Bcl-xl expression in multiple myeloma.

In the present study the immunohistochemical expression of Bcl-xl, a downstream target of the IL-6-controlled signal transducer and activator of transcription-3 (Stat3) was studied in 40 multiple myeloma (MM) cases before treatment and 11 MM patients at relapse. Correlation analysis was performed between Bcl-xl expression, C-reactive protein (CRP) level, beta-2-microglobulin (beta2m), microvessel density (MVD), and clinical outcome. Before treatment 28 (70%) patients demonstrated a Bcl-xl expression similar to normal plasma cells ("normal pattern"), while 12 (30%) patients demonstrated an elevated expression in a subgroup of the malignant plasma cells. At relapse, no change in Bcl-xl expression was observed as compared to pretreatment sample. No correlation was observed between the Bcl-xl expression and the level of CRP and b2m. In addition, no significant correlation was observed between the Bcl-xl expression and the MVD, but MVD was significantly increased as compared to normal bone marrow biopsy specimens (p=0.02). Patients with an elevated or normal Bcl-xl expression showed no statistically significant difference in overall and event-free survival. In summary, these data indicate that Bcl-xl is elevated in a subgroup of MM patients that so far did not correlate with CRP, b2m, MVD, and clinical outcome.