Subcutaneous immunoglobulin for maintenance treatment in chronic inflammatory demyelinating polyneuropathy (The PATH Study): study protocol for a randomized controlled trial

Pharmacometric analysis linking immunoglobulin exposure to clinical efficacy outcomes in chronic inflammatory demyelinating polyneuropathy

The two main objectives of this analysis were to (i) characterize the relationship between immunoglobulin (Ig) exposure and chronic inflammatory demyelinating polyneuropathy (CIDP) disease severity using data from 171 patients with CIDP who received either subcutaneous Ig (IgPro20; Hizentra^®) or placebo (PATH study), and to (ii) simulate and compare exposure coverage with various dosing approaches considering weekly dosing to be the reference dose. IgG pharmacokinetic (PK) parameters, including those from a previous population PK model, were used to predict individual IgG profile and exposure metrics. Treatment‐related changes in Inflammatory Neuropathy Cause and Treatment (INCAT) scores were best described by a maximum effect (E_max) model as a function of ΔIgG (total serum IgG at INCAT score assessment minus baseline IgG levels before intravenous Ig restabilization). Simulations indicate that flexible dosing from daily to biweekly (every other week) provide an exposure coverage equivalent to that of a weekly Ig dose.

Subcutaneous immunoglobulin treatment for chronic inflammatory demyelinating polyneuropathy

Immunoglobulin G (IgG) therapy is an established long‐term treatment in chronic inflammatory demyelinating polyneuropathy (CIDP) that is commonly administered intravenously (IVIg). The subcutaneous immunoglobulin (SCIg) administration route is a safe and effective alternative option, approved by the United States Food and Drug Administration (FDA) in 2018, for maintenance treatment of adults with CIDP. Physicians and patients alike need to be aware of all their treatment options in order to make informed decisions and plan long‐term treatment strategies. In this review, we collate the evidence for SCIg in CIDP from all published studies and discuss their implications and translation to clinical practice. We also provide guidance on the practicalities of how and when to transition patients from IVIg to SCIg and ongoing patient support. Evidence suggests that IVIg and SCIg have comparable long‐term efficacy in CIDP. However, SCIg can provide additional benefits for some patients, including no requirement for venous access or premedication, and reduced frequency of systemic adverse events. Local‐site reactions are more common with SCIg than IVIg, but these are mostly well‐tolerated and abate with subsequent infusions. Data suggest that many patients prefer SCIg following transition from IVIg. SCIg preference may be a result of the independence and flexibility associated with self‐infusion, whereas IVIg preference may be a result of familiarity and reliance on a healthcare professional for infusions. In practice, individualizing maintenance dosing based on disease behavior and determining the minimally effective IgG dose for individuals are key considerations irrespective of the administration route chosen.

The Cost Effectiveness of Immunoglobulin vs. Hematopoietic Stem Cell Transplantation for CIDP

Background: Intravenous immunoglobulin (IVIG) is effective as standard first line therapy for chronic inflammatory demyelinating polyradiculoneuropathy (CIDP), but some patients remain dependent on its long-term use. Recently, we have reported that autologous non-myeloablative hematopoietic stem cell transplantation (HSCT) is an effective second line therapy for CIDP. Objectives: To compare the cost of chronic IVIG vs. autologous HSCT (a one-time therapy), we collected data on patients with CIDP undergoing HSCT between 2017 and 2019. This was compared with published literature on the costs and efficacy defined by the Inflammatory Neuropathy Cause And Treatment (INCAT) disability score, Medical Research Council (MRC) sum score, hand grip strength, and SF-36 quality of life (QOL) for CIDP. Methods: Between 2017 and 2019, nineteen patients with chronic CIDP (mean disease treatment duration prior to HSCT of 6 years) underwent autologous HSCT with mean cost of $108,577 per patient (range $56,327-277,119, standard deviation $53,092). After HSCT, 80% of patients remain IVIG and immune treatment free for up to 5 years. In comparison, published cost of IVIG treatment in the USA for an average CIDP patient exceeds $136,000 per year. Despite remaining treatment free, HSCT demonstrated greater improvement in efficacy compared to immunoglobulins. Recommendations: Given the long-term treatment-free remission and better outcome measurements, autologous HSCT is more cost effective than long-term IVIG treatment in patients with chronic CIDP. However, costs will depend on patient selection, the HSCT regimen, and regional variations. Further analysis of the health economics, i.e., cost/outcome ratio, of HSCT as therapy for chronically IVIG dependent CIDP is warranted.

