Examining the clinical utility of lacosamide: pooled analyses of three phase II/III clinical trials

Specific binding of lacosamide to collapsin response mediator protein 2 (CRMP2) and direct impairment of its canonical function: implications for the therapeutic potential of lacosamide

The novel antiepileptic drug lacosamide (LCM; SPM927, Vimpat®) has been heralded as having a dual-mode of action through interactions with both the voltage-gated sodium channel and the neurite outgrowth-promoting collapsin response mediator protein 2 (CRMP2). Lacosamide's ability to dampen neuronal excitability through the voltage-gated sodium channel likely underlies its efficacy in attenuating the symptoms of epilepsy (i.e., seizures). While the role of CRMP2 in epilepsy has not been well studied, given the proposed involvement of circuit reorganization in epileptogenesis, the ability of lacosamide to alter CRMP2 function may prove disease modifying. Recently, however, the validity of lacosamide's interaction with CRMP2 has come under scrutiny. In this review, we address the contradictory reports concerning the binding of lacosamide to CRMP2 as well as the ability of lacosamide to directly impact CRMP2 function. Additionally, we address similarly the contradicting reports regarding the potential disease-modifying effect of lacosamide on the development and progression of epilepsy. As the vast majority of antiepileptic drugs influences only the symptoms of epilepsy, the ability to hinder disease progression would be a major breakthrough in efforts to cure or prevent this debilitating syndrome.

Successful treatment with adjunctive lacosamide in a patient with long term “drug resistant” focal epilepsy

Introduction. A significant number of patients suffering from epilepsy prove to be resistant to antiepileptic drugs (AEDs). Recent studies, however, suggest that 10–20% of seemingly drug resistant patients may still become seizure-free under the influence of subsequent dosage modifications.

Case report. We report on a young man with cryptogenic focal epilepsy. He had his first seizure at the age of fifteen. His seizure frequency was decreased during the following 11 years. However, seizure-freedom was never achieved even though he was treated with twelve to fourteen different AEDs during this time. Intensive presurgical evaluations did not allow identification of a surgically remediable focus. Adjunctive treatment with lacosamide 400 mg/day was not successful. However, the patient became seizure-free immediately after an increase of the lacosamide dose up to 500 mg/day. The patient is now seizure-free for more than two years based on a combination of 500 mg lacosamide and 350 mg lamotrigine, followed by 550 mg and 250 mg, respectively.

Discussion and conclusion. This case report highlights that there is always a chance that modifying the medication can result in a drug-resistant epilepsy patient experiencing a significant reduction of seizures and becoming seizure-free. The decisive step in this example was the off-label prescription of a high dose of lacosamide which the patient tolerated well.

Determining minimally important change thresholds for the Seizure Severity Questionnaire (SSQ)

The Seizure Severity Questionnaire (SSQ) was developed to evaluate changes in seizure severity and bothersomeness. Determination of a threshold value reflecting meaningful patient benefit on the SSQ would improve clinical interpretation of scale results. The objective of this analysis was to define a minimally important change (MIC) threshold for the SSQ, using data from patients with treatment-resistant partial-onset seizures from two clinical trials (N=776). Minimally important change thresholds were calculated using standard anchor-based methods, with the Patient Global Impression of Change (PGIC) score as the anchor with the categories of 'much improved,' 'minimally improved,' 'much worsened,' and 'minimally worsened' combined. The calculated MIC thresholds (range: 0.34 to 0.50) suggest that a 0.48-point change in the SSQ total score reflects a clinically meaningful change in seizure severity from the patients' perspective.

