Ravulizumab-CWVZ

Shares of Dianthus Therapeutics surged 22% Monday after the biotech reported positive results from its Phase II MaGic trial testing claseprubart (DNTH103) in generalised myasthenia gravis (gMG). The company now plans to move the antibody into Phase III studies in 2026, evaluating 300 mg doses given every two and four weeks.Claseprubart is designed to block only the active form of C1s, a protein that drives the classical complement pathway implicated in gMG, while sparing other immune functions to reduce infection risk. Administered subcutaneously, the drug incorporates half-life extension technology intended to support less frequent dosing and self-administration.The MaGic trial enrolled 65 patients with acetylcholine receptor antibody-positive (AChR+) gMG. After an initial loading dose, they received subcutaneous injections of claseprubart via autoinjector every two weeks at either 300 mg/2 mL or 600 mg/4 mL.At week 13, the 300-mg dose arm improved by 4.6 points on the Myasthenia Gravis - Activities of Daily Living (MG-ADL) scale versus baseline, with a placebo-adjusted benefit of 1.8 points. The higher 600-mg dose showed a 5.4-point absolute gain and 2.6-point advantage over placebo. Improvements were also observed on the Quantitative Myasthenia Gravis (QMG) assessment, where patients showed improvements of 4.4 and 4.5 points, on the low and high doses, respectively, compared with a 2-point gain in the placebo group.Dianthus said that benefits appeared quickly; on both the MG-ADL and QMG measures, claseprubart achieved significant improvements starting in the first week.Rethinking complement thresholdsCEO Marino Garcia contrasted Monday's results with Regeneron Pharmaceuticals' "eye-opening" late-stage readout last month for its C5-targeting siRNA cemdisiran. "The fact that they had a significant improvement on the MG-ADL… and they disclosed that they only achieved 75% inhibition of the complement system – that's, in a way, a groundbreaking bit of information that tells us that getting above IC90 was always really an artificial goal," Garcia during a call with analysts."So, if achieving something like 75% or 80% inhibition of the classical pathway is enough to give you similar results, we're very confident that's what [every-four-week dosing] would be doing. And remember, we have a 60-day half-life, so for every four weeks… is very much well within our half-life timeline," he added.As for safety, claseprubart was well tolerated in the study, with no treatment-related serious infections, signs of autoimmune disease, or drug-related adverse events leading to discontinuation, findings that support its potential to avoid a boxed warning or REMS requirement for meningococcal infections.Beating rivals, but…Wedbush analyst Laura Chico suggested that on all measures of the study, claseprubart appeared to outperform Ultomiris (ravulizumab), AstraZeneca's C5 complement inhibitor for gMG.However, Wedbush's David Nierengarten says that despite the positive MaGic readout, argenx's FcRn blocker Vyvgart (efgartigimod alfa), also available subcutaneously as Vyvgart Hytrulo, is expected to remain a dominant treatment. "We continue to see several years of unobstructed growth ahead for Vyvgart in MG and given its strong clinical profile and ease of administration with the availability of a prefilled syringe, we believe that use of other approved agents will largely be relegated to patients who do not respond well to Vyvgart," he said in a client note.Meanwhile, Garcia described 2026 as a "catalyst-rich year" for Dianthus, with the planned Phase III gMG trial, followed by a second-half interim responder analysis of claseprubart from the Phase III CAPTIVATE study in chronic inflammatory demyelinating polyneuropathy, and top-line results from the Phase II MoMeNtum trial testing the drug in multifocal motor neuropathy.

iStock, beast01 Regeneron’s cemdisiran, used alone or in combination with its complement inhibitor Veopoz, significantly improved activities of daily living in patients with generalized myasthenia gravis.   Regeneron’s investigational small interfering RNA therapy cemdisiran significantly improved disease activity in certain patients with generalized myasthenia gravis, opening up a path for regulatory filing early next year. Results from the Phase III NIMBLE study were published Tuesday , demonstrating a 2.3-point placebo-adjusted improvement in Myasthenia Gravis Activities of Daily Living (MG-ADL) scores, a patient-reported scale used to measure the daily impacts of the disease. Cemdisiran also achieved a 74% reduction of complement factor 5 (C5), a part of the complement system that is inappropriately activated in gMG. Regeneron also tested a combination regimen of cemdisiran with the company’s complement inhibitor Veopoz, which elicited a significant MG-ADL improvement of 1.74 points over placebo. Veopoz is approved for the treatment of patients 1 year and up with CD55-deficient protein-losing enteropathy. In premarket trading Wednesday, Regeneron’s stock was up 2.67%. Writing to investors on Tuesday, analysts at Truist Securities noted that cemdisiran  monotherapy  “surpassed our expectations,” given the “historical performance” of other anti-C5 therapies. NIMBLE did not detect instances of meningitis, a known side effect of this drug class, but Truist still expects cemdisiran to come with a boxed warning if approved, “based on the class precedent.” Aside from its apparent efficacy and safety edge, Truist also pointed to cemdisiran’s “convenient administration” as another point for Regeneron. The drug is given subcutaneously every 12 weeks, whereas its most notable competitors—AstraZeneca’s Soliris and Ultomiris—are delivered intravenously. This administration advantage could help cemdisiran “capture a significant share of the C5 gMG market,” according to the analysts. With NIMBLE data in hand, Regeneron is planning an FDA submission for the first quarter of 2026, the pharma noted in its Tuesday release. Full findings from the study will be shared at an upcoming meeting. Designed to target and destroy C5 mRNA, cemdisiran is a small interfering RNA therapy that helps suppress the complement cascade, which in gMG plays a role in damaging muscle nerves. The therapy was developed by Alnylam as part of a research collaboration with Regeneron, for which Regeneron in April 2019 paid $800 million upfront . The deal gave the pharma access to Alnylam’s RNAi experience for diseases of the eyes and central nervous system, a push that has cemdisiran at its core. Milestone payments for this agreement could reach up to $200 million. Elsewhere in the gMG arena, argenx on Monday reported positive Phase III data for its FcRn inhibitor Vyvgart, positioning it up for expansion into patients who are AChR seronegative. While argenx did not provide specific data, it emphasized a “statistically significant and clinically meaningful improvement” in disease activity in patients treated with Vyvgart, adding that it is preparing for a label expansion application into this specific patient population.