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Usage and safety of topical tacrolimus in patients with mycosis fungoides

Dear Editor, Tacrolimus is a calcineurin inhibitor, which in topical formulation is used to treat a variety of skin conditions, including eczema and psoriasis. Tacrolimus has an antiproliferative effect on T lymphocytes, a function that has the potential to treat cutaneous T-cell lymphoma (CTCL). However, tacrolimus is also immunosuppressive and systemic tacrolimus has itself been associated with CTCL and is therefore avoided in patients with CTCL. Unlike systemic tacrolimus, topical tacrolimus has not been clearly associated with CTCL. As topical tacrolimus is not commonly used in patients with CTCL, there is limited information on its usage and safety in this unique population. We conducted a retrospective study at the Hospital of the University of Pennsylvania of patients with mycosis fungoides (MF) who had received topical tacrolimus for any indication over the past 20 years. We collected data on the indication for and usage of topical tacrolimus, the course of MF, and rates of progression-free survival (PFS) and overall survival (OS). Disease progression was defined by the 2011 criteria from the Cutaneous Lymphoma Task Force of the European Organization for Research and Treatment of Cancer. In total, 13 patients meeting the criteria were identified, with a median age of 68 years (range 21–92 years) (Table 1). In most patients, topical tacrolimus was used to treat a condition other than MF, most commonly for suspected concurrent eczema or seborrhoeic dermatitis. Of the 13 patients, 6 patients with active MF (all Stage IA) received topical tacrolimus, while 4 patients received topical tacrolimus during MF remission and 3 received topical tacrolimus both before and after diagnosis of MF. Topical tacrolimus 0.1% ointment was prescribed for daily or twice-daily use for a median of 20.8 months (range 2.3– 76 months). The medication was applied to a median body surface area of 2% (range 1–10%), usually to sites uninvolved with known MF. Progression of MF occurred in only 1 of 13 patients (7.6%), and the 12-month PFS and 12-month OS were 100%. All other patients either remained in remission or had stable disease for median follow-up of 45 months (range 10–165 months). The one patient who progressed has skin involvement that has fluctuated between Stages IA and IB. In this retrospective study at a single institution, we did not observe worsening or recurrence of MF over several years of follow-up in the large majority of patients