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

BACKGROUND

In advanced-stage cutaneous T-cell lymphoma (CTCL), current therapeutic options rarely provide long-lasting responses. We aimed to evaluate the efficacy and safety of a histone deacetylase inhibitor, resminostat, as maintenance therapy in patients with advanced-stage mycosis fungoides or Sézary syndrome, in whom disease control had been previously met.

METHODS

We conducted a multicentre, double-blind, randomised, placebo-controlled, phase 2 trial (RESMAIN) at 55 medical centres in Austria, Belgium, France, Germany, Greece, Italy, the Netherlands, Poland, Spain, Switzerland, the UK, and Japan. Adult patients (aged ≥18 years) with histologically confirmed, stage IIB-IVB mycosis fungoides or Sézary syndrome; an Eastern Cooperative Oncology Group performance status score of 0-2; and disease control after at least one previous systemic therapy or total skin electron beam were eligible for inclusion. Patients were randomly assigned to receive either oral resminostat (600 mg) or matching oral placebo once daily for 5 days, followed by a treatment-free period of 9 days, within a 14-day treatment cycle. Randomisation was stratified by disease stage (IIB-IVA1 vs IVA2-IVB) and remission status following previous therapy (complete or partial response vs stable disease) by use of a dynamic block allocation process (block size 100 patients). Participants, investigators, site staff, and study personnel involved in outcome assessment and data analysis were masked to group assignment. Patients with disease progression during masked treatment were unmasked; patients on placebo were offered open-label resminostat. Treatment was continued until disease progression or unacceptable toxicity. The primary endpoint was progression-free survival, defined as the time from randomisation to disease progression or death from any cause (whichever occurred first), analysed by intention to treat. This trial is registered with ClincalTrials.gov (NCT02953301) and has been completed.

FINDINGS: Between Jan 9, 2017, and May 11, 2022, 234 patients were screened for eligibility, of whom 201 (86%) patients were randomly assigned: 100 (50%) to resminostat and 101 (50%) to placebo. 123 (61%) participants were men and 78 (39%) were women, with a median age of 64 years (range 30-87). Most participants (173 [86%]) were White, 19 (9%) were Asian (mainly Japanese), two (1%) were Black, and seven (3%) were either another race or ethnicity, or did not disclose these data. Median progression-free survival was 8·3 months (95% CI 4·2-15·7) in the resminostat group and 4·2 months (2·8-6·4) in the placebo group (HR 0·62 [95% CI 0·42-0·92]; p=0·015). Median follow-up time for progression-free survival was 11·2 months (95% CI 5·6-19·6) in the resminostat group and 17·0 months (13·9-30·5) in the placebo group. Adverse events were reported in 96 (96%) patients receiving resminostat and in 81 (80%) patients receiving placebo. Serious adverse events occurred in 19 (19%) patients in the resminostat group, 11 (11%) of which were considered related to treatment, and in 12 (12%) in the placebo group, of which one (1%) was considered to be treatment-related. Adverse events of grade 3 or above occurred in 38 (38%) patients in the resminostat group and in 15 (15%) patients in the placebo group. The most common treatment-related adverse events were nausea (68 [68%] in the resminostat group vs six [6%] in the placebo group), diarrhoea (44 [44%] vs nine [9%]), vomiting (32 [32%] vs one [1%]), and fatigue (29 [29%] vs 14 [14%]). There were no treatment-related deaths.

INTERPRETATION: These findings support the beneficial effect of resminostat maintenance therapy in patients with advanced CTCL. The overall safety profile of resminostat was acceptable, with gastrointestinal side-effects occurring most frequently. Anti-emetic prophylaxis should be considered in the future to manage side-effects and to improve tolerability and adherence to maintenance therapy.

FUNDING: 4SC AG.