Home-based subcutaneous immunoglobulin for chronic inflammatory demyelinating polyneuropathy patients: A Swiss cost-minimization analysis

PURPOSE

To compare the cost of two patient management strategies with similar efficacies for chronic inflammatory demyelinating polyneuropathy (CIDP) patients in the chronic phase: hospital-based IV immunoglobulin G (IVIg) and home-based subcutaneous immunoglobulin G (SCIg) associated with an interprofessional drug therapy management programme (initial training and follow-up).

METHODS

A 48-week model-based cost-minimization analysis from a societal perspective was performed. Resources included immunoglobulin (IVIg: 1 g/kg/3 weeks; SCIg: 0.4 g/kg/week initially and 0.2 g/kg/week in the maintenance phase), hospital charges, time of professionals, infusion material, transport and losses of productivity for patients. Costs were expressed in Swiss francs (CHF) (1 CHF = 0.93€ = US$1.10, www.xe.com, 2020/10/28).

RESULTS

The total costs of IVIg were higher than those of SCIg for health insurance and other payers: 114,747 CHF versus 86,558 CHF and 8,762 CHF versus 2,401 CHF, respectively. The results were sensitive to the immunoglobulin doses, as this was the main cost driver. The SCIg daily cost in the initial phase was higher for health insurance than hospital-based IVIg was, but the additional costs were compensated during the maintenance phase (from week 28). The professional costs associated with the switch were not fully covered by the insurance and were borne by the pharmacist and the nurse.

CONCLUSIONS

SCIg for CIDP patients reinforced by an interprofessional drug therapy management programme may be a cost-effective and sustainable alternative to IVIg in the Swiss system context. From an economic perspective, this therapy alternative should be more widely supported by healthcare systems and proposed to eligible patients by professionals.

Economic evaluation of subcutaneous versus intravenous immunoglobulin therapy in chronic inflammatory demyelinating polyneuropathy: a real-life study

OBJECTIVES

Chronic inflammatory demyelinating polyneuropathy (CIDP) is an acquired peripheral neuropathy of immunological origin with a clinical presentation and course that are extremely variable. The therapeutic approach generally includes corticosteroid drugs, intravenous immunoglobulins (IVIGs) or plasmapheresis alone or in combination as first line therapy, and immunosuppressants. In 2014 the Italian regulatory agency included subcutaneous immunoglobulins (SCIGs) in the list of off-label drugs reimbursed by the national health service. Our aim is to compare costs and outcomes of IVIG versus SCIG therapy.

METHODS

Patients medical records and therapeutic plans were retrospectively analysed to collect data on IVIG treatments 1 year before the switch to SCIG, and after 1 year of treatment with SCIG. A budget impact analysis was conducted through resource identification and quantification, and healthcare and non-health care costs evaluation.

RESULTS

13 of 34 patients affected by CIDP who were referred to our neurophysiopathological unit and treated with IVIG were switched to home-based SCIG. After 1 year of receiving SCIG, 12 patients remained neurologically stable and reported good outcomes. Considering the cost of IVIG (€30.97/g) and adding to this the direct and indirect healthcare costs, the total cost of IVIG treatment for the 12 patients in a year was €371 417.06, compared with the cost of SCIG (€51.57/g) for a total annual cost of €631 745.16, not including indirect costs.

CONCLUSIONS

We observe a higher cost for SCIG treatment versus IVIG, which is not in line with data in the literature. However, SCIGs offer some important safety benefits and improvements in patient quality of life.

