T-cell clonality in peripheral blood as a predictor of progression to systemic treatment in patients with stage IB mycosis fungoides (MF).

Abstract

e19538 Background: A major unmet clinical need in the care of early-stage MF patients is the identification of those with a high risk of failing skin directed therapy or progressing to advanced disease. Herein, we inquired if the identification of a clonal T-cell receptor (TCR) gene rearrangement by PCR in peripheral blood could predict the clinical outcome, particularly the need for systemic treatment, in patients with stage IB MF. Methods: This is a retrospective cohort study of patients with stage IB MF who underwent peripheral blood TCR clonality analysis by PCR. The primary outcome of the study was time from diagnosis to initiation of systemic treatment. Secondary outcomes were: (1) time to progression to advanced-stage disease (stages IIB-IV) and (2) overall survival. Patients were censored at time of last clinical follow up. Log rank test was used to compare the survival distributions of the two groups; p value < 0.05 was considered significant. Results: From May 2014 to October 2019, 56 consecutive stage IB pts with > 6 months follow up were included in this analysis. Peripheral blood TCR clonality status was available in 42 patients: 18 pts had a positive TCR clone and 24 did not. Median follow up time was 36 months (range 8.5 – 198 months). At 3 years, 39% of patients with peripheral clone had progressed to systemic treatment versus 8% of those without a peripheral clone (log rank test, p-value = 0.003). For the secondary outcomes, at 3 years 17% of patients with peripheral clone had progressed to advanced stage versus 4% of those without (log rank test, p-value = 0.10); 5% of patients with peripheral clone had died versus 0% of those without (log rank test, p-value = 0.03). Conclusions: Detection of a predominant TCR clone by PCR in the peripheral blood is an important prognostic marker in the initial workup of MF, as its presence is highly correlated with subsequent progression to systemic treatment and death. If this finding is validated, it can be used to risk stratify and individualize therapy for MF patients.[Table: see text]