Dr Scarisbrick on Mogamulizumab Outcomes in PROSPER

Our response criteria looks at responses in the skin, the blood, the lymph nodes — but it doesn’t take into account improvement in health-related quality of life. Without a cure, most patients live a long time with the disease, and on treatment, so we need to be improving how they feel.

Mycosis fungoides and Sézary syndrome are diseases patients usually live with for years — itching, pain, flaking skin, broken sleep, and fatigue grinding away at daily life long after a scan calls the disease controlled.

Julia J. Scarisbrick, MD, of the Centre for Rare Diseases at University Hospital Birmingham, set out in the PROSPER study to measure something the standard response criteria miss: whether mogamulizumab actually makes patients feel better.

At the 6th World Congress of Cutaneous Lymphoma (WCCL), Scarisbrick presented PROSPER, a real-world study of patient-reported outcomes in patients with relapsed or refractory MF/SS treated with mogamulizumab, built on cutaneous T-cell lymphoma–specific measures of symptoms and quality of life. She discussed how the findings are reshaping practice in a second part of this discussion.

PROSPER was designed to capture the patient’s own experience, Scarisbrick explained. Rather than relying on clinician-assessed disease metrics alone, the study used a CTCL-specific symptom diary — tracking skin itch, pain, redness, and flaking, along with sleep problems and difficulty regulating body temperature — together with an MF/SS-specific quality-of-life measure and a fatigue index.

The approximate 70 enrolled patients, split nearly evenly between MF and SS, completed these measures before and during treatment over 48 weeks, with caregivers also surveyed to capture the burden on those looking after them.

The improvements came early and held. Even at 4 weeks, patients were reporting meaningful reductions in skin itch and flaking, and those gains deepened at 12 weeks and continued through 48 weeks. The same upward trend appeared across fatigue, overall quality of life, sleep, and body-temperature regulation. Scarisbrick emphasized how broadly and quickly patients improved while on therapy.

On tolerability, the findings were reassuring: about 60% of patients remained on treatment at 48 weeks, and among those who stopped, roughly half did so because of disease progression and a smaller number because of adverse events.

The most common adverse event was mogamulizumab-associated rash (MAR). Set against MAVORIC — the registrational trial that first showed mogamulizumab’s quality-of-life advantage over vorinostat — the real-world PROSPER data suggest the drug continues to improve patients’ lives outside the controlled trial setting.

Scarisbrick used the results to make a broader argument about how the field measures benefit. Current response criteria score disease in the skin, blood, and lymph nodes but capture nothing about health-related quality of life. In an incurable disease that patients treat for years, Scarisbrick opined that how a patient feels deserves to be part of how response is defined.