Placebo effect in chronic inflammatory demyelinating polyneuropathy: The PATH study and a systematic review

The Polyneuropathy And Treatment with Hizentra (PATH) study required subjects with chronic inflammatory demyelinating polyneuropathy (CIDP) to show dependency on immunoglobulin G (IgG) and then be restabilized on IgG before being randomized to placebo or one of two doses of subcutaneous immunoglobulin (SCIG). Nineteen of the 51 subjects (37%) randomized to placebo did not relapse over the next 24 weeks. This article explores the reasons for this effect. A post‐hoc analysis of the PATH placebo group was undertaken. A literature search identified other placebo‐controlled CIDP trials for review and comparison. In PATH, subjects randomized to placebo who did not relapse were significantly older, had more severe disease, and took longer to deteriorate in the IgG dependency period compared with those who relapsed. Published trials in CIDP, whose primary endpoint was stability or deterioration, had a mean non‐deterioration (placebo effect) of 43%, while trials with a primary endpoint of improvement had a placebo response of only 11%. Placebo is an important variable in the design of CIDP trials. Trials designed to show clinical improvement will have a significantly lower effect of this phenomenon than those designed to show stability or deterioration.

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.

Daily grip strength response to intravenous immunoglobulin in chronic immune neuropathies

INTRODUCTION

Monitoring grip strength at home may detect improvement between intravenous immunoglobulin (IVIg) treatments in patients with chronic inflammatory neuropathies (CINs).

METHODS

Fifteen patients recorded grip strength each day, from one IVIg treatment until the next. We analyzed grip strength changes comparing thresholds of 8 kPa and 14 kPa. "Random" fluctuations of grip strength were distinguished from treatment response by smoothing the data.

RESULTS

"Random" fluctuations of at least 8 kPa occurred in 27% of patients. Smoothed daily grip strength increased by at least 8 kPa above baseline in 11 (73%) patients. Grip strength increased by at least 8 kPa for 3 consecutive days in 9 (60%) patients, and 5-day block mean increased by at least 8 kPa in 10 (67%) patients.

DISCUSSION

Home monitoring of grip strength confirmed treatment response in most patients with CINs on IVIg. To detect improvement in an individual patient, we suggest a threshold of at least 8 kPa on 3 consecutive days or on 5-day block mean.

Immunoglobulin administration for the treatment of CIDP: IVIG or SCIG?

Chronic inflammatory demyelinating polyneuropathy (CIDP) is an acquired neurological disorder characterized clinically by weakness and impaired sensory function evolving over 2 months or more, loss or significant decrease in deep tendon reflexes, and by electrophysiological evidence of peripheral nerve demyelination. Expeditious diagnosis and treatment of CIDP early in the disease course is critical such that irreversible disability can be avoided. Intravenous immunoglobulin (IVIG) is one first-line and maintenance therapy option for CIDP. The US Food & Drug Administration's (FDA's) approval of subcutaneous immunoglobulin (SCIG) in 2018 provides patients with CIDP more treatment options for maintenance therapy. The different options for administration of IG treatment create the need for information to assist clinicians and patients in choosing the optimal therapeutic approach. Considerations for pharmacokinetics, administration procedures, adverse events, patient variables, and cost will all be discussed in this article.

Long-term safety and efficacy of subcutaneous immunoglobulin IgPro20 in CIDP: PATH extension study

Objective

To investigate the long-term safety and efficacy of weekly subcutaneous IgPro20 (Hizentra, CSL Behring) in chronic inflammatory demyelinating polyneuropathy (CIDP).

Methods

In a 48-week open-label prospective extension study to the PATH study, patients were initially started on 0.2 g/kg or on 0.4 g/kg weekly and-if clinically stable-switched to 0.2 g/kg weekly after 24 weeks. Upon CIDP relapse on the 0.2 g/kg dose, 0.4 g/kg was (re)initiated. CIDP relapse was defined as a deterioration by at least 1 point in the total adjusted Inflammatory Neuropathy Cause and Treatment score.

