Tre-O2-03 - Mogamulizumab-associated rash frequently mimics cutaneous T-cell lymphoma recurrence but heralds a positive response to therapy: an updated single-center case series

Abstract

Mogamulizumab is a humanized antibody that targets CCR4, a transmembrane chemokine receptor predominantly expressed on effector T helper type 2 and malignant cutaneous T-cell lymphoma (CTCL) cells. This biologic was FDA approved for relapsed/refractory mycosis fungoides (MF)/Sézary syndrome (SS) in 2018. MARs are the most common adverse events reported; however, the clinicopathologic nature of these eruptions remains unclear. To inform future management and recognition of MAR, we report an update on our retrospective case series of MF/SS patients treated with mogamulizumab since its approval as standard of care. Among 24 CTCL (16 SS, 8 MF) patients, 17 developed MAR (68%). MAR development was associated with complete (11/17) or partial (4/17) responses, for an overall response rate (ORR) of 88% to mogamulizumab among patients with MAR. A lower ORR of 28% (2/7) was observed in patients that did not develop MAR. Median MAR time to onset (TTO) was 2.1 mo. (0.7–9.0). Median time to resolution (TTR) was 6.9 mo. (3.5–9.2) in 8/17 patients with MAR resolution. Five distinct but frequently concurrent clinical patterns were identified: lichenoid papules and plaques (9/17), MF-like lesions (9/17), photodistribution (7/17), psoriasiform plaques (7/17), and SS-like erythroderma (3/17). Histopathologic patterns included spongiotic (n=21), lichenoid (n=14), psoriasiform (n=10), and interface (n=8) features across 27 skin biopsies. Eosinophils (n=15), epithelioid granulomas (n=4), and bizarre bi- and multinucleated cells (n=6) that may represent highly activated macrophages were also noted. Although mild, features associated with CTCL were noted in all suspected MAR tissue samples [epidermotropism (n=10), exocytosis (n=12), and lymphoid atypia (n=16)]. When compared to baseline studies, flow cytometry analysis for circulating Sézary cells and TCR rearrangement studies in skin and blood were most often negative during suspected MAR despite the presence of CTCL-associated histological features, emphasizing the importance of ancillary studies in distinguishing MAR from CTCL. In conclusion, MAR may be characterized by distinct clinical, histopathologic, and molecular patterns. Notably, MAR can clinically mimic CTCL lesions and may occur more often in patients with clinical responses, highlighting the need for clinicians to rule out progressive disease vs. drug eruption in treating a condition that historically suffers from poor outcomes and treatment response.