Summary of the safety profile
The most common adverse reactions (incidence ≥10%) for patients treated with dimethyl fumarate were flushing and gastrointestinal events (i.e. diarrhoea, nausea, abdominal pain, abdominal pain upper). Flushing and gastrointestinal events tend to begin early in the course of treatment (primarily during the first month) and in patients who experience flushing and gastrointestinal events, these events may continue to occur intermittently throughout treatment with dimethyl fumarate. The most commonly reported adverse reactions leading to discontinuation (incidence >1%) in patients treated with dimethyl fumarate were flushing (3%) and gastrointestinal events (4%).
In placebo-controlled and uncontrolled clinical studies, a total of 2,513 patients have received dimethyl fumarate for periods of up to 12 years with an overall exposure equivalent to 11,318 person-years. A total of 1,169 patients have received at least 5 years of treatment with dimethyl fumarate, and 426 patients have received at least 10 years of treatment with dimethyl fumarate. The experience in uncontrolled clinical trials is consistent with the experience in the placebo-controlled clinical trials.
Tabulated summary of adverse reactions
Adverse reactions, arising from clinical studies, post-authorisation safety studies and spontaneous reports, are presented in the table below.
The adverse reactions are presented as MedDRA preferred terms under the MedDRA System Organ Class. The incidence of the adverse reactions below is expressed according to the following categories:
- Very common (≥1/10)
- Common (≥1/100 to <1/10)
- Uncommon (≥1/1,000 to <1/100)
- Rare (≥1/10,000 to <1/1,000)
- Very rare (<1/10,000)
- Not known (frequency cannot be estimated from the available data)
| MedDRA System Organ Class | Adverse reaction | Frequency category |
| Infections and infestations | Gastroenteritis | Common |
| Progressive multifocal leukoencephalopathy (PML) | Not known |
| Herpes zoster | Not known |
| Blood and lymphatic system disorders | Lymphopenia | Common |
| Leucopenia | Common |
| Thrombocytopenia | Uncommon |
| Immune system disorders | Hypersensitivity | Uncommon |
| Anaphylaxis | Not known |
| Dyspnoea | Not known |
| Hypoxia | Not known |
| Hypotension | Not known |
| Angioedema | Not known |
| Nervous system disorders | Burning sensation | Common |
| Vascular disorders | Flushing | Very common |
| Hot flush | Common |
| Respiratory, thoracic and mediastinal disorders | Rhinorrhoea | Not known |
| Gastrointestinal disorders | Diarrhoea | Very common |
| Nausea | Very common |
| Abdominal pain upper | Very common |
| Abdominal pain | Very common |
| Vomiting | Common |
| Dyspepsia | Common |
| Gastritis | Common |
| Gastrointestinal disorder | Common |
| Hepatobiliary disorders | Aspartate aminotransferase increased | Common |
| Alanine aminotransferase increased | Common |
| Drug-induced liver injury | Not known |
| Skin and subcutaneous tissue disorders | Pruritus | Common |
| Rash | Common |
| Erythema | Common |
| Alopecia | Common |
| Renal and urinary disorders | Proteinuria | Common |
| General disorders and administration site conditions | Feeling hot | Common |
| Investigations | Ketones measured in urine | Very common |
| Albumin urine present | Common |
| White blood cell count decreased | Common |
Description of selected adverse reactions
Flushing
In the placebo-controlled studies, the incidence of flushing (34% versus 4%) and hot flush (7% versus 2%) was increased in patients treated with dimethyl fumarate compared to placebo, respectively. Flushing is usually described as flushing or hot flush, but can include other events (e.g. warmth, redness, itching, and burning sensation). Flushing events tend to begin early in the course of treatment (primarily during the first month) and in patients who experience flushing, these events may continue to occur intermittently throughout treatment with dimethyl fumarate. In patients with flushing, the majority had flushing events that were mild or moderate in severity. Overall, 3% of patients treated with dimethyl fumarate discontinued due to flushing. The incidence of serious flushing, which may be characterised by generalised erythema, rash and/or pruritus, was seen in less than 1% of patients treated with dimethyl fumarate (see sections 4.2, 4.4 and 4.5).
