Long-term retention rates for antiepileptic drugs: A review of long-term extension studies and comparison with brivaracetam

Narrative Review of Brivaracetam: Preclinical Profile and Clinical Benefits in the Treatment of Patients with Epilepsy

One third of patients with epilepsy will continue to have uncontrolled seizures despite treatment with antiseizure medications (ASMs). There is therefore a need to develop novel ASMs. Brivaracetam (BRV) is an ASM that was developed in a major drug discovery program aimed at identifying selective, high-affinity synaptic vesicle protein 2A (SV2A) ligands, the target molecule of levetiracetam. BRV binds to SV2A with 15- to 30-fold higher affinity and greater selectivity than levetiracetam. BRV has broad-spectrum antiseizure activity in animal models of epilepsy, a favorable pharmacokinetic profile, few clinically relevant drug-drug interactions, and rapid brain penetration. BRV is available in oral and intravenous formulations and can be initiated at target dose without titration. Efficacy and safety of adjunctive BRV (50-200 mg/day) treatment of focal-onset seizures was demonstrated in three pivotal phase III trials (NCT00490035/NCT00464269/NCT01261325), including in patients who had previously failed levetiracetam. Efficacy and safety of adjunctive BRV were also demonstrated in adult Asian patients with focal-onset seizures (NCT03083665). In several open-label trials (NCT00150800/NCT00175916/NCT01339559), long-term safety and tolerability of adjunctive BRV was established, with efficacy maintained for up to 14 years, with high retention rates. Evidence from daily clinical practice highlights BRV effectiveness and tolerability in specific epilepsy patient populations with high unmet needs: the elderly (≥ 65 years of age), children (< 16 years of age), patients with cognitive impairment, patients with psychiatric comorbid conditions, and patients with acquired epilepsy of specific etiologies (post-stroke epilepsy/brain tumor related epilepsy/traumatic brain injury-related epilepsy). Here, we review the preclinical profile and clinical benefits of BRV from pivotal trials and recently published evidence from daily clinical practice.

Comparative analysis of adverse drug reactions associated with new antiseizure medications from the Korea Adverse Event Reporting System database

OBJECTIVE

This study aimed to compare and characterize the safety profiles of new antiseizure medications (ASMs) using a nationwide pharmacovigilance database from a long-term perspective in Korea.

METHODS

We reviewed adverse event reports from the Korea Adverse Event Reporting System database between January 2013 and December 2022 for descriptive analysis of six new ASMs (lacosamide, levetiracetam, lamotrigine, oxcarbazepine, topiramate, and zonisamide). We investigated the frequency and characteristics of adverse drug reactions (ADRs) based on the MedDRA terminology, system organ classes, and modified WHO classification.

RESULTS

We identified 5,733 reported cases of ADRs. The commonly reported ADRs associated with total ASMs were rash/urticaria (1,822, 31.8 %), dizziness (409, 7.1 %), somnolence/drowsiness (311, 5.4 %), and hepatotoxic effects (273, 4.8 %). Type B (idiosyncratic) effects (2,932; 51.1 %) were more commonly reported than Type A (related to known drug mechanisms) effects (2,613; 45.6 %). Skin and subcutaneous tissue disorders and type B effects were most commonly reported for lamotrigine and oxcarbazepine, whereas nervous system disorders and type A effects were most commonly reported for lacosamide, topiramate, and zonisamide. The pediatric group (<18 years) exhibited skin and subcutaneous tissue disorders and type B effects relatively more frequently than the adult and older adult groups.

CONCLUSION

Hypersensitivity skin reactions and type B effects remained significant ADRs in the new ASMs; however, type A effects were more commonly reported in some ASMs. The pediatric group showed a higher rate of type B effects. Overall, new ASMs should also be used with caution.

Real-world analysis of retention on cenobamate in patients with epilepsy in the United States

BACKGROUND

This retrospective, observational study used US claims data to assess retention rates on cenobamate compared with four branded antiseizure medications (ASMs) in patients with epilepsy.

METHODS

Adults (≥18 years) with prevalent epilepsy (ICD-10 code G40.xx) and ≥ 1 prescription for cenobamate or any of the newer branded ASMs (brivaracetam, eslicarbazepine, lacosamide, or perampanel) between May 1, 2020 and December 31, 2021 were identified from the HealthVerity Marketplace database. At least 360 days of continuous enrollment was required before and after the index date (Day 1 of initiating cenobamate or branded ASM). Patients were followed until cessation of cenobamate or branded ASM or the end of data collection using Kaplan-Meier methods. Retention was compared between cenobamate and the branded ASMs (both as a group and individually) using Chi-square tests.

RESULTS

In total, 4109 patients were included (195 cenobamate; 3914 branded ASMs). A higher proportion of patients in the cenobamate group compared with the branded ASMs group had concurrent focal and generalized epilepsy (65.6% vs 40.0%) and were on ≥ 3 concomitant ASMs (48.2% vs 12.8%) at the index date. Median time to discontinuation (i.e., the time that half the patients discontinued) was not quite reached after 12 months in the cenobamate group (50.3% of patients remained on cenobamate) and was 7.7 months in the branded ASMs group. Retention was significantly higher with cenobamate vs the branded ASMs group (p = 0.04545) and vs the individual ASMs lacosamide (p = 0.03044) and perampanel (p = 0.01558). Twelve-month retention rates (95% confidence intervals) were 50.3% (43.1%-57.0%) for cenobamate, 40.5% (38.9%-42.0%) for branded ASMs overall, 42.3% (38.6%-46.0%) for brivaracetam, 44.1% (39.2%-49.0%) for eslicarbazepine, 39.9% (38.0%-41.8%) for lacosamide, and 36.8% (31.9%-41.8%) for perampanel.

