IgG regulation through FcRn blocking: A novel mechanism for the treatment of myasthenia gravis

Impact of FcRn antagonism on vaccine-induced protective immune responses against viral challenge in COVID-19 and influenza mouse vaccination models

Antagonism of the neonatal Fc receptor through an engineered antibody Fc fragment, such as efgartigimod, results in a decrease in immunoglobulin G levels. This approach is being evaluated as a therapeutic strategy for the treatment of IgG-mediated autoimmune diseases. Our goal was to evaluate the impact of mFc-ABDEG, a mouse-adapted antibody Fc fragment with a mode of action highly similar to efgartigimod, on vaccine-induced protective immune responses against viral infections. Therefore, mouse vaccination models for COVID-19 and influenza were employed, utilizing an mRNA COVID-19 vaccine (COMIRNATY) and an adjuvanted, inactivated quadrivalent influenza vaccine (Seqirus+AddaVax), respectively. In both models, vaccination induced robust humoral responses. As expected, animals treated with mFc-ABDEG had lower levels of virus-specific IgG, while virus-specific IgM responses remained unaffected. The COVID-19 vaccine induced a strong Th1-type T cell response irrespective of mFc-ABDEG treatment. Influenza vaccination resulted in a poor T cell induction, regardless of mFc-ABDEG treatment, due to the Th2-biased response that inactivated influenza vaccines typically induce. Importantly, mFc-ABDEG treatment had no effect on protective immunity against live viral challenges in both models. Vaccinated animals treated with mFc-ABDEG were equally protected as the non-treated vaccinated controls. These non-clinical data demonstrate that FcRn antagonism with mFc-ABDEG did not affect the generation of vaccine-induced protective humoral and cellular responses, or protection against viral challenges. These data substantiate the clinical observations that, although IgG titers were reduced, FcRn antagonism with efgartigimod did not impair the ability to generate new specific IgG responses, regardless of the timing of vaccination.

Baicalein Ameliorates Experimental Ulcerative Colitis Recurrency by Downregulating Neonatal Fc Receptor via the NF-κB Signaling Pathway

Ulcerative colitis (UC) is a chronic autoimmune disease (AID) that causes mild to moderate unpredictable symptoms, including diarrhea and abdominal pain. Against neonatal Fc receptor (FcRn) has been proven to be a unique AID treatment strategy by decreasing the effects of pathogenic autoantibody. Our previous study revealed that FcRn inhibition is beneficial in UC treatment through reducing colonic neutrophil extracellular trap (NET) formation via accelerating serum antineutrophil cytoplasm antibodies (ANCA) clearance. In this study, we initially confirmed the specific impact of downregulating FcRn in preventing UC relapse by injecting rAAV, which is carrying Fcgrt-shRNA, in mice. Next, we investigated the inhibition effects and regulation mechanisms of baicalein (BCL) on FcRn and assessed its capacity to withstand UC recurrence using NCM460 cells and dextran sodium sulfate-induced mice models by determining the expression of FcRn and its related transcription factors. We also measured colonic NET-associated protein (NAP) expression and serum concentrations of IgG, ANCA, TNF-α, IL-1β, and c-reactive protein (CRP). UC inflammation severity was determined by using the disease activity index (DAI) and histopathological score (HS). BCL treatment remarkably decreased the mRNA and protein contents of FcRn, p50, and p65 but did not impact STAT1 expression or the phosphorylation of IκB and STAT1. Long-term BCL administration inhibited colonic FcRn expression and reduced serum ANCA levels, colonic NAP expression, serum inflammation-related indexes (including TNF-α, IL-1β, and CRP), and DAI and HS scores in UC mice during inflammation relapse better than salazosulfapyridine. Our study indicates that BCL ameliorates UC recurrency by inhibiting FcRn expression via p50/p65 heterodimer-mediated NF-κB signaling.

New and Emerging Biological Therapies for Myasthenia Gravis: A Focussed Review for Clinical Decision-Making

Myasthenia gravis (MG) is a rare autoimmune disease characterised by exertion-induced muscle weakness that can lead to potentially life-threatening myasthenic crises. Detectable antibodies are directed against specific postsynaptic structures of the neuromuscular junction. MG is a chronic condition that can be improved through therapies, but to date, not cured. Standard treatment has been unchanged for decades and includes symptomatic treatment with acetylcholine-esterase inhibitors and disease-modifying treatment with steroids, steroid-sparing immunosuppressants and thymectomy. Overall, a relevant proportion of patients does not achieve a satisfactory clinical improvement under standard treatment. Additionally, long-term therapy with steroids can cause significant side effects and latency to clinical improvement with standard steroid-sparing immunosuppressants and after thymectomy can take months to years. In recent years, treatment of MG has changed fundamentally due to improved evidence from phase 3 trials and the regulatory approval of complement inhibitors and FcRn inhibitors as add-on treatment options. This provides new optimism for substantially more patients reaching minimal manifestation status and has led to a shift in treatment strategy with more targeted therapies being employed early in the course of the disease, especially in patients with high disease activity. In this focussed review, we provide an overview of the diagnosis, classification and standard treatment of MG, followed by data from randomised controlled trials on the modern drugs already available for therapy and those still in the final stages of clinical development. In the second part, we provide an overview of real-world data for already approved therapies and outline how the availability of new biologicals is changing both clinical decision-making and patient journey.

