Chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) is an immune-mediated peripheral neuropathy characterized by demyelination and axonal damage of peripheral nerves (1). Patients present with progressive limb weakness and sensory disturbances, with symptoms progressing for at least 8 weeks, often in a relapsing-remitting pattern (2). Without treatment, it can lead to disability significantly impacting quality of life (3). First-line treatments recommended by international guidelines include corticosteroids, intravenous immunoglobulin (IVIG), and plasma exchange (PE). However, these options have limitations, and some patients do not achieve complete remission even after prolonged first-line therapy (2). Therefore, new treatment options are urgently needed.

The pathophysiological mechanism of CIDP is not fully understood. Previous studies suggest involvement of both cellular and humoral immunity, with autoantibodies playing a significant role (1, 4–6). Basic research shows that CIDP disease models can be established via antibody- or antigen-mediated immune responses. Multiple clinical studies confirm the efficacy of antibody-depleting therapies like IVIG, PE, and immunoadsorption (IA) in treating CIDP (7–10), indicating the potential pathophysiological role of autoantibodies. Thus, CIDP can be defined as an antibody-mediated autoimmune disease. Reducing circulating levels of pathogenic IgG antibodies is a key therapeutic strategy.

The neonatal Fc receptor (FcRn) plays a crucial role in maintaining IgG homeostasis. Through FcRn-mediated recycling, IgG is protected from intracellular degradation and transported extracellularly, maintaining high serum concentrations and prolonging its half-life (11–14).

Efgartigimod is the first globally approved FcRn inhibitor. It competitively binds to FcRn, reducing IgG recycling and thereby clearing pathogenic IgG antibodies, providing targeted therapy for neuroimmune diseases. Compared to traditional treatments, it specifically targets IgG without affecting other antibodies or cytokines, showing promising potential in antibody-mediated neuroimmune disorders (15–17). In a phase III clinical trial (ADAPT) for generalized myasthenia gravis (gMG), efgartigimod demonstrated favorable clinical efficacy and safety (18). Furthermore, efgartigimod has shown preliminary positive results in CIDP patients. A multicenter phase II trial (ADHERE) in CIDP patients demonstrated its effectiveness, tolerability, safety, and ability to reduce relapse risk (19). Real-world clinical studies have also corroborated efficacy and safety consistent with trial results (20–24). The intravenous formulation of efgartigimod was approved in China in September 2023 for treating adult AChR-positive gMG patients, and the subcutaneous formulation was approved in November 2024 for treating adult AChR-positive gMG and CIDP patients. However, real-world studies on this novel drug for CIDP remain scarce, with limited clinical experience.

This single-center prospective real-world study conducted at The First Affiliated Hospital of Chongqing Medical University aims to evaluate the short-term clinical efficacy and safety of efgartigimod in the Chinese CIDP population, providing more real-world experience for clinicians.

Since its approval, efgartigimod has been primarily used for immunotherapy in MG patients. With increasing patient benefit, CIDP has also been included in its indications. Currently, there are few reports on efgartigimod for CIDP in Chinese patients. A small-sample prospective observational case series from Huashan Hospital, Fudan University, China, showed good short-term efficacy and safety of efgartigimod in CIDP (22). Additionally, satisfactory results have been reported in real-world studies for other neurological autoimmune diseases like MG and immune-mediated necrotizing myopathy (IMNM) (20, 24, 25). This study enrolled 12 CIDP patients, evaluating the efficacy and safety of efgartigimod in a real-world clinical setting, providing valuable clinical experience.

Autoimmune antibodies are widely considered key in CIDP pathophysiology (4, 26, 27). FcRn inhibitors reduce serum IgG recycling and are used to treat various IgG-induced autoimmune diseases (12). Efgartigimod binds with high affinity to FcRn, enhancing IgG degradation (15, 28). The ADHERE study showed that 66% of patients had evidence of clinical improvement (ECI) after efgartigimod treatment in the open-label A phase. In the randomized double-blind B phase, efgartigimod significantly reduced the risk of CIDP relapse compared to placebo, with clinical benefits observed across all efficacy scales and patient subgroups regardless of prior treatment (19).

The ADHERE study demonstrated rapid onset of action for efgartigimod, with 40% (128/322) of patients showing ECI at week 4, the earliest possible time point. Our study included a broader patient population. In these patients, efgartigimod showed significant short-term efficacy, with the vast majority (91.7%) achieving clinically meaningful improvement after four weeks of treatment. MRC and I-RODS scores improved significantly, indicating marked effectiveness during the induction phase. Notably, 5 patients (41.7%) achieved clinical improvement as early as one week after the first dose, highlighting the importance of efgartigimod for early symptom relief. Most patients in our study had received prior immunotherapies. Five patients experienced relapse despite regular corticosteroid or tacrolimus use, but showed significant improvement after timely efgartigimod initiation, further supporting its effectiveness in the induction phase.