CONCLUSIONS

In this real-world analysis, retention was significantly higher with cenobamate vs a pooled group of four branded ASMs despite a greater frequency of patients in the cenobamate group having characteristics of more difficult-to-treat epilepsy.

Further advances in epilepsy

In 2017, one of us reviewed advances in epilepsy (Manford in J Neurol 264:1811-1824, 2017). The current paper brings that review up to date and gives a slight change in emphasis. Once again, the story is of evolution rather than revolution. In recognition that most of our current medications act on neurotransmitters or ion channels, and not on the underlying changes in connectivity and pathways, they have been renamed as antiseizure (ASM) medications rather than antiepileptic drugs. Cenobamate is the one newly licensed medication for broader use in focal epilepsy but there have been a number of developments for specific disorders. We review new players and look forward to new developments in the light of evolving underlying science. We look at teratogenicity; old villains and new concerns in which clinicians play a vital role in explaining and balancing the risks. Medical treatment of status epilepticus, long without evidence, has benefitted from high-quality trials to inform practice; like buses, several arriving at once. Surgical treatment continues to be refined with improvements in the pre-surgical evaluation of patients, especially with new imaging techniques. Alternatives including stereotactic radiotherapy have received further focus and targets for palliative stimulation techniques have grown in number. Individuals' autonomy and quality of life continue to be the subject of research with refinement of what clinicians can do to help persons with epilepsy (PWE) achieve control. This includes seizure management but extends to broader considerations of human empowerment, needs and desires, which may be aided by emerging technologies such as seizure detection devices. The role of specialist nurses in improving that quality has been reinforced by specific endorsement from the International League against Epilepsy (ILAE).

Comparison of the retention rate, safety, and efficacy of two different titration protocols for lamotrigine in newly diagnosed epilepsy patients

OBJECTIVES

To evaluate and compare the retention rate, safety, and efficacy of two different lamotrigine (LTG) titration protocols for newly diagnosed epilepsy patients.

METHODS

We retrospectively evaluated newly diagnosed epilepsy patients taking LTG from January 2012 to December 2021. In one titration protocol, LTG was taken once daily; in the other, LTG was taken twice daily. Clinical characteristics, seizure outcomes, adverse effects and patient retention rates were evaluated.

RESULTS

A total of 193 patients were included. There was no significant difference in seizure outcomes or adverse effects between patients treated with LTG once daily and twice daily. However, the retention rates were significantly higher in the once-daily group than in the twice-daily group (73.03% and 55.77%, respectively).

CONCLUSION

The effectiveness and safety of LTG were not significantly different between the two different LTG titration protocols groups. However, the retention rate of the patients treated with LTG once daily was higher than that of the patients treated with LTG twice daily.

Long-term cannabidiol treatment for seizures in patients with tuberous sclerosis complex: An open-label extension trial

Objective

To evaluate the long‐term safety and efficacy of add‐on cannabidiol (CBD) in patients with seizures associated with tuberous sclerosis complex (TSC) in the open‐label extension (OLE) of the randomized, placebo‐controlled phase 3 trial GWPCARE6 (NCT02544763). Results of an interim (February 2019 data cut) analysis are reported.

Methods

Patients who completed the randomized trial enrolled to receive CBD (Epidiolex^® in the United States; Epidyolex^® in the EU; 100 mg/mL oral solution). The initial target dose was 25 mg/kg/day, which, based on response and tolerability, could be decreased or increased up to 50 mg/kg/day. The primary end point was safety. Key secondary end points included percentage reduction in TSC‐associated (countable focal and generalized) seizures, responder rates, and Subject/Caregiver Global Impression of Change (S/CGIC).

Results

Of 201 patients who completed the randomized phase, 199 (99%) entered the OLE. Mean age was 13 years (range, 1–57). At the time of analysis, 5% of patients had completed treatment, 20% had withdrawn, and 75% were ongoing. One‐year retention rate was 79%. Median treatment time was 267 days (range, 18–910) at a 27 mg/kg/day mean modal dose. Most patients (92%) had an adverse event (AE). Most common AEs were diarrhea (42%), seizure (22%), and decreased appetite (20%). AEs led to permanent discontinuation in 6% of patients. There was one death that was deemed treatment unrelated by the investigator. Elevated liver transaminases occurred in 17 patients (9%) patients; 12 were taking valproate. Median percentage reductions in seizure frequency (12‐week windows across 48 weeks) were 54%–68%. Seizure responder rates (≥50%, ≥75%, 100% reduction) were 53%–61%, 29%–45%, and 6%–11% across 12‐week windows for 48 weeks. Improvement on the S/CGIC scale was reported by 87% of patients/caregivers at 26 weeks.

Significance

In patients with TSC, long‐term add‐on CBD treatment was well tolerated and sustainably reduced seizures through 48 weeks, with most patients/caregivers reporting global improvement.

Long-term efficacy and safety of perampanel as a first add-on therapy in patients with focal epilepsy: Three-year extension study

PURPOSE

We investigated the long-term efficacy and safety of perampanel as a first add-on therapy in patients with focal epilepsy.

METHODS

This retrospective study represented the 3-year extension phase of a multicenter, open-label, phase 4, prospective study of perampanel as a first add-on therapy in patients with focal epilepsy. Seizure and safety outcomes were assessed annually from the start of the extension study, and the retention rate was calculated from the start of perampanel exposure in the original study.

