Prospective open-label trial with rituximab in patients with chronic inflammatory demyelinating polyradiculoneuropathy not responding to conventional immune therapies.

BACKGROUND: To evaluate the efficacy of rituximab in chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) patients not responding to conventional immune therapies. METHODS: An open-label, prospective exploratory study was conducted with intravenous rituximab on 17 CIDP patients who had not responded to at least two first-line therapies. The primary endpoint was to determine the proportion of patients who showed improvement 6 months after rituximab therapy. The percentage of responders to rituximab, along with a 95% CI, was reported and compared with the 30% response rate after other immunosuppressive drugs previously documented in the literature. RESULTS: 13 of the 17 treated patients (76.5%) showed improvement at 6 months (95% CI 50.1 to 93.2). Among the 14 patients who completed the 12-month follow-up (2 were lost to follow-up after showing improvement at months 8 and 10, and 1 deteriorated at 6 months), 13 (92.9%) demonstrated improvement at 12 months (95% CI 66.1 to 99.8). Nerve conduction parameters improved by at least 20% in two nerves in 6 out of 15 (40%) patients at 6 months and in 7 out of 13 (53.9%) at 12 months. None of the treated patients withdrew from the study due to side effects. There was a significant reduction of circulating CD19+ cells 15 days, 2, 6 and 12 months after treatment. CONCLUSION: Rituximab seems to be a safe therapy in most patients with CIDP not responding to conventional immune therapies. The high percentage of patients who improved in this study suggests a possible positive effect of rituximab which is worth investigating in future randomised controlled clinical trials. TRIAL REGISTRATION NUMBER: NCT05877040.

Phosphorylated TDP-43 aggregates in peripheral motor nerves of patients with amyotrophic lateral sclerosis.

Phosphorylated TDP-43 (pTDP-43) aggregates in the cytoplasm of motor neurons and neuroglia in the brain are one of the pathological hallmarks of amyotrophic lateral sclerosis. Although the axons exceed the total volume of motor neuron soma by several orders of magnitude, systematic studies investigating the presence and distribution of pTDP-43 aggregates within motor nerves are still lacking. The aim of this study is to define the TDP-43/pTDP-43 pathology in diagnostic motor nerve biopsies performed on a large cohort of patients presenting with a lower motor neuron syndrome and to assess whether this might be a discriminating tissue biomarker for amyotrophic lateral sclerosis and non-amyotrophic lateral sclerosis cases. We retrospectively evaluated 102 lower motor neuron syndrome patients referred to our centre for a diagnostic motor nerve biopsy. Histopathological criteria of motor neuron disease and motor neuropathy were applied by two independent evaluators, who were blind to clinical data. TDP-43 and pTDP-43 were evaluated by immunohistochemistry, and results compared to final clinical diagnosis. We detected significant differences between amyotrophic lateral sclerosis and non-amyotrophic lateral sclerosis cases in pTDP-43 expression in myelinated fibres: axonal accumulation was detected in 98.2% of patients with amyotrophic lateral sclerosis versus 30.4% of non-amyotrophic lateral sclerosis samples (P < 0.0001), while concomitant positive staining in Schwan cell cytoplasm was found in 70.2% of patients with amyotrophic lateral sclerosis versus 17.4% of patients who did not have amyotrophic lateral sclerosis (P < 0.001). Importantly, we were also able to detect pTDP-43 aggregates in amyotrophic lateral sclerosis cases displaying normal features at standard histopathological analysis. Our findings demonstrated that a specific pTDP-43 signature is present in the peripheral nervous system of patients with amyotrophic lateral sclerosis, and could be exploited as a specific, accessible tissue biomarker. The detection of pTDP-43 aggregates within motor nerves of living patients with amyotrophic lateral sclerosis, occurring before axonal degeneration, suggests that this is an early event that may contribute to amyotrophic lateral sclerosis pathogenesis.

Home monitoring of maintenance intravenous immunoglobulin therapy in patients with chronic inflammatory neuropathy.

