CD274 and AL amyloidosis: In studies using immunohistochemical staining to assess PD-L1 expression in bone marrow biopsy specimens of multiple myeloma patients receiving autologous stem cell transplant (ASCT) at various time points (i.e., before ASCT, after ASCT, and/or at ASCT relapse), it has been shown that sustained/achieved PD-L1 expression may be one of the unfavourable prognostic markers of overall survival after autologous stem cell transplantation [206].