The emerging role of tacrolimus in myasthenia gravis

Drug-drug interaction between paxlovid and tacrolimus in a patient with myasthenia gravis and SARS-CoV-2 infection

Patients with both myasthenia gravis (MG) and SARS-CoV-2 infection face treatment challenges due to potential drug interactions. One common immunosuppressant for MG, Tacrolimus, is primarily metabolized by the cytochrome P450. However, Paxlovid, an antiviral medication, inhibits cytochrome P450 activity, which can lead to increased Tacrolimus levels and potential toxicity when the two drugs are combined. In this case report, we present the case of a 39-year-old woman with early-onset MG who was initially treated with Tacrolimus. Later, she received Paxlovid for SARS-CoV-2 infection, which resulted in a sudden spike in Tacrolimus levels due to the drug interaction. This case emphasizes the importance of personalized treatment plans and close monitoring of drug interactions in patients with multiple health conditions. Clinicians should exercise vigilance regarding potential Tacrolimus interactions and regularly monitor blood levels to prevent adverse effects. Caution and close monitoring of Tacrolimus levels are essential when administering Paxlovid to patients on Tacrolimus therapy.

Population PK/PD model of tacrolimus for exploring the relationship between accumulated exposure and quantitative scores in myasthenia gravis patients

Tacrolimus is an important immunosuppressant used in the treatment of myasthenia gravis (MG). However, the population pharmacokinetic (PK) characteristics together with the exposure-response of tacrolimus in the treatment of MG remain largely unknown. In this study, we aimed to develop a population PK/pharmacodynamic (PK/PD) model of tacrolimus in patients with MG, in order to explore the relationships among tacrolimus dose, exposure, and its therapeutic efficacy. The genotype of CYP3A5, Osserman's classification, and status of thymus, as well as demographic characteristics and other biomarkers from laboratory testing were tested as covariate, and simulations were performed based on the final model. The population PK model was described using a one-compartment model with first-order elimination and fixed absorption parameters. CYP3A5 genotype significantly influenced the apparent clearance, and total protein (TP) influenced the apparent volume of distribution as covariates. The quantitative MG scores were characterized by the cumulated area under curve of tacrolimus in a maximum effect function. Osserman's classification was a significant covariate on the initial score of patients with MG. The simulations demonstrated that tacrolimus showed an unsatisfying effect possibly due to insufficient exposure in some patients with MG. A starting dose of 2 mg/d and even higher dose for patients with CYP3A5 *1/*1 and *1/*3 and lower TP level were required for the rapid action of tacrolimus. The population PK/PD model quantitatively described the relationships among tacrolimus dose, exposure, and therapeutic efficacy in patients with MG, which could provide reference for the optimization of tacrolimus dosing regimen at the individual patient level.

Diagnosis and Management of Myasthenia Gravis

PURPOSE OF REVIEW

This article reviews updated diagnostic procedures and currently available treatment modalities for myasthenia gravis (MG).

RECENT FINDINGS

Patients with MG can be classified based on antibody status and their clinical presentation; treatment responses may differ based on disease subtypes. Improved diagnostic methods and recognition of new antigenic targets such as lipoprotein-related protein 4 have led to improved diagnostic efficiencies. Corticosteroids remain the first-line immunotherapy, but there is a trend toward minimizing their use at high doses and for long durations. Oral immunosuppressants such as mycophenolate mofetil, azathioprine, and tacrolimus remain useful. An international, multicenter randomized trial comparing thymectomy plus prednisone with prednisone alone demonstrated that thymectomy improves clinical outcomes in selected patients with nonthymomatous MG. Eculizumab, efgartigimod, and ravulizumab have recently been approved by the US Food and Drug Administration (FDA) for adult patients with generalized MG who are acetylcholine receptor-antibody positive. These drugs take advantage of novel mechanisms of action and expand treatment options for patients with MG. Data on rituximab suggest that it can be a good option, especially for patients with MG who are positive for antibodies against muscle-specific tyrosine kinase (MuSK). The number of clinical trials and drugs in development for MG is steadily increasing.

SUMMARY

The diagnosis of MG can generally be made from the patient's history, a neurologic examination, and laboratory and electrodiagnostic testing. Carefully selected treatment improves outcomes in MG. Additional treatment options for MG will likely be available in the near future.

Two-step nationwide epidemiological survey of myasthenia gravis in Japan 2018

Objective

To study the updated prevalence and clinical features of myasthenia gravis (MG) in Japan during 2017.

Methods

We sent survey sheets to the randomly selected medical departments (number = 7,545). First, we asked the number of MG patients who visited medical departments from January 1, 2017, to December 31, 2017. Then, we sent the second survey sheet to the medical departments that answered the first survey to obtain the clinical information of patients who received MG diagnosis between January 1, 2015, and December 31, 2017.

Results

The received answer to the first survey were 2,708 (recovery rate: 35.9%). After all, the prevalence of the 100,000 population was estimated as 23.1 (95%CI: 20.5–25.6). As a result of the second survey, we obtained 1,464 case records. After checking the duplications and lacking data, we utilized 1,195 data for further analysis. The median [interquartile range (IQR)] from the onset age of total patients was 59 (43–70) years old. The male-female ratio was 1: 1.15. The onset age [median (IQR)] for female patients was 58 (40–72) years old, and that for male patients was 60 (49–69) years old (Wilcoxon-Mann-Whitney test, p = 0.0299). We divided patients into four categories: 1) anti-acetylcholine receptor antibody (AChRAb) (+) thymoma (Tm) (-), 2) AChRAb(+)Tm(+), 3) anti-muscle-specific kinase antibody (MuSKAb) (+), and AChRAb(-)MuSKAb(-) (double negative; DN). The onset age [median (IQR)] of AChRAb(+)Tm(-) was 64 (48–73) years old, and AChRb(+)Tm(+) was 55 (45–66), MuSKAb(+) was 49 (36–64), DN was 47 (35–60) year old. The multivariate logistic regression analysis using sex, initial symptoms, repetitive nerve stimulation test (RNST), and edrophonium test revealed that sex, ocular symptoms, bulbar symptoms, and RNST were factors to distinguish each category. The myasthenia gravis activities of daily living profile at the severest state were significantly higher in MuSKAb(+). MuSKAb(+) frequently received prednisolone, tacrolimus plasmapheresis, and intravenous immunoglobulin; however, they received less acetylcholine esterase inhibitor. 99.2% of AChRAb(+)Tm(+) and 15.4% of AChRAb(+)Tm(-) received thymectomy. MuSKAb(+) did not receive thymectomy, and only 5.7% of DN received thymectomy. The prognosis was favorable in all categories.

Conclusion

Our result revealed that the prevalence of Japanese MG doubled from the previous study using the same survey method in 2006. We also found that the onset age shifted to the elderly, and the male-female ratio reached almost even. Classification in four categories; AChRAb(+)Tm(-), AChRAb(+)Tm(+), MuSKAb(+), and DN, well describe the specific clinical features of each category and differences in therapeutic approaches.

Remission and relapses of myasthenia gravis on long-term tacrolimus: a retrospective cross-sectional study of a Chinese cohort

Objective:

To identify the factors that predict the remission and relapses in myasthenia gravis (MG) patients improved by prednisone and tacrolimus treatment.

Methods:

A retrospective, observational cohort analysis of MG patients who achieved remission after receiving prednisone and tacrolimus were performed at Tongji Hospital. The main outcome measures were the time to remission, prednisone discontinuation, tacrolimus reduction–associated relapse, and treatment outcome.

