Several clinical trials have been completed and many others are ongoing using Hb-HDACIs in patients with different haematological malignancies, leading to approval of vorinostat on October 6, 2006 by the U.S. Food and Drug Administration (FDA) for the treatment of advanced forms of cutaneous T-cell lymphoma (CTCL) that have failed multiple other systemic treatment options [40,41,42,43]. Here, GSTM1 is linked to primary cutaneous T-cell non-Hodgkin lymphoma.