Mycophenolate mofetil and methotrexate efficacy in dermatomyositis-BJD study

The treatment typically follows a stepwise sequence starting with systemic corticosteroids along with immunosuppressants like methotrexate (MTX) or mycophenolate mofetil (MMF) after inadequate antimalarial response. However, data are scarce regarding the effectiveness of MTX and MMF in DM. Recently a study evaluating efficacy of mycophenolate mofetil and methotrexate in DM was published in the British Journal of Dermatology.

A cohort of 24 patients with skin predominant DM were identified from a prospective database at the University of Pennsylvania Perelman School of Medicine. Patients included in the cohort took MTX or MMF and had at least two study visits within a retrospective observation period

from October 2008 to February 2021. The Cutaneous Dermatomyositis Disease Area and Severity Index (CDASI), a validated disease scoring tool, was used to assess severity and outcomes. Patients with mild disease activity, defined as a CDASI activity (CDASI-A) score < 14 (maximum subscore of 100), were excluded as were any patients on medications used to treat DM other than MTX or MMF, with the exception of chronic antimalarials or topical medications.

For both MMF (n = 13) and MTX (n = 11), there was no baseline difference in CDASI-A scores at treatment initiation. There was no significant difference in the degree of improvement on either medication, with a mean difference in daily CDASI-A change between MTX and MMF of -0.0028 ± 0.0024 (P = 0.24) using a mixed linear effects model. For MTX, the median percentage change in CDASI-A between the first and last study visit was -74%. For MMF, the median percentage change was -76%.

A decrease of 40% or greater in the CDASI-A score has previously been associated with a meaningful change in quality of life. When 'responders' were defined as having a ≥ 40% improvement in their CDASI-A score between the first and second observations, 27% of the patients taking MTX were responders while 54% of patients taking MMF were responders.

The range of time varied between the first and second visits, with 50% of patients having a second study visit within 150 days. By last follow-up, 55% of patients taking MTX were considered responders and 77% of patients taking MMF met the criteria to be considered responders. For the patients treated with MTX, the median follow-up for the second visit was 178 days and for the last visit was 776 days. For those treated with MMF, the median follow-up was similar – 147 days for the second visit and 787 days for the last visit. Six patients who received MMF had previously been treated with MTX and one patient who received MTX had previously been treated with MMF.

In conclusion there was no significant difference between the efficacy of MTX and MMF in DM. The study suggests that responders continue to improve over time while most non- responders show little improvement at first follow-up during the observation period. Thus both MMF or MTX may be added to treatment plans for patients with DM who have not responded to antimalarials.

Source- Grinnell, M., Keyes, E., Diaz, D., Vazquez, T., Feng, R. and Werth, V.P. (2022), Mycophenolate mofetil and methotrexate efficacy in dermatomyositis. Br J Dermatol, 187: 437-438. https://doi.org/10.1111/bjd.21235