Acadesine Inhibits Proliferation and Induces Apoptosis In Multiple Myeloma Cells, and Synergizes with Standard of Care Antimyeloma Agents

Abstract 5023

Multiple myeloma (MM) is a malignancy characterized by the accumulation of plasma cells. The disease represents the second most common hematologic malignancy and remains incurable, despite recent advances in its treatment. Therefore, studies to develop new therapies are still necessary, particularly in patients with bad prognostic factors, such as 17p deleted/p53 mutated patients. In this study we describe the preclinical activity of 5-Aminoimidazole-4-carboxamide-1–4-ribofuranoside (AICAR or acadesine) in multiple myeloma. Acadesine is an analog of AMP that is widely used as an activator of AMP-kinase (AMPK), a protein that regulates the responses of the cell to energy changes.

Acadesine induces apoptosis in different cell types including CLL, mantle cell lymphoma (MCL) and splenic marginal zone B-cell lymphoma (SMZL) cells and tumor cell lines, without affecting primary T lymphocytes. Thus, acadesine is a promising drug for the treatment of B-cell neoplasms. A clinical phase I/II study of acadesine is currently being performed in CLL patients.

We studied the effects of acadesine on the MTT metabolization of several multiple myeloma cell lines (MM1S, MM1R, RPMI-8266, RPMI-LR5, U266, U266-LR7, U266 Dox4, MM144, MGG, SJR, OPM-2, NCIH-929). Acadesine inhibited MM cell growth and induced apoptosis, with IC50 values in the micromolar range, and independently of the p53 mutational status.

Cancer treatment, including myeloma, is generally based on combinations of drugs with different mechanisms of action. Thus, we studied the effect of acadesine in double combinations with drugs used in myeloma therapy, such as dexamethasone, melphalan, doxorubicin, bortezomib, and lenalidomide. Analyses of these data using the Chou and Talalay method indicated that acadesine was synergistic with dexamethasone (CI values of 0.60), and particularly with lenalidomide (CI values of 0.42). These promising results with double combinations promoted the investigation of triple combinations in the MM1S cell line. Triple combination of acadesine plus dexamethasone plus lenalidomide or bortezomib notably improved the efficacy of the respective double combinations, being the combination of acadesine plus lenalidomide plus dexamethasone especially efficient.

Further studies to determinate the mechanism of action, and in vivo studies in MM1S xenograph are ongoing.