RESULTS

The 50% responder and seizure freedom rates were 84.8% and 58.7%, respectively, during the third year and 71.7% and 32.6%, respectively, during the entire 3-year period of the extension study. The 1-, 2-, and 3-year retention rates were 62.5%, 53.1%, and 52.1%, respectively. Efficacies were higher in patients that were aged >55 years, male, and receiving ≤4 mg of perampanel. Perampanel was generally well tolerated; 47.3% of patients experienced at least one adverse event during the 3 years of extension (46 adverse events (AEs) in 35 patients). The most common AEs were dizziness (33.8%), somnolence (5.4%), anger (4.1%), and irritability (4.1%). AEs were resolved with perampanel dose reduction or discontinuation in 10 (13.5%) and 12 (16.2%) patients, respectively.

CONCLUSION

Long-term treatment with perampanel as a first add-on therapy did not raise new safety signals in patients with focal epilepsy. Especially at low perampanel doses (≤4 mg/day), sustained improvement in seizure control was achieved, which could potentially avoid adverse drug reactions.

Epilepsy Treatment Complacency in Patients, Caregivers, and Health Care Professionals

Objective

To explore the perspectives of adult patients with epilepsy, caregivers, and health care professionals (HCPs) on treatment for seizures and treatment decisions, we developed and administered the STEP Survey (Seize the Truth of Epilepsy Perceptions).

Methods

Participants were recruited from online panel M3 and by Rare Patient Voice and completed the self-administered online STEP Survey. Analysis of variance and chi-square tests were used for group comparisons.

Results

The STEP Survey was completed by 400 adult patients, 201 caregivers, and 258 HCPs. Patients estimated reporting 45% of their seizures to their HCP, whereas caregivers estimated 83% and HCPs estimated 73% were reported. The most common reason for not reporting seizures was that the seizures were not serious enough to mention (patients 57%; caregivers 66%). A minority of patients (25%) and caregivers (30%) were very or extremely likely to ask their HCP about changing antiseizure medication (ASM) in the next 12 months. The HCP was most frequently selected by patients, caregivers, and HCPs as the person who initiates discussion of changing ASMs (patients 73%/caregivers 66%/HCPs 75%) and increasing ASM dosage (patients 77%/caregivers 68%/HCPs 81%). A majority of patients (65%) and caregivers (68%) somewhat or strongly agreed that they do not change ASMs due to fear of getting worse. HCPs perceive this fear less often, stating that 50% of their patients feel afraid when a second ASM was added.

Conclusions

Improved reporting of all seizures, discussion of treatment changes, and the impact of fear on treatment decisions provide opportunities to reduce complacency and optimize patient outcomes.

Long-term individual retention with cenobamate in adults with focal seizures: Pooled data from the clinical development program

Objective

We determined retention on open‐label cenobamate therapy in the clinical development program to assess the long‐term efficacy and tolerability of adjunctive cenobamate in individuals with uncontrolled focal seizures.

Methods

Data from two randomized, controlled cenobamate studies and one open‐label safety and pharmacokinetic study were pooled. Based on the percentage of participants remaining on treatment, retention rates were estimated using Kaplan‐Meier survival analyses. We performed two additional analyses to assess factors contributing to retention, stratifying a robust data set (through 2 years) by cenobamate modal dose and frequently used concomitant anti‐seizure medications. Cenobamate discontinuations and treatment‐emergent adverse events were summarized.

Results

Data from 1844 participants were pooled: 149 from a single‐dose randomized trial, 355 from a multi‐dose randomized trial, and 1340 from an open‐label safety and pharmacokinetic study. Most participants from randomized trials continued in open‐label extensions, and pooled data represent >95% of participants exposed to cenobamate. Baseline characteristics and disease and treatment histories were similar across studies. Median duration of cenobamate exposure was 34 months, with a median modal dose of 200 mg/day. Kaplan‐Meier estimates of cumulative cenobamate retention rates were 80% at 1 year and 72% at 2 years. Once participants reached the maintenance phase, retention rates were consistently high in participants receiving ≥100 mg/day cenobamate, and concomitant anti‐seizure medications did not affect long‐term retention. By 2 years, 535 (29%) had actually discontinued cenobamate; the most common reasons for discontinuation were adverse events (37.6%), withdrawal of consent (21.1%), and other (16.8%).

Significance

Treatment retention rates provide a proxy measure for long‐term efficacy, safety, tolerability, and adherence. The consistently high retention rates we found suggest that cenobamate may be an effective and well‐tolerated new treatment option for people with drug‐resistant focal seizures.

Long-term efficacy, tolerability, and retention of brivaracetam in epilepsy treatment: A longitudinal multicenter study with up to 5 years of follow-up

OBJECTIVE

This study was undertaken to evaluate the long-term efficacy, retention, and tolerability of add-on brivaracetam (BRV) in clinical practice.

METHODS

A multicenter, retrospective cohort study recruited all patients who initiated BRV between February and November 2016, with observation until February 2021.