To evaluate the utility of different outcome measures to monitor dose adjustment of intravenous immunoglobulin (IVIg) therapy in patients with chronic inflammatory neuropathy (CIN). We assessed the adjustment of IVIg maintenance therapy in 20 patients (10 CIDP and 10 MMN) by regularly monitoring grip strength (GS) using a Martin Vigorimeter, RODS, and quality of life using the SF-36 questionnaire. These measures were regularly performed by the patient at home. We also assessed the extended MRC sumscore (eMRC sumscore) at each outpatient visit for IVIg infusion. We also enrolled 30 healthy controls to measure any possible training effect of GS with time and to analyze random fluctuation of GS. Clinically relevant change was detected by eMRC sumscore in 14 (93%) patients, by RODS in 11 (73%) patients, and by GS in 8 (53%) patients. Early sensitivity was greatest for RODS (73%), followed by GS (53%), and eMRC sumscore (27%). This differed from CIDP, with an early change in RODS in 100% of patients, and MMN with an early change in GS in 75%. None of the outcome measures alone was sufficient to detect clinically significant changes in all patients. Home monitoring of outcome measures objectively assisted clinical decision during individualization of IVIg treatment. We recommend a multimodal approach using different outcome measures to monitor the individual patient with CIN.

Lenalidomide and dexamethasone in patients with POEMS syndrome: results of a prospective, open-label trial.

Given its anti-angiogenic activity, lenalidomide may have a role in the treatment of POEMS (Peripheral neuropathy, Organomegaly, Endocrinopathy, Monoclonal plasma cell disorder and Skin changes) syndrome. This prospective, open-label, pilot study evaluated the combination of lenalidomide + dexamethasone (RD) in 18 POEMS syndrome patients (13 pre-treated, 5 newly-diagnosed but ineligible for high-dose therapy). Treatment consisted of six cycles of lenalidomide (25 mg/day for 21 days followed by 7 days rest) plus dexamethasone (40 mg/once a week). Patients responding after six cycles continued treatment until progression or unbearable toxicity. The primary endpoint was the proportion of patients with either neurological or clinical improvement. The RD combination was considered as deserving further evaluation if 9 of the first 15 patients responded. Ten responses were observed among the first 15 enrolled patients, meeting the primary endpoint. Fifteen of 18 patients (83%) completed six RD cycles: 13 (72%) patients responded and nine had both clinical and neurological improvement. Among the 15 patients who completed the six RD cycles, four were still on treatment after a 25-month follow-up. At 39 months of follow-up, all patients were alive with a 3-year progression-free survival of 59%. No patient discontinued RD for toxicity. Overall, the RD regimen showed a high incidence of prolonged symptoms improvement and was well tolerated in most POEMS patients.

High-dose Ig VENA is well tolerated and efficacious in patients with multifocal motor neuropathy.

Multifocal motor neuropathy (MMN) is a rare, chronic, motor neuropathy that progressively impairs physical functioning and quality of life. Randomised controlled trials have shown that high-dose intravenous immunoglobulin (IVIg) is superior to placebo in improving muscle strength and disability, but many patients require periodic infusions to maintain long-term improvement. This observational, multicentre, retrospective study investigated the efficacy and tolerability of human normal immunoglobulin (Ig VENA) at high intravenous infusion rates in 20 MMN patients (14 male, 6 female). Thirty days after the first infusion, there was an improvement of at least 1 point in two muscles compared to baseline on the Medical Research Council (MRC) scale and of 1 point in the ONLS (Overall Neuropathy Limitation Scale) scale in 15 patients (75%) and 10 patients (50%), respectively; 45% improved on both scales. At 6 months, 100% of 12 patients had improved on the MRC and 79% of 14 patients had improved on the ONLS scale; 83% improved on both scales. All reported adverse drug reactions (ADR) were mild, transient and possibly related to the study drug. Four patients (20%) reported ADRs, three reported headache and one fever. There were no serious or unexpected ADRs. By confirming that high-dose Ig VENA is efficacious and well tolerated, this study adds to the evidence base for IVIg in MMN and potentially increases clinicians' and patients' choice of therapy.

Efficacy and tolerability of different brands of intravenous immunoglobulin in the maintenance treatment of chronic immune-mediated neuropathies.

