Lymphopenia and fumaric acid esters for psoriasis: a retrospective case series prompted by the European Medicines Agency's Pharmacovigilance Risk Assessment Committee (PRAC) recommendations

A case series of persistent lymphopaenia following treatment with fumaric acid esters for psoriasis

WHAT IS KNOWN AND OBJECTIVE

Fumaric acid esters (FAEs) have been used for fifty years to treat moderate-to-severe psoriasis. However, recent case reports of progressive multifocal leukoencephalopathy, associated with FAE-induced lymphopaenia, have been a cause for concern (J Dtsch Dermatol Ges. 2009;7:603).

CASE SERIES

We report six cases of persistent lymphopaenia following cessation of treatment with FAEs, with a mean duration of lymphopaenia of 33 months.

WHAT IS NEW AND CONCLUSION

Given the lack of evidence regarding expected recovery of lymphocyte counts, further research is required to guide physicians in the risk stratification of patients prior to considering treatment with FAEs.

Dimethyl fumarate induced lymphopenia in multiple sclerosis: A review of the literature

Dimethyl fumarate (DMF) is a first line medication for multiple sclerosis. It has a favourable safety profile, however, there is concern regarding the occurrence of moderate-severe and sustained lymphopenia and the associated risk of progressive multifocal leukoencephalopathy. We carried out an extensive literature review to understand the molecular mechanisms underlying this adverse reaction. Dynamic changes in certain components of the immune system are likely to be important for the therapeutic effects of DMF, including depletion of memory T cells and decrease in activated T cells together with expansion of naïve T cells. Similar modifications were reported for the B cell components. CD8⁺ T cells are particularly susceptible to DMF-induced cell death, with marked reductions observed in lymphopenic subjects. The reasons underlying such increased sensitivity are not known, nor it is known how expansion of other lymphocyte subsets occurs. Understanding the molecular mechanisms underlying DMF action is challenging: in vivo DMF is rapidly metabolized to monomethyl fumarate (MMF), a less potent immunomodulator in vitro. Pharmacokinetics indicate that MMF is the main active species in vivo. However, the relative importance of DMF and MMF in toxicity remains unclear, with evidence presented in favour of either of the compounds as toxic species. Pharmacogenetic studies to identify genetic predictors of DMF-induced lymphopenia are limited, with inconclusive results. A role of the gut microbiome in the pharmacological effects of DMF is emerging. It is clear that further investigations are necessary to understand the mechanisms of DMF-induced lymphopenia and devise preventive strategies. Periodic monitoring of absolute lymphocyte counts, currently performed in clinical practise, allows for the early detection of lymphopenia as a risk-minimization strategy.

Fumaric acid ester-induced T-cell lymphopenia in the real-life treatment of psoriasis

Background

Fumaric acid esters (FAEs) are used to treat psoriasis and are known to cause lymphopenia in roughly 60% of the patients. Much remains to be elucidated about the biological effects of FAEs on lymphocytes.

Objective

To evaluate the influence of long‐term FAE (Fumaderm^®) treatment on peripheral blood CD4⁺ and CD8⁺ T cells, CD19⁺ B cells and CD56⁺ natural killer (NK) cells in psoriasis.

Methods

In this single‐centre retrospective observational subcohort study, we obtained leucocyte and lymphocyte subset counts before initiating FAE therapy in 371 psoriasis patients (mean age, 47.8 years; 63.3% males) and monitored them during treatment (mean treatment duration, 2.9 years). Multiparametric flow cytometry was used for immunophenotyping.

Results

FAEs significantly reduced the numbers of CD4⁺ T, CD8⁺ T, CD19⁺ B and CD56⁺NK cells. Among lymphocyte subsets, the mean percentage reduction from baseline was always highest for CD8⁺ T cells, with a peak of 55.7% after 2 years of therapy. The risk of T‐cell lymphopenia increased significantly with the age of the psoriasis patients at the time that FAE therapy was initiated. It was significantly decreased for the combination therapy with methotrexate and folic acid (vitamin B9) supplementation. Supporting evidence was found suggesting that T‐cell lymphopenia enhances the effectiveness of FAE therapy.

Conclusions

Monitoring distinct T‐cell subsets rather than just absolute lymphocyte counts may provide more meaningful insights into both the FAE treatment safety and efficacy. We therefore suggest optimizing pharmacovigilance by additionally monitoring CD4⁺ and CD8⁺ T‐cell counts at regular intervals, especially in patients of middle to older age. Thus, further prospective studies are needed to establish evidence‐based recommendations to guide dermatologists in the management of psoriasis patients who are taking FAEs and who develop low absolute T‐cell counts.

Long-term real-life safety profile and effectiveness of fumaric acid esters in psoriasis patients: a single-centre, retrospective, observational study

BACKGROUND

Fumaric acid esters (FAEs) are an established systemic treatment for moderate-to-severe psoriasis. However, the long-term clinical safety and effectiveness of continuous FAE monotherapy and combination therapy have not been established.

OBJECTIVE

To examine the long-term safety and effectiveness of FAEs as monotherapy and in combination with phototherapy or methotrexate in patients with psoriasis treated at a single centre in Germany.

METHODS

This monocentric, retrospective observational study, with a follow-up period of up to 32.5 years, included 859 patients: 626 received FAE monotherapy, 123 received FAEs with concomitant phototherapy and 110 received FAEs with methotrexate.

RESULTS

Approximately half of patients (49.0%) reported adverse events (566 total events), most of which involved the gastrointestinal tract. Serious adverse events were reported in 2.3% of patients, but none were deemed to have a causal relationship with any of the treatment regimens. Adverse events leading to treatment discontinuation were observed in 12.9% of patients. A median duration of 1 year was observed in all three treatment subcohorts (P = 0.70) from initiation of FAE treatment to a 50% response rate, where response was defined as achieving a cumulative static Physician's Global Assessment (PGA) score of 'light' and at least a 2-point reduction in baseline PGA. A 50% response rate for the cumulative Psoriasis Area and Severity Index 75 was achieved in the FAE monotherapy subcohort after a median of 3 years of treatment, in the FAEs + phototherapy subcohort after 6.7 years and in the FAEs + methotrexate subcohort after 8.1 years (P = 0.001).

CONCLUSION

According to our data, FAEs as monotherapy or in combination with phototherapy or methotrexate are safe and beneficial for long-term clinical use. However, multicentre, randomized controlled trials are required to establish the clinical value of monotherapy versus combination therapy and the optimal treatment duration.