RESULTS

Long-term data for 262 patients (mean age = 40 years, range = 5-81 years, 129 men) were analyzed, including 227 (87%) diagnosed with focal epilepsy, 19 (7%) with genetic generalized epilepsy, and 16 (6%) with other or unclassified epilepsy syndromes. Only 26 (10%) patients had never received levetiracetam (LEV), whereas 133 (50.8%) were switched from LEV. The length of BRV exposure ranged from 1 day to 5 years, with a median retention time of 1.6 years, resulting in a total BRV exposure time of 6829 months (569 years). The retention rate was 61.1% at 12 months, with a reported efficacy of 33.1% (79/239; 50% responder rate, 23 patients lost-to-follow-up), including 10.9% reported as seizure-free. The retention rate for the entire study period was 50.8%, and at last follow-up, 133 patients were receiving BRV at a mean dose of 222 ± 104 mg (median = 200, range = 25-400), including 52 (39.1%) who exceeded the recommended upper dose of 200 mg. Fewer concomitant antiseizure medications and switching from LEV to BRV correlated with better short-term responses, but no investigated parameters correlated with positive long-term outcomes. BRV was discontinued in 63 (24%) patients due to insufficient efficacy, in 29 (11%) for psychobehavioral adverse events, in 25 (10%) for other adverse events, and in 24 (9%) for other reasons.

SIGNIFICANCE

BRV showed a clinically useful 50% responder rate of 33% at 12 months and overall retention of >50%, despite 90% of included patients having previous LEV exposure. BRV was well tolerated; however, psychobehavioral adverse events occurred in one out of 10 patients. Although we identified short-term response and retention predictors, we could not identify significant predictors for long-term outcomes.

Add-on cannabidiol in patients with Dravet syndrome: Results of a long-term open-label extension trial

OBJECTIVE

Add-on cannabidiol (CBD) reduced seizures associated with Dravet syndrome (DS) in two randomized, double-blind, placebo-controlled trials: GWPCARE1 Part B (NCT02091375) and GWPCARE2 (NCT02224703). Patients who completed GWPCARE1 Part A (NCT02091206) or Part B, or GWPCARE2, were enrolled in a long-term open-label extension trial, GWPCARE5 (NCT02224573). We present an interim analysis of the safety, efficacy, and patient-reported outcomes from GWPCARE5.

METHODS

Patients received a pharmaceutical formulation of highly purified CBD in oral solution (100 mg/ml), titrated from 2.5 to 20 mg/kg/day over a 2-week period, added to their existing medications. Based on response and tolerance, CBD could be reduced or increased to 30 mg/kg/day.

RESULTS

Of the 330 patients who completed the original randomized trials, 315 (95%) enrolled in this open-label extension. Median treatment duration was 444 days (range = 18-1535), with a mean modal dose of 22 mg/kg/day; patients received a median of three concomitant antiseizure medications. Adverse events (AEs) occurred in 97% patients (mild, 23%; moderate, 50%; severe, 25%). Commonly reported AEs were diarrhea (43%), pyrexia (39%), decreased appetite (31%), and somnolence (28%). Twenty-eight (9%) patients discontinued due to AEs. Sixty-nine (22%) patients had liver transaminase elevations >3 × upper limit of normal; 84% were on concomitant valproic acid. In patients from GWPCARE1 Part B and GWPCARE2, the median reduction from baseline in monthly seizure frequency assessed in 12-week periods up to Week 156 was 45%-74% for convulsive seizures and 49%-84% for total seizures. Across all visit windows, ≥83% patients/caregivers completing a Subject/Caregiver Global Impression of Change scale reported improvement in overall condition.

SIGNIFICANCE

We show that long-term CBD treatment had an acceptable safety profile and led to sustained, clinically meaningful reductions in seizure frequency in patients with treatment-resistant DS.

Long-term safety of adjunctive cenobamate in patients with uncontrolled focal seizures: Open-label extension of a randomized clinical study

Objective

This study was undertaken to examine long‐term (up to 7.8 years) retention rate, safety, and tolerability of the antiseizure medication (ASM) cenobamate as adjunctive treatment in the open‐label extension (OLE) of study YKP3089C013 (C013; ClinicalTrials.gov: NCT01397968).

Methods

Patients who completed the 12‐week, multicenter, multinational, double‐blind, randomized, placebo‐controlled C013 study, which examined adjunctive cenobamate treatment of adults with uncontrolled focal seizures, were eligible to enroll in the OLE. During the OLE, dose adjustments of cenobamate and concomitant ASMs were allowed. Safety assessments included frequency of treatment‐emergent adverse events (TEAEs) and serious TEAEs, TEAE severity, and TEAEs leading to discontinuation. Probability of patient continuation in the OLE was examined using a Kaplan–Meier analysis.

Results

One hundred forty‐nine patients entered the OLE (median duration of cenobamate treatment = 6.25 years). As of the data cutoff, 57% of patients (85/149) remained in the OLE (median treatment duration = 6.8 years, range = 6.4–7.8 years). The median modal daily cenobamate dose was 200 mg (range = 50–400 mg). The probability of treatment continuation at 1–6 years of cenobamate treatment was 73%, 67%, 63%, 61%, 60%, and 59%, respectively. Among patients who continued at 1 year (n = 107), the probability of continuing at Years 2–5 was 92%, 87%, 83%, and 82%. The most common discontinuation reasons were patient withdrawal (19.5%, 29/149), adverse event (10.1%, 15/149), and lack of efficacy (5.4%, 8/149). TEAEs leading to discontinuation in 1% or more of patients were fatigue (1.3%, 2/149), ataxia (1.3%, 2/149), and memory impairment or amnesia (1.3%, 2/149). Dizziness (32.9%, 49/149), headache (26.8%, 40/149), and somnolence (21.5%, 32/149) were the most frequently reported TEAEs and were primarily mild or moderate in severity.

Significance

Long‐term retention in the C013 OLE study demonstrated sustained safety and tolerability of adjunctive cenobamate treatment up to 7.8 years in adults with treatment‐resistant focal seizures taking one to three ASMs.