A review of intravenous immunoglobulin in the treatment of neuroimmune conditions, acute COVID-19 infection, and post-acute sequelae of COVID-19 Syndrome

Intravenous immunoglobulin (IVIG) is an immunomodulatory therapy that has been studied in several neuroimmune conditions, such as Guillain-Barré Syndrome, chronic inflammatory demyelinating polyneuropathy, multifocal motor neuropathy, and multiple sclerosis. It has also been proposed as a potential treatment option for acute COVID-19 infection and post-acute sequelae of SARS-CoV-2 infection (PASC). IVIG is thought to function by providing the recipient with a pool of antibodies, which can, in turn, modulate immune responses through multiple mechanisms including neutralization of cytokines and autoantibodies, saturation of neonatal fragment crystallizable receptors, inhibition of complement activation, and regulation of T and B cell mediated inflammation. In acute COVID-19, studies have shown that early administration of IVIG and plasmapheresis in severe cases can reduce the need for mechanical ventilation, shorten ICU and hospital stays, and lower mortality. Similarly, in PASC, while research is still in early stages, IVIG has been shown to alleviate persistent symptoms in small patient cohorts. Furthermore, IVIG has shown benefits in another condition which has symptomatic overlap with PASC, myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS), though studies have yielded mixed results. It is important to note that IVIG can be associated with several potential adverse effects, such as anaphylaxis, headaches, thrombosis, liver enzyme elevations and renal complications. In addition, the high cost of IVIG can be a deterrent for payers and patients. This review provides a comprehensive update on the use of IVIG in multiple neuroimmune conditions, ME/CFS, acute COVID-19, and PASC, as well as covers its history, production, pricing, and mechanisms of action. We also identify key areas of future research, including the need to optimize the use of Ig product dosing, timing, and patient selection across conditions, particularly in the context of COVID-19 and PASC.

Association of Myasthenia Gravis With Autoimmune Thyroid Disease: A Bidirectional Mendelian Randomization Study

BACKGROUND AND PURPOSE

Observational studies have indicated a high occurrence of coexistence between myasthenia gravis (MG) and autoimmune thyroid disease (AITD) in clinical settings, but the causal relationship between the two conditions remains ambiguous. Therefore, this study endeavors to investigate the causal links between MG, along with its subgroups, and AITD through a Mendelian randomization (MR) approach.

METHODS

Genetic instrumental variables associated with MG and AITD were selected from three major publicly available GWAS databases for MR analysis. The primary method for evaluating causal effects was the inverse variance weighted (IVW) method. Supplementary methods included MR-Egger regression and weighted median. The reliability and stability of the results were ensured through tests for heterogeneity, assessment of pleiotropy, and sensitivity analysis using the leave-one-out approach.

RESULTS

The investigation revealed reciprocal causal associations between MG and both Graves' disease and autoimmune hypothyroidism. Genetic predisposition to MG was linked to an increased likelihood of developing Hashimoto's thyroiditis (OR = 1.242(1.073-1.437, P = 0.0036)), and early-onset MG also exhibited an association with an elevated risk of HT (OR = 1.157(1.073-1.246), P = 1.269×10-4). No statistically significant relationships were found for the other conditions.

CONCLUSION

This extensive MR analysis provides evidence suggesting a potential association between MG and AITD, particularly with Graves' disease and Hashimoto's thyroiditis. Consequently, proactive treatment strategies targeting either MG or autoimmune thyroid disorders may help mitigate the risk of comorbidities in affected patients.

Myasthenia gravis: The evolving therapeutic landscape

Pharmacological options in the management of generalized myasthenia gravis (gMG) have expanded rapidly in the last 7 years. There are now several complement inhibitors and neonatal Fc receptor antagonists on the market in many countries for patient management, following the successful completion of Phase 3 studies. In open-label extensions, these agents have proven to be effective over the longer term extending several years, with benefits such as reduction of corticosteroid requirements being observed. In the communication below, we will briefly summarize recent pharmacologic advancements in the management of gMG and outline how these agents are currently being used and may be used in the future.

The changing landscape of autoantibody testing in myasthenia gravis in the setting of novel drug treatments

Acquired myasthenia gravis (MG) is an autoimmune disease targeting the specific proteins in the postsynaptic muscle membrane. 50% of ocular and 80% of generalized MG have acetylcholine receptor antibodies (AChR Abs). 1-10% of MG patients have antibodies against muscle-specific kinase (MuSK), and 2-50 % of seronegative MG cases have antibodies against lipoprotein-receptor-related protein4 antibodies (LRP4 Abs). Serological testing is crucial for diagnosing and determining the appropriate therapeutic approach for MG patients. The radioimmunoprecipitation assay (RIPA) method is a historical standard test for detecting the AChR Abs and MuSK Abs. While it has nearly 100% specificity in the AChR Abs detection, its sensitivity is between 50--92%. The sensitivity and specificity of RIPA for detecting MuSK Abs is much lower. The fixed and live Cell-Based assays (f-CBA and L- CBA) have higher sensitivity than RIPA. With advancements in the serological diagnosis and management of MG, we now recommend a complete reflex testing algorithm on the first pretreatment sample of a suspected MG patient, starting with the binding and blocking assays for AChR Abs by RIPA and/ or f-CBA. If AChR Ab is negative, then reflex to MuSK Abs by RIPA and/ or CBAs. If AChR and MuSK Abs are negative, then use clustered L-CBA by request.

Current state and potential applications of neonatal Fc receptor (FcRn) inhibitors in hematologic conditions

The neonatal fragment crystallizable (Fc) receptor (FcRn) transports IgG across mucosal surfaces and the placenta and protects IgG from degradation. Numerous clinical trials are investigating therapeutic FcRn inhibition for various immune-mediated neuromuscular and rheumatologic conditions; however, FcRn inhibition also represents a potential therapy for IgG-mediated hematologic conditions (e.g., immune thrombocytopenia, autoimmune hemolytic anemia, immune thrombotic thrombocytopenic purpura, acquired hemophilia, red blood cell/platelet alloimmunization). Current evidence derived from both in vitro and in vivo studies suggests that FcRn inhibitors effectively reduce total IgG levels without impacting its production or altering the levels of other immunoglobulin isotypes. Moreover, the risk of serious adverse events, including serious infections, appears to be lower than that seen with other commonly used immunomodulatory/immunosuppressive therapies, albeit in the setting of limited clinical trial data. Ultimately, additional clinical trials that include varied patient populations are required prior to incorporating these agents into standard treatment algorithms for most hematologic conditions. However, based on the pathophysiology of IgG-mediated hematologic disorders and the mechanism of action of FcRn inhibitors, these agents may represent a future novel therapeutic strategy for patients with hematologic conditions caused by IgG antibodies.

