The potential role of pharmacogenomics in the prevention of serious adverse drug reactions in multiple sclerosis

The PNPLA3 rs738409 variant can increase the risk of liver toxicity in multiple sclerosis patients treated with beta-interferon

BACKGROUND

Liver toxicity can limit the use of interferon-beta (IFNβ), a well-established treatment for multiple sclerosis (MS). Unfortunately, known risk-factors for IFNβ-associated liver toxicity are few and of limited clinical utility. Susceptibility to drug-induced toxicity is influenced by genetic factors affecting hepatic lipid metabolism and drug-metabolizing activity.

METHODS

We designed a retrospective, multicentre study to evaluate whether specific polymorphisms in genes involved in hepatic lipid metabolism are associated with a higher risk of developing IFNβ-induced hepatotoxicity. The following single nucleotide polymorphisms were examined: rs738409 C > G in PNPLA3; rs4880 C > T in SOD2; rs3750861 C > T in KLF6; rs13412852 C > T in LPIN1; rs58542926 C > T in TM6SF2. Liver toxicity was defined as a new increase of aspartate aminotransferase (AST) and/or alanine aminotransferase (ALT) plasma levels above the laboratory upper normal limit after the start of IFNβ treatment.

RESULTS

One-hundred-thirteen MS patients were enrolled and twenty-nine experienced liver toxicity. Logistic regression analysis revealed that the PNPLA3 variant was significantly associated with the occurrence of liver toxicity. No associations were found between other polymorphisms and liver toxicity.

CONCLUSIONS

The results of our exploratory study suggest that the PNPLA3 variant can help to identify those patients at higher risk of IFNβ toxicity. The stratification of the risk of liver toxicity could increase the safety of IFNβ therapy.

Reaching an evidence-based prognosis for personalized treatment of multiple sclerosis

Personalized treatment is ideal for multiple sclerosis (MS) owing to the heterogeneity of clinical features, but current knowledge gaps, including validation of biomarkers and treatment algorithms, limit practical implementation. The contemporary approach to personalized MS therapy depends on evidence-based prognostication, an initial treatment choice and evaluation of early treatment responses to identify the need to switch therapy. Prognostication is directed by baseline clinical, environmental and demographic factors, MRI measures and biomarkers that correlate with long-term disability measures. The initial treatment choice should be a shared decision between the patient and physician. In addition to prognosis, this choice must account for patient-related factors, including comorbidities, pregnancy planning, preferences of the patients and their comfort with risk, and drug-related factors, including safety, cost and implications for treatment sequencing. Treatment response has traditionally been assessed on the basis of relapse rate, MRI lesions and disability progression. Larger longitudinal data sets have enabled development of composite outcome measures and more stringent standards for disease control. Biomarkers, including neurofilament light chain, have potential as early surrogate markers of prognosis and treatment response but require further validation. Overall, attainment of personalized treatment for MS is complex but will be refined as new data become available.

Pharmacogenetic Biomarkers to Predict Treatment Response in Multiple Sclerosis: Current and Future Perspectives

Disease-modifying therapies (DMTs) have significantly advanced the treatment of relapsing multiple sclerosis (MS), decreasing the frequency of relapses, disability, and magnetic resonance imaging lesion formation. However, patients' responses to and tolerability of DMTs vary considerably, creating an unmet need for biomarkers to identify likely responders and/or those who may have treatment-limiting adverse reactions. Most studies in MS have focused on the identification of pharmacogenetic markers, using either the candidate-gene approach, which requires prior knowledge of the genetic marker and its role in the target disease, or genome-wide association, which examines multiple genetic variants, typically single nucleotide polymorphisms (SNPs). Both approaches have implicated numerous alleles and SNPs in response to selected MS DMTs. None have been validated for use in clinical practice. This review covers pharmacogenetic markers in clinical practice in other diseases and then reviews the current status of MS DMT markers (interferon β, glatiramer acetate, and mitoxantrone). For a complex disease such as MS, multiple biomarkers may need to be evaluated simultaneously to identify potential responders. Efforts to identify relevant biomarkers are underway and will need to be expanded to all MS DMTs. These will require extensive validation in large patient groups before they can be used in clinical practice.

