Efficacy of rituximab treatment in chronic inflammatory demyelinating polyradiculoneuropathy: a systematic review and meta-analysis

Subcutaneous immunoglobulins (SCIG) for chronic inflammatory demyelinating polyneuropathy (CIDP): A comprehensive systematic review of clinical studies and meta-analysis

BACKGROUND

Chronic Inflammatory Demyelinating Polyneuropathy (CIDP) presents significant treatment challenges due to its chronic nature, varied clinical presentations, and rarity. Subcutaneous immunoglobulin (SCIG) has emerged as a maintenance therapy, offering potential advantages in administration and patient experience over the previously recognized intravenous immunoglobulin (IVIG).

METHODS

We included all clinical studies involving CIDP patients treated with SCIG from eleven databases up to March 2024.

RESULTS

50 clinical studies were included in the systematic review, with 22 involved in the meta-analysis. These studies offer clinical data on around 1400 CIDP patients. Almost all studies considered SCIG a maintenance therapy, with the majority of results suggesting it as a viable substitute that may offer comparable or enhanced advantages. Studies covered aspects such as efficacy, safety, quality of life, practicality, economic evaluation, and patient preference. Meta-analysis showed SCIG significantly improved muscle strength and sensory function, had fewer and milder side effects, reduced relapse rates, and received a strong preference.

CONCLUSIONS

Findings suggest that SCIG for CIDP maintenance not only provides a more feasible alternative, with economic evaluations showing considerable cost reductions over time, and patient preference for SCIG being pronounced, but may also deliver comparable or superior health outcomes. Ongoing research lines on formulations, techniques, and direct comparative studies are critical to further illuminate, enhance, and expand SCIG's role in treatment.

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.

Effectiveness and safety of rituximab in autoimmune nodopathy: a single-center cohort study

Autoimmune nodopathy is a peripheral neuropathy characterized by acquired motor and sensory deficit with autoantibodies against the node of Ranvier or paranodal region in the peripheral nervous system. The clinical and pathological characteristics of the disease are distinct from that of chronic inflammatory demyelinating polyradiculoneuropathy (CIDP), and the standard treatment for CIDP is partially effective. Rituximab is a chimeric monoclonal antibody which binds and depletes B cells in peripheral blood. This prospective observational study included 19 patients with autoimmune nodopathy. Participants received intravenous rituximab treatment 100 mg the first day and 500 mg the next day and given every 6 months. The Inflammatory Neuropathy Cause and Treatment (INCAT) disability score, Inflammatory Rasch-Built Overall Disability Scale (I-RODS), Medical Research Council (MRC) sum score, and Neuropathy Impairment Score (NIS) were collected at entry and before the rituximab infusion every 6 months. At the last visit, 94.7% (18/19) of the patients showed clinical improvement on either the INCAT, I-RODS, MRC, or NIS scale. After the first infusion, 9 patients (47.7%) showed improvement on the INCAT score, and 11 patients (57.9%) on cI-RODS. In patients who received more than one rituximab infusion, the improvement of INCAT score and cI-RODS at the last assessment was higher than that after the first infusion. We also observed tapered or withdrawn concomitant oral medications in these patients.

Anti-NF155/NF186 IgG4 Antibody Positive Autoimmune Nodopathy

Patients with chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) seropositive for autoantibodies against nodal and paranodal proteins display distinct clinical presentations. In the latest study, CIDP with autoantibodies against paranodal proteins was defined as autoimmune nodopathy (AN). We herein present a case of 39-year-old male with anti- neurofascin (NF) 155 and NF186 IgG4 antibody with gait disturbance and tremor, who was followed up for 4 months and demonstrated clinical improvements after apparently effective rituximab therapy. In addition, a literature review was conducted to investigate the clinical characteristics of anti-NF155/NF186-positive AN.

Effect of low-dose rituximab treatment on autoimmune nodopathy with anti-contactin 1 antibody

Background

Autoimmune nodopathy with anti-contactin-1 (CNTN1) responds well to rituximab instead of traditional therapies. Although a low-dose rituximab regimen was administered to patients with other autoimmune diseases, such as myasthenia gravis and neuromyelitis optica spectrum disorders, and satisfactory outcomes were obtained, this low-dose rituximab regimen has not been trialed in anti-CNTN1-positive patients.

Methods

Anti–CNTN1 nodopathy patients were enrolled in this prospective, open-label, self-controlled pilot study. A cell-based assay was used to detect anti-CNTN1 antibodies and their subclasses in both serum and cerebrospinal fluid. Clinical features were evaluated at baseline, 2 days, 14 days, and 6 months after single low-dose rituximab treatment (600 mg). The titers of the subclasses of anti-CNTN1 antibody and peripheral B cells were also evaluated at baseline, 2 days, and 6 months after the rituximab regimen.

