Hyaluronidase-facilitated subcutaneous immunoglobulin 10% as maintenance therapy for chronic inflammatory demyelinating polyradiculoneuropathy: The ADVANCE-CIDP 1 randomized controlled trial

Pediatric Chronic Inflammatory Demyelinating Polyneuropathy: Challenges in Diagnosis and Therapeutic Strategies

Chronic inflammatory demyelinating polyneuropathy (CIDP) is a rare autoimmune neurological disorder seen in both pediatric and adult populations. CIDP typically presents with progressive and persistent weakness over at least 4 weeks in addition to sensory symptoms in the extremities. Although CIDP shares common clinical features between children and adults, it sometimes presents as a distinct clinical entity in children that requires close attention and recognition. A major caveat when diagnosing a child with CIDP is the clinical and diagnostic overlap with inherited neuropathies, most commonly Charcot-Marie-Tooth disease (CMT). Demyelinating CMT (dCMT) and CIDP might share similar clinical presentations, and sometimes it might be difficult to differentiate them on the basis of the electrodiagnostic findings or cerebrospinal fluid (CSF) albumino-cytological dissociation. This indeed merits early consideration for genetic testing in patients who do not respond to conventional CIDP therapies. Current treatment options for CIDP include intravenous immunoglobulins (IVIG), corticosteroids (CS), and plasmapheresis (PLEX). The need for novel therapies is essential in instances where patients continue to have symptoms despite the standard therapies or due to adverse effects of long-term use of standard therapies such as CS. This paper reviews the challenges in the diagnosis of CIDP in children and the current as well as novel therapies for CIDP.

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.

Immune-Mediated Neuropathies: Top 10 Clinical Pearls

Immune-mediated neuropathies encompass a range of neurological disorders, including chronic inflammatory demyelinating polyradiculoneuropathy, Guillain-Barré syndrome, multifocal motor neuropathy, autoimmune autonomic neuropathies, and paranodal nodopathies. Recognizing clinical patterns is key to narrowing the broad range of differential diagnoses in immune-mediated neuropathies. Electrodiagnostic testing is a useful tool to support the diagnosis of immune-mediated neuropathies. Our understanding of autoimmune demyelinating neuropathies is rapidly advancing, particularly with the discovery of nodal and paranodal antibodies. Recent advances in neuropathy treatment include the utilization of neonatal Fc receptors to reduce antibody recycling, and the development of complement inhibitors to reduce inflammatory damage, offering promising new therapeutic avenues. Timely identification of immune-mediated neuropathies is imperative as delay in diagnosis and treatment may lead to irreversible disability.

Novel therapies in CIDP

Chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) is a heterogeneous but clinically well-described disease within circumscribed parameters. It is immunologically mediated through several poorly understood mechanisms. First-line therapies with steroids, intravenous immunoglobulin (IVIG) or plasma exchange are each effective in about two-thirds of patients. These treatments are seldom associated with complete resolution or cure, and often pose considerable practical, financial and medical implications.Our understanding of many of the key pathological processes in autoimmune diseases is expanding, and novel targeted therapeutics are being developed with promise in several autoimmune neurological disorders.This narrative review looks first at detailing key pathogenic mechanisms of disease in CIDP, followed by an in-depth description of potential novel therapies and the current evidence of their application in clinical practice.

Safety, tolerability, and efficacy of subcutaneous efgartigimod in patients with chronic inflammatory demyelinating polyradiculoneuropathy (ADHERE): a multicentre, randomised-withdrawal, double-blind, placebo-controlled, phase 2 trial

BACKGROUND

Chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) is an autoimmune disease of the peripheral nervous system that can lead to severe disability from muscle weakness and sensory disturbances. Around a third of patients do not respond to currently available treatments, and many patients with a partial response have residual neurological impairment, highlighting the need for effective alternatives. Efgartigimod alfa, a human IgG1 antibody Fc fragment, has demonstrated efficacy and safety in patients with generalised myasthenia gravis. We evaluated the safety, tolerability, and efficacy of subcutaneous efgartigimod PH20 in adults with CIDP.

METHODS

ADHERE, a multistage, double-blind, placebo-controlled trial, enrolled participants with CIDP from 146 clinical sites from Asia-Pacific, Europe, and North America. Participants with evidence of clinically meaningful deterioration entered an open-label phase of weekly 1000 mg subcutaneous efgartigimod PH20 for no longer than 12 weeks (stage A). Those with confirmed evidence of clinical improvement (ECI; treatment responders) entered a randomised-withdrawal phase of 1000 mg subcutaneous efgartigimod PH20 weekly treatment versus placebo for a maximum of 48 weeks (stage B). Participants were randomised (1:1) through interactive response technology and stratified by their adjusted Inflammatory Neuropathy Cause and Treatment (aINCAT) score change during stage A and their most recent CIDP medication within 6 months before screening. Investigators, the clinical research organisation, and participants were masked to the treatment. The primary endpoint in stage A, evaluated in the stage A safety population, was confirmed ECI (≥1 points aINCAT decrease, ≥4 points [centile metric] Inflammatory Rasch-built Overall Disability Scale increase, or ≥8 kPa grip strength increase after four injections and two consecutive visits). The primary endpoint in stage B, evaluated in the modified intention-to-treat population, was the risk of relapse (time to first aINCAT increase of ≥1 points). ADHERE is registered with ClinicalTrials.gov (NCT04281472) and EudraCT (2019-003076-39) and is completed.