Results:

After adding tacrolimus, 256 patients were able to achieve remission with a mean time to remission of 2.1 ± 1.4 months. After a median follow-up of 2.9 years, 167 patients (65.2%) discontinued prednisone, and 20 patients (7.8%) achieved complete stable remission. Moreover, 53 of the 109 patients who were tapering tacrolimus experienced relapses. In multivariable analysis, female sex, low tacrolimus concentrations, and quantitative myasthenia gravis (QMG) scores have a positive correlation with the time to remission; concomitant additional autoimmune disease (AID) and high anti-acetylcholine receptor antibody (AChR-ab) levels were significantly associated with low probabilities of prednisone discontinuation [odds ratio (OR) = 0.312–0.912, respectively]; rapid tacrolimus decrement speed (⩾0.76 mg/year) was an independent predictor for the development of relapse during tapering tacrolimus (OR = 5.662).

Conclusion:

Sex, tacrolimus concentrations, and QMG scores can be used as potential predictors of the time to remission in MG patients treated with tacrolimus and prednisone. Prednisone should be tapered slowly, especially in patients with additional AID or high serum titers of AChR-ab. To avoid symptoms recurrence, the dose of tacrolimus should reduce slowly, not exceeding 0.76 mg/year.

Long-Term Efficacy of Non-steroid Immunosuppressive Agents in Anti-Muscle-Specific Kinase Positive Myasthenia Gravis Patients: A Prospective Study

Background and Purpose

Anti-muscle-specific kinase (MuSK) positive myasthenia gravis (MG) is characterized by a high relapsing rate, thus, choosing the appropriate oral drug regimen is a challenge. This study aimed to evaluate the efficacy of oral immunosuppressants (IS) in preventing relapse in MuSK-MG.

Methods

This prospective cohort observational study included patients with MuSK-MG at Peking Union Medical College Hospital between January 1, 2018, and November 15, 2021. The patients were divided into 2 groups: those with (IS+) or without (IS-) non-steroid immunosuppressive agents. The primary outcome was relapsed at follow-up, and the log-rank test was used to compare the proportion of maintenance-free relapse between the groups; hazard ratio (HR) was calculated using the Cox proportional hazards models.

Results

Fifty-three of 59 patients with MuSK-MG were included in the cohort, 14 were in the IS+ group, and 39 were in the IS- group. Twenty-four cases in the cohort experienced relapse at least once; the relapse rate was 2/14 (14.3%) in the IS+ group and 22/39 (56.4%) in the IS- group. At the end of follow-up, the proportion of maintenance-free relapse was significantly different between the two groups (log-rank χ2 = 4.94, P = 0.02). Of all the potential confounders, only the use of IS was associated with a reduced risk of relapse. The HR for relapse among patients in the IS+ group was 0.21 (95%CI 0.05-0.58) and was 0.23 (95%CI 0.05-0.93) in a model adjusted for age, sex, relapse history, highest Myasthenia Gravis Foundation of America (MGFA), and accumulated time of steroid therapy.

Conclusions

This study provides evidence that oral non-steroid immunosuppressive agents may be beneficial in reducing relapse in patients with MuSK-MG.

Pharmacotherapy of Generalized Myasthenia Gravis with Special Emphasis on Newer Biologicals

Myasthenia gravis (MG) is a chronic, fluctuating, antibody-mediated autoimmune disorder directed against the post-synaptic neuromuscular junctions of skeletal muscles, resulting in a wide spectrum of manifestations ranging from mild to potentially fatal. Given its unique natural course, designing an ideal trial design for MG has been wrought with difficulties and evidence in favour of several of the conventional agents is weak as per current standards. Despite this, acetylcholinesterases and corticosteroids have remained the cornerstones of treatment for several decades with intravenous immunoglobulins (IVIG) and therapeutic plasma exchange (PLEX) offering rapid treatment response, especially in crises. However, the treatment of MG entails long-term immunosuppression and conventional agents are viable options but take longer to act and have a number of class-specific adverse effects. Advances in immunology, translational medicine and drug development have seen the emergence of several newer biological agents which offer selective, target-specific immunotherapy with fewer side effects and rapid onset of action. Eculizumab is one of the newer agents that belong to the class of complement inhibitors and has been approved for the treatment of refractory general MG. Zilucoplan and ravulizumab are other agents in this group in clinical trials. Neisseria meningitis is a concern with all complement inhibitors, mandating vaccination. Neonatal Fc receptor (FcRn) inhibitors prevent immunoglobulin recycling and cause rapid reduction in antibody levels. Efgartigimod is an FcRn inhibitor recently approved for MG treatment, and rozanolixizumab, nipocalimab and batoclimab are other agents in clinical trial development. Although lacking high quality evidence from randomized clinical trials, clinical experience with the use of anti-CD20 rituximab has led to its use in refractory MG. Among novel targets, interleukin 6 (IL6) inhibitors such as satralizumab are promising and currently undergoing evaluation. Cutting-edge therapies include genetically modifying T cells to recognise chimeric antigen receptors (CAR) and chimeric autoantibody receptors (CAAR). These may offer sustained and long-term remissions, but are still in very early stages of evaluation. Hematopoietic stem cell transplantation (HSCT) allows immune resetting and offers sustained remission, but the induction regimens often involve serious systemic toxicity. While MG treatment is moving beyond conventional agents towards target-specific biologicals, lack of knowledge as to the initiation, maintenance, switching, tapering and long-term safety profile necessitates further research. These concerns and the high financial burden of novel agents may hamper widespread clinical use in the near future.

Novel treatment strategies for acetylcholine receptor antibody-positive myasthenia gravis and related disorders

The presence of autoantibodies directed against the muscle nicotinic acetylcholine receptor (AChR) is the most common cause of myasthenia gravis (MG). These antibodies damage the postsynaptic membrane of the neuromuscular junction and cause muscle weakness by depleting AChRs and thus impairing synaptic transmission. As one of the best-characterized antibody-mediated autoimmune diseases, AChR-MG has often served as a reference model for other autoimmune disorders. Classical pharmacological treatments, including broad-spectrum immunosuppressive drugs, are effective in many patients. However, complete remission cannot be achieved in all patients, and 10% of patients do not respond to currently used therapies. This may be attributed to production of autoantibodies by long-lived plasma cells which are resistant to conventional immunosuppressive drugs. Hence, novel therapies specifically targeting plasma cells might be a suitable therapeutic approach for selected patients. Additionally, in order to reduce side effects of broad-spectrum immunosuppression, targeted immunotherapies and symptomatic treatments will be required. This review presents established therapies as well as novel therapeutic approaches for MG and related conditions, with a focus on AChR-MG.

Antibody Therapies in Autoimmune Neuromuscular Junction Disorders: Approach to Myasthenic Crisis and Chronic Management

Myasthenia gravis (MG) is a neurological autoimmune disorder characterized by muscle weakness and fatigue. It is a B cell-mediated disease caused by pathogenic antibodies directed against various components of the neuromuscular junction (NMJ). Despite the wide range of adverse effects, current treatment is still based on non-specific immunosuppression, particularly on long-term steroid usage. The increasing knowledge regarding the pathogenic mechanisms of MG has however allowed to create more target-specific therapies. A very attractive therapeutic approach is currently offered by monoclonal antibodies (mAbs), given their ability to specifically and effectively target different immunopathological pathways, such as the complement cascade, B cell-related cluster of differentiation (CD) proteins, and the human neonatal Fc receptor (FcRn). Up to now, eculizumab, a C5-directed mAb, has been approved for the treatment of generalized MG (gMG) and efgartigimod, a FcRn inhibitor, has just been approved by the U.S. Food and Drug Administration for the treatment of anti-acetylcholine receptor (AChR) antibody positive gMG. Other mAbs are currently under investigation with encouraging preliminary results, further enriching the new range of therapeutic possibilities for MG. This review article provides an overview of the present status of mAb-based therapies for MG, which offer an exciting promise for better outcomes by setting the basis of a precision medicine approach.