Results

Two patients with anti–CNTN1 antibodies were enrolled. Both patients had neurological symptoms including muscle weakness, tremor, sensory ataxia, numbness and mild nephrotic symptoms. In the field of neurological symptoms, sensory ataxia markedly improved, and the titer of anti-CNTN1 antibody as well as CD19+ B cells decreased only two days following low-dose rituximab treatment. Other neurological symptoms improved within two weeks of rituximab treatment. At the 6-month follow-up, all neurological symptoms steadily improved with steroid reduction, and both the anti-CNTN1 antibody titer and CD19+ B cells steadily decreased. No adverse events were observed after this single low-dose rituximab treatment.

Conclusions

We confirmed the clinical efficacy of low-dose rituximab by B cell depletion in autoimmune nodopathy with anti-CNTN1 antibody. This rapid and long-lasting response suggests that low-dose rituximab is a promising option for anti-CNTN1 nodopathy.

Therapeutic Monoclonal Antibody Therapies in Chronic Autoimmune Demyelinating Neuropathies

Autoimmune diseases of the peripheral nervous system have so far been treated mainly with exogenous high-dose intravenous immunoglobulins (IVIg), that act through several mechanisms, including neutralization of pathogenic autoantibodies, modulation of lymphocyte activity, interference with antigen presentation, and interaction with Fc receptors, cytokines, and the complement system. Other therapeutic strategies have recently been developed, in part to address the increasing shortage of IVIg, prime among which is the use of B cell depleting monoclonal antibodies, or small molecule inhibitors targeting the B-cell specific kinases. Rituximab, a chimeric monoclonal antibody against CD20 + B lymphocytes, is currently the most used, especially in anti-MAG antibody neuropathy and autoimmune neuropathies with antibodies to nodal/paranodal antigens that are unresponsive to IVIg. After several reports of its efficacy in chronic inflammatory demyelinating polyradiculoneuropathy (CIDP), rituximab is currently under investigation in three Phase 2 trials in CIDP. In addition, the possible role of complement activation in the pathogenesis of chronic autoimmune neuropathies has brought into consideration drugs that can block the complement cascade, such as eculizumab, a monoclonal antibody already assessed in acute polyradiculoneuropathies, and approved for myasthenia gravis. Preliminary data on eculizumab in multifocal motor neuropathy have been published, but randomized controlled studies are pending. Moreover, the neonatal Fc receptor, that recycles IgGs by preventing their lysosome degradation, is an important and attractive pharmacological target. Antibodies against FcRn, which reduce circulating IgG (both pathogenic and non-pathogenic) have been developed. The FcRn blocker efgartigimod, a humanized IgG1-derived Fc fragment, which competitively inhibits the FcRn, has recently been approved for the treatment of myasthenia gravis and is currently under investigation in CIDP. In addition, the anti-human FcRn monoclonal antibody rozanolixizumab is currently being assessed in phase 2 trials in CIDP. However, none of the abovementioned monoclonal antibodies is currently approved for treatment of any immune-mediated neuropathies. While more specific and individualized therapies are being developed, the possibility of combined treatments targeting different pathogenic mechanisms deserves consideration as well.

Potential therapeutic strategies in chronic inflammatory demyelinating polyradiculoneuropathy

Chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) is an autoimmune neuropathy involving peripheral nerve and nerve roots. The pathological hallmark of CIDP is macrophage-induced demyelination. Antibodies against nerve fibers, complement decomposition, abnormalities in plasma and cerebrospinal fluid cytokine profile, and changes of peripheral blood cell proportion were also reported in CIDP patients. These findings in immunopathology provide support for the introduction of potential therapeutic options for the treatment of CIDP. In this review, we systematically listed the potential therapeutic strategies targeting different components of the immune system by comparing the treatment of other autoimmune inflammatory diseases of the nervous system. Several ongoing clinical trials will assess the efficacy and safety of potential CIDP treatments.

Pathophysiology of the Different Clinical Phenotypes of Chronic Inflammatory Demyelinating Polyradiculoneuropathy (CIDP)

Chronic inflammatory demyelinating polyneuropathy (CIDP) is the most common form of autoimmune polyneuropathy. It is a chronic disease and may be monophasic, progressive or recurrent with exacerbations and incomplete remissions, causing accumulating disability. In recent years, there has been rapid progress in understanding the background of CIDP, which allowed us to distinguish specific phenotypes of this disease. This in turn allowed us to better understand the mechanism of response or non-response to various forms of therapy. On the basis of a review of the relevant literature, the authors present the current state of knowledge concerning the pathophysiology of the different clinical phenotypes of CIDP as well as ongoing research in this field, with reference to key points of immune-mediated processes involved in the background of CIDP.