Dr Beylot-Barry on Moga-Stop, Mogamulizumab Retreatment in Sézary Syndrome

We have several patients that have a very good response with [mogamulizumab], and sometimes they ask us, ‘Can I stop the treatment?’ So the question was really focused on patients with a very good response — is it a good opportunity to stop the treatment, or is it not a good opportunity?

Marie Beylot-Barry, MD, PhD, professor and head of the Department of Dermatology at CHU de Bordeaux in Bordeaux, France, discussed extended follow-up from the Moga-Stop study evaluating mogamulizumab (Poteligeo) discontinuation and retreatment in Sézary syndrome.

At the 6th World Congress of Cutaneous Lymphoma (WCCL), Beylot-Barry and colleagues presented extended follow-up from Moga-Stop, which tracked patients with Sézary syndrome who discontinued mogamulizumab for reasons other than disease progression, and compared them with a control cohort who continued treatment until progression. These data add to the body of WCCL research refining how mogamulizumab is used in this population, including a separate analysis presented at the meeting identifying potential response and resistance biomarkers to the agent.¹

Mogamulizumab, an anti-CCR4 monoclonal antibody, improves progression-free survival in Sézary syndrome and is typically continued until disease progression. However, patients who achieve a strong, durable response — and who may be managing cumulative toxicities such as mogamulizumab-associated rash (MAR) — increasingly ask whether treatment can be stopped. The Moga-Stop study was designed to address that question directly, focusing only on patients who discontinued after a very good response and explicitly excluding those who came off therapy because of progression.

In the extended follow-up, a meaningful proportion of patients remained free of relapse off treatment, and outcomes among those who discontinued were comparable to responders who stayed on therapy. The manner of discontinuation appeared to matter: gradual, tapered discontinuation was associated with longer time off treatment than abrupt cessation, pointing to a potentially more durable strategy that could also reduce treatment burden and cost.

For patients who did relapse after stopping, retreatment was a viable option. Among those who resumed mogamulizumab, roughly half regained a complete or partial response, and rechallenge was generally well tolerated — though recurrence of MAR was unpredictable, occurring in some but not all patients who had experienced it during initial treatment, and sometimes with a different presentation. Sézary syndrome–specific mortality remained low in this cohort.

Beylot-Barry noted that the findings support discontinuation as a reasonable, monitored option for selected patients with Sézary syndrome in a very good response, while underscoring the need for predictive criteria to identify who can safely stop and for prospective study to confirm the approach.

References

1. Analysis Identifies Potential Response, Resistance Biomarkers to Mogamulizumab in R/R Mycosis Fungoides/Sézary Syndrome. OncLive. Published June 25, 2026. Accessed June 25, 2026. https://www.onclive.com/view/analysis-identifies-potential-response-resistance-biomarkers-to-mogamulizumab-in-r-r-mycosis-fungoides-s-zary-syndrome