Long-Term Improvement in a Chinese Cohort of Glucocorticoid-Resistant Childhood-Onset Myasthenia Gravis Patients Treated With Tacrolimus

Objectives

To evaluate the long-term outcome of tacrolimus for childhood-onset myasthenia gravis (CMG) with an inadequate response to glucocorticoids, and investigate factors associated with favorable outcomes following tacrolimus treatment.

Methods

A retrospective, observational cohort study was performed for CMG patients who had not improved satisfactorily after sufficient prednisone therapy for at least 8 weeks. All patients were given tacrolimus in doses of 2–3 mg for more than 6 months. The primary efficacy outcome was assessed using the prednisone dose, quantitative MG (QMG), and MG-activity of daily living (ADL) scores. The participants were divided into improved and unimproved groups based on changes in QMG scores to investigate the risk factors that affected tacrolimus efficacy.

Results

A total of 149 glucocorticoid resistant CMG patients were finally enrolled in our study, with 113 (75.8%) responding well to tacrolimus (defined as minimal manifestation status or better). One month after initiating tacrolimus, there was a noticeable improvement in prednisone dose, QMG, and ADL scores, which continued to improve throughout the study. More importantly, the prednisone was eventually stopped in 89 of the patients (78.8%). Thymus type [odds ratio (OR) = 3.156, 95% confidence interval (CI) 1.427–6.978; P = 0.005] and pre-intervention status (OR = 0.284, 95%CI 0.109–0.741; P = 0.010) were independent predictors of tacrolimus efficacy after controlling for confounding factors in multiple logistic regression.

Conclusion

The majority of glucocorticoid-resistant CMG patients have a good long-term prognosis after adding tacrolimus. Thymus type and pre-intervention status can serve as potential predictors affecting the efficacy of tacrolimus.

Preoperative Management of Medications for Neurologic Diseases: Society for Perioperative Assessment and Quality Improvement Consensus Statement

Neurologic diseases are prevalent in patients undergoing invasive procedures; yet, no societal guidelines exist as to best practice in management of perioperative medications prescribed to treat these disorders. The Society for Perioperative Assessment and Quality Improvement tasked experts in internal medicine, anesthesiology, perioperative medicine, and neurology to provide evidence-based recommendations for preoperative management of these medications. The aim of this review is not only to provide consensus recommendations for preoperative management of patients on medications for neurologic disorders, but also to serve as an educational guide to perioperative clinicians. While, in general, medications for neurologic disorders should be continued preoperatively, an individualized approach may be needed in certain situations (eg, holding anticonvulsants on day of surgery if electroencephalographic mapping is planned during epilepsy surgery). Pertinent interactions with commonly used drugs in anesthesia practice, as well as considerations for targeted laboratory testing or perioperative drug substitutions, are addressed as well.

Safety of Tacrolimus in Autoimmune Disease: Results From Post-marketing Surveillance in South Korea

Objective

Tacrolimus, a macrolide immunosuppressant, is approved in Korea for the treatment of rheumatoid arthritis (RA), lupus nephritis (LN) and myasthenia gravis (MG) We report three prospective post-marketing surveillance studies of tacrolimus conducted in South Korea in these indications.

Methods

Studies were conducted according to South Korean Ministry of Food and Drug Safety requirements Patients were followed up for the duration of the study (up to 4 years) or until treatment discontinuation Occurrence and likely relationship with tacrolimus of adverse events (AEs), adverse drug reactions (ADRs; defined as AEs where causal relationship to tacrolimus could not be excluded) and serious AEs were recorded Association of AEs with demographic and medical factors was evaluated by multivariable analysis.

Results

The studies included 740 (RA), 307 (LN) and 104 (MG) patients The incidence of AEs was 127% in RA (642% of AEs potentially related to tacrolimus), 209% (378% potentially related) in LN and 298% (568% potentially related) in MG The incidence of ADRs was 84%, 98% and 202%, respectively Serious AEs were reported in 07%, 72% and 87%, respectively The most common AEs were abdominal pain (RA), pharyngitis (LN) and diarrhea (MG) Unexpected AEs occurred in 35% of patients with RA, 29% in LN and 87% in MG; no pattern of unexpected AEs was apparent Multivariable analysis demonstrated that patients with comorbidity had higher probability of experiencing an AE in RA and MG studies.

Conclusion

The incidence of AEs and the safety profile of tacrolimus in each indication was consistent with previous reports.

Progress in the therapy of myasthenia gravis: getting closer to effective targeted immunotherapies

PURPOSE OF REVIEW

To provide an update on immunomodulating and immunosuppressive therapies in myasthenia gravis and highlight newly approved, or pending approval, therapies with new biologics.

RECENT FINDINGS

Preoperative IVIg is not needed to prevent myasthenic crisis in stable myasthenia gravis patients scheduled for surgery under general anesthesia, based on controlled data. Rituximab, if initiated early in new-onset myasthenia gravis, can lead to faster and more sustained remission even without immunotherapies in 35% of patients at 2 years. Biomarkers determining the timing for follow-up infusions in Rituximab-responding AChR-positive patients are discussed. Most patients with MuSK-positive myasthenia gravis treated with Rituximab have sustained long-term remission with persistent reduction of IgG4 anti-MuSK antibodies. Eculizumb in the extension REGAIN study showed sustained long-term pharmacological remissions and reduced exacerbations. Three new biologic agents showed promising results in phase-II controlled myasthenia gravis trials: Zilucoplan, a subcutaneous macrocyclic peptide inhibiting complement C5; Efgartigimod, an IgG1-derived Fc fragment binding to neonatal FcRn receptor; and Rozanolixizumab, a high-affinity anti-FcRn monoclonal antibody. Finally, the safety of ongoing myasthenia gravis immunotherapies during COVID19 pandemic is discussed.

SUMMARY

New biologics against B cells, complement and FcRn receptor, are bringing us closer to successful targeted immunotherapies in the chronic management of myasthenia gravis promising an exciting future for antibody-mediated neurological diseases.

Protective effects of selenium in tacrolimus-induced lung toxicity: potential role of heme oxygenase 1

The present study aimed to evaluate the protective effects of selenium (Sel) administration against tacrolimus (Tac) - induced lung toxicity and to assess the relation between heme oxygenase 1 (HO-1) and these effects. The study was conducted on 36 Wistar male albino rats equally divided into four groups: (i) normal control; (ii) Sel (0.1 mg/kg per day p.o. for four weeks); (iii) TAC 3 mg/mL as single oral dose on 27th day; and (iv) Tac + Sel. Lung tissues, lung homogenate, and bronchoalveolar lavage of the sacrificed animals were investigated biochemically and histopathologically, by immunohistochemistry or by PCR. The Tac group showed significantly lower expression of HO-1. Administration of Sel was associated with increased HO-1 expression. Oxidative (malondialdehyde, reduced glutathione, superoxide dismutase, myeloperoxidase, and glutathione peroxidase activity) and nitrosative stress (nitric oxide) markers and markers of inflammation (interleukin 1β (IL-1β), IL-6, and IL-10) showed changes corresponding to HO-1 levels in rat groups. Tac group showed the highest expression of caspase-3. Sel exerted a protective role against Tac-induced lung toxicity.