Gastrointestinal
The incidence of gastrointestinal events (e.g. diarrhoea [14% versus 10%], nausea [12% versus 9%], upper abdominal pain [10% versus 6%], abdominal pain [9% versus 4%], vomiting [8% versus 5%] and dyspepsia [5% versus 3%]) was increased in patients treated with dimethyl fumarate compared to placebo, respectively.
Gastrointestinal events tend to begin early in the course of treatment (primarily during the first month) and in patients who experience gastrointestinal events, these events may continue to occur intermittently throughout treatment with dimethyl fumarate. In the majority of patients who experienced gastrointestinal events, it was mild or moderate in severity. Four per cent (4%) of patients treated with dimethyl fumarate discontinued due to gastrointestinal events. The incidence of serious gastrointestinal events, including gastroenteritis and gastritis, was seen in 1% of patients treated with dimethyl fumarate (see section 4.2).
Hepatic function
Based on data from placebo-controlled studies, the majority of patients with elevations had hepatic transaminases that were <3 times the upper limit of normal (ULN). The increased incidence of elevations of hepatic transaminases in patients treated with dimethyl fumarate relative to placebo was primarily seen during the first 6 months of treatment. Elevations of alanine aminotransferase and aspartate aminotransferase ≥3 times ULN, respectively, were seen in 5% and 2% of patients treated with placebo and 6% and 2% of patients treated with dimethyl fumarate.
Discontinuations due to elevated hepatic transaminases were <1% and similar in patients treated with dimethyl fumarate or placebo. Elevations in transaminases ≥3 times ULN with concomitant elevations in total bilirubin >2 times ULN, were not observed in placebo-controlled studies.
Increase of liver enzymes and cases of drug-induced liver injury (elevations in transaminases ≥3 times ULN with concomitant elevations in total bilirubin >2 times ULN), have been reported in post marketing experience following dimethyl fumarate administration, which resolved upon treatment discontinuation.
Lymphopenia
In the placebo-controlled studies most patients (>98%) had normal lymphocyte values prior to initiating treatment. Upon treatment with dimethyl fumarate, mean lymphocyte counts decreased over the first year with a subsequent plateau. On average, lymphocyte counts decreased by approximately 30% of baseline value.
Mean and median lymphocyte counts remained within normal limits. Lymphocyte counts <0.5x109/l were observed in <1% of patients treated with placebo and 6% of patients treated with dimethyl fumarate. A lymphocyte count <0.2x109/l was observed in 1 patient treated with dimethyl fumarate and in no patients treated with placebo.
In clinical studies (both controlled and uncontrolled), 41% of patients treated with dimethyl fumarate had lymphopenia (defined in these studies as <0.91x109/L). Mild lymphopenia (counts ≥0.8x109/L to <0.91 x109/L) was observed in 28% of patients; moderate lymphopenia (counts ≥0.5x109/L to <0.8x109/L) persisting for at least six months was observed in 11% of patients; severe lymphopenia (counts <0.5x109/L) persisting for at least six months was observed in 2% of patients. In the group with severe lymphopenia, the majority of lymphocyte counts remained <0.5x109/L with continued therapy.
In addition, in an uncontrolled, prospective, post-marketing study, at week 48 of treatment with dimethyl fumarate (n=185) CD4+ T cells were moderately (counts ≥0.2x109/L to <0.4x109/L) or severely (<0.2x109/L) decreased in up to 37% or 6% of patients, respectively, while CD8+ T cells were more frequently reduced with up to 59% of patients at counts <0.2x109/L and 25% of patients at counts <0.1x109/L. In controlled and uncontrolled clinical studies, patients who discontinued dimethyl fumarate therapy with lymphocyte counts below the lower limit of normal (LLN) were monitored for recovery of lymphocyte count to the LLN (see section 5.1).
Infections, including PML and opportunistic infections
Cases of infections with John Cunningham virus (JCV) causing Progressive Multifocal Leukoencephalopathy (PML) have been reported with dimethyl fumarate (see section 4.4). PML may be fatal or result in severe disability. In one of the clinical trials, one patient taking dimethyl fumarate developed PML in the setting of prolonged severe lymphopenia (lymphocyte counts predominantly <0.5x109/L for 3.5 years), with a fatal outcome. In the post-marketing setting, PML has also occurred in the presence of moderate and mild lymphopenia (>0.5x109/L to <LLN, as defined by local laboratory reference range).
