Resminostat for Maintenance Treatment of Patients With Advanced Stage Mycosis Fungoides (MF) or Sézary Syndrome (SS)

Main Inclusion Criteria: * Patients with histologically confirmed MF (Stage IIB-IVB) or SS in an ongoing complete response (CR), partial response (PR) or stable disease (SD) after at least one prior systemic therapy according to local standards (including but not limited to α-interferon, bexarotene, total skin electron beam irradiation, chemotherapy) \[the most recent systemic therapy must have been completed as planned or stopped due to unacceptable toxicity 2-12 weeks prior to randomisation\] * Eastern Cooperative Oncology Group (ECOG) status score 0-2 * Adequate haematological, hepatic and renal function Main Exclusion Criteria: * Patients with progressive disease (PD) * Baseline corrected QT (QTc) interval \> 500 milliseconds * Concurrent use of any other specific anti-tumour therapy including psoralen photo chemotherapy (PUVA), chemotherapy, immunotherapy, hormonal therapy, radiation therapy, or experimental medications