1. ¹Division of Haematology, Ospedali Riuniti, Bergamo, Italy
2. ²Italfarmaco SpA, Cinisello Balsamo, Milano, Italy
3. ³Laboratory of Molecular Genetic and Gene Expression, Fondazione Policlinico, IRCCS, Milano, Italy

Correspondence: Professor/Dr A Rambaldi, Division of Hematology, Ospedali Riuniti di Bergamo, Largo Barozzi 1, 24128 Bergamo, Italy. E-mail: arambaldi@ospedaliriuniti.bergamo.it

⁴LC and FL have equally contributed to the work.

Received 30 March 2007; Revised 12 June 2007; Accepted 13 June 2007; Published online 19 July 2007.

Abstract

We have investigated the activity of ITF2357, a novel hydroxamate histone deacetylase inhibitor, on multiple myeloma (MM) and acute myelogenous leukemia (AML) cells in vitro and in vivo. ITF2357 induced apoptosis in 8/9 MM and 6/7 AML cell lines, as well as 4/4 MM and 18/20 AML freshly isolated cases, with a mean IC₅₀ of 0.2 M. ITF2357 activated the intrinsic apoptotic pathway, upregulated p21 and downmodulated Bcl-2 and Mcl-1. The drug induced hyperacetylation of histone H3, H4 and tubulin. When studied in more physiological conditions, ITF2357 was still strongly cytotoxic for the interleukin-6 (IL-6)-dependent MM cell line CMA-03, or for AML samples maximally stimulated by co-culture on mesenchymal stromal cells (MSCs), but not for the MSCs themselves. Interestingly, ITF2357 inhibited the production of IL-6, vascular endothelial growth factor (VEGF) and interferon- by MSCs by 80–95%. Finally, the drug significantly prolonged survival of severe combined immunodeficient mice inoculated with the AML-PS in vivo passaged cell line already at the 10 mg/kg oral dose. These data demonstrate that ITF2357 has potent anti-neoplastic activity in vitro and in vivo through direct induction of leukemic cell apoptosis. Furthermore, the drug inhibits production of growth and angiogenic factors by bone marrow stromal cells, in particular IL-6 and VEGF.