Prognostic relevance of CD56 expression in multiple myeloma: a study including 107 cases treated with high-dose melphalan-based chemotherapy and autologous stem cell transplant.

CD56 is a neural adhesion molecule and expressed in 70-80% cases of multiple myeloma (MM). Lack of CD56 expression has shown to be a poor prognosis in MM patients treated with conventional chemotherapy, but its prognostic relevance in MM treated with high dose chemotherapy and autologous stem cell transplant (ASCT) is not known. CD56 expression was evaluated by immunohistochemistry on bone marrow paraffin embed specimens from 107 MM cases undergoing Melphalan-based high dose therapy and ASCT. CD56 was expressed by the myeloma cells in 71% of the patients. CD56 negative myeloma was associated with bone lesions (p = 0.032), but there was no association with any other biological or genetic risk factors including deletions 13q, p53 and IgH translocations, as evaluated by fluorescence in situ hybridization (FISH). There was no significant difference between CD56 positive and CD56 negative myeloma for progression free or overall survival (p = 0.28 and p = 0.67, respectively). In contrast to reports of CD56 in myeloma treated with conventional chemotherapy, CD56 negativity was not found to confer a poor prognosis in these patients, suggesting Melphalan-based high-dose chemotherapy and ASCT may overcome the adverse influence of CD56 negative myeloma.