Treatment of patients with multifocal motor neuropathy with immunoglobulins in clinical practice: the SIGNS registry

Using a scenario approach to assess for the current and future demand of immunoglobulins: An interview and literature study from The Netherlands

OBJECTIVES

To explore the current and future demand of immunoglobulins globally and specifically for the Netherlands by assessing: (I) which specialties contribute to current demand, (II) new areas of medical need, (III) which transformational factors may impact demand and to what effect, by using a scenario approach.

BACKGROUND

As immunoglobulin demand continues to increase globally, there is concern of increasing shortages and questions of whether and how future demand will continue based on medical need.

METHODS/MATERIALS

In line with scenario principles, a scoping review of Pubmed, Web of Science, Embase and Cochrane and grey literature was conducted. Semi-structured interviews with subject matter experts were held. The results of the review and interviews were analysed for major themes.

RESULTS

The scoping review resulted in 97 articles, 74 regarding clinical uses, and 23 regarding organisational and other themes. Fifteen clinical and non-clinical experts were interviewed. I) Neurology, immunology, and haematology were specialties that contribute most to current demand. II) Regarding potential new areas of medical need, the literature review resulted in more indications than the interviews, for example, post-renal transplants. III) Four groups of key transformational factors were found: factors that could increase immunoglobulin demand (e.g., EMA revisions), decrease demand (e.g., replacement products, Dutch Transfer Act 2021), factors that remain to be seen how it impacts demand (e.g., further evidence), and miscellaneous factors (e.g., supply-related).

CONCLUSION

Having identified the specialties and relevant transformational factors that affect immunoglobulin demand, more research is needed on what clinical or organisational strategies would be effective in controlling demand in general for the Netherlands and abroad. Other blood establishments may also use a scenario approach to increase preparedness for future (un)expected developments.

Excitability of motor and sensory axons in multifocal motor neuropathy

OBJECTIVE

To assess excitability differences between motor and sensory axons of affected nerves in patients with multifocal motor neuropathy (MMN).

METHODS

We performed motor and sensory excitability tests in affected median nerves of 20 MMN patients and in 20 age-matched normal subjects. CMAPs were recorded from the thenar and SNAPs from the 3rd digit. Clinical tests included assessment of muscle strength, two-point discrimination and joint position.

RESULTS

All MMN patients had weakness of the thenar muscle and normal sensory tests. Motor excitability testing in MMN showed an increased threshold for a 50% CMAP, increased rheobase, decreased stimulus-response slope, fanning-out of threshold electrotonus, decreased resting I/V slope, shortened refractory period, and more pronounced superexcitability. Sensory excitability testing in MMN revealed decreased accommodation half-time and S2-accommodation and less pronounced subexcitability. Mathematical modeling indicated increased Barrett-Barrett conductance for motor fibers and increase in internodal fast potassium conductance for sensory fibers.

CONCLUSIONS

Excitability findings in MMN suggest myelin sheath or paranodal seal involvement in motor fibers and, possibly, paranodal detachment in sensory fibers.

SIGNIFICANCE

Excitability properties of affected nerves in MMN differ between motor and sensory nerve fibers.

Expanding the Role of the Pharmacist: Immunoglobulin Therapy and Disease Management in Neuromuscular Disorders

Immunoglobulin G (IgG) is a commonly used treatment for chronic neuromuscular disorders (NMDs), such as chronic inflammatory demyelinating polyneuropathy and multifocal motor neuropathy. IgG therapy has also shown promise in treating other NMDs including myasthenia gravis, polymyositis, and dermatomyositis. IgG is administered as either intravenous immunoglobulin (IVIg) or subcutaneous immunoglobulin (SCIg), with SCIg use becoming more popular due to the treatment burden associated with IVIg. IVIg requires regular venous access; long infusions (typically 4-6 hours); and can result in systemic adverse events (AEs) for some patients. In contrast, SCIg can be self-administered at home with shorter infusions (approximately 1 hour) and fewer systemic AEs. As patient care shifts toward home-based settings, the role of the pharmacist is paramount in providing a continuation of care and acting as the bridge between patient and clinic. Pharmacists with a good understanding of current recommendations, dosing strategies, and administration routes for IgG therapy are best placed to support patients. The aims of this review are to highlight the evidence supporting IgG therapy in the treatment of NMDs and provide practical information on patient management and IVIg/SCIg dosing in order to guide pharmacists on optimizing clinical outcomes and patient care.

IqYmune® is an effective maintenance treatment for multifocal motor neuropathy: A randomised, double-blind, multi-center cross-over non-inferiority study vs Kiovig®-The LIME Study

Intravenous immunoglobulin (IVIg) is the gold‐standard for maintenance treatment of multifocal motor neuropathy (MMN). This phase III, randomised, double‐blind, multi‐centre, active‐control, crossover study, aimed to evaluate the non‐inferiority of IqYmune® relative to Kiovig®, primarily based on efficacy criteria. Twenty‐two adult MMN patients, treated with any brand of IVIg (except Kiovig® or IqYmune®) at a stable maintenance dose within the range of 1 to 2 g/kg every 4 to 8 weeks, were randomised to receive either Kiovig® followed by IqYmune®, or IqYmune® followed by Kiovig®. Each product was administered for 24 weeks. The primary endpoint was the difference between IqYmune® and Kiovig® in mean assessments of modified Medical Research Council (MMRC) 10 sum score (strength of 5 upper‐limb and 5 lower‐limb muscle groups, on both sides, giving a score from 0 to 100) during the evaluation period (non‐inferiority margin of Δ = 2). A linear mixed model analysis demonstrated the non‐inferiority of IqYmune® relative to Kiovig®, independently of the covariates (value at baseline, treatment period, and treatment sequence). The estimated “IqYmune® − Kiovig®” difference was −0.01, with a 95% confidence interval (CI) −0.51 to 0.48. The number of adverse reactions (ARs) and the percentage of patients affected were similar for the two products: 39 ARs in 10 patients with IqYmune® vs 32 ARs in 11 patients with Kiovig®. No thromboembolic events nor haemolysis nor renal impairment were observed. In this first clinical trial comparing two IVIg brands for maintenance treatment of MMN, efficacy and tolerability of both brands were similar.