Lacosamide: a review of its use as adjunctive therapy in the management of partial-onset seizures

Lacosamide (Vimpat(®)) is a functionalized amino acid available orally (as a syrup or tablet) and as an intravenous infusion. It is believed to exert its antiepileptic effect by selectively enhancing the slow inactivation of voltage-gated sodium channels. Lacosamide is approved in several countries worldwide as an adjunctive therapy for the treatment of partial-onset seizures; however, prescribing regulations differ between countries. This article reviews the use of lacosamide as indicated in adults and adolescents (aged 16-18 years) in the EU, where it is approved in this patient population as an adjunctive therapy to other AEDs in the treatment of partial-onset seizures, with or without secondary generalization. In three randomized, double-blind, placebo-controlled, multicentre studies in adults and adolescents (aged 16-18 years) with partial-onset seizures, adjunctive therapy with oral lacosamide (administered for an initial titration period followed by 12 weeks' maintenance therapy) generally reduced the frequency of seizures to a significantly greater extent than placebo, with antiepileptic efficacy sustained following longer-term treatment (up to 8 years) in this patient population. Oral and intravenous lacosamide were generally well tolerated in clinical studies, with the majority of adverse events being mild or moderate in severity. Very common adverse reactions following adjunctive therapy with oral lacosamide included diplopia, dizziness, headache and nausea; the tolerability profile of intravenous lacosamide appeared consistent with that of oral lacosamide, although intravenous administration was associated with local adverse events, such as injection site discomfort or pain, irritation and erythema. Thus, oral and intravenous lacosamide as an adjunctive therapy to other AEDs provides a useful option in the treatment of patients with partial-onset seizures.

Lacosamide adjunctive therapy for partial-onset seizures: a meta-analysis

Background. The relative efficacy and safety of lacosamide as adjunctive therapy compared to other antiepileptic drugs has not been well established. Objective. To determine if lacosamide provides improved efficacy and safety, reduced length of hospital stay and improved quality of life compared with other anti-epileptic therapies for adults with partial-onset seizures. Data Sources. A systematic review of the medical literature using Medline (1946-Week 4, 2012), EMBASE (1980-Week 3, 2012), Cochrane Central Register of Controlled Trials (Issue 1 of 12, January 2012). Additional studies were identified (through to February 7, 2012) by searching bibliographies, the FDA drug approval files, clinical trial registries and major national and international neurology meeting abstracts. No restrictions on publication status or language were applied. Study Selection. Randomized controlled trials of lacosamide in adults with partial-onset seizures were included. Data Extraction. Study selection, extraction and risk of bias assessment were performed independently by two authors. Authors of studies were contacted for missing data. Data Synthesis. All pooled analyses used the random effects model. Results. Three trials (1311 patients) met inclusion criteria. Lacosamide increased the 50% responder rate compared to placebo (RR 1.68 [95% CI 1.36 to 2.08]; I(2) = 0%). Discontinuation due to adverse events was statistically significantly higher in the lacosamide arm (RR3.13 [95% CI 1.94 to 5.06]; I(2) = 0%). Individual adverse events (ataxia, dizziness, fatigue, and nausea) were also significantly higher in the lacosamide group. Limitations. All dosage arms from the included studies were pooled to make a single pair-wise comparison to placebo. Selective reporting of outcomes was found in all of the included RCTs. Conclusions. Lacosamide as adjunctive therapy in patients with partial-onset seizures increases the 50% responder rate but with significantly more adverse events compared to the placebo.

Development of lacosamide for the treatment of partial-onset seizures

Lacosamide is an antiepileptic drug (AED) available in multiple formulations that was first approved in 2008 as adjunctive therapy for partial-onset seizures (POS) in adults. Unlike traditional sodium channel blockers affecting fast inactivation, lacosamide selectively enhances sodium channel slow inactivation. This mechanism of action results in stabilization of hyperexcitable neuronal membranes, inhibition of neuronal firing, and reduction in long-term channel availability without affecting physiological function. Lacosamide has a well-characterized and favorable pharmacokinetic profile, including a fast absorption rate, minimal or no interaction with cytochrome P-450 izoenzymes, and a low potential for drug-drug interactions. Lacosamide clinical development included three placebo-controlled, double-blind, randomized trials conducted in more than 1300 patients, each demonstrating safety and efficacy of lacosamide compared to placebo as adjunctive therapy for adults with POS. The clinical use of lacosamide may broaden, pending results of trials evaluating its use as monotherapy for POS in adults, as treatment for epilepsy in pediatric subjects, and as adjunctive treatment for uncontrolled primary generalized tonic-clonic seizures in those with idiopathic generalized epilepsy.