Clinical Evaluation of the Efficacy and Safety of Co-Administration of Wuzhi Capsule and Tacrolimus in Adult Chinese Patients with Myasthenia Gravis

BACKGROUND

Tacrolimus has been recommended as an effective immunosuppressant for patients with myasthenia gravis (MG), while the high price, variable bioavailability, and narrow therapeutic window restrict its clinical application. Wuzhi capsule (WZC) could improve tacrolimus blood concentration by inhibiting the metabolism of cytochrome P450 3A (CYP3A) and P-glycoprotein (P-gp). There are few studies focused on the coadministration of WZC and tacrolimus in autoimmune diseases. This study was aimed at quantifying the efficacy and safety of coadministration of WZC and tacrolimus in adult Chinese patients with MG.

METHODS

In this retrospective study, 122 patients with MG on tacrolimus were enrolled. The initial tacrolimus dose was 2 mg/d. Patients with standard initial tacrolimus concentration were classified into group A (standard-dose group). Those failed to reach target concentration were divided into group B (high-dose group) and group C (co-administering WZC group), according to treatment adjustment of increasing tacrolimus dose and co-administration of WZC, respectively. A logistic analysis was used to identify factors associated with clinical outcome. Adverse drug reactions (ADRs) were recorded for safety analysis.

RESULTS

The tacrolimus concentration after coadministration of WZC was remarkably increased. It was higher compared with simply increasing the tacrolimus dose (p<0.001). The multivariate logistic analysis indicated that the baseline quantitative MG score was a predictive factor for clinical outcomes (OR=0.189; 95% CI 0.082-0.436; p<0.001). Fourteen patients (11.5%) reported ADRs after tacrolimus therapy. ADRs incidence was not related to WZC coadministration.

CONCLUSION

The coadministration of WZC and tacrolimus can substantially elevate the tacrolimus concentration. It is a safe and economic treatment for adult Chinese patients with MG. Patients with a worse disease condition tend to present a better clinical outcome after tacrolimus therapy.

History of Myasthenia Gravis Revisited

The first description of myasthenia gravis (MG) was given by Thomas Willis in 1672. MG was the focus of attention after mid-nineteenth century and a great amount of information has been accumulated in a span of 150 years. The aim of this review is to convey this information according to a particular systematic and to briefly relate the experience of Istanbul University. MG history was examined in four periods: 1868-1930, 1930-1960, 1960-1990, and 1990-2020. In the first period (1868-1930), all the clinical characteristics of MG were defined. Physiological/pharmacological studies on the transmission at the neuromuscular junction were initiated, and the concept of repetitive nerve stimulation emerged. A toxic agent was believed to be the cause of MG which appeared to resemble curare intoxication. Association of MG with thymus was noticed. No noteworthy progress was made in its treatment. In the second period (1930-1960), acetylcholine was discovered to be the transmitter at the neuromuscular junction. Repetitive nerve stimulation was used as a diagnostic test. The autoimmune nature of MG was suspected and experiments to this end started to give results. The hallmark of this period was the use of anticholinesterases and thymectomy in the treatment of MG. The third period (1960-1990) can probably be considered a revolutionary era for MG. Important immunological mechanisms (acetylcholine receptor isolation, discovery of anti-acetylcholine receptor antibodies) were clarified and the autoimmune nature of MG was demonstrated. Treatment modalities which completely changed the prognosis of MG, including positive pressure mechanic ventilation and corticosteroids as well as plasma exchange/IVIg and azathioprine, were put to use. In the fourth period (1990-2020), more immunological progress, including the discovery of anti-MuSK antibodies, was achieved. Videothoracoscopic thymectomy reduced the morbidity and mortality rate associated with surgery. New drugs emerged and clinical trials were performed. Valuable guidelines were published. In the last part of the review, the experience in MG of Istanbul University, a pioneer in Turkey, is related.

Administration of FK506 from Late Stage of Disease Prolongs Survival of Human Prion-Inoculated Mice

Human prion diseases are etiologically categorized into three forms: sporadic, genetic, and infectious. Sporadic Creutzfeldt-Jakob disease (sCJD) is the most common type of human prion disease that manifests as subacute progressive dementia. No effective therapy for sCJD is currently available. Potential therapeutic compounds are frequently tested in rodents infected with mouse-adapted prions that differ from human prions. However, therapeutic effect varies depending on the prion strain, which is one of the reasons why candidate compounds have shown little effect in sCJD patients. We previously reported that intraperitoneal administration of FK506 was able to prolong the survival of mice infected with a mouse-adapted prion by suppressing the accumulation of abnormal prion protein (PrP) and inhibiting the activation of microglia. In this study, we tested oral administration of FK506 in knock-in mice expressing chimeric human prion protein (KiChM) that were infected with sCJD to determine if this compound is also effective against a clinically relevant human prion, i.e., one that has not been adapted to mice. Treatment with FK506, started either just before or just after disease onset, suppressed typical sCJD pathology (gliosis) and slightly but significantly prolonged the survival of sCJD-inoculated mice. It would be worthwhile to conduct a clinical trial using FK506, which has been safety-approved and is widely used as a mild immunosuppressant.

[Clinical effect of tacrolimus in the treatment of myasthenia gravis in children]

OBJECTIVE

To evaluate the efficacy and safety of tacrolimus in the treatment of children with myasthenia gravis (MG).

METHODS

A total of 28 children with MG were treated with tacrolimus. MG-Activities of Daily Living (MG-ADL) scale was used to assess clinical outcome and safety after 1, 3, 6, 9, and 12 months of treatment.

RESULTS

After tacrolimus treatment, the MG-ADL score at 1, 3, 6, 9 and 12 months was lower than that at baseline (P<0.05), and the MG-ADL score showed a gradually decreasing trend. The response rates to tacrolimus treatment at 1, 3, 6, 9, and 12 months were 59%, 81%, 84%, 88%, and 88% respectively. At 6, 9, 12, and 18 months of treatment, 4, 13, 14, and 15 children respectively were withdrawn from prednisone. No recurrence was observed during treatment. Major adverse reactions/events were asymptomatic reduction in blood magnesium in 5 children and positive urine occult blood in 1 child, which turned negative without special treatment, and tacrolimus was not stopped due to such adverse reactions/events. One child was withdrawn from tacrolimus due to recurrent vomiting. According to CYP3A5 genotypes, all of the patients were divided into two groups: slow metabolic type (n=19) and non-slow metabolic type (fast metabolic type + intermediate type; n=9). The non-slow metabolism group received a higher dose of tacrolimus, but had a lower trough concentration of tacrolimus than the slow metabolism group (P<0.05). The slow metabolism group had a higher response rates to tacrolimus treatment than the non-slow metabolism group (P<0.05).

CONCLUSIONS

Tacrolimus appears to be effective and safe in the treatment of children with MG and is thus an option for immunosuppressive therapy. CYP3A5 genotyping has a certain guiding significance for determining the dosage of tacrolimus.

[Clinical effect of tacrolimus in the treatment of myasthenia gravis in children]

OBJECTIVE

To evaluate the efficacy and safety of tacrolimus in the treatment of children with myasthenia gravis (MG).

METHODS

A total of 28 children with MG were treated with tacrolimus. MG-Activities of Daily Living (MG-ADL) scale was used to assess clinical outcome and safety after 1, 3, 6, 9, and 12 months of treatment.

