Evaluation of Gefurulimab (ALXN1720) Efficacy and Safety in Adults with Generalized Myasthenia Gravis: A Phase 3 Randomized, Double-Blind, Placebo-Controlled Study

The primary objective of this Phase 3, randomized, double-blind, placebo-controlled, parallel, multicenter study is to assess the **efficacy** of ALXN1720, also known as Gefurulimab, compared with placebo in the treatment of **Generalized Myasthenia Gravis** (gMG) with autoantibodies against acetylcholine receptor (AChR). This is evaluated based on the change in the MG-ADL (Myasthenia Gravis Activities of Daily Living) total score. The clinical relevance of this objective lies in its potential to provide a new therapeutic option for patients with gMG, a chronic autoimmune neuromuscular disorder characterized by weakness and fatigue of voluntary muscles.

Secondary objectives include assessing the efficacy of ALXN1720 compared with placebo in the treatment of gMG based on the change in the QMG (Quantitative Myasthenia Gravis) total score. This secondary measure provides additional insights into the therapeutic impact of ALXN1720 on muscle strength and overall disease severity, further supporting the primary efficacy findings.

The clinical trial involves a total of **151 participants** diagnosed with **Generalized Myasthenia Gravis** with autoantibodies against the acetylcholine receptor (AChR). The study population includes both male and female subjects, aged 18 years and older, who exhibit generalized muscle weakness consistent with the Myasthenia Gravis Foundation of America (MGFA) Class II, III, or IV. Participants were selected based on a positive serological test for autoantibodies against AChR. The trial population encompasses a vulnerable group, indicating careful consideration of ethical standards in participant selection. Lifestyle factors such as diet, physical activity, or habits were not specified in the available data. The selection criteria ensure a focus on individuals with a confirmed diagnosis and specific clinical presentation of the disease.

The clinical trial is a **Phase 3**, randomized, double-blind, placebo-controlled, parallel, multicenter study designed to evaluate the safety and efficacy of ALXN1720 in adults with **generalized myasthenia gravis**. The trial aims to assess the efficacy of ALXN1720 compared with placebo based on changes in the Myasthenia Gravis-Activities of Daily Living (MG-ADL) total score. The study is expected to run from November 30, 2022, to July 31, 2027, with a total duration of approximately 5 years. Participants will be involved in the study for a maximum treatment period of 131 days.

The trial will include several key visits: an initial screening visit to confirm eligibility based on criteria such as age (≥18 years), diagnosis of generalized myasthenia gravis with positive serological tests for autoantibodies against the acetylcholine receptor, and meeting the clinical criteria defined by the Myasthenia Gravis Foundation of America (MGFA) Class II, III, or IV. Following the screening, participants will be randomized to receive either the investigational product, **Gefurulimab**, administered as a subcutaneous injection, or a placebo. The primary endpoint will be evaluated at Week 26, focusing on the change from baseline in the MG-ADL total score. Secondary endpoints include changes in the Quantitative Myasthenia Gravis (QMG) total score and the Myasthenia Gravis Composite (MGC) total score at specified intervals.

Participants will attend follow-up visits at regular intervals to monitor safety and efficacy outcomes, with the end-of-study visit marking the conclusion of their participation. The expected length of participant involvement is contingent upon adherence to the study protocol, and any deviation or adverse events may lead to early termination from the study. The trial employs a Neopak prefillable syringe with BD Ultrasafe Plus passive needle guard for the administration of the investigational product, ensuring standardized delivery and safety measures throughout the study.

The clinical trial involves the administration of **Gefurulimab**, an experimental medication developed by Alexion Pharmaceuticals, Inc. Gefurulimab is provided in the form of a **solution for injection** and is administered via **subcutaneous injection**. The medication is delivered using a Neopak prefillable syringe equipped with a BD Ultrasafe Plus passive needle guard. The active substance in Gefurulimab is a protein of other origin, specifically designed for this study. The dosing schedule and frequency of administration are determined by the study protocol, with a maximum treatment period of 131 days. The trial does not specify a maximum daily or total dose amount, indicating that dosing is likely adjusted based on individual participant needs and study requirements.

In addition to the experimental treatment, the study includes a **placebo** group, referred to as the ALXN1720 Placebo Product. The placebo is used as a comparator to evaluate the efficacy and safety of Gefurulimab in treating adults with generalized myasthenia gravis. The placebo does not contain any active substance and is administered in a manner consistent with the experimental treatment to maintain the study's double-blind design. The pharmaceutical form and route of administration for the placebo are not specified, but it is implied to match the experimental treatment to ensure blinding.

The efficacy of ALXN1720 in the treatment of **generalized myasthenia gravis (gMG)** will be assessed in a Phase 3, randomized, double-blind, placebo-controlled, parallel, multicenter study. The primary endpoint for evaluating efficacy is the change from baseline in the Myasthenia Gravis-Activities of Daily Living (MG-ADL) total score at Week 26. Secondary endpoints include the change from baseline in the Quantitative Myasthenia Gravis (QMG) total score at Week 26, the percentage of responders based on the reduction of the MG-ADL total score at Week 26, the percentage of responders based on the reduction of the QMG total score at Week 26, the change from baseline in the Myasthenia Gravis Composite (MGC) total score at Week 26, and the change from baseline in the QMG total score at Week 4.

These efficacy parameters will be measured using validated scales specific to myasthenia gravis, such as the MG-ADL, QMG, and MGC scores. Data collection will occur at specified timepoints, including baseline, Week 4, and Week 26, to ensure comprehensive assessment of treatment effects over time. The analysis will focus on comparing the changes in these scores between the ALXN1720 treatment group and the placebo group, providing insights into the therapeutic potential of ALXN1720 for patients with gMG.