Patient 12 did not achieve clinical improvement after three consecutive weeks of treatment, with no significant change in scale scores. This patient had chronic onset, was initially misdiagnosed, and only received immunotherapy eight months after symptom onset. Electromyography indicated demyelination with secondary axonal damage. The poor response is likely attributable to delayed diagnosis and treatment, leading to severe secondary axonal injury. In contrast, Patient 3 had a 14-year disease history but presented acutely initially, diagnosed with Guillain-Barré syndrome (GBS). Early treatment with IVIG and corticosteroids led to a good overall response despite relapses. Efgartigimod was chosen due to relapses after conventional therapy. At enrollment, symptoms were mild, and post-treatment score changes met the “improvement” criteria, indicating efficacy. Thus, patients receiving timely treatment early in the disease course, even with multiple relapses, may benefit more from efgartigimod. Furthermore, Patient 8 had severe symptoms at onset (INCAT score 10 at baseline) but, due to short disease duration and prompt diagnosis/treatment, showed marked improvement (INCAT score 2) one week after the fourth dose. Additionally, we observed that all A-CIDP patients in our cohort responded well and rapidly to efgartigimod: 71.4% met improvement criteria one week after the first dose, and 100% after four weeks. This may be related to their early diagnosis as GBS, prompt initiation of effective therapies like IVIG or PE, and relatively short disease duration at enrollment. CIDP is a chronic or relapsing-remitting inflammatory peripheral neuropathy requiring immunomodulatory therapy during active phases to prevent secondary axonal damage and permanent disability. Previous studies show that disability is associated with delayed initial treatment, which may also prolong overall treatment duration, increase complications, and impose greater economic burden (29–33). Therefore, early, effective, and sustained treatment is key to improving long-term CIDP prognosis.

This study employed both subcutaneous and intravenous administration, with six patients in each group. Analysis revealed no significant difference in score improvement between routes. Currently, there are no studies comparing the efficacy and safety of these two routes specifically for CIDP. However, the ADAPT NXT and ADAPT SC+ studies comparing IV and SC administration in MG are ongoing, and future clinical studies will further elucidate potential differences.

Efgartigimod is highly specific, reducing serum levels of all IgG subclasses. Other immunoglobulins are not FcRn-dependent, and efgartigimod targets FcRn, thus not affecting their levels. Compared to therapies like PE that remove all immunoglobulins, this translates to a potentially lower infection risk and a clearer safety advantage (15). In our study, except for one patient, IgG levels decreased post-treatment in all measured cases, while IgM and IgA showed no significant decrease. The exceptional patient had markedly lower baseline IgG. Although IgG levels changed little, clinical symptoms improved (INCAT score dropped to 0 after the fourth dose), suggesting efgartigimod is relatively safe and effective even in patients with low pre-treatment IgG. Albumin binds to FcRn at a site distinct from the IgG binding site. Efgartigimod is an IgG1 Fc fragment with minimal steric hindrance, not blocking albumin binding, thus not affecting albumin levels. We even observed increased albumin in some patients, similar to a previous case series report (22), though the reason remains unclear. Furthermore, previous studies on the FcRn inhibitor batoclimab showed significant LDL-C elevation, which was not observed in our study with efgartigimod.

The ADHERE study showed efgartigimod was well-tolerated and safe, with common treatment-emergent adverse events (TEAEs) including injection site reactions, headache, and infections, mostly mild or moderate. In our study, only one patient experienced a localized rash during one infusion, which resolved spontaneously. Our safety profile appears more favorable compared to RCTs, though the small sample size and short follow-up may influence this observation.

Compared to the ADHERE trial, real-world CIDP treatment is more complex, often involving concomitant immunosuppressants before or during efgartigimod therapy. In our study, most patients on combination therapy showed good efficacy and safety. Therefore, tailored combination therapy may benefit patients, though whether it is superior to efgartigimod monotherapy remains unclear.

This study has limitations. The sample size was small and from a single center, introducing potential selection bias. The wide age range and presence of comorbidities in some patients may affect efficacy assessment. The lack of a placebo control also impacts conclusion accuracy. All enrolled patients had typical CIDP, lacking observation of variant forms, which may influence drug efficacy evaluation. In practice, dose and interval adjustments based on individual circumstances may affect outcomes. Furthermore, the short follow-up period precludes assessment of long-term effectiveness and safety, Optimal dosage and interval for maintenance therapy remain undefined due to a lack of relevant studies or guidelines, necessitating further long-term follow-up to establish an appropriate regimen. Future studies with larger samples, longer follow-up, and controlled designs are needed to confirm our findings.

Currently, the use of efgartigimod for CIDP is still exploratory, requiring more clinical evidence. This study explored and validated the short-term efficacy and safety of efgartigimod for CIDP patients in a real-world setting, compared intravenous and subcutaneous formulations, and specifically noted the response in A-CIDP patients. It provides valuable experience for the practical clinical application of efgartigimod in CIDP and offers a reference for treating other antibody-mediated autoimmune diseases.