Resminostat Maintenance Therapy Delays Disease Progression in Advanced Mycosis Fungoides and Sézary Syndrome

Original Article : Resminostat for maintenance treatment in patients with advanced-stage mycosis fungoides or Sézary syndrome: a multicentre, double-blind, randomised, placebo-controlled, phase 2 trial

What are the key takeaways of this article?

Advanced-stage mycosis fungoides (MF) and Sézary syndrome (SS) are aggressive forms of cutaneous T-cell lymphoma (CTCL) characterized by frequent relapses, progressive disease, and limited durable treatment options. While several systemic therapies can manage disease control, maintaining remission remains challenging as most patients eventually experience progression. The RESMAIN trial evaluated whether resminostat, an oral histone deacetylase (HDAC) inhibitor, could prolong disease control when used as maintenance therapy following a successful response to previous treatment. 

In this international, multicentre, double-blind, placebo-controlled phase 2 study, Stadler et al.  enrolled 201 adults with stage IIB–IVB MF or SS across 55 centres in Europe and Japan. Patients who had achieved complete response, partial response, or stable disease after previous systemic therapy or total skin electron beam therapy were randomized to receive either resminostat (600 mg orally for five consecutive days once every two weeks) or placebo until disease progression or unacceptable toxicity. The primary outcome was progression-free survival (PFS). 

As a result, resminostat significantly improved PFS compared with placebo. Median PFS was 8.3 months in the resminostat group versus 4.2 months in the placebo group, corresponding to a 38% reduction in the risk of progression or death (HR 0.62, p=0.015). Their findings represent the first adequately powered randomized evidence supporting maintenance therapy in advanced CTCL, demonstrating that continued treatment after disease control can meaningfully delay relapse. 

While treatment-related adverse events were more frequent with resminostat, they were generally well manageable. Gastrointestinal toxicities, including nausea, diarrhea, vomiting, and fatigue, were the most common side effects. Grade 3 or higher adverse events occurred more frequently in the resminostat group (38% vs. 15% with placebo), but importantly, no treatment-related deaths occurred. The authors suggest that prophylactic antiemetics may further improve tolerability and adherence during long-term therapy.

Therefore, the RESMAIN trial introduces maintenance therapy as a promising treatment strategy for advanced MF and SS. By significantly extending PFS with an acceptable safety profile, resminostat may help address an important unmet need in CTCL management. Future studies evaluating overall survival, quality of life, and comparisons with emerging targeted therapies will further clarify its role in routine clinical practice for those with advanced MF and SS.

Publication Date: July 27, 2026

Reference:

Stadler R, Quaglino P, Woei-A-Jin FJSH, Dummer R, Mitteldorf C, Papadavid E, et al. Resminostat for maintenance treatment in patients with advanced-stage mycosis fungoides or Sézary syndrome: a multicentre, double-blind, randomised, placebo-controlled, phase 2 trial. The Lancet Haematology. 2026 Feb;13(2):e98–109. doi:10.1016/S2352-3026(25)00322-9

Summary By: Megan Lowe