Efficacy of Mirogabalin (DS-5565) on Patient-Reported Pain and Sleep Interference in Patients with Diabetic Neuropathic Pain: Secondary Outcomes of a Phase II Proof-of-Concept Study

Pharmacological and Nonpharmacological Treatments for Painful Diabetic Peripheral Neuropathy

Diabetic peripheral neuropathy (DPN) is one of the most prevalent chronic complications of diabetes. The lifetime prevalence of DPN is thought to be >50%, and 15%-25% of patients with diabetes experience neuropathic pain, referred to as "painful DPN." Appropriate treatment of painful DPN is important because this pain contributes to a poor quality of life by causing sleep disturbance, anxiety, and depression. The basic principle for the management of painful DPN is to control hyperglycemia and other modifiable risk factors, but these may be insufficient for preventing or improving DPN. Because there is no promising diseasemodifying medication for DPN, the pain itself needs to be managed when treating painful DPN. Drugs for neuropathic pain, such as gabapentinoids, serotonin-norepinephrine reuptake inhibitors, tricyclic antidepressants, alpha-lipoic acid, sodium channel blockers, and topical capsaicin, are used for the management of painful DPN. The U.S. Food and Drug Administration (FDA) has approved pregabalin, duloxetine, tapentadol, and the 8% capsaicin patch as drugs for the treatment of painful DPN. Recently, spinal cord stimulation using electrical stimulation is approved by the FDA for the treatment for painful DPN. This review describes the currently available pharmacological and nonpharmacological treatments for painful DPN.

The Clinical Application and Progress of Mirogabalin on Neuropathic Pain as a Novel Selective Gabapentinoids

Background

Neuropathic pain is a complex sort of pain that is detrimental to individuals' health, both physically and mentally, but merely a small portion of them could witness pain alleviation. Mirogabalin, by distinctive binding characteristics of voltage-gated calcium channels, has won approval from the Japanese authority as a third member of gabapentinoids in Japan. Our review was aimed at encompassing the bulk of clinical research on mirogabalin, which included clinical trials, special considerations, coadministration studies, case reports, and cost-effectiveness studies.

Methods

A review was carried out on a series of platforms, such as PubMed, MEDLINE, and Scopus, up to December 2021 using the keywords as follows: "mirogabalin OR mirogabalin besylate OR Tarlige OR DS-5565" AND "neuropathic pain OR Neuropathy."

Results

Mirogabalin demonstrated analgesic activity and manageable adverse reactions and provides a new alternative for individuals with PHN or DPNP in 3 phase II and 4 III trials. Mirogabalin alleviated pain markedly in comparison with placebo. Administration of mirogabalin on a long-term basis is a flexible dosage regimen for patients with PHN. It is noteworthy that mirogabalin should be administrated cautiously when combined with probenecid and cimetidine on account of a slight increase in pharmacodynamics effects of mirogabalin.

Conclusion

The development of mirogabalin allows further optimization of individual treatment strategies so as to provide more therapeutic choices in this medical domain.

The Treatment of Painful Diabetic Neuropathy

Painful diabetic peripheral neuropathy (painful-DPN) is a highly prevalent and disabling condition, affecting up to one-third of patients with diabetes. This condition can have a profound impact resulting in a poor quality of life, disruption of employment, impaired sleep, and poor mental health with an excess of depression and anxiety. The management of painful-DPN poses a great challenge. Unfortunately, currently there are no Food and Drug Administration (USA) approved disease-modifying treatments for diabetic peripheral neuropathy (DPN) as trials of putative pathogenetic treatments have failed at phase 3 clinical trial stage. Therefore, the focus of managing painful- DPN other than improving glycaemic control and cardiovascular risk factor modification is treating symptoms. The recommended treatments based on expert international consensus for painful- DPN have remained essentially unchanged for the last decade. Both the serotonin re-uptake inhibitor (SNRI) duloxetine and α2δ ligand pregabalin have the most robust evidence for treating painful-DPN. The weak opioids (e.g. tapentadol and tramadol, both of which have an SNRI effect), tricyclic antidepressants such as amitriptyline and α2δ ligand gabapentin are also widely recommended and prescribed agents. Opioids (except tramadol and tapentadol), should be prescribed with caution in view of the lack of definitive data surrounding efficacy, concerns surrounding addiction and adverse events. Recently, emerging therapies have gained local licenses, including the α2δ ligand mirogabalin (Japan) and the high dose 8% capsaicin patch (FDA and Europe). The management of refractory painful-DPN is difficult; specialist pain services may offer off-label therapies (e.g. botulinum toxin, intravenous lidocaine and spinal cord stimulation), although there is limited clinical trial evidence supporting their use. Additionally, despite combination therapy being commonly used clinically, there is little evidence supporting this practise. There is a need for further clinical trials to assess novel therapeutic agents, optimal combination therapy and existing agents to determine which are the most effective for the treatment of painful-DPN. This article reviews the evidence for the treatment of painful-DPN, including emerging treatment strategies such as novel compounds and stratification of patients according to individual characteristics (e.g. pain phenotype, neuroimaging and genotype) to improve treatment responses.