High-dose intravenous immunoglobulin (IVIg) is effective in chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) and multifocal motor neuropathy (MMN). Not all brands of IVIg are however licensed for these neuropathies. We reviewed six patients with CIDP and seven with MMN treated with maintenance therapy with IVIg from 2009 to 2013. In all patients, we measured the Medical Research Council (MRC) and Overall Neuropathy Limitation Scale (ONLS) scores before each infusion, registered the monthly dose and brand of IVIg, and recorded adverse events. Patients were treated for 25-60 months (mean 49 months) alternating different brands of IVIg including IgVena, Gammagard, Kiovig, and Flebogamma. Minor and transient side effects were equally observed with each brand. No difference in the MRC or ONLS scores was observed in relation to the brand of IVIg used. Chronic maintenance treatment with IVIg in patients with MMN and CIDP was not associated with a different tolerability or efficacy despite the use of different brands of IVIg.

Update on the treatment of chronic inflammatory demyelinating polyradiculoneuropathy.

PURPOSE OF REVIEW: Chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) is a chronic and often disabling neuropathy, which often responds to immune therapies including corticosteroids, plasma exchange, and high-dose intravenous immunoglobulin (IVIg). The reasons for choosing one of these therapies and the factors that may predict response to these therapies remain, however, unclear. It is also unclear whether other immune therapies may be useful in CIDP. We will here review the studies addressing these points in CIDP. RECENT FINDINGS: Recent studies have shown that IVIg are initially more frequently effective than steroids in CIDP even if steroids, when effective, have a more prolonged efficacy. Some clinical and immunological features including the presence of antibodies against proteins at the nodes of Ranvier were associated with specific response to therapy even if the data need to be confirmed in large series of patients. A few anecdotal studies also reported the efficacy in some patients of new immune therapies whose efficacy needs to be confirmed in controlled trials. SUMMARY: IVIg are initially more frequently effective than steroids in CIDP, but the latter have a more prolonged efficacy. Some clinical presentations and their association with specific antibodies reactions may help in predicting the response to specific treatment. The possible benefit of new immune therapies await confirmation from randomized studies.

Frequency and time to relapse after discontinuing 6-month therapy with IVIg or pulsed methylprednisolone in CIDP.

BACKGROUND: We reported that 6-month therapy with intravenous immunoglobulin (IVIg) was more frequently effective or tolerated than intravenous methylprednisolone (IVMP) in patients with chronic inflammatory demyelinating polyradiculoneuropathy (CIDP). We now retrospectively compared the proportion of patients who eventually worsened after discontinuing therapy and the median time to clinical worsening. METHODS: By March 2013, data were available from 41 of the 45 patients completing the trial with a median follow-up after therapy discontinuation of 42 months (range 1-60). Three patients withdrew during the original study and one failed to respond to either of the therapies. No patient received a diagnosis alternative to CIDP during the follow-up. RESULTS: Twenty-eight of the 32 patients treated with IVIg (as primary or secondary therapy after failing to respond to IVMP) improved after therapy (87.5%) as compared with 13 of the 24 patients treated with IVMP as primary or secondary therapy (54.2%). After a median follow-up of 42 months (range 1-57), 24 out of 28 patients responsive to IVIg (85.7%) worsened after therapy discontinuation. The same occurred in 10 out of 13 patients (76.9%) responsive to IVMP (p=0.659) after a median follow-up of 43 months (range 7-60). Worsening occurred 1-24 months (median 4.5) after IVIg discontinuation and 1-31 months (median 14) after IVMP discontinuation (p=0.0126). CONCLUSIONS: A similarly high proportion of patients treated with IVIg or IVMP eventually relapse after therapy discontinuation but the median time to relapse was significantly longer after IVMP than IVIg. This difference may help to balance the more frequent response to IVIg than to IVMP in patients with CIDP.

The circular RNA landscape in multiple sclerosis: Disease-specific associated variants and exon methylation shape circular RNA expression profile.

