Gefurulimab Maintains Myasthenia Gravis Benefits Through 1 Year

TL;DR

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In an open-label extension of the phase III PREVAIL trial, participants with generalized myasthenia gravis had sustained improvements in three disease-rating scales through 52 weeks of gefurulimab treatment. The results were reported at an AANEM meeting; the drug is under FDA review, and the European Medicines Agency’s medicines committee has recommended it for approval.

People with anti-AChR antibody-positive generalized myasthenia gravis who received investigational gefurulimab maintained improvements in disease-rating scores through 52 weeks, according to results from the open-label extension of the phase III PREVAIL trial. Tuan Vu, MD, of the University of South Florida presented the findings at an American Association of Neuromuscular and Electrodiagnostic Medicine meeting; the drug remains under review by the U.S. Food and Drug Administration.

Among participants treated with gefurulimab, scores at one year were better than at the start of the study by 5.3 points on the MG-ADL scale, which ranges from 0 to 24; 5.3 points on the QMG scale, which ranges from 0 to 39; and 9.4 points on the MGC scale, which ranges from 0 to 50. Lower scores on these scales indicate fewer symptoms or less disease impact. The reported changes describe improvement from baseline, not a comparison with a placebo group at week 52.

Participants initially assigned to placebo switched to gefurulimab at week 26. By week 52, their scores had improved from baseline by 4.9 points on MG-ADL, 4.6 points on QMG, and 8.3 points on MGC. Vu said improvements appeared at the first assessments after they began treatment and continued through the end of the reported period.

The extension included all 249 participants who completed PREVAIL’s 26-week randomized period. At the November 2025 data cutoff, 211 were still receiving treatment. Median treatment duration among patients receiving gefurulimab was 575 days. Vu described the treatment as well tolerated, with a safety profile consistent with the randomized phase and no emerging safety signals. These are findings from an open-label extension, in which participants and investigators know the treatment being given.

One-Year Results in PREVAIL

The findings add longer-term information to the initial 26-week trial results. Sustained improvements across three separate measures suggest the observed benefits did not disappear during the reported year of treatment. This is relevant to people with generalized myasthenia gravis, a chronic condition that can affect voluntary muscles and daily activities, and to clinicians weighing treatment options over time.

However, the extension results do not establish how gefurulimab compares with other treatments after the placebo-controlled phase ended. The continued-treatment data also cannot settle whether benefits and safety will remain similar over longer periods or across all patients. The findings are encouraging trial evidence, not proof that every patient will experience the same response.

From Placebo-Controlled Trial to Extension

PREVAIL randomized 260 adults with anti-AChR antibody-positive generalized myasthenia gravis to weekly, self-administered subcutaneous gefurulimab or placebo for 26 weeks. Its primary endpoint was change in MG-ADL score at week 26, with QMG change among the key secondary endpoints. The trial met its primary and secondary endpoints, and reported improvements appeared within one week on MG-ADL and within four weeks on QMG.

Gefurulimab is an investigational C5 complement inhibitor designed as a dual-binding nanobody. It also binds serum albumin, a feature intended to extend its half-life and support once-weekly dosing. The FDA has approved other C5 inhibitors for myasthenia gravis, including eculizumab, ravulizumab and zilucoplan. This drug class carries a boxed warning about the risk of Neisseria meningitidis infection, and vaccination recommendations apply to patients receiving approved C5 inhibitors.

In September, the European Medicines Agency’s Committee for Medicinal Products for Human Use recommended gefurulimab for approval in the European Union. That recommendation is not itself final authorization. The drug is also under FDA review.

“Vu reported that improvements across MG-ADL, QMG and MGC scores continued through week 52.”

— Tuan Vu, MD, University of South Florida

Questions Beyond Week 52

The extension report does not provide a placebo-controlled comparison beyond the original 26-week period. Because the extension was open-label, its one-year findings should not be read as a direct measure of gefurulimab’s advantage over placebo at week 52. The report also does not establish how long benefits persist beyond the available follow-up.

At the November 2025 cutoff, 211 of the 249 extension participants remained on treatment. The supplied results do not explain each discontinuation or provide detailed individual reasons for leaving the study. Vu reported no emerging safety signals, but the available summary does not give full adverse-event counts for the extension or resolve the drug’s longer-term safety profile. Regulatory review and final authorization status remain separate from these clinical findings.

Regulatory Review and Longer Follow-Up

The next major decision is the FDA’s review of gefurulimab; the source material does not provide a decision date. In Europe, the medicines committee’s September recommendation must be followed by the relevant authorization process before the drug can be treated as approved for use there.

Further follow-up from PREVAIL’s extension may clarify how many participants continue treatment, whether score improvements are maintained beyond 52 weeks, and how safety events accumulate over time. Until more data and regulatory decisions are available, the one-year report adds evidence about durability but does not change gefurulimab’s investigational status in the United States.

Key Questions

What did the PREVAIL extension find?

Participants receiving gefurulimab had improvements from baseline through week 52 on MG-ADL, QMG and MGC measures. The report describes sustained score changes in an open-label extension, not a placebo-controlled comparison at one year.

How much did the scores improve?

At one year, the reported changes from baseline were 5.3 points on MG-ADL, 5.3 points on QMG and 9.4 points on MGC among patients treated with gefurulimab. For participants who switched from placebo at week 26, the corresponding changes by week 52 were 4.9, 4.6 and 8.3 points.

Is gefurulimab approved for myasthenia gravis?

The source material describes gefurulimab as investigational and under FDA review. In Europe, the EMA’s medicines committee recommended approval in September, but that recommendation is not the same as final authorization.

How was gefurulimab given in the trial?

Participants received weekly, self-administered subcutaneous gefurulimab during the randomized phase. The drug is designed to bind complement component C5 and serum albumin, with albumin binding intended to extend its half-life.

What safety information was reported?

Vu said the extension’s safety profile was consistent with the randomized period and that no emerging safety signals were identified. The available report does not provide full extension adverse-event counts; C5 inhibitors as a class carry a warning about meningococcal infection risk.

Source: rss