Long-term safety, efficacy, and quality of life during adjunctive brivaracetam treatment in patients with uncontrolled epilepsy: An open-label follow-up trial

OBJECTIVES

The primary objective of this long-term follow-up (LTFU) trial was to evaluate the long-term safety and tolerability of brivaracetam (BRV). The secondary objective was to evaluate the maintenance of efficacy of BRV (including quality of life) over time.

METHODS

This open-label, multicenter, flexible-dose trial (N01379 [NCT01339559]) was conducted in adults (≥16 years) with focal or generalized-onset seizures, who had participated in a placebo (PBO)-controlled trial of adjunctive BRV (N01258: NCT01405508 or N01358: NCT01261325).

RESULTS

Seven hundred and sixty-six patients received BRV in this LTFU trial (753 had focal seizures and 13 had generalized-onset seizures). Kaplan-Meier-estimated retention was 71.9% at 12 months, and 53.7% at 36 months. Treatment-emergent adverse events (TEAEs) were reported by 643 (83.9%) patients, most commonly headache (104 [13.6%] patients) and dizziness (100 [13.1%] patients). Two hundred and fifty-seven (33.6%) patients had drug-related TEAEs, most commonly somnolence (49 [6.4%] patients) and dizziness (41 [5.4%] patients). Permanent discontinuation of BRV due to TEAEs occurred in 91 (11.9%) patients. Patients with focal seizures had a median percentage reduction in focal seizure frequency of 52.0% and 51.7% were 50% responders (sustained over time); 26.0% were seizurefree for 6 months, and 17.9% were seizurefree for 12 months. 42.4% of patients at 12 months and 46.8% at 24 months had clinically meaningful improvements in Patient Weighted Quality of Life in Epilepsy Questionnaire 31 total score.

CONCLUSIONS

In this select group of patients who entered the LTFU trial, BRV was generally safe and well tolerated. Results indicate the long-term efficacy of BRV in patients with focal seizures.

Comparison of the Therapeutic Effects of Sodium Valproate and Levetiracetam on Pediatric Epilepsy and the Effects of Nerve Growth Factor and γ-Aminobutyric Acid

Background:

We aimed to investigate the therapeutic effect of sodium valproate combined with levetiracetam on pediatric epilepsy and the effects of nerve growth factor and γ-aminobutyric acid.

Methods:

Eighty-three epileptic children admitted to Xuzhou Municipal Hospital of Xuzhou Medical University (Xuzhou, China) from Jan 2018 to Nov 2019 were collected and divided into a control group (40 cases, treated with sodium valproate alone) and an observation group (43 cases, treated with sodium valproate combined with levetiracetam). The therapeutic effect and incidence of adverse reactions were observed. The levels of nerve growth factor (NGF), γ-aminobutyric acid (GABA) and serum neuron-specific enolase (NSE) of children were compared. Changes of cognitive function and the total effective rate were evaluated. Logistic regression analysis was used to analyze the risk factors affecting the therapeutic effect.

Results:

After treatment, NGF, GABA and NSE in the observation group were significantly improved compared with those before treatment. The cognitive function of the observation group was significantly improved after treatment when compared with the control group. The total effective rate in the observation group was higher than that in the control group. Adverse reactions in the observation group were less than those in the control group. Seizure type, NGF, GABA, NSE and treatment methods were independent risk factors affecting the therapeutic effect of pediatric epilepsy.

Conclusion:

The application of sodium valproate combined with levetiracetam in the treatment of pediatric epilepsy is helpful to improve the overall therapeutic effect, significantly improve the cognitive function of children, and improve the levels of NGF, GABA and NSE.

Critical Appraisal of Cenobamate as Adjunctive Treatment of Focal Seizures in Adults

Cenobamate (CNB) is the latest antiseizure medication (ASM) authorized for the treatment of focal-onset seizures in adults. Although the precise mechanism of action of CNB is not yet fully understood, this drug inhibits the persistent, rather than transient, voltage-gated sodium channel currents and is a positive allosteric modulator of synaptic and extrasynaptic GABA_A receptors, differently from benzodiazepines. CNB has a non-linear pharmacokinetic with a terminal half-life range of about 50/60 hours within the therapeutic dose range, which allows once daily administration. Cenobamate inhibits cytochrome P450 (CYP) 2C19 and induces CYP3A4 and 2B6, and hence can potentially interact with ASMs (eg, phenytoin, carbamazepine and clobazam) and no-ASMs drugs. In two randomized, double-blind, placebo-controlled trials in patients with focal epilepsies, CNB has shown a particularly good efficacy with a rate of seizure freedom of about 20% during the maintenance period in participants treated with the dose of 400 mg/day. The most common treatment-emergent adverse effects include central nervous system-related symptoms, like dizziness, diplopia, somnolence, and gait disturbances. Safety issues of particular interest are severe skin reactions (drug reaction with eosinophilia and systemic symptoms) and QT shortening, which contraindicates its use in subjects with familial short QT syndrome or in combination with other QT-shortening drugs. The recommended starting dose is 12.5 mg/day, which can be gradually titrated to the target dose (200 mg/day) and further increased up to 400 mg/day. There are several aspects of CNB that need to be still addressed, including the long-term efficacy and the efficacy in patients with generalized seizures. Ongoing studies will clarify these issues. The clinical relevance of the peculiar pharmacokinetics and the pattern of drug-drug interactions also require further investigation.

