment the patients received, especially radiotherapy, which was observed to decrease the appearance of PD-L1 on tumor cells. Conclusion: IHC for PD-L1 in tumor cells or MKs suggested to be used as a screening tool to predict the response the current therapies and may have a role in the selection of suitable therapeutic modalities that are likely compating their immunosuppressive effect.