“…The shift from a Th1- to a Th2-biased tumor microenvironment ( Figure 1 ) is thought to play a critical role in the transition from indolent to progressive disease by impairing cellular anti-tumor responses whilst fostering the proliferation of malignant T cells. Indeed, administration of Toll-like receptor (TLR) agonists boosting cellular immunity has shown clinical efficacy, and treatment with IL-12 and IFNγ can induce regression of CTCL lesions which is associated with increased numbers of CD8 T cells in the resolving skin ( Rook et al, 1999 , 2001 , 2015 ; Suchin et al, 2002 ; Dummer et al, 2004 ; Duvic et al, 2006 ; Wysocka et al, 2007 ; Kim et al, 2010 ; Accart et al, 2013 ). Of notice, recent case reports have surprisingly described that long-term treatment with dupilumab, a neutralizing antibody targeting IL-4 receptor alpha, may exacerbate CTCL and possibly even trigger the disease in certain patients with severe atopic dermatitis (AD) ( Chiba et al, 2019 ; Espinosa et al, 2020 ; Miyashiro et al, 2020 ; Tran et al, 2020 ; Umemoto et al, 2020 ).…”