4. Patients must have been treated with an HDAC inhibitor given for the treatment of CTCL. Patients must have had disease progression on or following treatment with an HDAC inhibitor. Patients are also eligible if they had an inadequate response to an HDAC inhibitor defined as stable disease as the best response after at least 3 months of therapy. Patients previously treated with an HDAC inhibitor are also eligible if they experienced intolerance due to adverse events.