RESULTS

After tacrolimus treatment, the MG-ADL score at 1, 3, 6, 9 and 12 months was lower than that at baseline (P<0.05), and the MG-ADL score showed a gradually decreasing trend. The response rates to tacrolimus treatment at 1, 3, 6, 9, and 12 months were 59%, 81%, 84%, 88%, and 88% respectively. At 6, 9, 12, and 18 months of treatment, 4, 13, 14, and 15 children respectively were withdrawn from prednisone. No recurrence was observed during treatment. Major adverse reactions/events were asymptomatic reduction in blood magnesium in 5 children and positive urine occult blood in 1 child, which turned negative without special treatment, and tacrolimus was not stopped due to such adverse reactions/events. One child was withdrawn from tacrolimus due to recurrent vomiting. According to CYP3A5 genotypes, all of the patients were divided into two groups: slow metabolic type (n=19) and non-slow metabolic type (fast metabolic type + intermediate type; n=9). The non-slow metabolism group received a higher dose of tacrolimus, but had a lower trough concentration of tacrolimus than the slow metabolism group (P<0.05). The slow metabolism group had a higher response rates to tacrolimus treatment than the non-slow metabolism group (P<0.05).

CONCLUSIONS

Tacrolimus appears to be effective and safe in the treatment of children with MG and is thus an option for immunosuppressive therapy. CYP3A5 genotyping has a certain guiding significance for determining the dosage of tacrolimus.

Management of Juvenile Myasthenia Gravis

Juvenile Myasthenia Gravis (JMG) is a rare disorder, defined as myasthenia gravis in children younger than 18 years of age. While clinical phenotypes are similar to adults, there are a number of caveats that influence management: broader differential diagnoses; higher rates of spontaneous remission; and the need to initiate appropriate treatment early, to avoid the long-term physical and psychosocial morbidity. Current practice is taken from treatment guidelines for adult MG or individual experience, with considerable variability seen across centers. We discuss our approach to treating JMG, in a large specialist JMG service, and review currently available evidence and highlight potential areas for future research. First-line treatment of generalized JMG is symptomatic management with pyridostigmine, but early use of immunosuppression, where good control is not achieved is important. Oral prednisolone is used as first-line immunosuppression with appropriate prevention and monitoring of side effects. Second-line therapies including azathioprine and mycophenolate may be considered where there is: no response to steroids, inability to wean to a reasonable minimum effective dose or if side-effects are intolerable. Management of ocular JMG is similar, but requires close involvement of ophthalmology in young children to prevent amblyopia. Muscle-specific tyrosine kinase (MuSK)-JMG show a poorer response to pyridostigmine and anecdotal evidence suggests that rituximab should be considered as second-line immunosuppression. Thymectomy is indicated in any patient with a thymoma, and consideration should be given in acetylcholine receptor (AChR) positive JMG allowing time for spontaneous remission. The benefit is less clear in ocular JMG and is not advised in MuSK-JMG. Children experiencing a myasthenic crisis require urgent hospital admission with access to the intensive care unit. PLEX is preferred over IVIG due to rapid onset of action, but this needs to be balanced with feasibility in very young children. Key questions remain in the management of JMG: when to initiate both first- and second-line treatments, choosing between steroid-sparing agents, and determining the optimal dose and treatment duration. We feel that given the rarity of this disease, the establishment of national registries and collaboration across groups will be needed to address these issues and facilitate future drug trials in JMG.

A Practical Approach to Managing Patients With Myasthenia Gravis-Opinions and a Review of the Literature

When the diagnosis of myasthenia gravis (MG) has been secured, the aim of management should be prompt symptom control and the induction of remission or minimal manifestations. Symptom control, with acetylcholinesterase inhibitors such as pyridostigmine, is commonly employed. This may be sufficient in mild disease. There is no single universally accepted treatment regimen. Corticosteroids are the mainstay of immunosuppressive treatment in patients with more than mild MG to induce remission. Immunosuppressive therapies, such as azathioprine are prescribed in addition to but sometimes instead of corticosteroids when background comorbidities preclude or restrict the use of steroids. Rituximab has a role in refractory MG, while plasmapheresis and immunoglobulin therapy are commonly prescribed to treat MG crisis and in some cases of refractory MG. Data from the MGTX trial showed clear evidence that thymectomy is beneficial in patients with acetylcholine receptor (AChR) antibody positive generalized MG, up to the age of 65 years. Minimally invasive thymectomy surgery including robotic-assisted thymectomy surgery has further revolutionized thymectomy and the management of MG. Ocular MG is not life-threatening but can be significantly disabling when diplopia is persistent. There is evidence to support early treatment with corticosteroids when ocular motility is abnormal and fails to respond to symptomatic treatment. Treatment needs to be individualized in the older age-group depending on specific comorbidities. In the younger age-groups, particularly in women, consideration must be given to the potential teratogenicity of certain therapies. Novel therapies are being developed and trialed, including ones that inhibit complement-induced immunological pathways or interfere with antibody-recycling pathways. Fatigue is common in MG and should be duly identified from fatigable weakness and managed with a combination of physical therapy with or without psychological support. MG patients may also develop dysfunctional breathing and the necessary respiratory physiotherapy techniques need to be implemented to alleviate the patient's symptoms of dyspnoea. In this review, we discuss various facets of myasthenia management in adults with ocular and generalized disease, including some practical approaches and our personal opinions based on our experience.

Effects of Mitophagy on Regulatory T Cell Function in Patients With Myasthenia Gravis

Objective: This study was conducted to determine whether regulatory T cells (CD4⁺CD25⁺T, Tregs) show abnormal mitophagy as well as the function of Tregs in patients with myasthenia gravis (MG).

Methods: CD4⁺T cells and CD4⁺CD25⁺Treg cells were obtained from 15 patients with MG (MG group) and 15 controls (N group). Tregs from the MG group were subjected to rapamycin-induced culture for 48 h (Rapa group) and 3-methyladenine-induced culture for 48 h (3-MA group). The levels of mitophagy in Tregs were then observed through electron and confocal microscopy. Expression of the autophagy-related protein LC3-II was detected by western blotting, and mitochondrial function in each group was evaluated by flow cytometry. Inhibition of Treg cell proliferation was detected by flow cytometry.

Results: Mitophagy in the MG group was lower than that in the N group; it was higher in the Rapa group compared to that in the MG group and lowered in the 3-MA group than in the MG group. Expression of the autophagy-related protein LC3-II was lower in the MG group than in the N group, higher in the Rapa group than in the MG group, and lower in the 3-MA group than in the MG group. The mitochondrial membrane potential was lower in the MG group compared to that in the N group; it was higher in the Rapa group than in the MG group and lowered in the 3-MA group than in the MG group. Inhibition of Treg proliferation was lower in the MG group than in the N group; it was higher in the Rapa group than in the MG group and lowered in the 3-MA group than in the MG group.

Conclusion: The decreased mitochondrial membrane potential and mitophagy in Tregs in the MG group may be related to a decreased inhibition of Treg proliferation. The mitochondrial membrane potential was increased after adding the autophagy agent Rapa to enhance mitophagy, and the proliferation inhibition function of Tregs was also enhanced. The autophagy agent 3-MA down-regulated mitophagy, which decreased the mitochondrial membrane potential and inhibitory effect of Tregs. These results reveal the possible cellular immune mechanism of Treg dysfunction in MG.