Synergism of lacosamide with established antiepileptic drugs in the 6-Hz seizure model in mice

PURPOSE

Lacosamide (LCM, Vimpat) is an anticonvulsant with a unique mode of action. This provides lacosamide with the potential to act additively or even synergistically with other antiepileptic drugs (AEDs). The objective of this study was to determine the presence of such interactions by isobolographic analysis.

METHODS

The anticonvulsant effect of LCM in combination with other AEDs including carbamazepine (CBZ), phenytoin (PHT), valproate (VPA), lamotrigine (LTG), topiramate (TPM), gabapentin (GBP), and levetiracetam (LEV) at fixed dose ratios of 1:3, 1:1, and 3:1, was evaluated in the 6-Hz-induced seizure model in mice. In addition, the impact of the combinations of LCM with the other AEDs on motor coordination was assessed in the rotarod test. Finally, AED concentrations were measured in blood and brain to evaluate potential pharmacokinetic drug interactions.

KEY FINDINGS

All studied AEDs produced dose-dependent anticonvulsant effects against 6-Hz-induced seizures. Combinations of LCM with CBZ, LTG, TPM, GBP, or LEV were synergistic. All other LCM/AED combinations displayed additive effects with a tendency toward synergism. Furthermore, no enhanced adverse effects were observed in the rotarod test by combining LCM with other AEDs. No pharmacokinetic interactions were seen on brain AED concentrations. Coadministration of LCM and TPM led to an increase in plasma levels of LCM, whereas the plasma concentration of PHT was increased by coadministration of LCM.

SIGNIFICANCE

The synergistic anticonvulsant interaction of LCM with various AEDs, without exacerbation of adverse motor effects, highlights promising properties of LCM as add-on therapy for drug refractory epilepsy.

When one plus one makes three: the quest for rational antiepileptic polytherapy with supraadditive anticonvulsant efficacy

The experimental and clinical evidence in support of "rational polytherapy" is sparse, and to date, no clear evidence-based indications can be made to help physicians in their choice of a specific drug combination against specific forms of epilepsy. This article briefly reviews the data available in the literature and obtained from studies conducted in humans to evaluate which main AED combinations might possess supraadditive, synergistic effects in terms of efficacy, with infraadditive toxicity. By far, the most documented association resulting in supraadditive anticonvulsant effects against focal seizures is that of VPA and LTG. There are some indications that combinations of drugs with different primary mechanisms of action may be more effective than combining drugs with the same mechanisms of action. However, further animal and human research studies that focus both on toxicity and anticonvulsant effects of various combinations of AEDs are required.

Clinical experience with using lacosamide for the treatment of epilepsy in a tertiary centre

OBJECTIVE

Lacosamide is approved for the adjunctive treatment of partial-onset seizures in adults. Phase II/III clinical trials suggest that it is a safe, effective and well-tolerated medication. However, there is little post-marketing information available about this medication.

METHODS

We report our clinical experience from a tertiary referral epilepsy centre, which has been using lacosamide for the past 18 months, with 128 patients treated during this time.

RESULTS

Fifty-three patients (41%) achieved at least a 50% reduction in seizure frequency, with 14 patients (11%) achieving seizure freedom for a mean time of 35 weeks. This 50% responder rate matches, and the seizure free rate outperforms that seen in previous pooled trials. The efficacy of lacosamide did not vary with concurrent sodium channel blocking agent (SCB) use, and a statistically significant dose-dependent response was not shown, which is in contrast to previous trials. Treatment emergent adverse effects (TEAEs) were noted in 52 patients (41%), with 24 patients (19%) discontinuing the medication. TEAEs were more frequent in patients on concurrent SCBs, affecting 51% vs. 28% of patients not on other SCBs. This increased risk of TEAEs from concurrent SCB use was of statistical significance (P = 0.01). The most frequently noted TEAEs from lacosamide were dizziness, sedation and diplopia, which all appeared to be dose-related.