Results

Eighty-two patients were enrolled. Sixty-two patients initially received 0.4 g/kg, 20 patients 0.2 g/kg weekly. Seventy-two received both doses during the study. Sixty-six patients (81%) completed the 48-week study duration. Overall relapse rates were 10% in 0.4 g/kg-treated patients and 48% in 0.2 g/kg-treated patients. After dose reduction from 0.4 to 0.2 g/kg, 51% (27/53) of patients relapsed, of whom 92% (24 of 26) improved after reinitiation of the 0.4 g/kg dose. Two-thirds of patients (19/28) who completed the PATH study without relapse remained relapse-free on the 0.2 g/kg dose after dose reduction in the extension study. Sixty-two patients had adverse events (AEs) (76%), of which most were mild or moderate with no related serious AEs.

Conclusions

Subcutaneous treatment with IgPro20 provided long-term benefit at both 0.4 and 0.2 g/kg weekly doses with lower relapse rates on the higher dose. Long-term dosing should be individualized to find the most appropriate dose in a given patient.

Classification of evidence

This study provides Class IV evidence that for patients with CIDP, long-term treatment with SCIG beyond 24 weeks is safe and efficacious.

Tolerability of Ig20Gly during onboarding in patients with primary immunodeficiency diseases

BACKGROUND

The subcutaneous immune globulin (SCIG) 20% product, Ig20Gly, was shown to be efficacious and well tolerated in 2 phase 2/3 North American and European studies at infusion volumes up to 60 mL/site and rates up to 60 mL/h/site in patients with primary immunodeficiency diseases.

OBJECTIVE

To assess patient experience after switching to Ig20Gly with fast infusion rates and large infusion volumes/site in the North American study.

METHODS

In this analysis of the open-label phase 2/3 study in which patients aged ≥2 years received weekly Ig20Gly infusions for up to approximately 1.3 years, tolerability and infusion parameters were assessed throughout the study for all patients and by prestudy treatment regimen (intravenous [IV] switchers or SC switchers).

RESULTS

Overall, 61% of patients reached the infusion rate of ≥60 mL/h/site and continued at this rate for 1 or more subsequent infusions; the median infusion number when patients first reached ≥60 mL/h/site was 3. No association was found between higher infusion volumes or rates and increased incidences of local and systemic adverse events (AEs) in the total population and patients younger than 16 years. Infusion parameters and tolerability were generally comparable regardless of the route of prestudy treatment (IV or SC switchers); however, IV switchers experienced lower rates of local AEs than SC switchers and had a slightly higher median infusion volume per site and longer infusion duration vs SC switchers.

CONCLUSION

High Ig20Gly infusion rates of at least 60 mL/h/site and volumes ≥60 mL/site were well tolerated during onboarding and throughout treatment, regardless of prestudy treatment.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier NCT01218438.

Restabilization treatment after intravenous immunoglobulin withdrawal in chronic inflammatory demyelinating polyneuropathy: Results from the pre-randomization phase of the Polyneuropathy And Treatment with Hizentra study

In patients with chronic inflammatory demyelinating polyneuropathy (CIDP), intravenous immunoglobulin (IVIG) is recommended to be periodically reduced to assess the need for ongoing therapy. However, little is known about the effectiveness of restabilization with IVIG in patients who worsen after IVIG withdrawal. In the Polyneuropathy And Treatment with Hizentra (PATH) study, the pre‐randomization period included sudden stopping of IVIG followed by 12 weeks of observation. Those deteriorating were then restabilized with IVIG. Of 245 subjects who stopped IVIG, 28 did not show signs of clinical deterioration within 12 weeks. Two hundred and seven received IVIG restabilization with an induction dose of 2 g/kg bodyweight (bw) IgPro10 (Privigen, CSL Behring, King of Prussia, Pennsylvania) and maintenance doses of 1 g/kg bw every 3 weeks for up to 13 weeks. Signs of clinical improvement were seen in almost all (n = 188; 91%) subjects. During IVIG restabilization, 35 subjects either did not show CIDP stability (n = 21, analyzed as n = 22 as an additional subject was randomized in error) or withdrew for other reasons (n = 14). Of the 22 subjects who did not achieve clinical stability, follow‐up information in 16 subjects after an additional 4 weeks was obtained. Nine subjects were reported to have improved, leaving a maximum of 27 subjects (13%) who either showed no signs of clinical improvement during the restabilization phase and 4 weeks post‐study or withdrew for other reasons. In conclusion, sudden IVIG withdrawal was effective in detecting ongoing immunoglobulin G dependency with a small risk for subjects not returning to their baseline 17 weeks after withdrawal.