Immune-mediated neuropathies

Since the discovery of an acute monophasic paralysis, later coined Guillain-Barré syndrome, almost 100 years ago, and the discovery of chronic, steroid-responsive polyneuropathy 50 years ago, the spectrum of immune-mediated polyneuropathies has broadened, with various subtypes continuing to be identified, including chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) and multifocal motor neuropathy (MMN). In general, these disorders are speculated to be caused by autoimmunity to proteins located at the node of Ranvier or components of myelin of peripheral nerves, although disease-associated autoantibodies have not been identified for all disorders. Owing to the numerous subtypes of the immune-mediated neuropathies, making the right diagnosis in daily clinical practice is complicated. Moreover, treating these disorders, particularly their chronic variants, such as CIDP and MMN, poses a challenge. In general, management of these disorders includes immunotherapies, such as corticosteroids, intravenous immunoglobulin or plasma exchange. Improvements in clinical criteria and the emergence of more disease-specific immunotherapies should broaden the therapeutic options for these disabling diseases.

Multifocal motor neuropathy in Austria: a nationwide survey of clinical features and response to treatment

BACKGROUND AND OBJECTIVES

Multifocal motor neuropathy (MMN) is a rare neuropathy and detailed descriptions of larger patient cohorts are scarce. The objective of this study was to evaluate epidemiological, clinical, and laboratory features of MMN patients and their response to treatment in Austria and to compare these data with those from the literature.

METHODS

Anonymized demographic and clinical data about MMN patients until 31.12.2017 were collected from registered Austrian neurologists. Exploratory statistics on clinical and laboratory features as well as treatment regimens and responses were performed.

RESULTS

57 Patients with MMN were identified, resulting in a prevalence of 0.65/100.000. Mean age of onset was 44.1 ± 13.1 years, the diagnostic delay 5.5 ± 8.4 years. In 77% of patients, symptom onset was in the upper limbs, and in 92%, it occurred in distal muscles. Proximal onset was never observed in the lower limbs. At the final follow-up, the majority of patients had atrophy (88%) in affected regions. Definite motor conduction blocks (CB) were found in 54 patients. Anti-GM1-IgM antibodies were present in 43%. Treatment with intravenous immunoglobulins improved muscle strength and INCAT score initially, but at last follow-up, both scores deteriorated to values before treatment.

DISCUSSION

The findings of the present study corroborate the previous findings in MMN. Onset typically occurs in the upper limbs and mostly distal, CBs are found in the majority of cases, while anti-GM1-IgM antibodies are detected in only approximately 40%. Our study underlines that the initial good response to treatment fades over time.

MULTIFOCAL MOTOR NEUROPATHY: CASE REPORTS

SUMMARY – Multifocal motor neuropathy (MMN) is a chronic demyelinating neuropathy mainly characterized by multifocal distribution; affecting only motor nerve fibers of two or more peripheral nerves, with the absence of symptoms and signs of upper motor neuron; chronic, sometimes cascading progressive course; demyelination with partial block of motor conduction; immune-mediated pathogenesis and good response to intravenous immunoglobulin treatment (IVIG). The diagnosis of MMN is based on clinical, laboratory and electrophysiological characteristics. Steroids are ineffective in MMN and may lead to worsening of the disease. Similarly, therapeutic plasma exchange is negligibly effective in this neuropathy. However, more than 80% of patients with MMN experience improvement after IVIG. We present our three cases of MMN with positive response to IVIG.

Management of patients with malignancies and secondary immunodeficiencies treated with immunoglobulins in clinical practice: Long-term data of the SIGNS study

OBJECTIVE

We aimed to describe the current management and outcomes of patients with secondary immunodeficiencies (SID) on intravenous (IV) or subcutaneous (SC) immunoglobulins (IG) as maintenance therapy to prevent infections.

METHODS

Non-interventional, prospective study (average follow-up 20.5 months).

RESULTS

Of the 307 SID patients (mean age 63.7±14.4 years, 52% males, in 31% IG newly initiated), 95.4% received IV IG (mean dosing interval 4.6 weeks, average dose 199 mg/kg per 4 weeks) and 4.6% were treated with SC IG (2.6 weeks, 343 mg/kg per 4 weeks). Median IG through level at first documentation was 5.8 g/L and did not differ between IV and SC treatment or between underlying malignancies. In 24.1% of patients, treatment was interrupted temporarily, over a mean of 11.6±6.3 months. In patients with newly initiated IG treatment the 82% overall infection rate prior to treatment dropped to 21% at 1 year.

CONCLUSIONS

Under clinical practice conditions, IG replacement therapy in SID patients was feasible, diminished infection rates and improved quality of life. Average IG doses were relatively low. Tolerability of IV IG treatment was excellent.