CONCLUSION

This post-marketing analysis suggests that lacosamide in clinical practice at least mirrors, and possibly outperforms the results seen in previous phase II/III trials.

Long-term safety and efficacy in patients with uncontrolled partial-onset seizures treated with adjunctive lacosamide: results from a Phase III open-label extension trial

PURPOSE

To evaluate the long-term (up to 5 years exposure) safety and efficacy of lacosamide as adjunctive therapy in patients with uncontrolled partial-onset seizures taking one to three concomitant antiepileptic drugs (AEDs) in open-label extension trial SP756 (NCT00522275).

METHODS

Patients who completed the double-blind trial SP754 (NCT00136019) were eligible to participate in this open-label extension trial (SP756). At the conclusion of trial SP754, patients had transitioned to lacosamide 200 mg/day. Subsequent dosage adjustments of lacosamide (100-800 mg/day) and/or concomitant AEDs were allowed to optimize tolerability and seizure reduction. Treatment-emergent adverse events (TEAEs), vital signs, body weight, clinical laboratory data, electrocardiography studies, and seizure frequency were evaluated.

KEY FINDINGS

A total of 308 patients received open-label lacosamide and 138 patients (44.8%) completed the long-term trial. The median modal dose (defined as the daily lacosamide dose a patient received for the longest duration during the treatment period) was 500 mg/day. The percentages of patients with lacosamide exposure >1, >2, >3, or >4 years were 75%, 63%, 54%, and 29%, respectively. Primary reasons for discontinuation were lack of efficacy (26%) and adverse events (11%). Common TEAEs (≥15%) were dizziness, headache, contusion, nausea, convulsion, nasopharyngitis, fall, vomiting, and diplopia. TEAEs that led to discontinuation in ≥1.0% of patients were dizziness (1.6%) and convulsion (1.0%). The median percent reductions from baseline of trial SP754 in 28-day seizure frequency were 53.4%, 55.2%, 58.1%, and 62.5%, respectively, for 1-, 2-, 3-, and 4-year completers. The ≥50% responder rates were 52.8%, 56.5%, 58.7%, and 62.5% for 1-, 2-, 3-, and 4-year completers, respectively. Seven of eight patients on lacosamide monotherapy for ≥12 months were deemed 50% responders. Of patients exposed to lacosamide ≥2 years, 3.1% remained seizure-free for a period ≥2 years.

SIGNIFICANCE

Long-term (up to 5 years) lacosamide treatment was generally well tolerated. The safety profile of lacosamide observed in this trial is consistent with that established in previous double-blind, placebo-controlled trials. Although the open-label trial design limits the analysis of efficacy, long-term reduction in seizure frequency and maintenance of efficacy was observed.

Pharmacotherapy of the third-generation AEDs: lacosamide, retigabine and eslicarbazepine acetate

INTRODUCTION

The search for new, more effective antiepileptic drugs (AEDs) continues. The three most recently approved drugs, the so-called third-generation AEDs, include lacosamide, retigabine and eslicarbazepine acetate and are licensed as adjunctive treatment of partial epilepsy in adults.

AREAS COVERED

For the above three AEDs, their mechanisms of action, pharmacokinetic characteristics, drug-drug interactions, pharmacotherapeutics, dose and administration and therapeutic drug monitoring are reviewed in this paper.