BACKGROUND: Circular RNAs (circRNAs) are a class of non-coding RNAs increasingly emerging as crucial actors in the pathogenesis of human diseases, including autoimmune and neurological disorders as multiple sclerosis (MS). Despite several efforts, the mechanisms regulating circRNAs expression are still largely unknown and the circRNA profile and regulation in MS-relevant cell models has not been completely investigated. In this work, we aimed at exploring the global landscape of circRNA expression in MS patients, also evaluating a possible correlation with their genetic and epigenetic background. METHODS: We performed RNA-seq experiments on circRNA-enriched samples, derived from peripheral blood mononuclear cells (PBMCs) of 10 MS patients and 10 matched controls and performed differential circRNA expression. The genetic background was evaluated using array genotyping, and an expression quantitative trait loci (eQTL) analysis was carried out. RESULTS: Expression analysis revealed 166 differentially expressed circRNAs in MS patients, 125 of which are downregulated. One of the top dysregulated circRNAs, hsa_circ_0007990, derives from the PGAP3 gene, encoding a protein relevant for the control of autoimmune responses. The downregulation of this circRNA was confirmed in two independent replication cohorts, suggesting its implementation as a possible RNA-based biomarker. The eQTL analysis evidenced a significant association between 89 MS-associated loci and the expression of at least one circRNA, suggesting that MS-associated variants could impact on disease pathogenesis by altering circRNA profiles. Finally, we found a significant correlation between exon methylation and circRNA expression levels, supporting the hypothesis that epigenetic features may play an important role in the definition of the cell circRNA pool. CONCLUSION: We described the circRNA expression profile of PBMCs in MS patients, suggesting that MS-associated variants may tune the expression levels of circRNAs acting as "circ-QTLs", and proposing a role for exon-based DNA methylation in regulating circRNA expression.

Chronic motor axonal neuropathy.

The identification of a distinct subgroup of patients within the spectrum of lower motor neuron syndromes (LMNS) is crucial as some are potentially treatable. We describe the clinical and neuropathological characteristics of a patient presenting with a rapidly progressive LMNS associated with high titers of anti-GM1 antibodies, leading to respiratory failure within 10 months. Histopathological study of a biopsy of a obturator nerve motor branch demonstrated a predominantly axonal motor neuropathy, while electron microscopy analysis localized macrophages located within the periaxonal space. Immunohistochemistry demonstrated deposits of complement activation products (C3i) and immunoglobulins (IgM) on nerve fibers. The patient's clinical, immunological and pathological findings are consistent with a diagnosis of a chronic motor axonal neuropathy (CMAN), likely of immune-mediated origin.

Chronic inflammatory demyelinating polyradiculoneuropathy and multifocal motor neuropathy: treatment update.

PURPOSE OF REVIEW: Chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) and multifocal motor neuropathy usually respond to immune therapies including steroids and plasma exchange for CIDP and high-dose intravenous immunoglobulins (IVIgs) for both diseases. Other immune therapies have been used to reduce the costs or the side-effects of these therapies, but their efficacy was only recently assessed in randomized controlled trials (RCTs). RECENT FINDINGS: The prolonged efficacy of IVIg in CIDP has been confirmed in a 48-week RCT. Two other RCTs showed that oral methotrexate or intramuscular interferon beta were not more effective than placebo in improving the efficacy or reducing the dose of IVIg or steroids. In multifocal motor neuropathy, a RCT showed that oral mycophenolate mofetil was not more effective than placebo in increasing the efficacy or reducing the dose of IVIg. Other immune therapies were assessed in open trials in both diseases, but their efficacy remains unclear, even if in some patients a possible efficacy of rituximab was reported. Some preliminary studies suggest that subcutaneous immunoglobulin may be as effective as IVIg in the maintenance therapy of CIDP and multifocal motor neuropathy. SUMMARY: After several years of anecdotal reports, a number of RCT have now appeared in CIDP and multifocal motor neuropathy, but their results are still insufficient to support the use of new therapies in these diseases.

Sensitivity and specificity of a commercial ELISA test for anti-MAG antibodies in patients with neuropathy.

