A Pilot Trial To Assess The Feasibility And Efficacy Of SCIG In Patients With MG Exacerbation (SCIG-MG)

This is a prospective open-label, uncontrolled, single-blind, pilot clinical trial.

The primary objective is to assess the efficacy, safety, feasibility and tolerability of SCIG in patients with worsening MG.

Study Rationale and Significance

Subcutaneous immunoglobulin (SCIG) is a novel form of immune therapy for neuromuscular diseases and may offer several advantages over intravenous immunoglobulin (IVIG).

Although no large-scale studies have been in conducted in MG patients, pilot studies with SCIG in multifocal motor neuropathy indicate that it may be a feasible, effective and safe alternative to IVIG in a condition, which like MG, shows excellent response to IVIG infusion.

Patients are able to tolerate it better and have improved quality of life due to added flexibility to the treatment schedule. SCIG is also potentially less expensive than IVIG since the costs associated with inpatient treatment as well as nursing support are saved.

SCIG also has the potential to be more effective and durable since the serum levels of immunoglobulin show a more sustained increase compared to IVIG. A drawback associated with SCIG is the small amount of immunoglobulin that can be infused over a short period. As compared to IVIG where the usual dose (2gm/kg for neuromuscular diseases) can be infused over 2 - 5 days, the same dose of SCIG would require 3 - 4 weeks to be administered with the currently available formulations. This may mean a delayed onset of peak-dose effect and SCIG may not be feasible for MG patients who are rapidly worsening or in MG crisis.

Nevertheless, SCIG may be an attractive option in a large subpopulation of MG patients who have mild to moderate disease exacerbations or who are on maintenance IVIG therapy provided its efficacy, tolerability and feasibility is determined in this patient population.

Methodology

Participants with moderate worsening of MG symptoms (MGFA Class II and III) who are considered to be appropriate for immunoglobulin therapy at the MG clinic at the University of Alberta will be screened for the study by the treating neurologist.

Patients will be receive 2gm/kg (150gm for a 75kg patient) of 20% SCIG (Hizentra) infused over 4 weeks in a dose escalating manner. Participants will undergo infusions two to four times a week, depending on their tolerance, beginning with a dose of 10 ml per site at four injection sites, increasing by 5 ml per week for a total of 25 ml per site at four injection sites after four weeks.

The dose is flexible and will vary based on the patient's tolerance to the medication and the total amount of medication the patient will be receiving based on their body weight. The initial (one or two) doses will be infused within the medical outpatient facility at the University of Alberta Hospital. This will allow for the observation of any infusion reactions and will also serve as nurse-provided self- infusion training sessions for patients.

Participants will be assessed weekly for symptomatic change and reports of satisfaction and quality of life. The primary outcome variable is the change in the Quantitative Myasthenia Gravis (QMG) Score for Disease Severity from baseline to day 42 (6 weeks). A change of 3.5 points will be considered to be clinically significant.

Safety and pharmacokinetic assessments of SCIG will be performed weekly throughout the study.

Additionally, this study will be assessing the feasibility of employing SCIG as an alternative therapy to IVIG in patients with MG exacerbation. The cost-effectiveness of SCIG versus IVIG will be evaluated, and the impact of SCIG therapy will be assessed from both a health-resource perspective and from a patient perspective.

The practicality of using SCIG in patients with MG will be determined by documenting the number of patients who are able to be trained for self- administration of SCIG, and by the patients' self-reported satisfaction with SCIG treatment.

The speed of SCIG treatment onset will also be assessed and compared to IVIG treatment onset. All of these described measures will be used to determine the feasibility and practicality of using SCIG in patients with MG exacerbation and its impact on the healthcare system.

Inclusion criteria

• Patients between18 to 80 years of age, diagnosed with MG (see below) who have worsening myasthenic symptoms - (defined as increasing diplopia, ptosis, dysarthria, dysphagia, difficulty chewing, or limb weakness severe enough to warrant immunoglobulin therapy.
• MG diagnosis will be based upon the clinical evaluation by a neuromuscular expert and meeting any two of the following supportive criteria:

• Abnormal Tensilon test
• Abnormal repetitive nerve stimulation studies
• Abnormal single fiber electromyography (EMG)
• Increased serum acetylcholine receptor or anti-MuSK antibodies
• Prior response to immunotherapy

Exclusion criteria

• Respiratory distress requiring ICU admission or a vital capacity <1 L
• Severe swallowing difficulties with a high risk of aspiration
• Change in corticosteroid dosage in the 4 weeks prior to screening
• Known immunoglobulin A (IgA) deficiency
• Pregnant or breast feeding women
• Active renal or hepatic insufficiency, clinically significant cardiac disease
• Patients with worsening weakness associated with an infectious process
• Previous lack of responsiveness to IVIG
• History of previous MG crises