CDDO-imidazolide mediated inhibition of malignant cell growth in Waldenström macroglobulinemia.

Waldenström macroglobulinemia (WM) is a B-cell malignancy that remains incurable. Synthetic triterpenoids (ST), 2-cyano-3,12-dioxoolean-1,9-dien-28-oic acid (CDDO), its methyl ester derivative (CDDO-Me) and imidazolide derivative (CDDO-Im) induce cell death and inhibit growth of various malignancies and hold promise as treatment for cancer patients. We examined the therapeutic potential of these compounds in WM. All three forms of CDDO induced equal toxicity in BCWM.1 cells. In malignant B cells from WM patients, CDDO-Im induced the greatest toxicity. CDDO-Im inhibited proliferation at nanomolar concentrations and arrested the cells in G0/G1. CDDO-Im induced apoptotic cell death that was partially abolished in the presence of caspase inhibitor. CDDO-Im also inhibited survival pathways that have been shown to be important in WM. Overall, our data suggest that ST are likely to provide therapeutic efficacy for WM patients.