For the diagnosis of anti-MAG polyneuropathy the commercial ELISA manufacturer currently recommends a cut-off of 1000 Bühlmann Titer Units (BTU). We analyzed sera from 80 anti-MAG neuropathy patients and 383 controls (with other neuropathies or healthy controls) to assess the ELISA sensitivity and specificity at different thresholds. A better combination of sensitivity/specificity was found at a threshold >1500 BTU than at >1000 BTU. The best value of specificity was obtained at threshold >7000 BTU. There was a diagnostic grey area between 1500 and 7000 BTU in which the clinical phenotypes as well as electrophysiological studies need to be carefully assessed particularly to differentiate CIDP and anti-MAG neuropathy.

How useful are anti-neural IgM antibodies in the diagnosis of chronic immune-mediated neuropathies?

Antibodies against several neural antigens have been associated with different chronic immune-mediated neuropathies but their practical clinical relevance remains unclear. To determine the possible diagnostic usefulness of these antibodies we reviewed the clinical correlate of IgM antibodies to the myelin-associated glycoprotein (MAG), sulfatide, the gangliosides GM1, GM2, GD1a and GD1b in 539 consecutive patients examined for neuropathy or related diseases in our Neuropathy Clinics and tested for these antibodies in our laboratory since 1985. 302 patients (56%) had an established diagnosis of definite or possible chronic immune-mediated neuropathy while 237 had a neuropathy of non-immune-mediated origin or of unknown aetiology or a closely related disease. Antibodies to one or more antigen were more frequent (chi(2)=63.32; p<0.00001) in patients with chronic immune-mediated neuropathy (37.7%) than with other neuropathy or related diseases (7.2%) and their presence was associated in 87% of the patients with an immune-mediated neuropathy, incrementing by 31% the probability of having this form. Testing for MAG permitted to identify 24.8% of patients with an immune-mediated neuropathy, GM1 an additional 9.9%, while GM2, GD1b, GD1a and sulfatide altogether an additional 3% of the patients. Concerning clinical correlations, all 75 patients with anti-MAG IgM had neuropathy and IgM monoclonal gammopathy (PN+IgM) with a positive predictive value for this neuropathy of 100%. A similarly high predictive value for neuropathy (91.4%) was observed among 269 patients with IgM monoclonal gammopathy including 103 patients without neuropathy. Anti-sulfatide IgM, though rare, were also significantly and constantly associated with PN+IgM and permitted to identify few patients not bearing anti-MAG IgM. Anti-GM1 IgM were significantly associated with multifocal motor neuropathy (MMN) (29.2%) but where also found in a few patients with other immune or non-immune neuropathies or related diseases with a positive predictive value for MMN of 25.5%. Anti-GM2 IgM were also significantly associated with MMN and increased the sensitivity (36.2%) for MMN obtained with anti-GM1 IgM only, without affecting its specificity and positive predictive value. Anti-GD1a, GD1b, though not significantly more frequent in patients with immune-mediated neuropathy, were associated in 80 to 100% of patients with these neuropathies. In conclusion anti-neural IgM antibodies may help in identifying patients with a chronic immune-mediated neuropathy, even if only anti-MAG and anti-sulfatide IgM appear to be strictly associated with a definite clinical syndrome.

Comparing treatment options for chronic inflammatory neuropathies and choosing the right treatment plan.

INTRODUCTION: Chronic inflammatory neuropathies are disorders caused by an immune response to peripheral nerve. They include chronic inflammatory demyelinating polyradiculoneuropathy (CIDP), multifocal motor neuropathy (MMN) and neuropathy associated with anti-MAG IgM monoclonal gammopathy and other less frequent neuropathies. Several immune therapies have been proven to be effective in these neuropathies even if the best therapeutic option is still unsettled. Areas covered: The authors reviewed the literature to compare the efficacy and safety of currently used immune therapies in these neuropathies. The authors also analyzed the effect of other immune suppressive agents and of biological agents including rituximab, eculizumab, natalizumab, alemtuzumab and fingolimod that were found effective in other autoimmune diseases. Expert commentary: Despite the reported efficacy of a number of new immune therapies in some patients with immune mediated neuropathies, their efficacy has not been so far confirmed in randomized controlled studies. High-dose intravenous immunoglobulin (IVIg) (and subcutaneous immunoglobulin [SCIg] for maintenance treatment), steroids and plasma exchange remain the only therapy of proven efficacy in CIDP, IVIg in MMN and, with certain limits, rituximab and, occasionally plasma exchange in neuropathy associated with anti-MAG antibodies. New biological agents are also on the horizon but their efficacy needs to be proved in controlled studies.

