ITF2357, a Novel Histone-Deacetylase Inhibitor, Is Effective against Peripheral T-Cell Lymphomas in Vivo

Background. Recently, gene expression profiling (GEP) indicated histone-deacetylases (HDAC) as potential therapeutic targets in peripheral T-cell lymphomas (PTCL) not otherwise specified (NOS), the commonest PTCL type. Consistently, phase II trials demonstrated the efficacy of some HDAC inhibitors (HDACi), including SAHA, which was approved for cutaneous T-cell lymphomas (CTCL) treatment.

Aims and methods. We investigated the anti-tumour effects of ITF2357 (Italfarmaco, Italy), a novel hydroxamic acid HDACi, on PTCL primarily-cultured cells and cell lines (HH and FEDP), and in a xenografted mouse-model of CTCL.

Cultured cells were incubated with different dosages of ITF2357 and SAHA (ranging from 0.5 to 2.5 mM). Cell viability, assessed by trypan-blue exclusion assay, cell-cycle progression, assessed by bromodeossiuridine assay, and apoptotic rate, determined by flow-cytometry analysis of annexin-V binding populations were determined at 48, 72 and 120 hours. Nude mice, injected with HH cells, received ITF2357 (10–20mg/Kg, per os) for 14 days. Micro-PET scan was adopted for disease measurement and treatment response evaluation. Finally, GEP of cell lines exposed to ITF2357 and SAHA were generated to elucidate their mechanisms of action.

Results. Cell viability of HH cells treated with ITF2357 ranged from 50% (0.5 mM, at 48 h), to <10% (0.5–2.5 mM, at 72–120 h), in comparison to untreated cells. Differently, cell viability of HH cells treated with SAHA ranged from 80% (0.5 mM, at 48–120 h) to 25% (2.5 mM at 48 h). Analogue effects were documented in FEDP and primarilycultured PTCL cells. Conversely, viability of normal T-lymphocyte was not significantly affected. Interestingly, exposure to ITF2357 was associated to G0/G1 cell-cycle arrest and apoptosis induction. Finally, ITF2357 determined significant reduction of tumoral masses and survival benefit in a xenografted mice-model inoculated with HH cells.

Conclusion. Taken together, these data demonstrate that ITF2357 is effective against PTCLs ex vivo and in vivo, by nominating it for clinical evaluation in this setting.