Cyclooxygenase-2 (COX-2) is frequently expressed in multiple myeloma and is an independent predictor of poor outcome

Cyclooxygenase 2 (COX-2) is an inflammation-associated enzyme involved in the pathogenesis of many solid tumors, but little is known about its presence and role in hematologic neoplasms. Multiple myeloma (MM) is known to involve a deregulated cytokine network with secretion of inflammatory mediators. We thus decided to investigate the involvement of COX-2 in this neoplasm. Western blotting (WB) was used to evaluate 142 bone marrow (BM) specimens, including MM and monoclonal gammopathy of undetermined significance (MGUS). Selected cases underwent further evaluation by WB on purified CD138⁺ cells, immunohistochemistry (IC), and real-time polymerase chain reaction (PCR) for mRNA expression. COX-2 was expressed in 11% (2 of 18) of MGUS specimens, 31% (29 of 94) of MM at diagnosis, and 47% (14 of 30) of MM with relapsed/refractory disease. COX-2 positivity was associated with a poor outcome in terms of progression-free (18 vs 36 months; P < .001) and overall survival (28 vs 52 months; P < .05). Real-time PCR showed COX-2 mRNA overexpression. IC and cell separation studies demonstrated COX-2 expression to be restricted to malignant plasma cells. This is the first report of the presence and prognostic role of COX-2 expression in MM. Future studies will assess COX-2 involvement in other hematologic tumors and its potential use as a therapeutic or chemo-preventive target in onco-hematology.