A high hydrophobic moment arginine-rich peptide screened by a machine learning algorithm enhanced ADC antitumor activity

Cell-penetrating peptides (CPPs) with better biomolecule delivery properties will expand their clinical applications. Using the MLCPP2.0 machine algorithm, we screened multiple candidate sequences with potential cellular uptake ability from the nuclear localization signal/nuclear export signal database and verified them through cell-penetrating fluorescent tracing experiments. A peptide (NCR) derived from the Rev protein of the caprine arthritis-encephalitis virus exhibited efficient cell-penetrating activity, delivering over four times more EGFP than the classical CPP TAT, allowing it to accumulate in lysosomes. Structural and property analysis revealed that a high hydrophobic moment and an appropriate hydrophobic region contribute to the high delivery activity of NCR. Trastuzumab emtansine (T-DM1), a HER2-targeted antibody-drug conjugate, could improve its anti-tumor activity by enhancing targeted delivery efficiency and increasing lysosomal drug delivery. This study designed a new NCR vector to non-covalently bind T-DM1 by fusing domain Z, which can specifically bind to the Fc region of immunoglobulin G and effectively deliver T-DM1 to lysosomes. MTT results showed that the domain Z-NCR vector significantly enhanced the cytotoxicity of T-DM1 against HER2-positive tumor cells while maintaining drug specificity. Our results make a useful attempt to explore the potential application of CPP as a lysosome-targeted delivery tool.

Efficacy and safety of rozanolixizumab in patients with muscle-specific tyrosine kinase autoantibody-positive generalised myasthenia gravis: a subgroup analysis of the randomised, double-blind, placebo-controlled, adaptive phase III MycarinG study

Background

Muscle-specific tyrosine kinase (MuSK) autoantibody-positive (Ab+) generalised myasthenia gravis (gMG) is a rare and frequently severe subtype of gMG.

Objectives

To assess the efficacy and safety of rozanolixizumab in the subgroup of patients with MuSK Ab+ gMG in the MycarinG study.

Design

A randomised, double-blind, placebo-controlled phase III study.

Methods

Patients with acetylcholine receptor (AChR) Ab+ or MuSK Ab+ gMG (aged ⩾18 years, Myasthenia Gravis Foundation of America Disease Class II-IVa, Myasthenia Gravis Activities of Daily Living [MG-‍ADL] score ⩾3.0 [non-ocular symptoms], Quantitative Myasthenia Gravis score ⩾11.0) were randomly assigned (1:1:1) to receive once-weekly subcutaneous infusions of rozanolixizumab 7 mg/kg, rozanolixizumab 10 mg/kg or placebo for 6 weeks, followed by an 8-week observation period. Randomisation was stratified by AChR and MuSK autoantibody status. The primary study endpoint was change from baseline to Day 43 in MG-ADL score. Treatment-emergent adverse events (TEAEs) were also assessed.

Results

Overall, 200 patients were randomised, of whom 21 had MuSK Ab+ gMG and received rozanolixizumab 7 mg/kg (n = 5), 10 mg/kg (n = 8) or placebo (n = 8). In patients with MuSK Ab+ gMG, reductions from baseline to Day 43 in MG-ADL scores were observed: rozanolixizumab 7 mg/kg least squares mean (LSM) change (standard error), -7.28 (1.94); 10 mg/kg, -4.16 (1.78); and placebo, 2.28 (1.95). Rozanolixizumab 7 mg/kg LSM difference from placebo was -9.56 (97.5% confidence interval: -15.25, -3.87); 10 mg/kg, -6.45 (-11.03, -1.86). TEAEs were experienced by four (80.0%), five (62.5%) and three (37.5%) patients with MuSK Ab+ gMG receiving rozanolixizumab 7 mg/kg, 10 mg/kg and placebo, respectively. No patients experienced serious TEAEs. No deaths occurred.

Conclusion

This subgroup analysis of adult patients with MuSK Ab+ gMG enrolled in the MycarinG study supports the use of rozanolixizumab as an effective treatment option for patients with gMG who have MuSK autoantibodies.

Trial registration

ClinicalTrials.gov: NCT03971422 (https://clinicaltrials.gov/study/NCT03971422); EU Clinical Trials Register: EudraCT 2019-000968-18 (https://www.clinicaltrials‌register.eu/ctr-search/trial/2019-000968-18/GB).

Subcutaneous efgartigimod PH20 in generalized myasthenia gravis: A phase 3 randomized noninferiority study (ADAPT-SC) and interim analyses of a long-term open-label extension study (ADAPT-SC+)

ADAPT-SC (NCT04735432) was designed to evaluate noninferiority of subcutaneous (SC) efgartigimod PH20 to intravenous (IV) efgartigimod in participants with generalized myasthenia gravis (gMG). ADAPT-SC+ (NCT04818671) is an open-label extension study designed to assess long-term safety, tolerability, and efficacy of efgartigimod PH20 SC. Adult participants in ADAPT-SC were randomly assigned to receive a treatment cycle of 4 once-weekly administrations of efgartigimod PH20 SC 1000 ​mg or efgartigimod IV 10 ​mg/kg, followed by 7 weeks of follow-up. Primary endpoint was percentage change from baseline in total immunoglobulin G (IgG) level at week 4 (1 week after the fourth administration). Secondary efficacy endpoints assessed number and percentage of Myasthenia Gravis Activities of Daily Living (MG-ADL) and Quantitative Myasthenia Gravis (QMG) responders and mean change from baseline in total score for each measure. The primary endpoint was met, demonstrating noninferiority in total IgG reduction between efgartigimod PH20 SC 1000 ​mg and efgartigimod IV 10 ​mg/kg. Clinically meaningful improvements were seen as early as 1 week following the first administration in both treatment arms, with maximal improvements at week 4. Continued treatment cycles of efgartigimod PH20 SC in ADAPT-SC+ have demonstrated long-term safety and consistent improvements in MG-ADL total score. Findings from ADAPT-SC and ADAPT-SC+ demonstrate similar safety and efficacy as observed in the placebo-controlled ADAPT study. Collectively, these findings support noninferiority between efgartigimod PH20 SC 1000 ​mg and efgartigimod IV 10 ​mg/kg, as well as long-term safety, tolerability, and efficacy of efgartigimod PH20 SC for treatment of a broad population of patients with gMG.