Unraveling gene expression profiles in peripheral motor nerve from amyotrophic lateral sclerosis patients: insights into pathogenesis.

The aim of the present study is to investigate the molecular pathways underlying amyotrophic lateral sclerosis (ALS) pathogenesis within the peripheral nervous system. We analyzed gene expression changes in human motor nerve diagnostic biopsies obtained from eight ALS patients and seven patients affected by motor neuropathy as controls. An integrated transcriptomics and system biology approach was employed. We identified alterations in the expression of 815 genes, with 529 up-regulated and 286 down-regulated in ALS patients. Up-regulated genes clustered around biological process involving RNA processing and protein metabolisms. We observed a significant enrichment of up-regulated small nucleolar RNA transcripts (p = 2.68*10-11) and genes related to endoplasmic reticulum unfolded protein response and chaperone activity. We found a significant down-regulation in ALS of genes related to the glutamate metabolism. Interestingly, a network analysis highlighted HDAC2, belonging to the histone deacetylase family, as the most interacting node. While so far gene expression studies in human ALS have been performed in postmortem tissues, here specimens were obtained from biopsy at an early phase of the disease, making these results new in the field of ALS research and therefore appealing for gene discovery studies.

Lower motor neuron disease with respiratory failure caused by a novel MAPT mutation.

OBJECTIVE: To investigate the molecular defect underlying a large Italian kindred with progressive adult-onset respiratory failure, proximal weakness of the upper limbs, and evidence of lower motor neuron degeneration. METHODS: We describe the clinical features of 5 patients presenting with prominent respiratory insufficiency, proximal weakness of the upper limbs, and no signs of frontotemporal lobar degeneration or semantic dementia. Molecular analysis was performed combining linkage and exome sequencing analyses. Further investigations included transcript analysis and immunocytochemical and protein studies on established cell models. RESULTS: Genome-wide linkage analysis showed an association with chromosome 17q21. Exome analysis disclosed a missense change in MAPT segregating dominantly with the disease and resulting in D348G-mutated tau protein. Motor neuron cell lines overexpressing mutated D348G tau isoforms displayed a consistent reduction in neurite length and arborization. The mutation does not seem to modify tau interactions with microtubules. Neuropathologic studies were performed in one affected subject, which exhibited α-motoneuron loss and atrophy of the spinal anterior horns with accumulation of phosphorylated tau within the surviving motor neurons. Staining for 3R- and 4R-tau revealed pathology similar to that observed in familial cases harboring MAPT mutations. CONCLUSION: Our study broadens the phenotype of tauopathies to include lower motor neuron disease and implicate tau degradation pathway defects in motor neuron degeneration.

Multifocal motor neuropathy: current therapies and novel strategies.

Multifocal motor neuropathy (MMN) is a purely motor mononeuritis multiplex characterized by the presence of conduction block on motor but not on sensory nerves and by the presence of high titers of anti-GM1 antibodies. Several data point to a pathogenetic role of the immune system in this neuropathy, although this has not yet been proved. Several uncontrolled studies and randomized controlled trials have demonstrated the efficacy of therapy with high-dose intravenous immunoglobulin (IVIg) in MMN. However, this therapy has a short-lasting effect that needs to be maintained with periodic infusions. This can be partly overcome by the use of subcutaneous immunoglobulin (SCIg) at the same dose. The high cost and need for repeated infusions have led to the search for other immune therapies, the efficacy of which have not yet been confirmed in randomized trials. In addition, some therapies, including corticosteroids and plasma exchange, are not only ineffective but have been associated with clinical worsening. More recently, a number of novel therapies have been investigated in MMN, including interferon-ß1a, the anti-CD20 monoclonal antibody rituximab and the complement inhibitor eculizumab. Preliminary data from open-label uncontrolled studies show that some patients improve after these therapies; however, randomized controlled trials are needed to confirm efficacy. Until then, IVIg (and SCIg) remains the mainstay of treatment in MMN, and the use of other immune therapies should only be considered for patients not responding to, or becoming resistant to, IVIg.