Pharmacotherapeutic Options for Managing Neuropathic Pain: A Systematic Review and Meta-Analysis

Despite an increasing number of available therapies, the treatment of neuropathic pain remains a major issue. Systematic reviews and meta-analyses indicate that only a minority of patients with neuropathic pain have an adequate response to pharmacological treatment and that most drugs have dose-limiting side effects. We conducted a systematic review and meta-analysis of randomised controlled trials published in the last five years. We searched for relevant papers within PubMed, EMBASE, the Cochrane Database of Systematic Reviews, and the Clinical Trials database (ClinicalTrials.gov). Two authors independently selected studies for inclusion, data extraction, and bias assessment. We identified 39 randomised controlled trials and included 16 in the meta-analysis. Trial outcomes were generally modest even for first-line drugs such as tricyclic antidepressants, serotonin-noradrenaline reuptake inhibitors, and gabapentinoids. Many drugs acting on new pain targets are currently under development. Clinical data are currently available for sodium channel isoform-specific antagonists, anti-nerve growth factor molecules, and fatty acid amide hydrolase inhibitors.

Preclinical Neuropathic Pain Assessment; the Importance of Translatability and Bidirectional Research

For patients suffering with chronic neuropathic pain the need for suitable novel therapies is imperative. Over recent years a contributing factor for the lack of development of new analgesics for neuropathic pain has been the mismatch of primary neuropathic pain assessment endpoints in preclinical vs. clinical trials. Despite continuous forward translation failures across diverse mechanisms, reflexive quantitative sensory testing remains the primary assessment endpoint for neuropathic pain and analgesia in animals. Restricting preclinical evaluation of pain and analgesia to exclusively reflexive outcomes is over simplified and can be argued not clinically relevant due to the continued lack of forward translation and failures in the clinic. The key to developing new analgesic treatments for neuropathic pain therefore lies in the development of clinically relevant endpoints that can translate preclinical animal results to human clinical trials. In this review we discuss this mismatch of primary neuropathic pain assessment endpoints, together with clinical and preclinical evidence that supports how bidirectional research is helping to validate new clinically relevant neuropathic pain assessment endpoints. Ethological behavioral endpoints such as burrowing and facial grimacing and objective measures such as electroencephalography provide improved translatability potential together with currently used quantitative sensory testing endpoints. By tailoring objective and subjective measures of neuropathic pain the translatability of new medicines for patients suffering with neuropathic pain will hopefully be improved.

Mirogabalin: could it be the next generation gabapentin or pregabalin?