Treating myasthenia gravis beyond the eye clinic

Myasthenia gravis (MG) is one of the most well characterised autoimmune disorders affecting the neuromuscular junction with autoantibodies targeting the acetylcholine receptor (AChR) complex. The vast majority of patients present with ocular symptoms including double vision and ptosis, but may progress on to develop generalised fatiguable muscle weakness. Severe involvement of the bulbar muscles can lead to dysphagia, dysarthria and breathing difficulties which can progress to myasthenic crisis needing ventilatory support. Given the predominant ocular onset of the disease, it is important that ophthalmologists are aware of the differential diagnosis, investigations and management including evolving therapies. When the disease remains localised to the extraocular muscles (ocular MG) IgG1 and IgG3 antibodies against the AChR (including clustered AChR) are present in nearly 50% of patients. In generalised MG this is seen in nearly 90% patients. Other antibodies include those against muscle specific tyrosine kinase (MuSK) and lipoprotein receptor related protein 4 (LRP4). Even though decremental response on repetitive nerve stimulation is the most well recognised neurophysiological abnormality, single fibre electromyogram (SFEMG) in experienced hands is the most sensitive test which helps in the diagnosis. Initial treatment should be using cholinesterase inhibitors and then proceeding to immunosuppression using corticosteroids and steroid sparing drugs. Patients requiring bulbar muscle support may need rescue therapies including plasma exchange and intravenous immunoglobulin (IVIg). Newer therapeutic targets include those against the B lymphocytes, complement system, neonatal Fc receptors (FcRn) and various other elements of the immune system.

Retrospective analysis of efgartigimod use in patients with double-seronegative generalized myasthenia gravis: a case series

The effect of treatment with efgartigimod in seronegative myasthenia gravis (MG) remains unclear. This retrospective study aimed to evaluate symptomatic changes and safety of treatment with efgartigimod in patients with generalized MG (gMG) double-seronegative for acetylcholine receptor antibody and muscle-specific kinase antibody. We reviewed the medical records of double-seronegative gMG treated with 10 mg/kg efgartigimod once/week per cycle (4 weeks) from June 2022 to June 2023. A total of 16 patients were included. MG-activities of daily living (ADL) scores improved from 9.2 to 7.4. Mean prednisolone dose was reduced from 5.4 to 4.1 mg/day. The duration before MG-ADL deterioration after the end of a cycle was 6.1 weeks. Five patients had mild adverse events. This retrospective study revealed no significant treatment benefit in the outcomes of patients with double-seronegative gMG treated with efgartigimod.

Real-World experience with efgartigimod in patients with myasthenia gravis

Recommendations for the treatment of myasthenia gravis (MG) have been difficult to develop because of limited evidence from large randomized controlled trials. New drugs and treatment approaches have recently been shown to be effective in phase 3 studies in seropositive generalized (g) MG. One such drug is efgartigimod, a human-Fc-fragment of IgG1, with a high affinity for the endosomal FcRn. We conducted a multicenter study to evaluate the real-world clinical and safety effects of efgartigimod in 22 gMG patients. We evaluated the strategies for the timing of re-treatment with it. The participants received a total of 59 efgartigimod -treatment cycles. The median number of cycles was 2 (range 1-6). Twenty patients (86.3%) improved by at least 2 MG-ADL points after the first treatment cycle. The median MG-ADL score at baseline was 6.5 (range: 3-17) and 2.5 (range: 0-9) post-treatment (p < 0.001). A consistent improvement of at least 2 points in the MG-ADL score after each cycle occurs in 18 patients. The effect duration of the treatment was usually between 4 and 12 weeks. Two major clinical patterns of treatment response were found. Treatment with efgartigimod was also associated with significant reductions of prednisone doses Overall, the treatment was safe and associated with only minor adverse events. The single fatality was apparently due tosevere respiratory failure. We found that efgartigimod is clinically effective, may be used as a steroid sparing agent and is generally safe for gMG patients. We recommend a personalized preventive treatment approach until clinical stabilization, followed by discontinuation and periodic evaluations.

Bullous pemphigoid induced by IgG targeting type XVII collagen non-NC16A/NC15A extracellular domains is driven by Fc gamma receptor- and complement-mediated effector mechanisms and is ameliorated by neonatal Fc receptor blockade

Bullous pemphigoid (BP) is an autoimmune blistering disease characterized by autoantibodies targeting type XVII collagen (Col17) with the noncollagenous 16A (NC16A) ectodomain representing the immunodominant site. The role of additional extracellular targets of Col17 outside NC16A has not been unequivocally demonstrated. In this study, we showed that Col17 ectodomain-reactive patient sera depleted in NC16A IgG induced dermal-epidermal separation in a cryosection model indicating the pathogenic potential of anti-Col17 non-NC16A extracellular IgG. Moreover, injection of IgG targeting the murine Col17 NC14-1 domains (downstream of NC15A, the murine homologue of human NC16A) into C57BL/6J mice resulted in erythematous skin lesions and erosions. Clinical findings were accompanied by IgG/C3 deposits along the basement membrane and subepidermal blistering with inflammatory infiltrates. Disease development was significantly reduced in either Fc-gamma receptor (FcγR)- or complement-5a receptor-1 (C5aR1)-deficient mice. Inhibition of the neonatal FcR (FcRn), an atypical FcγR regulating IgG homeostasis, with the murine Fc fragment IgG2c-ABDEG, a derivative of efgartigimod, reduced anti-NC14-1 IgG levels, resulting in ameliorated skin inflammation compared with isotype-treated controls. These data demonstrate that the pathogenic effects of IgG targeting the Col17 domain outside human NC16A/murine NC15A are partly attributable to antibody-mediated FcγR- and C5aR1 effector mechanisms while pharmacological inhibition of the FcRn represents a promising treatment for BP. The mouse model of BP will be instrumental in further investigating the role of Col17 non-NC16A/NC15A extracellular epitopes and validating new therapies for this disease. © 2023 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