Application of pharmacogenomics to investigate adverse drug reactions to the disease-modifying treatments for multiple sclerosis: a case-control study protocol for dimethyl fumarate-induced lymphopenia

INTRODUCTION

Adverse drug reactions (ADRs) are a global public health issue. The potential for pharmacogenomic biomarkers has been demonstrated in several therapeutical areas, including HIV infection and oncology. Dimethyl fumarate (DMF) is a licensed disease-modifying therapy for the treatment of multiple sclerosis (MS). The use of DMF in MS has been associated with a severe reduction in lymphocyte counts and reports of progressive multifocal leukoencephalopathy. Here, we outline the protocol for a case-control study designed to discover genomic variants associated with DMF-induced lymphopenia. The ultimate goal is to replicate these findings and create an efficient and adaptable approach towards the identification of genomic markers that could assist in mitigating adverse drug reactions in MS.

METHODS AND ANALYSIS

The population sample will comprise DMF-exposed patients with MS, with cases representing those who developed lymphopenia and controls who did not. DNA genotyping will take place using a high-throughput genome-wide array. Fine mapping and imputation will be performed to focus in on the potentially causal variants associated with lymphopenia. Multivariable logistic regression will be used to compare genotype and allele frequencies between the cases and the controls, with consideration of potential confounders. The association threshold will be set at p<1.0×10^-5 for the discovery of genomic association analyses to select variants for replication.

ETHICS AND DISSEMINATION

Ethics approval has been obtained from the respective research ethics board, which includes written informed consent. Findings will be disseminated widely, including at scientific conferences, via podcasts (targeted at both healthcare professionals as well as patients and the wider community), through patient engagement and other outreach community events, written lay summaries for all participants and formal publication in peer-reviewed scientific journals.

What's new about oral treatments in Multiple Sclerosis? Immunogenetics still under question

Multiple Sclerosis (MS) is a chronic pathology affecting the Central Nervous System characterized by inflammatory processes that lead to demyelination and neurodegeneration. In MS treatment, disease modifying therapies (DMTs) are essential to reduce disease progression by suppressing the inflammatory response responsible for promoting lesion formation. Recently, in addition to the classical injectable DMTs like Interferons and Glatiramer acetate, new orally administered drugs have been approved for MS therapy: dimethyl fumarate, teriflunomide and fingolimod. These drugs act with different mechanisms on the immune system, in order to suppress the harmful inflammatory process. An additional layer of complexity is introduced by the influence of polymorphic gene variants in the Human Leukocyte Antigen region on the risk of developing MS and its progression. To date, pharmacogenomic studies have mainly focused on the patient's response following admission of injectable drugs. Therefore, greater consideration must be made to pharmacogenomics with a view to developing more effective and personalized therapies. This review aims to shed light on the mechanism of action of the new oral drugs dimethyl fumarate, teriflunomide and fingolimod, taking into account both the importance of immunogenetics in drug response and pharmacogenomic studies.

Acute liver failure and liver transplantation in a patient with multiple sclerosis treated with interferon beta

In the treatment of multiple sclerosis (MS), interferon beta (IFNβ) applies. It rarely can lead to acute liver failure (ALF). A 42-year-old female with MS was admitted to the Department because of jaundice, general weakness, drowsiness and nausea. Four weeks earlier, she had started therapy with IFNβ-1a. Liver tests made prior to initiation of IFNβ-1a were normal but on admission to the Department exceed several times the upper limit. ALF was recognized and IFNβ-1a was immediately stopped. In the fourth day of hospitalization, symptoms of hepatic encephalopathy have progressed. The patient was transferred to the Department of Transplantation, where hepatic coma developed and three days later the orthotopic liver transplantation was performed. In histopathological picture of the removed liver extensive necrosis and fibrosis dominated. Immunosuppressive therapy consisted of tacrolimus, mycophenolate mofetil and tapering prednisone. Within five years after surgery, there was no recurrence of symptoms of MS and the transplanted organ is functioning properly. ALF is a rare complication of IFNβ therapy but it can occur. The appearance of symptoms suggestive of liver injury should prompt extension of diagnosis and, if necessary, discontinuation of therapy.