Except for carbamazepine for trigeminal neuralgia, gabapentinoid anticonvulsants have been the standard for the treatment of neuropathic pain. Pregabalin, which followed gabapentin, was developed with the benefit of rapid peak blood concentration and better bioavailability. Mirogabalin besylate (DS-5565, Tarlige^®) shows greater sustained analgesia due to a high affinity to, and slow dissociation from, the α₂δ-1 subunits in the dorsal root ganglion (DRG). Additionally, it produces a lower level of central nervous system-specific adverse drug reactions (ADRs), due to a low affinity to, and rapid dissociation from, the α₂δ-2 subunits in the cerebellum. Maximum plasma concentration is achieved in less than 1 hour, compared to 1 hour for pregabalin and 3 hours for gabapentin. The plasma protein binding is relatively low, at less than 25%. As with all gabapentinoids, it is also largely excreted via the kidneys in an unchanged form, and so the administration dose should also be adjusted according to renal function. The equianalgesic daily dose for 30 mg of mirogabalin is 600 mg of pregabalin and over 1,200 mg of gabapentin. The initial adult dose starts at 5 mg, given orally twice a day, and is gradually increased by 5 mg at an interval of at least a week, to 15 mg. In conclusion, mirogabalin is anticipated to be a novel, safe gabapentinoid anticonvulsant with a greater therapeutic effect for neuropathic pain in the DRG and lower ADRs in the cerebellum.

Therapeutic Effect of Mirogabalin on Peripheral Neuropathic Pain due to Lumbar Spine Disease

Study Design

Retrospective study.

Purpose

This study aims to evaluate the effectiveness of mirogabalin in treatment of peripheral neuropathic pain due to lumbar spine disease.

Overview of Literature

Mirogabalin is a novel selective ligand for the α2δ subunit of voltage-gated Ca channels.

Methods

Between April and December 2019, we used mirogabalin to treat 60 consecutive patients (mean age, 67.6 years) with leg symptoms due to lumbar disease. The treatment outcome after 8 weeks of mirogabalin therapy was evaluated by comparing the preand post-administration Numerical Rating Scale (NRS) for leg symptoms and sleep disturbance, the NRS and Roland–Morris Disability Questionnaire for low back pain (LBP), and the quality of life (QOL) score (based on EuroQol five-dimension five-level scale).

Results

Mirogabalin treatment was stopped at less than eight weeks in eight patients. The remaining 52 patients for evaluation were divided as group 1 (17 patients who presented with leg symptoms that lasted for less than 3 months) and group 2 (35 patients with leg symptoms that lasted longer than 3 months). The leg symptoms and LBP in both groups significantly improved at 4 and 8 weeks of treatment, and sleep disturbance and QOL were improved at 8 weeks as well. Compared to group 2, the pretreatment leg symptoms and QOL were significantly worse in group 1, and their improvement after 8 weeks of mirogabalin treatment was significantly better (p<0.05). Of the 60 original patients, 17 suffered adverse effects, which were mild in 16 patients and required treatment cessation due to excessive weight gain in one patient.

Conclusions

We have validated the effect of mirogabalin on neuropathic pain due to lumbar spine disease, which has effectively addressed the associated leg symptoms, LBP, and sleep disturbance.

Long-term safety and efficacy of mirogabalin in Asian patients with diabetic peripheral neuropathic pain

AIMS/INTRODUCTION

Diabetic peripheral neuropathic pain (DPNP) affects the functionality, mood and sleep patterns of patients with diabetes. Mirogabalin, an α2 δ ligand with a slower dissociation for α2 δ-1 versus α2 δ-2 subunits, showed efficacy and safety in a randomized, double-blind, placebo-controlled, 14-week study in Asian patients with DPNP. This open-label extension study evaluated the long-term safety and efficacy of mirogabalin in Asian patients with DPNP.

MATERIAL AND METHODS

This 52-week open-label extension study was carried out in Japan, Korea and Taiwan in patients with DPNP. Patients received mirogabalin, initiated at 5 mg twice daily and increased to a flexible maintenance dosage of 10 or 15 mg twice daily. Adverse events were monitored throughout the study. Patients provided a self-assessment of pain using the Short-Form McGill Pain Questionnaire.

RESULTS

Of the 214 patients who entered the study, 172 (80.4%) completed the extension study. Of 172 patients who completed the study, 149 received the highest dosage of mirogabalin (15 mg twice daily). The most common treatment-emergent adverse events were nasopharyngitis, diabetic retinopathy, peripheral edema, somnolence, diarrhea, increased weight and dizziness. Most treatment-emergent adverse events were mild or moderate in severity. The incidence of treatment-emergent adverse events leading to treatment discontinuation was 13.1%. The visual analog scale and all other Short-Form McGill Pain Questionnaire subscales (sensory score, affective score, total score and present pain intensity) generally decreased over time from baseline until week 52.