Therapeutic Plasma Exchange Versus FcRn Inhibition in Autoimmune Disease

Therapeutic plasma exchange (TPE or PLEX) is used in a broad range of autoimmune diseases, with the goal of removing autoantibodies from the circulation. A newer approach for the selective removal of immunoglobulin G (IgG) antibodies is the use of therapeutic molecules targeting the neonatal Fc receptor (FcRn). FcRn regulates IgG recycling, and its inhibition results in a marked decrease in circulating autoantibodies of the IgG subtype. The difference between FcRn inhibition and PLEX is often questioned. With anti-FcRn monoclonal antibodies (mAbs) and fragments only recently entering this space, limited data are available regarding long-term efficacy and safety. However, the biology of FcRn is well understood, and mounting evidence regarding the efficacy, safety, and potential differences among compounds in development is available, allowing us to compare against nonselective plasma protein depletion methods such as PLEX. FcRn inhibitors may have distinct advantages and disadvantages over PLEX in certain scenarios. Use of PLEX is preferred over FcRn inhibition where removal of antibodies other than IgG or when concomitant repletion of missing plasma proteins is needed for therapeutic benefit. Also, FcRn targeting has not yet been studied for use in acute flares or crisis states of IgG-mediated diseases. Compared with PLEX, FcRn inhibition is associated with less invasive access requirements, more specific removal of IgG versus other immunoglobulins without a broad impact on circulating proteins, and any impacts on other therapeutic drug levels are restricted to other mAbs. In addition, the degree of IgG reduction is similar with FcRn inhibitors compared with that afforded by PLEX. Here we describe the scientific literature regarding the use of PLEX and FcRn inhibitors in autoimmune diseases and provide an expert discussion around the potential benefits of these options in varying clinical conditions and scenarios.

Myasthenia gravis-Pathophysiology, diagnosis, and treatment

Myasthenia gravis (MG) is an autoimmune disease characterized by dysfunction of the neuromuscular junction resulting in skeletal muscle weakness. It is equally prevalent in males and females, but debuts at a younger age in females and at an older age in males. Ptosis, diplopia, facial bulbar weakness, and limb weakness are the most common symptoms. MG can be classified based on the presence of serum autoantibodies. Acetylcholine receptor (AChR) antibodies are found in 80%-85% of patients, muscle-specific kinase (MuSK) antibodies in 5%-8%, and <1% may have low-density lipoprotein receptor-related protein 4 (Lrp4) antibodies. Approximately 10% of patients are seronegative for antibodies binding the known disease-related antigens. In patients with AChR MG, 10%-20% have a thymoma, which is usually detected at the onset of the disease. Important differences between clinical presentation, treatment responsiveness, and disease mechanisms have been observed between these different serologic MG classes. Besides the typical clinical features and serologic testing, the diagnosis can be established with additional tests, including repetitive nerve stimulation, single fiber EMG, and the ice pack test. Treatment options for MG consist of symptomatic treatment (such as pyridostigmine), immunosuppressive treatment, or thymectomy. Despite the treatment with symptomatic drugs, steroid-sparing immunosuppressants, intravenous immunoglobulins, plasmapheresis, and thymectomy, a large proportion of patients remain chronically dependent on corticosteroids (CS). In the past decade, the number of treatment options for MG has considerably increased. Advances in the understanding of the pathophysiology have led to new treatment options targeting B or T cells, the complement cascade, the neonatal Fc receptor or cytokines. In the future, these new treatments are likely to reduce the chronic use of CS, diminish side effects, and decrease the number of patients with refractory disease.

Ravulizumab in Myasthenia Gravis: A Review of the Current Evidence

The terminal complement C5 inhibitor ravulizumab was engineered from the humanized monoclonal antibody eculizumab to have an extended half-life and duration of action. It binds to human terminal complement protein C5, inhibiting its cleavage into C5a and C5b, thus preventing the cascade of events that lead to architectural destruction of the postsynaptic neuromuscular junction membrane by the membrane attack complex, and consequent muscle weakness in patients with anti-acetylcholine receptor (AChR) antibody-positive generalized myasthenia gravis (gMG). The 26-week randomized, placebo-controlled period (RCP) of the phase 3 CHAMPION MG study demonstrated the rapid efficacy of ravulizumab in reducing MG symptoms. Weight-based dosing of ravulizumab every 8 weeks provided sustained efficacy, in terms of patient-reported (Myasthenia Gravis-Activities of Daily Living) and clinician-reported (Quantitative Myasthenia Gravis) endpoints in patients with anti-AChR antibody-positive gMG. Pharmacokinetic and pharmacodynamic analyses showed therapeutic serum ravulizumab concentrations (>175 µg/mL) were achieved immediately after the first dose and were maintained throughout 26 weeks, irrespective of patient body weight; inhibition of serum free C5 was immediate, complete (<0.5 μg/mL), and sustained in all patients. Interim results from the open-label extension (OLE) showed that after 60 weeks, efficacy was maintained in patients continuing on ravulizumab. Rapid and sustained improvements in efficacy, similar to those seen in patients initiating ravulizumab in the RCP, were observed after initiation of ravulizumab treatment in patients who switched from placebo in the RCP to ravulizumab in the OLE. The findings from the RCP and OLE support ravulizumab's favorable safety profile. In conclusion, ravulizumab has a simple weight-based administration and long dosing interval. Its targeted mechanism of action without generalized immunosuppression is reflected in its rapid onset of symptom improvement, sustained efficacy and good safety profile in the treatment of patients with anti-AChR antibody-positive gMG.

Myasthenia gravis: Molecular mechanisms and promising therapeutic strategies

Myasthenia gravis (MG) is a type of autoimmune disease caused by the blockage of neuromuscular junction transmission owing to the attack of autoantibodies on transmission-related proteins. Related antibodies, such as anti-AChR, anti-MuSK and anti-LRP4 antibodies, can be detected in most patients with MG. Although traditional therapies can control most symptoms, several challenges remain to be addressed, necessitating the development of more effective and safe treatment strategies for MG. With the in-depth exploration on the mechanism and immune targets of MG, effective therapies, especially therapies using biologicals, have been reported recently. Given the important roles of immune cells, cytokines and intercellular interactions in the pathological process of MG, B-cell targeted therapy, T-cell targeted therapy, proteasome inhibitors targeting plasma cell, complement inhibitors, FcRn inhibitors have been developed for the treatment of MG. Although these novel therapies exert good therapeutic effects, they may weaken the immunity and increase the risk of infection in MG patients. This review elaborates on the pathogenesis of MG and discusses the advantages and disadvantages of the strategies of traditional treatment and biologicals. In addition, this review emphasises that combined therapy may have better therapeutic effects and reducing the risk of side effects of treatments, which has great prospects for the treatment of MG. With the deepening of research on immunotherapy targets in MG, novel opportunities and challenges in the treatment of MG will be introduced.