Immunotherapy in myasthenia gravis in the era of biologics

No consensus has been reached on the ideal therapeutic algorithm for myasthenia gravis (MG). Most patients with MG require induction therapy with high doses of corticosteroids and maintenance with an immunosuppressant. Severe cases and acute worsening require intravenous immunoglobulin or plasmapheresis before oral immunosuppressants start having an effect. However, biologics are emerging as important therapeutic tools that promise to provide better corticosteroid sparing effects than standard treatments and can even induce remission. In particular, eculizumab, a monoclonal antibody against complement C5, has been approved by the FDA for refractory MG on the basis of a phase III trial. Rituximab, an anti-CD20 monoclonal antibody that depletes peripheral B cells, has also been effective in many large uncontrolled series, although was not in a small phase III trial. Whether the newer anti-CD20 agents ocrelizumab, ofatumumab, obinutuzumab, ublituximab or inebilizumab will be more effective remains unclear. Belimumab, an antibody against the B cell trophic factor BAFF, was ineffective in phase III trials, and efgartigimod, which depletes antibodies, was effective in a phase II study. Some anti-cytokine agents relevant to MG immunopathogenesis also seem promising. Checkpoint inhibitors can trigger MG in some patients, necessitating early intervention. Increased availability of new biologics provides targeted immunotherapies and the opportunities to develop more specific therapies.

Multiple genetic factors affecting the pharmacokinetic and pharmacodynamic processes of tacrolimus in Chinese myasthenia gravis patients

PURPOSE

Tacrolimus is a novel effective immunosuppressant for myasthenia gravis (MG) patients. However, the narrow therapeutic window, and high inter- and intrapatient variation in bioavailability largely limited its clinical application. This article intended to find the SNPs influencing clinical outcome and discover the possible mechanisms.

METHODS

Based on the tagSNPs genotyped by Improved Multiple Ligase Detection Reaction, Plink 1.07 was used to find the SNPs having close interaction to tacrolimus serum concentration, QMG score changes or even reasonable drug dose. Then we searched several databases to predict the possible miRNA binding rs15524 sequence. Based on the prediction, dual-luciferase reporter assay and miRNA transfection were used to discover the mechanism of how SNP rs15524 controls tacrolimus serum concentration through influencing CYP3A5 expression.

RESULTS

In this article, we found multiple SNPs on CYP3A4, CYP3A5, FKBP1A, NFATC2 genes were predicted closely related to tacrolimus serum concentration, therapeutic effect which reflected by QMG score changes or even reasonable drug dose. After in silico miRNA selection, possible relationship between hsa-miR-500a and rs15524 was found. With the help of dual-luciferase reporter assay, wild-type rs15524 (T allele) was found having a stronger binding affinity for hsa-miR-500a. Higher expression of CYP3A5 may also led by lower hsa-miR-500a level.

CONCLUSIONS

SNP rs15524 may control CYP3A5 expression by affecting the binding affinity between CYP3A5 3'UTR and hsa-miR-500a. Wild type (T allele) 3'UTR of CYP3A5 has stronger binding affinity to hsa-miR-500a and cause lower CYP3A5 expression and higher tacrolimus serum concentration.

Maintenance immunosuppression in myasthenia gravis, an update

Therapies for myasthenia gravis (MG) include symptomatic and immunosuppressive/immunomodulatory treatment. Options for immunosuppression include corticosteroids, azathioprine, mycophenolate mofetil, cyclosporine, tacrolimus, methotrexate, rituximab, cyclophosphamide, eculizumab, intravenous immunoglobulin, subcutaneous immunoglobulin, plasmapheresis, and thymectomy. The practical aspects of long-term immunosuppressive therapy in MG are critically reviewed in this article. Application of one or more of these specific therapies is guided based on known efficacy, adverse effect profile, particular disease subtype and severity, and patient co-morbidities.

Current pharmacotherapeutic options for myasthenia gravis

Introduction: Novel options for immune-based therapy in myasthenia gravis are improving the therapeutic outlook for patients. Multiple clinical trials on immunomodulation, complement inhibitors, and FcR inhibitors are providing evidence for novel immune-based therapies that promise to improve outcomes in myasthenia patients. These more focused immune treatments are reviewed in this paper.Areas covered: This paper outlines classical treatment for myasthenia gravis and then reviews recent clinical trial evidence for novel immune therapies, particularly complement inhibitors and FcR inhibitors. Further, as immune therapies expand in other areas of medicine, such as oncology, iatrogenic myasthenia is being observed as a complication of some novel treatments.Expert opinion: Exciting new options to help patients with myasthenia gravis are now available or in phase 3 trials based on promising phase 2 results. Manipulation of the immune system can also lead to iatrogenic MG. Although novel treatments can improve care for myasthenia gravis patients, future developments that prevent the production of specific abnormal auto-antibodies are desirable.

Safety of tapering tacrolimus dose in patients with well-controlled anti-acetylcholine receptor antibody-positive myasthenia gravis

BACKGROUND AND PURPOSE

Tapering immunosuppressants is desirable in patients with well-controlled myasthenia gravis (MG). However, the association between tapering of calcineurin inhibitor dosage and reduction-associated exacerbation is not known. The aim of this study was to clarify the frequency of reduction-associated exacerbation when tacrolimus is tapered in stable patients with anti-acetylcholine receptor antibody-positive MG, and to determine the factors that predict exacerbations.

METHODS

We retrospectively analyzed 115 patients in whom tacrolimus dosage was tapered. The reduction-associated exacerbation was defined as the appearance or worsening of one or more MG symptoms <3 months after the reduction.

RESULTS

Tacrolimus dosage was successfully tapered in 110 patients (96%) without any exacerbation. Five patients (4%) experienced an exacerbation, but symptoms were reversed in all patients when the tacrolimus dose was increased to the previous maintenance level. No patient developed an MG crisis. The age at onset was significantly earlier (30 vs. 56 years, P = 0.025) and the reduction in dosage was significantly larger (2.0 vs. 1.0 mg/day, P = 0.002) in patients with reduction-associated exacerbation than in those without exacerbation. The cut-off values determined in a receiver-operating characteristic curve analysis were 52 years (sensitivity, 57%; specificity, 100%) for the age at onset and 1.5 mg (sensitivity, 80%; specificity, 100%) for the dose reduction.

CONCLUSION

Tapering of tacrolimus was possible in most patients with well-controlled anti-acetylcholine receptor antibody-positive MG. Early age at onset and a large reduction from maintenance dosage were associated with exacerbation. Reductions ≤1.5 mg/day from the maintenance dosage should be considered for patients with late-onset disease.

Long-Term Safety and Efficacy of Tacrolimus in Myasthenia Gravis

PURPOSE

Myasthenia gravis (MG) is a lifelong autoimmune disorder that affects neuromuscular transmission. The long-term treatment plan should include immunotherapy. We investigated the long-term safety and efficacy of tacrolimus for the treatment of MG in real-world clinical practice.

MATERIALS AND METHODS

We retrospectively reviewed 160 MG patients treated with tacrolimus from 2005 to 2015. Myasthenia Gravis Foundation of America (MGFA) clinical classification, MGFA post-intervention status, myasthenic functional score, and dose of oral prednisolone were investigated.

RESULTS

Adverse events occurred in 68 patients (42.5%), most of which were minor and well-managed. Clinical severity scales improved after administration of tacrolimus, compared to the baseline. Compared to 6 months before administration of tacrolimus, prednisolone dose significantly decreased at 12 months after treatment (2.85±0.92 mg/day, p=0.002), 18 months after treatment (3.36±0.99 mg/day, p=0.001), and 24 months after treatment (3.71±0.93 mg/day, p<0.001).

CONCLUSION

Tacrolimus may be effective in reducing the severity of MG and may permit a reduction in the steroid dose prescribed to the patients. Adverse events due to tacrolimus treatment were not serious.