CONCLUSIONS

This extension study showed the safety and efficacy of a long-term flexible dosing regimen of mirogabalin 10 or 15 mg twice daily in patients with DPNP.

Mirogabalin for the treatment of diabetic peripheral neuropathic pain: A randomized, double-blind, placebo-controlled phase III study in Asian patients

AIMS/INTRODUCTION

This study evaluated the efficacy and safety of mirogabalin, a novel, potent, selective ligand of the α2 δ subunit of voltage-dependent Ca2+ channels, for the treatment of diabetic peripheral neuropathic pain (DPNP).

MATERIALS AND METHODS

During this double-blind, multisite, placebo-controlled phase III study, Asian patients aged ≥20 years with type 1 or 2 diabetes and DPNP were randomized 2:1:1:1 to a placebo, mirogabalin 15, 20 or 30 mg/day for up to 14 weeks, with a 1- to 2-week titration (NCT02318706). The primary endpoint was the change from baseline in average daily pain score (ADPS) at week 14, defined as a weekly average of daily pain (0 = no pain to 10 = worst possible pain, for the past 24 h).

RESULTS

Of 834 randomized patients, 330, 164, 165 and 165 received placebo, mirogabalin 15, 20 or 30 mg/day, respectively, and were included in analyses (modified intention-to-treat population, n = 824); 755 (90.5%) completed the study. At week 14, the least squares mean average daily pain score change from baseline was -1.31, -1.34, -1.47 and -1.81, respectively, showing statistical significance for mirogabalin 30 mg/day versus placebo (P = 0.0027). The treatment-emergent adverse events observed were mostly mild-to-moderate in all mirogabalin doses, and the most frequent treatment-emergent adverse events were nasopharyngitis, somnolence, dizziness, peripheral edema and weight increase.

CONCLUSIONS

Mirogabalin relieved DPNP in a dose-dependent manner; mirogabalin 30 mg/day showed statistically significant pain relief (vs placebo) in Asian DPNP patients. All doses of mirogabalin tested were well tolerated.

Abuse potential of mirogabalin in recreational polydrug users

Mirogabalin is a selective calcium channel α₂δ subunit ligand being developed to treat neuropathic pain. In accordance with US Food and Drug Administration (FDA) guidance, the human abuse potential of mirogabalin (15–105 mg) was examined, relative to placebo, diazepam (15 or 30 mg), and pregabalin (200 or 450 mg), in two single-dose, randomized, double-blind, placebo- and active-controlled crossover studies in recreational polydrug users who could discern between positive comparator and placebo. The primary endpoint was maximum observed effect (E_max) for Drug Liking Visual Analog Scale. At therapeutic doses, mirogabalin Drug Liking E_max did not differ significantly from placebo and was significantly lower than diazepam and pregabalin. This indicates therapeutic doses mirogabalin may have less abuse potential versus diazepam or pregabalin. At supratherapeutic doses (⩾4× therapeutic dose), mirogabalin had significantly higher Drug Liking E_max than placebo, but lower E_max than pregabalin. In both studies, therapeutic doses of mirogabalin demonstrated limited evidence of abuse potential.

Analgesic effects of mirogabalin, a novel ligand for α2δ subunit of voltage-gated calcium channels, in experimental animal models of fibromyalgia