Current drug treatment of myasthenia gravis

PURPOSE OF REVIEW

Myasthenia Gravis (MG) is a rare neurological disorder affecting the neuromuscular junction. Clinical hallmarks are fatigability and weakness affecting the extraocular, axial, limb and/or respiratory muscles. Despite immunosuppressive treatment, mainly based on corticosteroids and nonsteroidal immunosuppressants, the burden of MG is still significant, both in terms of inadequate disease control and burdensome side effects. Driven by such limits, the past years have been characterized by an escalation of MG drug development, with novel molecules which now focuses on having a more targeted effect, with a higher safety and efficacy profile.

RECENT FINDINGS

As the pathogenic mechanism of MG are slowly being unravelled, new potential targets for treatments are being considered. This has led since 2017 to the Food and Drug Administration (FDA)-approval of three new drugs that either act by blocking the complement system (i.e., eculizumab and ravulizumab) or by blocking the neonatal Fc receptor thus preventing immunoglobulin recycling and reducing imunoglobulin G (IgG) antibodies (i.e., efgartigimod). Other drugs, with similar mechanism of action, are currently under review for approval.

SUMMARY

The repertoire of available and developmental therapies for MG is rapidly expanding, finally responding to the unmet need of a more targeted and effective therapeutic approach in MG.

Therapeutic modalities in thrombotic thrombocytopenic purpura management among Jehovah's Witness patients: A review of reported cases

INTRODUCTION

Devout members of the Jehovah's Witness faith flatly refuse transfusions of white blood cells, red blood cells, platelets, and plasma. The latter agent is a mainstay in the treatment of thrombotic thrombocytopenic purpura (TTP). Alternative treatment options for Jehovah's Witness patients are needed and reviewed herein.

METHODS

Cases of TTP treatment among Jehovah's Witnesses were obtained from the published literature. Key baseline and clinical data were extracted and summarized.

RESULTS

A total of 13 reports spanning a 23-year period and 15 TTP episodes were identified. Median (IQR) age was 45.5 (29.0-57.5) and 12/13 (93%) patients were female. Neurologic symptoms were present in 7/15 (47%) episodes at presentation. Disease confirmation with ADAMTS13 testing was present in 11/15 (73%) of episodes. Corticosteroids and rituximab were employed in 13/15 (87%) and 12/15 (80%) of cases, respectively, with apheresis-based therapy employed in 9/15 (60%) episodes. For eligible cases, caplacizumab was used in 4/5 (80%) episodes; average time to platelet response was shortest in these cases. Sources of exogenous ADAMTS13 accepted by patients in this series included cryo-poor plasma, FVIII concentrate, and cryoprecipitate.

CONCLUSIONS

Successful management of TTP within the boundaries of the Jehovah's Witness faith is possible.

Fc receptors act as innate immune receptors during infection?

Innate immunity constitutes the first nonspecific immunological line of defense against infection. In this response, a variety of mechanisms are activated: the complement system, phagocytosis, and the inflammatory response. Then, adaptive immunity is activated. Major opsonization mediators during infections are immunoglobulins (Igs), the function of which is mediated through Fc receptors (FcRs). However, in addition to their role in adaptive immunity, FcRs have been shown to play a role in innate immunity by interacting directly with bacteria in the absence of their natural ligands (Igs). Additionally, it has been hypothesized that during the early phase of bacterial infection, FcRs play a protective role via innate immune functions mediated through direct recognition of bacteria, and as the infection progresses to later phases, FcRs exhibit their established function as receptors in adaptive immunity. This review provides detailed insight into the potential role of FcRs as innate immune mediators of the host defense against bacterial infection independent of opsonins.

A novel fasting regimen revealed protein reservation and complement C3 down-regulation after 14-day's continual dietary deprivation

Objectives

The aim is to evaluate the effect of a novel 14-day fasting regimen on the balance between skeletal muscle and adipose tissue composition which might associate with inflammatory factors. Our analysis includes basic physical examinations, clinical laboratory analysis, bioelectrical impedance and biochemical analytic assessments of healthy volunteers.

Methods

Eight healthy subjects were randomly selected from a pool of volunteers to undergo a continual dietary deprivation (CDD) regimen. Individuals were assigned to take Flexible Abrosia (FA, prebiotic combination) plus appropriate mineral supplement of potassium and magnesium at 3 mealtime every day to prevent potential injury from starved intestinal flora and avoid spasms of smooth muscle due to hunger. Physical and medical examinations were conducted and blood samples were collected at following timepoints: before CDD as self-control (0D), day 7 and day 14 during fasting, and 7-21days and/or 2~3mo after refeeding.

Results

The combination of FA and mineral supplements significantly decreased self-reported physical response of starvation, with tolerable hunger-mediated sensations experienced during CDD. Bioelectrical and biochemical results indicated significant reduction in both muscle lean and fat mass on day 7. Meanwhile, markers related to fat composition consistently decreased during and after CDD. In addition, most biochemical marker levels, including serum proteins, reached their inflection points at the 7th day of CDD as compared to the control measurements. Levels of these factors started to show a relative plateau, or reversed direction upon the 14th day of CDD. The exceptions of above factors were myostatin and complement protein C3, which remained at lower concentrations in the blood throughout CDD, and were unable to fully recover toward baseline levels even after 3 months' refeeding.

Conclusion

Our results indicated that human subjects undergoing prolonged dietary restriction were well protected by FA and mineral ions from gut injury or physical discomfort of starvation. Most factors showed a relative plateau response at the end of 14D-CDD. The muscle tissues were well preserved during prolonged fasting, and an improved protein/lipid ratio was observed. Upon refeeding, constant lower levels of myostatin and complement C3 were maintained after CDD implies a long-term beneficial effect in dealing with anti-aging and inflammation.

