Case report of novel combination of anthralin and calcipotriene leading to trichologic response in alopecia areata

Alopecia areata (AA) is an autoimmune, nonscarring alopecic disorder with a lifetime prevalence of about 2%.1 This disorder presents with varying amounts of hair loss, ranging from focal patchy loss to entire scalp and body hair loss as in alopecia totalis (AT) and alopecia universalis (AU), respectively. Severe subtypes are difficult to treat and contribute to significant patient burden. Current treatment strategies center on immunomodulation, both systemically and topically. Systemic therapies such as oral corticosteroids, cyclosporine, and methotrexate can be efficacious, with regrowth rates between 30% and 76%.2 However, side-effect profiles, lengthy treatment durations, and relapse rates after discontinuation of therapy limit their use.2 Newer Janus kinase (JAK) inhibitors appear promising, yet patients relapse after treatment cessation, and cost is often prohibitive.3 Topical glucocorticoids offer variable efficacy; 17.8% of patients with AT or AU had long-term regrowth with clobetasol use.4 Topical calcineurin inhibitors have not demonstrated efficacy, perhaps because of insufficient depth of penetration.5 Intralesional triamcinolone at concentrations of 2.5 to 5 mg/mL are considered first-line therapy with regrowth seen in 61% of subjects with AT at 6 weeks and minimal side effects.2, 6 An additional therapeutic option used for more severe forms of AA is the topical immunomodulator, diphenylcyclopropenone (DPCP). Although the exact mechanism of DPCP is unknown, its resultant allergic contact dermatitis is thought to cause antigenic competition and an alteration of the inflammatory cytokine milieu.2, 7 In one retrospective study of 50 patients treated with DPCP, terminal hair regrowth of 50% or more was seen in 56% and 71% of those with AU and AT, respectively.7 Anthralin (dithranol), available in 0.25% to 1% concentrations, is another topical treatment option. Anthralin functions via the production of a localized irritant dermatitis with resultant pruritus, erythema, and scale. Patients who do not have a robust inflammatory response to anthralin may not achieve significant therapeutic response.2 Response rates with anthralin in AA and AT are between 25% and 75%.2 Combination treatment strategies may provide a more robust therapeutic response, such as the combination of minoxodil with topical glucocorticoids and anthralin with DPCP.2, 8 Calcipotriol/calcipotriene is a topical vitamin D3 analogue commonly used in plaque psoriasis. Recently, a significant benefit of combination therapy with calcipotriol and 5-fluorouracil has been identified in the treatment of actinic keratoses.9 When used together, these medications show a synergistic mechanism of action, perhaps because of calcipotriol's induction of antitumor immunity and allergic skin inflammation via thymic stromal lymphopoietin cytokine.9 The efficacy of this combination offers a potential corollary for the treatment of additional dermatologic conditions in which immunomodulation plays a key role. The combination of anthralin and calcipotriene may likewise demonstrate synergistic effects in the treatment of AA.