Mirogabalin, a novel ligand for the α₂δ subunit of voltage-gated calcium channels, is under the development for the treatment of neuropathic pain. Mirogabalin specifically and potently binds to α₂δ subunits, and it shows analgesic effects in both peripheral and central neuropathic pain models in rats. To expand pharmacological findings on mirogabalin and provide additional information of its potential for chronic pain therapy, we examined the effects of mirogabalin in 2 experimental models of fibromyalgia, namely, the intermittent cold stress model (ICS model) and the unilateral intramuscular acidic saline injection model (Sluka model). To induce chronic mechanical hypersensitivity, mice were placed under ICS conditions for 3 days, whereas rats were injected twice with acidic saline (pH 4) into the gastrocnemius muscle in a 4-day interval. The pain sensitivity was evaluated by the von Frey test. Long-lasting increases in pain response score or decreases in pain threshold to the von Frey stimulation were observed in both the ICS and Sluka models. Mirogabalin (1, 3, or 10 mg/kg, p.o.) dose-dependently alleviated the mechanical hypersensitivity, with significant effects persisting at 6 or 8 h following administration. The standard α₂δ ligand, pregabalin (30 mg/kg, p.o.), also significantly reduced the mechanical hypersensitivity. In summary, mirogabalin showed analgesic effects in the ICS model mice and in the Sluka model rats. Therefore, mirogabalin may have the potential to provide effective pain relief in patients with fibromyalgia.

An update on the diagnosis and treatment of diabetic somatic and autonomic neuropathy

Diabetic peripheral neuropathy (DPN) is the most common chronic complication of diabetes. It poses a significant challenge for clinicians as it is often diagnosed late when patients present with advanced consequences such as foot ulceration. Autonomic neuropathy (AN) is also a frequent and under-diagnosed complication unless it is overtly symptomatic. Both somatic and autonomic neuropathy are associated with increased mortality. Multiple clinical trials have failed because of limited efficacy in advanced disease, inadequate trial duration, lack of effective surrogate end-points and a lack of deterioration in the placebo arm in clinical trials of DPN. Multifactorial risk factor reduction, targeting glycaemia, blood pressure and lipids can reduce the progression of DPN and AN. Treatment of painful DPN reduces painful symptoms by about 50% at best, but there is limited efficacy with any single agent. This reflects the complex aetiology of painful DPN and argues for improved clinical phenotyping with the use of targeted therapy, taking into account co-morbid conditions such as anxiety, depression and sleep disturbance.

Diagnosing and managing diabetic somatic and autonomic neuropathy

The diagnosis and management of diabetic neuropathy can be a major challenge. Late diagnosis contributes to significant morbidity in the form of painful diabetic neuropathy, foot ulceration, amputation, and increased mortality. Both hyperglycaemia and cardiovascular risk factors are implicated in the development of somatic and autonomic neuropathy and an improvement in these risk factors can reduce their rate of development and progression. There are currently no US Food and Drug Administration (FDA)-approved disease-modifying treatments for either somatic or autonomic neuropathy, as a consequence of multiple failed phase III clinical trials. While this may be partly attributed to premature translation, there are major shortcomings in trial design and outcome measures. There are a limited number of partially effective FDA-approved treatments for the symptomatic relief of painful diabetic neuropathy and autonomic neuropathy.

An Assessment of Clinically Important Differences on the Worst Pain Severity Item of the Modified Brief Pain Inventory in Patients with Diabetic Peripheral Neuropathic Pain

Objectives

Using patient global impression of change (PGIC) as an anchor, an approximately 30% reduction on an 11-point numeric pain intensity rating scale (PI-NRS) is considered a clinically important difference (CID) in pain. Our objective was to define the CID for another pain measure, the worst pain severity (WPS) item of the modified Brief Pain Inventory (m-BPI).

Methods

In this post hoc analysis of a double-blind, placebo-controlled, phase 2 study, 452 randomized patients with diabetic peripheral neuropathic pain (DPNP) were followed over 5 weeks, with m-BPI data collected weekly and PGIC at treatment conclusion. Receiver operating characteristic (ROC) curves (via logistic regression) were used to determine the changes in the m-BPI-WPS score that best predicted ordinal clinical improvement thresholds (i.e., "minimally improved" or better) on the PGIC.

Results

Similar to the PI-NRS, a change of -3 (raw) or -33.3% from the baseline on the m-BPI-WPS optimized prediction for the "much improved" or better PGIC threshold and represents a CID. There was a high correspondence between observed and predicted PGIC categories at each PGIC threshold (ROC AUCs were 0.78-0.82).

Conclusions

Worst pain on the m-BPI may be used to assess clinically important improvements in DPNP studies. Findings require validation in larger studies.