Cost-Effectiveness of Cannabidiol Adjunct Therapy versus Usual Care for the Treatment of Seizures in Lennox-Gastaut Syndrome

BACKGROUND

Cannabidiol (CBD) is a novel therapy for the treatment of Lennox-Gastaut Syndrome (LGS), a rare, treatment-refractory epileptic encephalopathy. Two pivotal trials found CBD 20 mg/kg/day conferred a reduction from baseline in median drop seizure frequency of 44% and 42%, respectively, compared with 22% and 17%, respectively, in the usual care arms. No economic evaluations have been published to date. This analysis assessed the cost effectiveness of CBD adjunct therapy compared with usual care alone in LGS from the US payer perspective.

METHODS

We developed a lifetime horizon Markov decision analytic model. Efficacy, healthcare costs (2020 US$), and health state utilities were ascertained from published clinical trials, retrospective analyses, and time trade-off interviews conducted in the UK, respectively. Fifteen-year-old patients entering the model transitioned to states representing a percentage reduction in drop seizure frequency from baseline, where they remained until reverting back to baseline drop seizure frequency, or death. One-way and probabilistic sensitivity analyses were conducted to evaluate parameter uncertainty, and scenario analyses investigated the impact of various assumptions. Costs and outcomes were discounted at 3%.

RESULTS

Compared with usual care alone, CBD yielded 0.7 additional quality-adjusted life-years (QALYs) and $314,900 additional healthcare expenditure, resulting in $451,800 per QALY. Uncertainty in health state utilities were the largest contributor to uncertainty in the results. Results from the 5000-simulation probabilistic sensitivity analysis indicated a 0% chance of CBD being cost effective at a $150,000 per QALY willingness-to-pay threshold, with a 95% credible range for the incremental cost-effectiveness ratio of $325,300-$690,000 per QALY.

CONCLUSION

CBD does not appear to be a cost-effective therapeutic option in LGS patients at a willingness-to-pay threshold of $150,000/QALY.

Long-term safety, efficacy, and quality of life outcomes with adjunctive brivaracetam treatment at individualized doses in patients with epilepsy: An up to 11-year, open-label, follow-up trial

Objective

To evaluate long‐term safety/tolerability of brivaracetam at individualized doses ≤200 mg/d (primary) and maintenance of efficacy over time (secondary) in adults with focal seizures or primary generalized seizures (PGS) enrolled in phase 3, open‐label, long‐term follow‐up trial N01199 (NCT00150800).

Methods

Patients ≥16 years of age who had completed double‐blind, placebo‐controlled adjunctive brivaracetam trials NCT00175825, NCT00490035, NCT00464269, or NCT00504881 were eligible. Outcomes included safety, efficacy, and quality of life.

Results

The safety set included 667 patients (focal seizures, 97.8%; PGS, 2.2%); the efficacy set included 648 patients with focal seizures and 15 patients with PGS. Overall, 49.2% of patients had ≥48 months of exposure. Treatment‐emergent adverse events (TEAEs) occurred in 91.2% of all patients (91.3% of focal seizures group), brivaracetam discontinuation due to TEAEs in 14.8%, drug‐related TEAEs in 56.7%, and serious TEAEs in 22.8%. The most common TEAEs in the focal seizures group (≥15%) were headache (25.3%) and dizziness (21.9%). Mean changes from baseline in Hospital Anxiety and Depression Scale scores at last value during 2‐year evaluation were −0.7 (standard deviation [SD] = 4.3) and −0.2 (SD = 4.4) overall. In the focal seizures group, median reduction from baseline in focal seizure frequency/28 days was 57.3%, 50% responder rate was 55.6%, and 6‐month and 12‐month seizure freedom rates were 30.3% and 20.3%, respectively. Efficacy outcomes improved by exposure duration cohort and then stabilized through the 108‐month cohort. Mean improvement from baseline in Patient‐Weighted Quality of Life in Epilepsy Inventory total score (efficacy set) was 5.7 (SD = 16.1, Cohen's d = 0.35) at month 12 and 6.5 (SD = 18.0, Cohen's d = 0.36) at month 24.

Significance

Adjunctive brivaracetam was well tolerated, with a good safety profile in long‐term use in adults with epilepsy at individualized doses. Approximately half of the patients remained in the trial at 4 years. Brivaracetam reduced focal seizure frequency versus baseline. Efficacy improved with increasing exposure duration and remained stable through the 9‐year cohort.

Long-term safety, tolerability, and efficacy of magnesium valproate versus sodium valproate in acute seizures

Objectives: To evaluate the safety, tolerability and efficacy of magnesium valproate and sodium valproate as monotherapies in patients with epilepsy in China.Methods: We recruited patients admitted with seizures over a two-year period. All patients underwent early neurological assessments, electroencephalogram testing, and neuroimaging. The treatments received at baseline and at one year of follow-up were compared.Results: In total, 175 patients were included. The retention rates of the magnesium valproate and sodium valproate treatments were 73.1% and 64.2%, respectively. The main cause of discontinuation was the development of intolerable adverse events. The retention rate and total effective rate in the magnesium valproate group were significantly higher than those in the sodium valproate group (73.1% and 70.2% versus 64.2% and 47.2%, respectively). The safety endpoints included 120 patients (magnesium valproate: n = 67; sodium valproate: n = 53). The incidence of adverse events in the magnesium valproate group was significantly lower than that in the sodium valproate group (30% versus 51%).Conclusions: Magnesium valproate treatment shows favorable safety and tolerability and is associated with markedly improved seizure control. Ideally, future large, prospective, randomized, and double-blind studies are needed to confirm these findings.

Economic Value of Adjunctive Brivaracetam Treatment Strategy for Focal Onset Seizures in Finland

Introduction

There is an unmet need for well-tolerated antiepileptic drugs (AEDs) that effectively control focal onset seizures. This study aimed to evaluate the economic value of new AEDs in the treatment of focal onset seizure, with or without secondary generalization, in Finnish adults and adolescents with epilepsy, comparing brivaracetam with perampanel as adjunctive AEDs.