Antibody-guided proteases enable selective and catalytic degradation of challenging therapeutic targets

The exquisite specificity, natural biological functions, and favorable development properties of antibodies make them highly effective agents as drugs. Monoclonal antibodies are particularly strong as inhibitors of systemically accessible targets where trough-level concentrations can sustain full target occupancy. Yet beyond this pharmacologic wheelhouse, antibodies perform suboptimally for targets of high abundance and those not easily accessible from circulation. Fundamentally, this restraint on broader application is due largely to the stoichiometric nature of their activity - one drug molecule is generally able to inhibit a maximum of two target molecules at a time. Enzymes in contrast are able to catalytically turnover multiple substrates, making them a natural sub-stoichiometric solution for targets of high abundance or in poorly accessible sites of action. However, enzymes have their own limitations as drugs, including, in particular the polypharmacology and broad specificity often seen with native enzymes. In this study, we introduce antibody-guided proteolytic enzymes to enable selective sub-stoichiometric turnover of therapeutic targets. We demonstrate that antibody-mediated substrate targeting can enhance enzyme activity and specificity, with proof of concept for two challenging target proteins, amyloid-β (Aβ) and immunoglobulin G (IgG). This work advances a new biotherapeutic platform that combines the favorable properties of antibodies and proteolytic enzymes to more effectively suppress high-bar therapeutic targets.

Novel Immunotherapies for Myasthenia Gravis

Myasthenia gravis (MG), a prototype autoimmune neurological disease, had its therapy centred on corticosteroids, non-steroidal broad-spectrum immunotherapy and cholinesterase inhibitors for several decades. Treatment-refractory MG and long-term toxicities of the medications have been major concerns with the conventional therapies. Advances in the immunology and pathogenesis of MG have ushered in an era of newer therapies which are more specific and efficacious. Complement inhibitors and neonatal Fc receptor blockers target disease-specific pathogenic mechanisms linked to myasthenia and have proven their efficacy in pivotal clinical studies. B cell-depleting agents, specifically rituximab, have also emerged as useful for the treatment of severe MG. Many more biologicals are in the pipeline and in diverse stages of development. This review discusses the evidence for the novel therapies and the specific issues related to their clinical use.

Understanding Pathogenesis Intersects With Effective Treatment for Thyroid Eye Disease

CONTEXT

Thyroid eye disease (TED), a vision-threatening and disfiguring autoimmune process, has thwarted our efforts to understand its pathogenesis and develop effective and safe treatments. Recent scientific advances have facilitated improved treatment options.

OBJECTIVE

Review historically remote and recent advances in understanding TED.

DESIGN/SETTING/PARTICIPANTS

PubMed was scanned using search terms including thyroid-associated ophthalmopathy, thyroid eye disease, Graves' orbitopathy, autoimmune thyroid disease, and orbital inflammation.

MAIN OUTCOME MEASURES

Strength of scientific evidence, size, scope, and controls of clinical trials/observations.

RESULTS

Glucocorticoid steroids are widely prescribed systemic medical therapy. They can lessen inflammation-related manifestations of TED but fail to reliably reduce proptosis and diplopia, 2 major causes of morbidity. Other current therapies include mycophenolate, rituximab (anti-CD20 B cell-depleting monoclonal antibody), tocilizumab (interleukin-6 receptor antagonist), and teprotumumab (IGF-I receptor inhibitor). Several new therapeutic approaches have been proposed including targeting prostaglandin receptors, vascular endothelial growth factor, mTOR, and cholesterol pathways. Of potentially greater long-term importance are attempts to restore immune tolerance.

CONCLUSION

Despite their current wide use, steroids may no longer enjoy first-tier status for TED as more effective and better tolerated medical options become available. Multiple current and emerging therapies, the rationales for which are rooted in theoretical and experimental science, promise better options. These include teprotumumab, rituximab, and tocilizumab. Restoration of immune tolerance could ultimately become the most effective and safe medical management for TED.

Effects of Plasma Exchange Combined with Immunoglobulin Therapy on Consciousness, Immune Function, and Prognosis in Patients with Myasthenia Gravis Crisis: A Prospective Randomized Test

Background

Myasthenia gravis (MG) is an acquired autoimmune disease. The main clinical features of MG are skeletal muscle fatigue and pathological fatigue, which worsen at night or after fatigue, such as dyspnea, dysphagia, and systemic weakness. Plasma exchange (PE) is often used in patients with acute exacerbation of MG. Intravenous immunoglobulin (IVIG) is a collection of immunoglobulins from thousands of donors. IVIG can replace a variety of immunosuppressants or PE. However, the effect of PE or IVIG on patients' consciousness, immune function, and prognosis is not clear.

Objective

A prospective randomized test of the effects of PE combined with immunoglobulin on consciousness, immune function, and prognosis in patients with myasthenia gravis crisis (MGC).

Methods

Sixty patients with MGC treated from February 2019 to April 2021 were enrolled in our hospital. The cases who received PE were set as the PE group, and those who received PE combined with immunoglobulin were set as the PE+immunoglobulin group. The efficacy, clinical score, state of consciousness, immune function, acetylcholine receptor antibody (AChR-Ab), lymphocyte (LYM), albumin (ALB) levels, and the incidence of adverse reactions were compared.

Results

The improvement rate was 100.005% in the treatment group and 83.33% in the PE group. After treatment, the clinical score of the PE+immunoglobulin group was lower than that of the PE group, and the clinical relative score of the PE+immunoglobulin group was higher than that of the PE group (P < 0.05). The number of conscious people in the PE+immunoglobulin group was more than that in the PE group (P < 0.05). Immunoglobulin A, immunoglobulin M, immunoglobulin G, and immunoglobulin G in the PE+immunoglobulin group were higher than those in the PE group (P < 0.05). The levels of AChR-Ab and ALB in the PE+immunoglobulin group were higher than those in the PE group, while the level of LYM in the PE+immunoglobulin group was lower than that in the PE group. The incidence of skin system, gastrointestinal system, nervous system, and systemic damage in the PE+immunoglobulin group was lower than that in the PE group (P < 0.05).

Conclusion

The treatment of MGC with PE combined with immunoglobulin can not only effectively enhance the consciousness and immune function of patients but also effectively promote the prognosis, and the safety of treatment can be guaranteed.

