Fast-Acting Drug Pair Pulls Patient Back From Brink of Myasthenic Crisis

A 73-year-old man arrived at a Chinese hospital with double vision, difficulty swallowing, and mounting breathlessness — the classic warning signs that his rare autoimmune disease was about to spiral into a life-threatening emergency. He was harboring antibodies against muscle-specific kinase (MuSK), a variant of myasthenia gravis that strikes the muscles of the face, throat, and lungs and accounts for only 5 to 8 percent of all myasthenia cases. Yet what makes his story remarkable is not the diagnosis, but the treatment: a newly reported sequential regimen of two fast-acting drugs that pulled him back from the edge of crisis in a matter of weeks, despite severe lung infection and acute heart failure that ruled out nearly every standard option.

The case, published in Immunity, Inflammation and Disease by clinicians at the Second Xiangya Hospital of Central South University, describes what the authors believe is the first use of sequential efgartigimod and telitacicept in a MuSK-positive patient. The man was in a state of impending myasthenic crisis — a clinical window, measured in days to weeks, during which rapid intervention can prevent full respiratory failure. His quantitative myasthenia gravis (QMG) score, a standardized measure of muscle weakness, stood at 31 out of a possible maximum, and his activities-of-daily-living score was 22, both indicating profound disability. Bulbar and respiratory muscle involvement alone contributed 9 points, crossing the threshold that clinicians use to flag imminent crisis.

Ordinarily, a patient in this state would receive plasma exchange or intravenous immunoglobulin (IVIG) to strip harmful antibodies from the blood, followed by slow-acting immunosuppressants and corticosteroids to hold the disease at bay. But this patient’s comorbidities slammed those doors shut. Plasma exchange requires invasive vascular access and carries a hypercoagulable risk, while IVIG adds substantial fluid volume — dangerous for someone in acute heart failure. High-dose steroids were contraindicated by his pulmonary infection, osteoporosis, and history of gastrointestinal ulcers. And because MuSK antibodies are predominantly of the IgG4 subclass, IVIG tends to work poorly in this subgroup anyway, a known pharmacological quirk that further narrowed the therapeutic toolkit.

The team turned instead to efgartigimod, a neonatal Fc receptor (FcRn) inhibitor that works by an elegant piece of immunological engineering. FcRn normally acts as a recycling chaperone, binding IgG antibodies in endosomes and ferrying them back into circulation, which is why IgG persists for weeks in the bloodstream. By blocking this interaction, efgartigimod lets IgG antibodies — including the pathogenic ones — be swept into lysosomal degradation. In the pivotal ADAPT trial, clinical improvement appeared within two weeks in a majority of patients, accompanied by sharp drops across all IgG subtypes. Real-world Japanese data have since suggested the drug may work even better in MuSK-positive patients, with a responder rate of 83 percent compared to 59 percent in those with the more common acetylcholine receptor antibodies.

That prediction held. Five days after the first 400-milligram infusion, the man’s QMG score fell from 31 to 23 and his MG-ADL score dropped from 22 to 12. After the second dose, his feeding tube came out and he resumed eating independently — a small milestone with enormous clinical meaning in a disease that progressively steals the ability to swallow. Meanwhile, antibiotics and natriuretic peptides kept his lung infection and heart failure in check, allowing the neurological treatment to proceed without destabilizing his cardiovascular system.

But efgartigimod alone cannot sustain remission; it clears existing antibodies without touching the factories that keep producing them. For long-term control, the clinicians layered in telitacicept, a recombinant fusion protein that simultaneously blocks two cytokines — BLyS and APRIL — that B cells need to mature, activate, and differentiate into antibody-secreting cells. This dual blockade targets a gap left by rituximab, the CD20-depleting antibody most often used as first-line maintenance in MuSK disease. CD20 sits on immature B cells but is absent from long-lived memory cells and plasmablasts, and studies have found that roughly a quarter of plasmablasts in patients who relapse after rituximab do not express the target at all. Elevated BAFF, the same cytokine telitacicept inhibits, has been documented in both MuSK-positive and acetylcholine receptor-positive patients, making the pathway a rational bullseye.

One week after the second efgartigimod dose, weekly subcutaneous telitacicept at 240 milligrams began. By day 28, after just two injections, the man’s swallowing difficulties and limb weakness had resolved completely, leaving only slight horizontal double vision. He was discharged with a QMG score of 10. Five injections later, on day 47, his daily life had returned entirely to normal: QMG score of 2, MG-ADL score of 0, meaning minimal symptom expression — the treatment benchmark that typically takes 11 weeks to 10.5 months to reach with conventional immunosuppressants — achieved in about a month and a half.

Laboratory data traced the pharmacological logic of the sequential approach. IgG levels dropped markedly by day 19, the fingerprint of efgartigimod’s recycling-blockade mechanism, while IgM remained essentially untouched, reflecting the drug’s selectivity for the IgG pathway. Telitacicept then took the long view: as B cell maturation slowed, MuSK antibody titers fell over the following month, and the injection interval was stretched from weekly to every 10 days for maintenance. The clinical trajectory and the antibody decline moved in lockstep, offering a mechanistic narrative — fast antibody clearance followed by slow suppression of antibody production — that the authors suggest could become a template for acute MuSK disease management.

Caution is warranted, as it always is with a single case. Telitacicept, approved in China for systemic lupus erythematosus and rheumatoid arthritis, included only four MuSK-positive patients in its phase 3 myasthenia trial, and no randomized data exist for the sequential regimen described here. The optimal dosing schedule, the duration of maintenance therapy, and the safety profile in larger and more diverse populations all remain open questions. The authors themselves flag that their report reflects one medication experience in one complex patient, however encouraging the outcome.

Still, the case lands at a moment when the treatment landscape for myasthenia gravis is shifting rapidly. FcRn inhibitors such as efgartigimod and rozanolixizumab — the latter showing roughly 60 percent responder rates in MuSK-positive subgroups of its own phase 3 trial — have made fast, targeted antibody clearance feasible outside the plasmapheresis suite. Pairing that acute punch with B cell cytokine blockade extends the strategy from symptom rescue to disease modification. For elderly patients with the kind of stacked comorbidities that make conventional crisis management impossible, a drug combination that achieves minimal symptom expression in six weeks with no observed adverse effects is exactly the kind of therapeutic blueprint the field has been waiting to test in properly powered multicenter trials.

Subject of Research: Sequential efgartigimod and telitacicept treatment of impending myasthenic crisis in MuSK-positive myasthenia gravis

Article Title: A Novel Sequential Regimen of Efgartigimod and Telitacicept as Fast‐Acting Treatment for Impeding Crisis of MuSK‐MG

Article References: Duan, T., Ouyang, S., Lu, W., & Yin, W. (2026). A Novel Sequential Regimen of Efgartigimod and Telitacicept as Fast‐Acting Treatment for Impeding Crisis of MuSK‐MG. Immunity, Inflammation and Disease, 14(10), Article e70521. https://doi.org/10.1002/iid3.70521

Image Credits: AI Generated

DOI: 10.1002/iid3.70521

Keywords: MuSK myasthenia gravis, efgartigimod, telitacicept, FcRn inhibitor, BLyS, APRIL, myasthenic crisis, autoantibodies, B cell blockade, immunotherapy, neuromuscular junction, case report