Methods

Economic value was assessed using cost-utility analysis. Periods of AED initiation, titration, response assessment (seizure freedom, ≥ 50% reduction, no response), switching in no response or treatment-emergent adverse events (TEAEs), and death were simulated using a discrete-event simulation model. Responses and switching were simulated based on a comprehensive Bayesian network meta-analysis. The primary modeled outcome was the 3%/year discounted incremental cost-effectiveness ratio (ICER). Discounted quality-adjusted life-years (QALYs), payer costs (year 2017 Euro) per patient, and net monetary benefit (NMB) were secondary outcomes. Probabilistic and comprehensive deterministic sensitivity analyses were conducted.

Results

Brivaracetam was more efficacious and had fewer TEAEs than perampanel and other AEDs. Modeled average 5-year QALYs and costs were 3.671 and €28,297 for brivaracetam and 3.611 and €27,979 for perampanel, respectively. The resulting ICER for brivaracetam versus perampanel was only €5345/QALY gained in a deterministic base case scenario. Brivaracetam had a positive NMB and high probability of cost-effectiveness of €1190 and 71% or €1944 and 80% with the assumed willingness to pay of €25,358 or €38,036/QALY gained, respectively. The primary result was robust, with a positive NMB persistent in all sensitivity analysis scenarios. When switching from brivaracetam to perampanel was excluded from the modeling or switching from perampanel to brivaracetam was included, brivaracetam was cost-saving and more effective than perampanel (dominant).

Conclusion

These simulated comparisons demonstrated that brivaracetam was more effective and potentially also more affordable than perampanel. Thus, brivaracetam is likely a cost-effective and net beneficial alternative to perampanel for treatment of focal onset seizures.

Plain Language Summary

Plain language summary available for this article.

Electronic supplementary material

The online version of this article (10.1007/s12325-019-01155-6) contains supplementary material, which is available to authorized users.

Cannabidiol in patients with Lennox-Gastaut syndrome: Interim analysis of an open-label extension study

Objective

Patients with Lennox‐Gastaut syndrome (LGS) who completed 1 of 2 randomized, double‐blind, placebo‐controlled trials of add‐on cannabidiol (CBD) (GWPCARE3, NCT02224560 or GWPCARE4, NCT02224690) were invited to enroll in an open‐label extension (OLE) study evaluating the long‐term safety and efficacy of CBD (GWPCARE5, NCT02224573). Herein we present an interim analysis of the safety, efficacy, and patient‐reported outcomes from this trial.

Methods

Patients received a pharmaceutical formulation of highly purified CBD oral solution (Epidiolex; 100 mg/mL), titrated from 2.5 to 20 mg/kg/d over a 2‐week titration period, in addition to their existing medications. Doses could be reduced if not tolerated or increased up to 30 mg/kg/d if thought to be of benefit.

Results

This interim analysis was based on a November 2016 data cut. Of 368 patients who completed treatment in GWPCARE3 and GWPCARE4, 366 (99.5%) enrolled in the OLE study (GWPCARE5). Median treatment duration was 38 weeks at a mean modal dose of 23 mg/kg/d. Most patients (92.1%) experienced adverse events (AEs), primarily of mild (32.5%) or moderate (43.4%) severity. The most common AEs were diarrhea (26.8%), somnolence (23.5%), and convulsion (21.3%). Thirty‐five patients (9.6%) discontinued treatment due to AEs. Liver transaminase elevations were reported in 37 patients (10.1%), of whom 29 were receiving concomitant valproic acid; 34 cases resolved spontaneously or with dose modification of CBD or concomitant medication. Median reduction from baseline in drop seizure frequency (quantified monthly over 12‐week periods) ranged from 48% to 60% through week 48. Median reduction in monthly total seizure frequency ranged from 48% to 57% across all 12‐week periods through week 48. Eighty‐eight percent of patients/caregivers reported an improvement in the patient's overall condition per the Subject/Caregiver Global Impression of Change scale.

Significance

In this study, long‐term add‐on CBD treatment had an acceptable safety profile in patients with LGS and led to sustained reductions in seizures.

Long-term cannabidiol treatment in patients with Dravet syndrome: An open-label extension trial

OBJECTIVE

Add-on cannabidiol (CBD) significantly reduced seizures associated with Dravet syndrome (DS) in a randomized, double-blind, placebo-controlled trial: GWPCARE1 Part B (NCT02091375). Patients who completed GWPCARE1 Part A (NCT02091206) or Part B, or a second placebo-controlled trial, GWPCARE2 (NCT02224703), were invited to enroll in a long-term open-label extension trial, GWPCARE5 (NCT02224573). We present an interim analysis of the safety, efficacy, and patient-reported outcomes from GWPCARE5.

METHODS

Patients received a pharmaceutical formulation of highly purified CBD in oral solution (100 mg/mL), titrated from 2.5 to 20 mg/kg/d over a 2-week period, with their existing medications. Based on response and tolerance, CBD could be reduced or increased up to 30 mg/kg/d.

