Effect of efgartigimod on muscle group subdomains in participants with generalized myasthenia gravis: post hoc analyses of the phase 3 pivotal ADAPT study.

BACKGROUND AND PURPOSE: Generalized myasthenia gravis (gMG) is a rare, chronic, neuromuscular autoimmune disease mediated by pathogenic immunoglobulin G (IgG) autoantibodies. Patients with gMG experience debilitating muscle weakness, resulting in impaired mobility, speech, swallowing, vision and respiratory function. Efgartigimod is a human IgG1 antibody Fc fragment engineered for increased binding affinity to neonatal Fc receptor. The neonatal Fc receptor blockade by efgartigimod competitively inhibits endogenous IgG binding, leading to decreased IgG recycling and increased degradation resulting in lower IgG concentration. METHODS: The safety and efficacy of efgartigimod were evaluated in the ADAPT study. Key efficacy outcome measures included Myasthenia Gravis Activities of Daily Living (MG-ADL) and Quantitative Myasthenia Gravis (QMG) scores. Efgartigimod demonstrated significant improvement in both the MG-ADL and QMG scores. This post hoc analysis aimed to determine whether all subdomains of MG-ADL and QMG improved with efgartigimod treatment. Individual items of MG-ADL and QMG were grouped into four subdomains: bulbar, ocular, limb/gross motor and respiratory. Change from baseline over 10 weeks in each subdomain was calculated for each group. RESULTS: Greater improvements from baseline were seen across MG-ADL subdomains in participants treated with efgartigimod compared with placebo. These improvements were typically observed 1 to 2 weeks after the first infusion and correlated with reductions in IgG. Similar results were observed across most QMG subdomains. CONCLUSIONS: These post hoc analyses of MG-ADL and QMG subdomain data from ADAPT suggest that efgartigimod is beneficial in improving muscle function and strength across all muscle groups, leading to the observed efficacy in participants with gMG.

Real-world utilization patterns of intravenous immunoglobulin in adults with generalized myasthenia gravis in the United States.

OBJECTIVE: To evaluate real-world utilization patterns of intravenous immunoglobulin (IVIg) among patients with generalized myasthenia gravis (gMG) over 3 years post-IVIg initiation. METHODS: Patients with gMG who initiated IVIg treatment were identified from a United States claims database (Symphony Health's Integrated Dataverse [IDV]®, January 1, 2014 - December 31, 2019). The frequency of subsequent IVIg treatment and associated cost during the year post-IVIg initiation were analyzed. Usage patterns of IVIg and concomitant gMG treatments during the year preceding and 3 years post-IVIg initiation were compared. RESULTS: Among 1225 patients with gMG who initiated IVIg treatment, 706 patients (57.6%) received 1 to 5 IVIg treatment courses (intermittent IVIg users), and 519 patients (42.4%) received ≥6 IVIg treatment courses (chronic IVIg users) within the subsequent year. Mean annual medical cost per patient was nearly 2.5-fold higher for chronic vs. intermittent IVIg users ($161,478 vs. $64,888, p < 0.001). The proportion of patients using corticosteroids and nonsteroidal immunosuppressive treatments (NSISTs) was not reduced over the 3-year follow-up period following IVIg initiation, even for patients who continued annual chronic IVIg for 3 consecutive years post-initiation. CONCLUSIONS: Nearly half of patients with gMG received chronic and multiple IVIg treatment courses within the first year once initiating IVIg treatment, indicating higher usage than expected. For all IVIg initiators, the proportion of patients using corticosteroids and NSISTs did not decrease over 3 years despite IVIg initiation.

Real-World Healthcare Resource Utilization and Cost Burden Assessment for Adults With Generalized Myasthenia Gravis in the United States.

INTRODUCTION: Limited evidence exists for healthcare resource utilization (HCRU) and costs associated with generalized myasthenia gravis (gMG), a rare autoimmune disorder, for adults in the United States. METHODS: Adults with ≥1 diagnostic claim for MG between 2014 and 2019 were identified using Symphony Health's Integrated Dataverse®. Using a novel algorithm, HCRU and costs over 12 months following index dates were evaluated for patients with gMG including those with exacerbation events. For patients who experienced crisis events, HCRU and costs were analyzed during the 36 months preceding, during, and 12 months following the events. RESULTS: Mean HCRU and costs were higher for newly diagnosed patients compared with previously diagnosed patients (hospitalizations: 0.46 vs. 0.34; all-cause costs: $26,419.20 vs. $24,941.47; direct costs for gMG treatments: $9,890.37 vs. $9,186.47) and further increased for patients with exacerbation events (hospitalizations: 0.72; all-cause costs: $43,734.15; direct costs for gMG treatments: $21,550.02). For patients who experienced crisis events, HCRU and costs markedly increased during the 12 months immediately before the crisis event (hospitalizations: 1.35; all-cause costs: $49,236.68) compared with the 2 preceding years and increased further during the 12 months following the crisis index date (hospitalizations: 2.78; all-cause costs: $173,956.99). Cost increases were, in large part, attributed to treatments received. DISCUSSION: New diagnosis, exacerbation, and crisis events were drivers of HCRU and cost for patients with gMG. Particularly, high costs of gMG-specific medications associated with intervention for exacerbation and crisis events contributed to increased all-cause costs.

Prediction of Antimalarial Drug Clearance in Children: A Comparison of Three Different Interspecies Scaling Methods.

BACKGROUND AND OBJECTIVE: Allometric scaling is extensively used for the prediction of pharmacokinetic parameters from animals to humans and is often used for the selection of first-in-human dose. Allometric scaling can also be used to predict a pharmacokinetic parameter in children from adult data including animal species such as rat and dog. The current study was undertaken to evaluate if the clearances of antimalarial drugs in children with malaria can be predicted allometrically (interspecies scaling) from adult rat, dog, and human adult (healthy as well patients with malaria) clearance values. METHODS: Three methods [simple allometry, maximum lifespan potential (MLP), and MLP with an empirical correction factor] using clearance values from adult rat, dog, and adult humans with and without malaria were used for the prediction of antimalarial drug clearance in children with malaria. RESULTS: The results of this study indicated that the simple allometry would systematically over-predict antimalarial drug clearance in children with malaria whereas the application of MLP would under-predict the clearances of these drugs in children. Therefore, an empirical correction factor was introduced to MLP which substantially improved the antimalarial drug clearances in children. CONCLUSIONS: Overall, the results of the study indicated that interspecies scaling using adult rat, dog, and human clearance values of antimalarial drugs could possibly be used to predict drug clearance in children with malaria of different age groups and may be useful during pediatric drug development of antimalarial drugs.