FINDINGS

Between April 15, 2020, and May 11, 2023, 629 participants were screened; 322 (114 female, 208 male) entered stage A, of whom 214 (66%, 95% CI 61·0-71·6) had confirmed ECI. In stage B, 221 participants were randomised (79 female, 142 male; 111 to subcutaneous efgartigimod PH20, 110 to placebo). Subcutaneous efgartigimod PH20 significantly reduced the risk of relapse versus placebo (hazard ratio 0·39 [95% CI 0·25-0·61]; p<0·0001). 31 (27·9% [19·6-36·3]) participants given subcutaneous efgartigimod PH20 had a relapse versus 59 (53·6% [44·3-63·0]) given placebo. In stage A, treatment-emergent adverse events (TEAEs) occurred in 204 (63%) participants and serious TEAEs in 21 (7%). In stage B, TEAEs occurred in 71 (64%) participants on subcutaneous efgartigimod PH20 and 62 (56%) participants on placebo, and serious TEAEs in six (5%) on subcutaneous efgartigimod PH20 and six (5%) on placebo. Three deaths occurred: two in stage A (one non-related and one unlikely related to treatment) and one in stage B (placebo group).

INTERPRETATION

ADHERE showed the efficacy of subcutaneous efgartigimod PH20 in reducing the risk of relapse versus placebo in people with CIDP who responded to treatment. Further studies are needed to provide data on the longer-term effects of efgartigimod alfa and how it compares with currently available treatment options.

FUNDING

argenx.

Treatment response amplitude and timing in chronic inflammatory demyelinating polyneuropathy with routine care: Study of a UK cohort

BACKGROUND AND PURPOSE

The amplitude, timing, and determinants of improvement with available treatments are uncertain in chronic inflammatory demyelinating polyneuropathy (CIDP). Our primary objective was to quantify categorized outcomes with routine care.

METHODS

We retrospectively studied treatment response within 36 months from initiation in 112 consecutive subjects with CIDP. Response was classified into a proposed new "CIDP treatment-response category" (CT-RC), based on achieved endpoints. Determinants of the CT-RC, of timing of maximum improvement, and of treatment discontinuation were ascertained.

RESULTS

The CT-RC demonstrated high concurrent validity with current outcome measures. Thirty-six subjects (32.1%) achieved a "complete response," 37 (33%) a "good partial response," 10 (8.9%) a "moderate partial response," and 15 (13.4%) a "poor partial response." Fourteen subjects (12.5%) were "nonresponsive." The CT-RC was independently predicted only by age. Mean time to maximum improvement was 12.1 months (range = 1-36) and was not associated with any pretreatment covariate. Treatment discontinuation occurred in 24 of 62 (38.2%) partial responders and was only associated with shorter pretreatment disease duration. Nonresponders were older and received a similar number of treatments compared to responders.

CONCLUSIONS

CT-RC classification indicates persistent disability in >60% of treatment responders in CIDP. Timing of maximum improvement is variable, frequently delayed, and unpredictable. Treatment withdrawal without deterioration is achievable in approximately 40% of subjects and may be more likely with prompt treatment. Treatment withdrawal in partial responders and limited escalation in nonresponders suggest implication of physician- and patient-related factors in suboptimal response. More effective treatments/treatment methods and better understanding of other factors influencing response are needed in CIDP.

Tolerability and Safety of Large-Volume Hyaluronidase-Facilitated Subcutaneous Immunoglobulin 10% Administered with or without Dose Ramp-Up: A Phase 1 Study in Healthy Participants

PURPOSE

Facilitated subcutaneous immunoglobulin (fSCIG; immune globulin infusion 10% [human] with recombinant human hyaluronidase [rHuPH20]) permits high-volume subcutaneous immunoglobulin (SCIG) infusion, shorter infusion times and reduced dosing frequency relative to conventional SCIG. It is initiated by gradually increasing infusion volumes over time (dose ramp-up) to achieve target dose level (TDL). Whether ramp-up strategies have tolerability or safety advantages over direct initiation at full TDL has not been evaluated clinically.

METHODS

This phase 1 open-label study assessed tolerability and safety of fSCIG 10% with accelerated or no ramp-up compared with conventional ramp-up in healthy adults (NCT04578535). Participants were assigned to one of the three ramp-up arms to achieve TDLs of 0.4 or 1.0 g/kg/infusion. The primary endpoint was the proportion of infusions completed without interruption or infusion rate reduction owing to treatment-emergent adverse events (TEAEs). Safety was assessed as a secondary endpoint.

RESULTS

Of 51 participants enrolled, 50 (98.0%) tolerated all fSCIG 10% infusions initiated (n = 174). Infusion rate was reduced in one participant owing to headache in the 0.4 g/kg/infusion conventional ramp-up arm. Study discontinuations were higher in the no ramp-up arm (70%) versus the conventional (0%) and accelerated (22%) arms at the 1.0 g/kg/infusion TDL. Safety outcomes did not substantially differ between treatment arms.