RESULTS

By November 2016, a total of 278 patients had completed the original randomized trials, and 264 (95%) enrolled in this open-label extension. Median treatment duration was 274 days (range 1-512) with a mean modal dose of 21 mg/kg/d, and patients received a median of 3 concomitant antiepileptic medications. Adverse events (AEs) occurred in 93.2% of patients and were mostly mild (36.7%) or moderate (39.0%). Commonly reported AEs were diarrhea (34.5%), pyrexia (27.3%), decreased appetite (25.4%), and somnolence (24.6%). Seventeen patients (6.4%) discontinued due to AEs. Twenty-two of the 128 patients from GWPCARE1 (17.2%), all taking valproic acid, had liver transaminase elevations ≥3 times the upper limit of normal. In patients from GWPCARE1 Part B, the median reduction from baseline in monthly seizure frequency assessed in 12-week periods up to week 48 ranged from 38% to 44% for convulsive seizures and 39% to 51% for total seizures. After 48 weeks of treatment, 85% of patients/caregivers reported improvement in the patient's overall condition on the Subject/Caregiver Global Impression of Change scale.

SIGNIFICANCE

This trial shows that long-term CBD treatment had an acceptable safety profile and led to sustained, clinically meaningful reductions in seizure frequency in patients with treatment-resistant DS.

Long-term retention rates of antiepileptic drugs used in acute seizures

PURPOSE

A number of antiepileptic drugs (AEDs) are currently available for treating acute seizures. It is recommended to select the initial treatment option according to the type of epileptic syndrome and the patient's clinical characteristics, but little is known about the long-term retention rates of AEDs started in the emergency department.

METHODS

We recruited patients admitted with seizures over a two-year period. All patients underwent early neurological assessment, EEG testing, and neuroimaging. The treatments received at baseline and at one year of follow-up were compared.

RESULTS

In total, 225 patients were included. Overall, monotherapy with levetiracetam was the regimen most often used in patients with new-onset seizures, whereas other AEDs were mainly used in patients previously treated with other drugs. Lacosamide use was most likely associated with the presence of lesion related seizures in elderly patients, and carboxamides with focal onset seizures of unknown cause. The mean retention rate of the total of AED treatments was nearly 70%. The main cause leading to discontinuation was the development of intolerable adverse events. Levetiracetam use decreased as lacosamide use increased in the overall group of patients.

CONCLUSION

Our study shows that there is a trend to use newer AEDs, particularly levetiracetam, as the first option in new-onset seizures in the emergency room. However, levetiracetam use significantly decreased over follow-up, mainly because of the development of adverse events. The use of other, better-tolerated AEDs, such lacosamide predominated in elderly patients and patients with lesion related seizures, or carboxamides in epilepsies of unknown etiology.

Long-term safety and treatment effects of cannabidiol in children and adults with treatment-resistant epilepsies: Expanded access program results

Objective

Since 2014, cannabidiol (CBD) has been administered to patients with treatment‐resistant epilepsies (TREs) in an ongoing expanded‐access program (EAP). We report interim results on the safety and efficacy of CBD in EAP patients treated through December 2016.

Methods

Twenty‐five US‐based EAP sites enrolling patients with TRE taking stable doses of antiepileptic drugs (AEDs) at baseline were included. During the 4‐week baseline period, parents/caregivers kept diaries of all countable seizure types. Patients received oral CBD starting at 2‐10 mg/kg/d, titrated to a maximum dose of 25‐50 mg/kg/d. Patient visits were every 2‐4 weeks through 16 weeks and every 2‐12 weeks thereafter. Efficacy endpoints included the percentage change from baseline in median monthly convulsive and total seizure frequency, and percentage of patients with ≥50%, ≥75%, and 100% reductions in seizures vs baseline. Data were analyzed descriptively for the efficacy analysis set and using the last‐observation‐carried‐forward method to account for missing data. Adverse events (AEs) were documented at each visit.

Results

Of 607 patients in the safety dataset, 146 (24%) withdrew; the most common reasons were lack of efficacy (89 [15%]) and AEs (32 [5%]). Mean age was 13 years (range, 0.4‐62). Median number of concomitant AEDs was 3 (range, 0‐10). Median CBD dose was 25 mg/kg/d; median treatment duration was 48 weeks. Add‐on CBD reduced median monthly convulsive seizures by 51% and total seizures by 48% at 12 weeks; reductions were similar through 96 weeks. Proportion of patients with ≥50%, ≥75%, and 100% reductions in convulsive seizures were 52%, 31%, and 11%, respectively, at 12 weeks, with similar rates through 96 weeks. CBD was generally well tolerated; most common AEs were diarrhea (29%) and somnolence (22%).

Significance

Results from this ongoing EAP support previous observational and clinical trial data showing that add‐on CBD may be an efficacious long‐term treatment option for TRE.

Comparing Safety and Efficacy of "Third-Generation" Antiepileptic Drugs: Long-Term Extension and Post-marketing Treatment

Four "third-generation" antiepileptic drugs (AEDs) were approved for adjunctive treatment of refractory focal onset seizures during the past 10 years. Long-term efficacy and safety of the drugs were demonstrated in large extension studies and in reports of subgroups of patients not studied in pivotal trials. Reviewing extension study and post-marketing outcome series for the four newer AEDs-lacosamide, perampanel, eslicarbazepine acetate and brivaracetam-can guide clinicians in treating and monitoring patients. AED extension studies evaluate treatment retention, drug tolerability, and drug safety during individualized treatment with flexible dosing and thus provide information not available in rigid pivotal trials. Patient retention in the studies ranged from 75 to 80% at 1 year and from 36 to 68% at 2-year treatment intervals. Safety findings were generally similar to those of pivotal trials, with no major safety risks identified and with several specific adverse drug effects, such as hyponatremia, reported. The third-generation AEDs, some through new mechanisms and others with improved tolerability compared to related AEDs, provide new options in efficacy and tolerability.