EXPERT OPINION

Lacosamide and retigabine act through novel mechanisms, while eslicarbazepine acetate, a pro-drug for eslicarbazepine, acts in a similar manner to several other AEDs. All three AEDs are associated with linear pharmacokinetic and rapid absorption and undergo metabolism. Their drug-drug interaction profile is low (lacosamide and retigabine) to modest (eslicarbazepine) in propensity. At the highest approved doses for the three AEDs, responder rates were similar. The most commonly observed adverse effects compared with placebo were dizziness, headache, diplopia and nausea for lacosamide; dizziness, somnolence and fatigue for retigabine and dizziness and somnolence for eslicarbazepine acetate. The precise role that these new AEDs will have in the treatment of epilepsy and whether they will make a significant impact on the prognosis of intractable epilepsy is not yet known and will have to await further clinical experience.

Rational polytherapy with lacosamide in clinical practice: results of a Spanish cohort analysis RELACOVA

There has been little long-term success with polytherapy for patients with refractory partial-onset epilepsy. The rational combination of antiepileptic drugs based on their mechanism of action may help improve treatment efficacy and tolerability. Lacosamide, a novel sodium channel blocker (SCB), was investigated in 158 patients with partial-onset epilepsy in the prospective, multicenter, observational, RELACOVA cohort study conducted in Spain. After 12 months' treatment with lacosamide, 47% of patients were responders (≥50% reduction in seizure frequency) and 24% were seizure free. Lacosamide was well tolerated; dizziness was the most frequent adverse event. Efficacy was better (responder rate, 65% vs 38%; seizure free rate, 35% vs 17%) and there was a lower adverse event rate (33% vs 58%) in patients receiving non-SCBs (n=49) versus those receiving SCBs (n=104) as concomitant therapy at baseline. Further investigation of lacosamide combination therapy is warranted.

New developments in the treatment of partial-onset epilepsy

Although most people presenting with partial-onset seizures will achieve control with antiepileptic medication, a considerable minority will have difficult-to-treat epilepsy that is resistant to existing medication. Over the last few years, a large number of new antiepileptic drugs have been developed. Some of these have a novel mode of action. Many of the older antiepileptic drugs act through sodium channels or by enhancement of gamma amino butyric acid (GABA). Lamotrigine has sodium-channel blocking properties but also has other important modes of action, indicated by efficacy in treating not only partial-onset but also generalized seizures. Vigabatrin and tiagabine both increase GABA activity, by inhibiting GABA transaminase and limiting GABA reuptake, respectively. The main mode of action of gabapentin and pregabalin is not via GABA but through a selective inhibitory effect on voltage-gated calcium channels containing the α(2)δ-1 subunit. Levetiracetam inhibits the recycling of SV2A (synaptic vesicle protein 2A) neurotransmitter vesicles but also has other effects, including inhibition of voltage-dependent calcium channels. Some drugs, eg, felbamate, zonisamide, and topiramate, have multiple modes of action. In many cases, although the main mode of action may have been identified, other modes of action also play a role. Two recently developed antiepileptic drugs appear to have completely novel primary modes of action; retigabine (ezogabine) and perampanel act on the potassium channel and on AMPA (α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid) receptors, respectively. The hope is that antiepileptic drugs with a novel mode of action will be effective where previous drugs have failed and will not have unacceptable adverse effects. However, experience with these medications is too limited to allow any conclusions to be drawn at present.

New and emerging treatments for epilepsy: review of clinical studies of lacosamide, eslicarbazepine acetate, ezogabine, rufinamide, perampanel, and electrical stimulation therapy

Although many different medical and surgical treatment options for epilepsy exist, approximately 30% of epilepsy patients remain poorly controlled. For those patients who are refractory to medical treatment, epilepsy surgery often provides meaningful improvement. However, when surgical resection of epileptic foci cannot be offered or failed, combined administration of AEDs or the application of novel AEDs is the most appropriate therapeutic options. The most recent AEDs tend to offer new mechanisms of action and more favorable safety profiles than the first generation of AEDs. More recently, alternative options of thalamic or cortical stimulation emerged as potentiall effective treatment for epilepsy. The purpose of this article is to compare and review clinical information for the new and emerging medications such as lacosamide, eslicarbazepine acetate, ezogabine (retigabine), rufinamide, perampanel, as well as deep brain stimulation and responsive neurostimulation devices.