Effect of berubicin, the 4'-o-benzylated doxorubicin analog, on growth inhibition and apoptosis in multiple myeloma.

e18557 Background: Doxorubicin (DOX), an anthracycline, topoisomerase II inhibitor, is routinely used for hematologic malignancies including multiple myeloma (MM); however, its efficacy is limited by drug resistance and cardiotoxcity. To overcome these limitations, we designed, synthesized and tested Berubicin (BRN). BRN has been evaluated in clinical trials in neuroblastoma multiforme. It is a representative of a novel class of mechanistically altered anthracycline analogs. The data obtained from this study will serve as the basis for the rapid translation of BRN from the bench to the clinic in a phase I clinical trial for patients with MM at MD Anderson Cancer Center. Methods: We investigated the effects of BRN, DOX and Bortezomib (BTZ) in 3 human MM cell lines, MM1S, ARP-1, U266, and freshly isolated primary samples from patients with MM. MM cells were treated with BRN, DOX, and BTZ. The effects of these compounds on cell proliferation, apoptosis, and the cell cycle were analyzed using MTS assay and flow cytometry analysis. Results: BRN potently inhibited the growth of the established MM cell lines, as well as the freshly isolated primary MM cells in a dose-dependent manner. It showed growth inhibition at IC50 of 5.99 nM (U266), 5.21 nM (MM1S) and 3.99 nM (ARP-1), and was more potent than doxorubicin (IC50 14.63 nM, 7.24 nM and 11.06 nM) and bortezomib (IC50 304.9 nM, 15.47 nM and 53.19 nM). In contrast, BRN did not affect the proliferation of patient-derived normal bone marrow cells (CD138- cells) at the concentrations that were lethal to MM cells. Conclusions: Berubicin not only induced apoptosis in 3 cell lines in dose-dependent manners but also induced G2/M cell cycle arrest in 3 cell lines. In conclusion, BRN was effective against MM cells in vitro and will be applied to our planned clinical trial.