Add-on gMG treatment lowers costs, cuts time spent in hospital

Adding Imaavy (nipocalimab-aahu) to standard treatment reduces hospital days by as much as 68% and lowers estimated annual hospital costs by $11,000 to $13,000 per patient for adults with generalized myasthenia gravis (gMG).

That’s according to a post hoc analysis of data from the global Phase 3 Vivacity-MG3 clinical trial (NCT04951622), whose top-line, six-month results supported regulatory approvals of the therapy for gMG. Post hoc analyses examine hypotheses conceptualized after the data are collected.

Data also showed that worsening daily function scores and more severe pre-study breathing-related muscle weakness independently predicted which patients would need hospital or emergency room admission.

“These findings reinforce the critical role of early, consistent and sustained disease control in mitigating the risk of costly acute events and highlight the potential for [Imaavy] to address pervasive unmet needs and the economic burden in gMG management,” the researchers wrote.

The study, “Hospital resource utilization in patients with generalized myasthenia gravis treated with nipocalimab: results from the VIVACITY-MG3 study,” was published in the Journal of Medical Economics. It was funded by the therapy’s developer, Johnson & Johnson, and three of its four authors work for the company.

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Immune system goes awry

In gMG, the immune system produces self-reactive antibodies that attack the connection between nerves and muscles. This leads to fluctuating muscle weakness and fatigue that can affect the eyes, limbs, swallowing, and breathing.

In severe cases, gMG can lead to a myasthenic crisis, a dangerous worsening of breathing symptoms that may require hospitalization and mechanical ventilation. Because of these flare-ups, people with gMG often need emergency care and hospital stays, which drive up healthcare costs substantially.

Imaavy is approved for adolescents and adults with gMG who test positive for the two most common types of MG-causing antibodies. Administered directly into the bloodstream, it works by blocking a protein called FcRn, reducing blood levels of antibodies, including those that drive gMG.

Regulatory approvals were backed by VIVACITY-MG3 data, which showed that Imaavy, given every two weeks on top of standard care, improved muscle strength and daily functioning and lowered self-reactive antibody levels after six months in adults with gMG. Interim data from the study’s ongoing open-label extension portion, in which all patients are receiving Imaavy, showed that continued treatment with Imaavy sustained these benefits.

The researchers used efficacy results from the 153 VIVACITY-MG3 participants who completed the study’s placebo-controlled portion to evaluate healthcare resource utilization, costs, and predictors of high-cost events in adults with gMG treated with Imaavy.

Over six months, fewer participants on Imaavy had to visit the hospital or emergency department for any reason than those on the placebo (9.1% vs. 15.8%). Similarly, gMG-related events were less common in the Imaavy group (3.9% vs. 7.9%). The rate of these combined hospital and emergency events was about 51% lower with Imaavy.

The mean length of stay for any hospital admission was shorter for patients on Imaavy than for those on the placebo (8.4 days vs. 14.6 days) and for admissions specifically related to gMG (11.2 days vs. 17.6 days). Imaavy was associated with a significant reduction in all-cause hospital days (by 60%) and gMG-related hospital days (by 68%) compared with the placebo.

Using published U.S. healthcare cost data, the researchers estimated that the reduced hospital use with Imaavy translated into substantial savings. The estimated annual hospital cost per patient was $8,482 for those on Imaavy compared with $21,736 for those on the placebo, a difference of $13,253.

A separate analysis using a different cost database (Optum’s Clinformatics claims data) produced a similar estimated savings range, of $10,860.

Statistical analyses adjusted for potential influencing factors identified two independent predictors of a hospital or emergency visit. A one-point worsening on the MG-Activities of Daily Living (MG-ADL) scale, a measure of the disease’s impact on daily activities, during treatment was linked to a 29% higher risk of such events.

Also, at the study’s start (baseline), a one-point higher (worse) score on the breathing-related portion of the Quantitative MG (QMG) scale, a measure of muscle weakness, was tied to a 66% higher risk of a hospital or emergency event.

Patients who were originally assigned the placebo and switched to Imaavy in the study’s extension phase saw their all-cause hospital days drop significantly, by 64%, and by 81% for gMG-related hospital days.

Among the study’s limitations, the researchers noted its post hoc nature and the fact that cost estimates covered only direct hospital-related expenses, not the cost of Imaavy itself or indirect costs such as lost work productivity or caregiver burden.

“This post-hoc analysis of VIVACITY-MG3 demonstrates that [Imaavy] added to [standard-of-care] meaningfully reduces [healthcare resource utilization] in adults with gMG,” the researchers wrote. “Analyses identified worsening MG-ADL score and elevated baseline QMG respiratory score as independent predictors of hospital admission.”