Clinical Significance of Serum Albumin and Implications of FcRn Inhibitor Treatment in IgG-Mediated Autoimmune Disorders

Serum albumin (SA), the most abundant soluble protein in the body, maintains plasma oncotic pressure and regulates the distribution of vascular fluid and has a range of other important functions. The goals of this review are to expand clinical knowledge regarding the functions of SA, elucidate effects of dysregulated SA concentration, and discuss the clinical relevance of hypoalbuminemia resulting from various diseases. We discuss potential repercussions of SA dysregulation on cholesterol levels, liver function, and other processes that rely on its homeostasis, as decreased SA concentration has been shown to be associated with increased risk for cardiovascular disease, hyperlipidemia, and mortality. We describe the anti-inflammatory and antioxidant properties of SA, as well as its ability to bind and transport a plethora of endogenous and exogenous molecules. SA is the primary serum protein involved in binding and transport of drugs and as such has the potential to affect, or be affected by, certain medications. Of current relevance are antibody-based inhibitors of the neonatal Fc receptor (FcRn), several of which are under clinical development to treat immunoglobulin G (IgG)-mediated autoimmune disorders; some have been shown to decrease SA concentration. FcRn acts as a homeostatic regulator of SA by rescuing it, as well as IgG, from intracellular degradation via a common cellular recycling mechanism. Greater clinical understanding of the multifunctional nature of SA and the potential clinical impact of decreased SA are needed; in particular, the potential for certain treatments to reduce SA concentration, which may affect efficacy and toxicity of medications and disease progression.

Immunotherapy in autoimmune encephalitis

PURPOSE OF REVIEW

Autoimmune encephalitis (AE) refers to immune-mediated neurological syndromes often characterised by the detection of pathogenic autoantibodies in serum and/or cerebrospinal fluid which target extracellular epitopes of neuroglial antigens. There is increasing evidence these autoantibodies directly modulate function of their antigens in vivo. Early treatment with immunotherapy improves outcomes. Yet, these patients commonly exhibit chronic disability. Importantly, optimal therapeutic strategies at onset and during escalation remain poorly understood. In this review of a rapidly emerging field, we evaluate recent studies on larger cohorts, registries, and meta-analyses to highlight existing evidence for contemporary therapeutic approaches in AE.

RECENT FINDINGS

We highlight acute and long-term treatments used in specific AE syndromes, exemplify how understanding disease pathogenesis can inform precision therapy and outline challenges of defining disability outcomes in AE.

SUMMARY

Early first-line immunotherapies, including corticosteroids and plasma exchange, improve outcomes, with emerging evidence showing second-line immunotherapies (especially rituximab) reduce relapse rates. Optimal timing of immunotherapy escalation remains unclear. Routine reporting of outcome measures which incorporate cognitive impairment, fatigue, pain, and mental health will permit more accurate quantification of residual disability and comprehensive comparisons between international multicentre cohorts, and enable future meta-analyses with the aim of developing evidence-based therapeutic guidelines.

What is in the Neuromuscular Junction Literature?

ABSTRACT

This update covers a number of treatment topics starting with Fc receptor inhibitors and the Federal Drug Administration approval of efgartigimod. Some uncertainties regarding the use of corticosteroids are addressed, namely the risk of exacerbation with initiation of treatment and how to taper. The presence and potential importance of antibody overshoot following plasmapheresis is noted and the evolving increase in usefulness of acetylcholine receptor antibodies in diagnosing ocular myasthenia. Several recent series and case reports regarding coronavirus 2019 and myasthenia gravis are reviewed. The topics of myasthenia gravis and pregnancy, and another look at thymectomy in MG are provided. Finally, a couple of case reports on Lambert-Eaton myasthenic syndrome concentrate on the ice pack test and an autoantibody association with paraneoplastic cerebellar degeneration and Lambert-Eaton myasthenic syndrome in the same patient.

Molecular Therapy in Myasthenia Gravis

Myasthenia gravis (MG) is an autoimmune disorder caused by antibodies that act against the myoneural junction. Conventional immunosuppressants such as corticosteroids, azathioprine and mycophenolate are associated with long-term side effects and many patients do not achieve remission and may become refractory. Thus, there is an unmet need for target-specific therapies that act faster, have fewer side effects and lead to stable disease remission. However, many of the novel therapeutic agents being described are not meeting their primary endpoints. We reviewed the current status of novel immunotherapies for MG, their mechanisms of action, along with the side effect profiles. Fast onset of action, sustained disease remission and relatively low frequency of side effects of the new agents are attractive. However, the unknown long-term safety and high cost are precluding factors. Better preclinical studies and more randomized trials are needed before novel agents are routinely employed.

Efficacy and Safety of Immunotherapies in Refractory Myasthenia Gravis: A Systematic Review and Meta-Analysis

Introduction: Approximately 10–20% of patients WITH myasthenia gravis (MG) are refractory to conventional immunotherapies. The purpose of this study was to conduct a systematic review and meta-analysis to explore the optimal therapies for refractory MG.

Method: Correlative studies were performed through a search in PubMed, Cochrane Library, and Embase databases. The primary outcome was defined by changes in the quantitative myasthenia gravis score (QMG). Secondary outcomes were defined by the Myasthenia Gravis Activities of Daily Living Scale (MG-ADL), Myasthenia Gravis Foundation of America (MGFA) post intervention status, adverse events, and disease exacerbation after treatment.

Result: A total of 16 studies were included with 403 patients with refractory MG on therapies with rituximab, eculizumab, tacrolimus, and cladribine. Therapeutic efficacy of rituximab and eculizumab was identified with an estimated reduction in QMG score (4.158 vs. 6.928) and MG-ADL (4.400 vs. 4.344), respectively. No significant changes were revealed in efficacy or exacerbation density between the two independent therapeutic cohorts. The estimated adverse event density of eculizumab was more significant than that in the rituximab group (1.195 vs. 0.134 per patient-year), while the estimated serious event density was similar.

Conclusion: The efficacy and safety of rituximab and eculizumab have been approved in patients with refractory MG. Rituximab had a superior safety profile than eculizumab with a lower incidence of adverse events.

Systematic Review Registration:https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42021236818, identifier CRD42021236818.