Myasthenia gravis

Myasthenia gravis (MG) is an autoimmune disease caused by antibodies against the acetylcholine receptor (AChR), muscle-specific kinase (MuSK) or other AChR-related proteins in the postsynaptic muscle membrane. Localized or general muscle weakness is the predominant symptom and is induced by the antibodies. Patients are grouped according to the presence of antibodies, symptoms, age at onset and thymus pathology. Diagnosis is straightforward in most patients with typical symptoms and a positive antibody test, although a detailed clinical and neurophysiological examination is important in antibody-negative patients. MG therapy should be ambitious and aim for clinical remission or only mild symptoms with near-normal function and quality of life. Treatment should be based on MG subgroup and includes symptomatic treatment using acetylcholinesterase inhibitors, thymectomy and immunotherapy. Intravenous immunoglobulin and plasma exchange are fast-acting treatments used for disease exacerbations, and intensive care is necessary during exacerbations with respiratory failure. Comorbidity is frequent, particularly in elderly patients. Active physical training should be encouraged.

A Neurologist's Perspective on Understanding Myasthenia Gravis: Clinical Perspectives of Etiologic Factors, Diagnosis, and Preoperative Treatment

Myasthenia gravis (MG) is a disease of neuromuscular transmission caused by antibodies directed toward proteins concentrated at the neuromuscular junction. Mild to life-threatening weakness varies in severity over time and with level of activity. Therefore, clinical diagnosis is often challenging. MG may be categorized by autoantibody type, thymic pathologic condition, and age of onset. Treatments are tailored for each group. A key management concern is severe exacerbation of weakness resulting from infections or exposure to certain medications, including antibiotics, which may be severe enough to produce respiratory decompensation. The article reviews key diagnostic issues and treatment options.

Italian recommendations for the diagnosis and treatment of myasthenia gravis

Myasthenia gravis is a well-treatable disease, in which a prompt diagnosis and an adequate management can achieve satisfactory control of symptoms in the great majority of patients. Improved knowledge of the disease pathogenesis has led to recognition of patient subgroups, according to associated antibodies, age at onset and thymus pathology, and to a more personalized treatment. When myasthenia gravis is suspected on clinical grounds, diagnostic confirmation relies mainly on the detection of specific antibodies. Neurophysiological studies and, to a lesser extent, clinical response to cholinesterase inhibitors support the diagnosis in seronegative patients. In these cases, the differentiation from congenital myasthenia can be challenging. Treatment planning must consider weakness extension and severity, disease subtype, thymus pathology, together with patient characteristics and comorbidities. Since most subjects with myasthenia gravis require long-term immunosuppressive therapy, surveillance of expected and potential adverse events is critical. For patients refractory to conventional immunosuppression, the use of biologic agents is highly promising. These recommendations are addressed to non-experts on neuromuscular transmission disorders. The diagnostic procedures and therapeutic approaches hereafter described are largely accessible in Italy.

Advances in autoimmune myasthenia gravis management

INTRODUCTION

Myasthenia gravis (MG) is an autoimmune neuromuscular disorder with no cure and conventional treatments limited by significant adverse effects and variable benefit. In the last decade, therapeutic development has expanded based on improved understanding of autoimmunity and financial incentives for drug development in rare disease. Clinical subtypes exist based on age, gender, thymic pathology, autoantibody profile, and other poorly defined factors, such as genetics, complicate development of specific therapies. Areas covered: Clinical presentation and pathology vary considerably among patients with some having weakness limited to the ocular muscles and others having profound generalized weakness leading to respiratory insufficiency. MG is an antibody-mediated disorder dependent on autoreactive B cells which require T-cell support. Treatments focus on elimination of circulating autoantibodies or inhibition of effector mechanisms by a broad spectrum of approaches from plasmapheresis to B-cell elimination to complement inhibition. Expert commentary: Standard therapies and those under development are disease modifying and not curative. As a rare disease, clinical trials are challenged in patient recruitment. The great interest in development of treatments specific for MG is welcome, but decisions will need to be made to focus on those that offer significant benefits to patients.

Independent long-term result of robotic thymectomy for myasthenia gravis, a single center experience

Background

Robotic thymectomy has been suggested a feasible and safe approach for myasthenia gravis (MG). Few investigations have revealed the independent effect of robotic thymectomy without the confounding impact of immunosuppressive (IM) therapy.

Methods

Between May 2009 and December 2012, robotic extended thymectomy was carried out for patients with diagnosis of MG. The clinical data, subsequent neurological therapy and postintervention status were collected.

Results

Data of 37 cases was available for analysis. The mean follow-up was 70.0±13.3 months. The median age was 40 years. Twelve (32.4%) patients kept free of IM therapy, and 25 (67.6%) patients accepted postoperatively. The overall 5-year complete stable remission (CSR) rate was 40.6% and improvement rate was 81.6%. The young (age ≤40) displayed a significant better CSR rate (P=0.015) and a trend of better improvement rate (P=0.050) compared to the old (age >40). Patients without usage of IM therapy showed significant higher CSR rate (P=0.014) and improvement rate (P=0.024) compared to those with usage of IM therapy. Patients with Myasthenia Gravis Foundation of America (MGFA) classes I showed a trend of higher remission rate by multivariate analysis. No significant differences were found for the remission rate according to gender, pathology, and the duration of symptoms.

Conclusions

The mono-therapy of robotic thymectomy may bring with a satisfactory long-term result for part of MG patients. Precision selection and individualized therapy are of the most importance.

Successful Lung Transplantation in a Patient with Myasthenia Gravis

A 47-year-old man with myasthenia gravis (MG) was admitted for a lung transplant. He had bronchiolitis obliterans after allogeneic hematopoietic stem cell transplantation due to acute myeloid leukemia. MG developed after stem cell transplantation. Bilateral sequential lung transplantations and a total thymectomy were performed. The patient underwent right diaphragmatic plication simultaneously due to preoperatively diagnosed right diaphragmatic paralysis. A tracheostomy was performed and bilevel positive airway pressure (BiPAP) was applied on postoperative days 8 and 9, respectively. The patient was transferred to the general ward on postoperative day 12, successfully weaned off BiPAP on postoperative day 18, and finally discharged on postoperative day 62.

Efficacy and safety of tacrolimus for myasthenia gravis: a systematic review and meta-analysis

To evaluate the efficacy and safety of tacrolimus in patients with myasthenia gravis (MG), a systematic review and meta-analysis was performed. We searched PubMed and Embase for randomized controlled trials and clinical controlled trials in English language. Demographic and clinical characteristics of the MG patients were extracted. Differences in the current glucocorticoids (GC) dose in each included study were the primary outcome measure. The adverse events reported in each included study were used as safety evaluation. There were 5 trials included involving 683 patients. In this systematic review, we identified treatment with tacrolimus did not exhibit a statistically significant difference in the GC dose reduction at 6 months and 12 months compared with placebo. The standard mean differences in the GC dose reduction were -1.95 [(-4.20 to 0.30); p = 0.09] at 6 months and -1.72 [(-4.21 to 0.77); p = 0.18] at 12 months. But GC dose reduction from baseline in the tacrolimus group exceeded that in the controlled group. The weighted mean differences were -1.34 [(-2.46 to 0.23); p = 0.02] in the quantitative myasthenia gravis score and -1.10 [(-1.84 to -0.36); p = 0.004] in the myasthenia gravis activities of daily living score at 6 months. Adverse events were recorded in 80 of 347 patients (23%) treated with tacrolimus and most of them were mild. This meta-analysis proves that tacrolimus therapy is beneficial to improve clinical symptoms in MG patients. Tacrolimus may be a worthy therapy to relieve MG symptoms.

