Disease characteristics, prognosis, and response to therapy in patients with large-cell transformed mycosis fungoides: A single-center retrospective study

Background: Mycosis fungoides with large-cell transformation (MF-LCT) is associated with an aggressive clinical course, yet data comparing treatment outcomes in MF-LCT are sparse. Objective: To compare treatment outcomes and to determine disease prevalence and characteristics associated with survival in MF-LCT. Methods: A retrospective review was conducted of mycosis fungoides patients from 2012 to 2020 treated at Thomas Jefferson University. Patients with histopathologic diagnosis of MF-LCT were included. Treatment outcomes were assessed by mean changes in the modified Severity Weighted Assessment Tool (mSWAT) and stage. Results: Of 171 patients with mycosis fungoides, 23 (13.4%) had histologic diagnosis of MF-LCT. The overall 5-year survival rate for MF-LCT was 74% and was not significantly associated with sex, age, or initial stage at the timeof MF-LCT diagnosis. Brentuximabvedotinshowed the greatest mean decrease in mSWAT(-20.53) and stage progression (change in Delta stage: -0.4) in MF-LCTcompared to oral bexarotene (Delta mSWAT: 14.51; Delta stage: 10.27), skin-directed therapy (Delta mSWAT: - 5.93; Delta stage: - 0.08), and chemotherapy (Delta mSWAT: 14.97; Delta stage: 10.85). Limitations: Single-center retrospective design, and patients often on multiple treatment modalities. Conclusions: We report superior treatment outcomes for brentuximab vedotin compared to oral bexarotene, skin-directed therapy, and chemotherapy in MF-LCT in both early and advanced disease.