IgPro20, the Polyneuropathy and Treatment with Hizentra® study (PATH), and the treatment of chronic inflammatory demyelinating polyradiculoneuropathy with subcutaneous IgG

Subcutaneous IgG (SCIG) administration may be preferred over the intravenous route (IVIG) in chronic inflammatory demyelinating polyneuropathy (CIDP) because it minimizes ‘end of cycle’ treatment-related fluctuations, reduces systemic adverse effects, improves convenience/quality of life and potentially lowers overall costs. Early reports of the use of highly concentrated SCIG preparations suggested they were effective and well-tolerated in chronic inflammatory demyelinating polyneuropathy. This was confirmed in the Polyneuropathy and Treatment with Hizentra® study of 172 subjects randomized to receive maintenance therapy with placebo or one of two doses of IgPro20 (20% IgG stabilized with L-Proline) for 6 months. Risk of relapse was reduced by SCIG in a dose-related manner as compared with placebo. A total of 88% of polyneuropathy and treatment with hizentra subjects felt the subcutaneous method was ‘easy to learn’. Local adverse events were mostly mild or moderate, and systemic adverse events were infrequent. Some patients may prefer maintenance therapy with SCIG over IVIG.

A randomised, multi-centre phase III study of 3 different doses of intravenous immunoglobulin 10% in patients with chronic inflammatory demyelinating polyradiculoneuropathy (ProCID trial): Study design and protocol

Patients with chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) show varying degrees of response to intravenous immunoglobulin (IVIg) therapy. This randomised phase III study in patients with CIDP (ProCID trial) will compare the efficacy and safety of 3 different doses (0.5, 1.0, and 2.0 g/kg) of IVIg 10% (panzyga) administered every 3 weeks for 24 weeks. The primary efficacy endpoint is the rate of treatment response, defined as a decrease in adjusted inflammatory neuropathy cause and treatment disability score of ≥1 point, in the IVIg 1.0 g/kg arm at week 24. Patients with definite or probable CIDP according to European Federation of Neurological Sciences/Peripheral Nerve Society criteria with IVIg or corticosteroid dependency and active disease are eligible. All potentially eligible patients will undergo IVIg or corticosteroid dose reduction (washout phase) over ≤12 weeks or until deterioration of CIDP (active disease). Patients with deterioration during the washout phase will be randomised to receive study treatment during a dose‐evaluation phase starting with a loading dose of IVIg 2.0 g/kg followed by maintenance treatment with IVIg 0.5, 1.0, or 2.0 g/kg every 3 weeks. Rescue medication (2 doses of IVIg 2.0 g/kg given 3 weeks apart) will be administered to patients in the IVIg 0.5 and 1.0 g/kg groups who deteriorate after week 3 and before week 18 or who do not improve at week 6. Safety, tolerability and quality of life will be assessed. The ProCID study will provide new information on the best maintenance dose of IVIg for patients with CIDP.

Subcutaneous immunoglobulin treatment in CIDP and MMN. Efficacy, treatment satisfaction and costs

Subcutaneous administration of immunoglobulin (SCIG) in chronic inflammatory demyelinating polyneuropathy (CIDP) and multifocal motor neuropathy (MMN) has been reported in several case reports and in a few randomized trials during the last decade. In this review we present the studies on SCIG in CIDP and MMN with special focus on the clinical effects. Moreover, the effect on quality of life, side effects to SCIG and the health economic perspectives are reviewed. Nine case studies, three randomized trials and six long-term, follow-up studies were identified. Most of the studies are conducted in patients switched from regular IVIG to SCIG treatment; one study involves treatment-naïve patients. The review shows that none of the studies have been powered to demonstrate an effect on disability. SCIG can maintain muscle strength for a period of 1 to 2years and ability seems preserved for a similar period. Quality of life is generally unchanged or improved after switch to SCIG and generalized side-effects seem fewer, whereas local reactions at the injection site occur. Health economic analyses favour SCIG at the doses used in the reviewed studies.