In several PML cases with determination of T cell subsets at the time of diagnosis of PML, CD8+ T cell counts were found to be decreased to <0.1x109/L, whereas reductions in CD4+ T cells counts were variable (ranging from <0.05 to 0.5x109/L) and correlated more with the overall severity of lymphopenia (<0.5 x109/L to <LLN). Consequently, the CD4+/CD8+ ratio was increased in these patients.
Prolonged moderate to severe lymphopenia appears to increase the risk of PML with dimethyl fumarate, however, PML also occurred in patients with mild lymphopenia. Additionally, the majority of PML cases in the post-marketing setting have occurred in patients >50 years.
Herpes zoster infections have been reported with dimethyl fumarate use. In an ongoing long-term extension study, in which 1,736 MS patients are treated with dimethyl fumarate, approximately 5% experienced one or more events of herpes zoster, the majority of which were mild to moderate in severity. Most subjects, including those who experienced a serious herpes zoster infection, had lymphocyte counts above the lower limit of normal. In a majority of subjects with concurrent lymphocyte counts below the LLN, lymphopenia was rated moderate or severe. In the post-marketing setting most cases of herpes zoster infection were non-serious and resolved with treatment. Limited data is available on absolute lymphocyte count (ALC) in patients with herpes zoster infection in the post-marketing setting.
However, when reported, most patients experienced moderate (≥0.5 x 109/L to <0.8 x 109/L) or severe (<0.5 x 109/L to 0.2 x 109/L) lymphopenia (see section 4.4).
Laboratory abnormalities
In the placebo-controlled studies, measurement of urinary ketones (1+ or greater) was higher in patients treated with dimethyl fumarate (45%) compared to placebo (10%). No untoward clinical consequences were observed in clinical trials.
Levels of 1,25-dihydroxyvitamin D decreased in dimethyl fumarate treated patients relative to placebo (median percentage decrease from baseline at 2 years of 25% versus 15%, respectively) and levels of parathyroid hormone (PTH) increased in dimethyl fumarate treated patients relative to placebo (median percentage increase from baseline at 2 years of 29% versus 15%, respectively). Mean values for both parameters remained within normal range.
A transient increase in mean eosinophil counts was seen during the first 2 months of therapy.
Paediatric population
In a 96 week open label, randomised active controlled trial in paediatric patients with RRMS aged 10 to less than 18 years (120 mg twice a day for 7 days followed by 240 mg twice a day for the remainder of treatment; study population, n=78), the safety profile in paediatric patients appeared similar to that previously observed in adult patients.
The paediatric clinical trial design differed from the adult placebo-controlled clinical trials. Therefore, a contribution of clinical trial design to numerical differences in adverse reactions between the paediatric and adult populations, cannot be excluded.
The following adverse events were more frequently reported (≥10%) in the paediatric population than in the adult population:
• Headache was reported in 28% of patients treated with dimethyl fumarate versus 36% in patients treated with interferon beta-1a.
• Gastrointestinal disorders were reported in 74% of patients treated with dimethyl fumarate versus 31% in patients treated with interferon beta-1a. Among them, abdominal pain and vomiting were the most frequently reported with dimethyl fumarate.
• Respiratory, thoracic and mediastinal disorders were reported in 32% of patients treated with dimethyl fumarate versus 11% in patients treated with interferon beta-1a. Among them, oropharyngeal pain and cough were the most frequently reported with dimethyl fumarate.
• Dysmenorrhea was reported in 17% of patients treated with dimethyl fumarate versus 7% of patients treated with interferon beta-1a.
In a small 24 week open-label uncontrolled study in paediatric patients with RRMS aged 13 to 17 years (120 mg twice a day for 7 days followed by 240 mg twice a day for the remainder of treatment; safety population, n=22), followed by a 96 week extension study (240 mg twice per day; safety population n=20), the safety profile appeared similar to that observed in adult patients.
There are limited data available in children between 10 and 12 years old. The safety and efficacy of dimethyl fumarate in children aged less than 10 years have not yet been established.
Reporting of suspected adverse reactions
Reporting suspected adverse reactions after authorization of the medicinal product is important. It allows continued monitoring of the benefit/risk balance of the medicinal product. Healthcare professionals are asked to report any suspected adverse reactions via via the Yellow Card Scheme Website: www.mhra.gov.uk/yellowcard or search for MHRA Yellow Card in the Google Play or Apple App Store.