Dr Scarisbrick on Refining MF/Sézary Treatment With PROSPER Findings

If it’s a MAR reaction, frequently it gets better when you stop the treatment. On biopsy, it’s more likely to be a CD8-positive infiltrate rather than the CD4-positive of typical mycosis fungoides, and it tends to respond very well to topical steroids.

One of the hardest calls in treating mycosis fungoides and Sézary syndrome is what to do when the skin gets worse on mogamulizumab — is the lymphoma progressing, or is this the drug’s own immune reaction?

Julia J. Scarisbrick, MD, of the Centre for Rare Diseases at University Hospital Birmingham, says the field reads that distinction far better now than it did a few years ago — and the PROSPER findings are part of why mogamulizumab is moving earlier in treatment.

In a second part of her discussion at the 6th World Congress of Cutaneous Lymphoma (WCCL), Scarisbrick turned from the PROSPER outcomes themselves to how they are reshaping practice.

Understanding of MAR has advanced considerably since MAVORIC, Scarisbrick said. In the earlier trial era, worsening skin was often assumed to be disease progression. Clinicians now have reliable clues to tell a MAR reaction apart.

A MAR reaction frequently improves once treatment is paused; on biopsy it tends to show a CD8-positive infiltrate rather than the CD4-positive infiltrate typical of mycosis fungoides; and it usually responds well to topical steroids. That diagnostic confidence lets clinicians manage the reaction rather than abandon an effective therapy.

That improved understanding, combined with the drug’s profile, is shifting when mogamulizumab gets used. It is licensed after failure of at least one prior systemic therapy but its safety profile, ease of use, and response data have made it an agent clinicians reach for earlier in the treatment course.

The PROSPER data reinforced that direction by showing how quickly patients benefit. Scarisbrick highlighted that improvements were reported as early as 4 weeks rather than after months of waiting, and that the gains spanned the symptoms that matter most to patients day to day: itch, pain, flaking, sleep, body-temperature regulation, and fatigue, all improving relatively quickly and continuing to do so.