CONCLUSION

The favorable tolerability and safety profiles of fSCIG 10% in healthy participants support initiating treatment with fSCIG 10% with accelerated ramp-up at TDLs up to 1.0 g/kg. Data support no ramp-up at TDLs close to 0.4 g/kg but additional data are needed for higher doses.

Chronic Inflammatory Demyelinating Polyradiculoneuropathy: Current Therapeutic Approaches and Future Outlooks

Chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) is a treatable autoimmune disorder, for which different treatment options are available. Current first-line evidence-based therapies for CIDP include intravenous and subcutaneous immunoglobulins, corticosteroids and plasma exchanges. Despite lack of evidence, cyclophosphamide, rituximab and mycophenolate mofetil are commonly used in circumstances of refractoriness and, more debatably, of perceived overdependence on first-line therapies. Rituximab is currently the object of a randomized controlled trial for CIDP. Based on case series, and although rarely considered, haematopoietic autologous stem cell transplants may be effective in refractory disease, with low mortality and high remission rates. A new therapeutic option has appeared with efgartigimod, a neonatal Fc receptor blocker, recently shown to significantly lower relapse rate versus placebo, after withdrawal from previous immunotherapy. Other neonatal Fc receptor blockers, nipocalimab and batoclimab, are under study. The C1 complement-inhibitor SAR445088, acting in the proximal portion of the classical complement system, is currently the subject of a new study in treatment-responsive, refractory and treatment-naïve subjects. Finally, Bruton Tyrosine Kinase inhibitors, which exert anti-B cell effects, may represent another future research avenue. The widening of the therapeutic armamentarium enhances the need for improved evaluation of treatment effects and reliable biomarkers in CIDP.

A Phase 1 Open-Label Study to Assess the Tolerability, Safety, and Immunogenicity of Hyaluronidase-Facilitated Subcutaneous Immunoglobulin 20% in Healthy Adults

PURPOSE

Hyaluronidase-facilitated subcutaneous immunoglobulin (fSCIG) 20% will allow reduced infusion volumes and frequency versus existing subcutaneous therapies such as fSCIG 10% and conventional subcutaneous immunoglobulin 20%, respectively. We assessed the tolerability, safety, and immunogenicity of warmed and unwarmed fSCIG 20%.

METHODS

This phase 1, single-dose, open-label, three-arm study enrolled healthy adults aged 19-50 years (inclusive) at a single US center (NCT05059977). Post-screening, participants received a single fSCIG 20% dose comprising recombinant human hyaluronidase and varying doses of in-line warmed or unwarmed immunoglobulin G (IgG) during a 4-day treatment period in a sentinel and sequential dosing design (treatment arm 1, warmed IgG 20% 0.4 g/kg; treatment arm 2, warmed IgG 20% 1.0 g/kg; treatment arm 3, unwarmed IgG 20% 1.0 g/kg). Participants were followed for 12 (± 1) weeks post-infusion. The primary endpoint was tolerability ("tolerable" infusions were not interrupted, stopped, or reduced in rate owing to fSCIG 20%-related treatment-emergent adverse events (TEAEs)). Secondary endpoints included occurrence of TEAEs.

RESULTS

Overall, 24 participants were included, 8 per treatment arm (mean age 39.0 years, 54.2% men). All participants tolerated the infusions. All TEAEs were mild (107 events, in all participants), and all participants experienced fSCIG 20%-related (105 events) and local (102 events) TEAEs. Infusion site erythema and infusion site swelling were most frequently reported. No serious TEAEs occurred, and no participants discontinued the study owing to TEAEs.

CONCLUSION

fSCIG 20% was well-tolerated with a favorable safety profile in healthy adults. Future studies will evaluate fSCIG 20% in primary immunodeficiency diseases. Trial registration number (ClinicalTrials.gov): NCT05059977 (registered 28 September 2021).

Subcutaneous Immunoglobulin in Chronic Inflammatory Demyelinating Polyneuropathy: A Historical Perspective

The therapeutic administration of subcutaneous immunoglobulin (SCIg) offers various advantages over intravenous immunoglobulin (IVIg). This narrative review examines and compares SCIg versus IVIg in chronic inflammatory demyelinating polyneuropathy (CIDP). SCIg is as effective as IVIg but is better tolerated and easier to administer, as intravenous access is not required. Furthermore, SCIg administration is more convenient and cost-effective than IVIg, enabling flexible treatment scheduling at home and improving patients' overall quality of life. The availability of highly concentrated immunoglobulin G (IgG) subcutaneous solutions, such as IgPro20, a 20% IgG solution stabilized with L-proline, allows for the administration of larger volumes in a single session, while the parallel development of new technological devices enables the delivery of higher doses over a shorter time. Based on the results of the PATH study, SCIg has become a well-established therapy in CIDP. In addition to discussing the advantages of SCIg, this review summarizes the evolution of SCIg by discussing all the relevant clinical studies which have considered its use in the treatment of CIDP.