Importance: Erythema multiforme (EM) may become long term, with a recurrent or persistent course. First-line treatment for chronic EM is valaciclovir. There is no consensus for selection of second-line treatment of chronic EM.
Objective: The aim of this study was to assess the effectiveness of treatment with thalidomide for patients with chronic EM.
Design, setting, and participants: In this retrospective national multicenter cohort study, among 68 French hospital dermatology departments contacted by e-mail, 10 reported having eligible cases. All adults aged 18 years or older under dermatology care for chronic EM (including recurrent and persistent forms) who had received thalidomide between 2010 and 2018 were included. Analyses were conducted from June 24, 2019, to December 31, 2019.
Main outcomes and measures: The primary outcome was the proportion of patients who did not experience an EM flare within 6 months of initiating thalidomide treatment for recurrent EM or with complete clearance at 6 months for persistent EM (complete remission).
Results: Overall, 35 patients with chronic EM (median [range] age, 33 [15-65] years; 20 [57%] female) experienced failure of at least 1 previous treatment prior to initiating treatment with thalidomide. After 6 months of continuous thalidomide treatment, 23 (66%) were in complete remission, 5 (14%) had stopped the treatment, and 7 (20%) experienced at least 1 flare. The median (IQR) initial dose followed by remission was 50 (50-100) mg/d. Main adverse effects were asthenia (16 [46%]) and neuropathy (14 [40%]). Twenty-five (71%) of patients stopped thalidomide treatment after a median (IQR) of 12 (8-20) months owing to lack of effect (7/25 [28%]), neuropathy or another adverse effect (14/25 [56%]), or long-term complete remission (4/25 [16%]). Low-dose thalidomide, less than 50 mg every other day was sufficient in 9 of 23 (39%) of responders and was associated with less neuropathy and longer treatment duration.
Conclusions and relevance: In this cohort study, second-line therapy with thalidomide was associated with complete remission in two-thirds of the 35 patients with chronic EM. However, adverse events were a common cause of thalidomide withdrawal. In the long term, dose reduction when possible may allow for continuation by improving tolerance.