Population pharmacokinetic analysis of tacrolimus in Chinese myasthenia gravis patients

The importance of tacrolimus in the treatment of myasthenia gravis (MG) as a substitute for corticosteroid-dependent immunosuppressive therapy is increasing. Thus far, however, no population pharmacokinetic (PopPK) analysis of tacrolimus in treating MG patients has been published. This article aimed to construct a PopPK model of tacrolimus for Chinese MG patients with the goal of improving its performance in MG treatment. A total of 253 trough concentration records were obtained from 83 Chinese MG patients. The effects of demographics, lifestyle and health status, biochemical test data, disease progression and treatment-related information (including co-administered medications) as covariates on the various parameters were investigated. The covariate selection was based on biological plausibility, clinical significance, statistical significance and reduction in inter-individual variability (IIV). Bootstrap and normalized prediction distribution error (NPDE) analysis were performed to validate the final model. A one-compartment PopPK model with first-order elimination and a fixed absorption phase was constructed. The estimated apparent oral clearance (CL/F) and apparent oral volume of distribution (V/F) were 3.6 L/h and 1700 L, respectively, in the MG patients. Hematocrit and blood urea nitrogen were identified as two covariates that significantly influenced the CL/F. Immunoglobulin treatment (PRO) also had the potential to influence V/F, which was consistent with the clinical observations and the high protein-binding property of tacrolimus. Other covariates including age, weight, gender and co-administered medications had no obvious influence on CL/F or V/F. The first PopPK model of tacrolimus in MG patients was established. The identified covariates were of biological plausibility and clinical importance to help individualize the dosing schedule in MG patients.

Tacrolimus in the treatment of myasthenia gravis in patients with an inadequate response to glucocorticoid therapy: randomized, double-blind, placebo-controlled study conducted in China

Background

To determine the efficacy of low-dose, immediate-release tacrolimus in patients with myasthenia gravis (MG) with inadequate response to glucocorticoid therapy in a randomized, double-blind, placebo-controlled study.

Methods

Eligible patients had inadequate response to glucocorticoids (GCs) after ⩾6 weeks of treatment with prednisone ⩾0.75 mg/kg/day or 60–100 mg/day. Patients were randomized to receive 3 mg tacrolimus or placebo daily (orally) for 24 weeks. Concomitant glucocorticoids and pyridostigmine were allowed. Patients continued GC therapy from weeks 1–4; from week 5, the dose was decreased at the discretion of the investigator. The primary efficacy outcome measure was a reduction, relative to baseline, in quantitative myasthenia gravis (QMG) score assessed using a generalized linear model; supportive analyses used alternative models.

Results

Of 138 patients screened, 83 [tacrolimus (n = 45); placebo (n = 38)] were enrolled and treated. The change in adjusted mean QMG score from baseline to week 24 was −4.9 for tacrolimus and −3.3 for placebo (least squares mean difference: –1.7, 95% confidence interval: −3.5, −0.1; p = 0.067). A post-hoc analysis demonstrated a statistically significant difference for QMG score reduction of ⩾4 points in the tacrolimus group (68.2%) versus the placebo group (44.7%; p = 0.044). Adverse event profiles were similar between treatment groups.

Conclusions

Tacrolimus 3 mg treatment for patients with MG and inadequate response to GCs did not demonstrate a statistically significant improvement in the primary endpoint versus placebo over 24 weeks; however, a post-hoc analysis demonstrated a statistically significant difference for QMG score reduction of ⩾4 points in the tacrolimus group versus the placebo group. This study was limited by the low number of patients, the absence of testing for acetylcholine receptor antibody and the absence of stratification by disease duration (which led to a disparity between the two groups).

ClinicalTrials.gov identifier: NCT01325571

Efficacy and Safety of Tacrolimus in Myasthenia Gravis: A Systematic Review and Meta-analysis

Aims:

This study was designed to determine whether treatments with tacrolimus would provide benefit for patients with myasthenia gravis (MG).

Materials and Methods:

The databases of Medline, EMBASE, the Cochrane Library, and four Chinese databases were searched for eligible studies. Weighted mean differences and standardized mean differences (SMD) with corresponding 95% confidence intervals (CIs) were used to summarize the primary outcome, namely, steroid-sparing effect of tacrolimus in maintaining minimal manifestations, and the secondary outcome, namely, the effect of tacrolimus in reducing the severity of MG, respectively.

Results:

After systematic retrieval, 13 researches with two randomized controlled trials (RCTs) and 11 prospective open-label single-arm clinical trials were included in the study. For the primary outcome of two RCTs, one RCT which was followed up for 1 year showed a positive effect and the other RCT which was associated with treatment duration of 28 weeks showed a negative result. For the secondary outcome, meta-analyses of other 11 trials showed a benefit effect, overall. For the quantitative MG (QMG) score, there were significant differences with high heterogeneity (SMD: 2.93; 95% CI: 1.14–4.73; I² = 86%). In contrast, for MG activities of daily living (MGADL) score, it was reduced by tacrolimus with significant SMD and less heterogeneity (SMD: 0.59; 95% CI: 0.33–0.85; I² = 7%). Adverse effects were mentioned as mild.

Discussion:

The opposite results of two RCTs showed that tacrolimus with enough treatment duration might have positive steroid-sparing effect. The most possible cause of heterogeneity in the outcome of QMG score between trials was the baseline severity of MG.

Conclusion:

The above finding suggests that there might be a potential beneficial role with no serious side effects of tacrolimus, and additional better RCTs including larger sample sizes and long-term study are needed to confirm or refute the results.

Development of myasthenia gravis 8 years after interstitial lung disease associated with antisynthetase (anti-EJ antibody) syndrome

Patients with antisynthetase-positive interstitial lung disease (ILD) alone sometimes develop myositis during follow-up, but myasthenia gravis (MG) overlapping on antisynthetase syndrome is unusual. A 56-year-old woman with ILD and anti-EJ antibody treated for 8 years developed MG. Physicians should consider myositis and MG when patients develop muscle symptoms during follow-up.

A study of the utility of azathioprine metabolite testing in myasthenia gravis

Myasthenia gravis (MG) is an autoimmune neuromuscular disorder characterised by fatigable voluntary skeletal muscle weakness. The underlying pathogenesis is complex involving adaptive autoimmune responses. Azathioprine remains a first line broad acting immunosuppressant for MG. Due to varied clinical responses to azathioprine we aimed to investigate the relationship between azathioprine metabolites and symptom control. Mild correlations between Quantitative Myasthenia Gravis Score (QMG) vs. 6-thioguanine nucleotides (R=-0.317 p=0.186) and QMG vs. lymphocyte count (R=0.402 p=0.08) were found. Azathioprine metabolite measurement should be considered in MG patients with; pancytopenia, deranged liver function or recurrent infections.

Overcoming challenges in the diagnosis and treatment of myasthenia gravis

In recent years, the discovery of new autoantigens and the use of sensitive assays have expanded the clinical spectrum of myasthenia gravis (MG). In particular, antibodies binding to clustered acetylcholine receptors and to the low-density lipoprotein receptor-related protein 4 have not only bridged a significant gap in diagnosis but also have relevant clinical implications. MG management includes different therapeutic options, from symptomatic agents as the only therapy in mildly affected cases to combined long-term immunosuppression and thymectomy in patients with severe disabling disease. MG biological diversity can influence the response to therapies and should be taken into account when planning treatment. Biologic agents are promising, though their use is currently limited to patients with refractory disease.