Effect of 13q deletion on IL-6 production in patients with multiple myeloma: a hypothesis may hold true.

Background: Numerous studies have shown a correlation between 13q deletion and poor prognosis in multiple myeloma (MM), but the mechanisms are not fully understood. Earlier studies suggest that this lesion involves large segments or the entire long arm involving the retinoblastoma (Rb) gene. In myeloma, Rb gene is believed to down regulate interleukin-6 (IL-6) which plays a central role in the pathogenesis of MM. Therefore, it has been hypothesized that loss of the Rb gene might be associated with very high expression of IL-6 and subsequent bad prognosis. Hence this study evaluates IL-6 production in MM patients with and without 13q deletions and assesses their response to conventional and new therapeutic regimens.

Methods: Forty MM patients and 20 matched controls were included in this study. Interphase fluorescence in situ hybridization (FISH) analysis was performed using LSI 13q14-specific probe. Serum levels of IL-6 were determined by ELISA. All patients received conventional chemotherapy. Refractory patients received other therapeutic regimens of Thalidomide or Bortezomib.

Results: Significant increase (p < 0.001) of IL-6 production was recorded in patients with a 13q deletion compared to patients with normal chromosome 13q status. These patients were also refractory to conventional chemotherapy but showed striking response to Thalidomide or Bortezomib.

Conclusions: This study suggests that 13q deletions are associated with increased production of IL-6 in MM and this could be a possible cause of the associated bad prognosis. In addition, the results also show the potential to improve responses in patients with refractory MM with the introduction of novel therapies.