Announcement • Aug 18

Zai Lab Limited and Argenx Announces Positive Topline Results From Phase 3 Alkivia Trial Of Efgartigimod In Autoimmune Myositis

Zai Lab Limited and Argenx announced positive topline results from the ALKIVIA Phase 3 study evaluating VYVGART Hytrulo (efgartigimod alfa and hyaluronidase-qvfc) in adults with autoimmune myositis. Study met its primary endpoint (p=0.0011). In the combined immune-mediated necrotizing myopathy (IMNM) and dermatomyositis (DM) population, patients treated with efgartigimod demonstrated statistically significant and clinically meaningful 15.4-point greater improvement in mean Total Improvement Score (TIS) at Week 52 versus placebo (47.95 vs 32.56). In the combined population, patients treated with efgartigimod consistently showed improvements over placebo starting at Week 4 that were statistically significant and sustained through the full year of treatment, even with steroid tapering. In prespecified subtype analyses, the primary endpoint of Mean TIS at 52 weeks was also met in IMNM patients treated with efgartigimod (p=0.0048), with a 14.8-point greater improvement over placebo (45.05 vs 30.24). In DM, a similar clinically meaningful improvement of 14.5 points (p=0.1093) was observed (51.51 vs 36.96), though statistical significance was not reached in this smaller cohort. In both IMNM and DM, all six core set measures of TIS contributed to the treatment effect, each favoring efgartigimod over placebo, spanning muscle strength, everyday physical function, and disease activity beyond the muscle. In DM, improvement in skin disease activity was also observed. Efgartigimod was well-tolerated by patients in the ALKIVIA study. The observed safety profile was consistent with prior studies and the known safety profile of efgartigimod. Detailed results from the ALKIVIA study will be presented at an upcoming medical meeting. Efgartigimod continues to be evaluated as a potential treatment in other autoimmune rheumatologic diseases, including Sjögren’s disease and systemic sclerosis. The ALKIVIA study was a global, randomized, double-blind, placebo-controlled, multicenter, operationally seamless Phase 2/3 study of efgartigimod SC for the treatment of autoimmune myositis across IMNM, DM and PM. The ALKIVIA study enrolled 264 patients who had active disease and were on background treatment. Participants were randomized (1:1) to receive weekly injections of efgartigimod PH20 SC or matched to placebo PH20 SC. The study was conducted in two phases, with an analysis of the Phase 2 portion of the clinical trial after the first 89 patients completed the study, followed by Phase 3. The Phase 3 study enrolled 175 patients and included a protocol-mandated corticosteroid taper throughout the study. The primary endpoint of Phase 3 was the mean Total Improvement Score (TIS) at the end of the treatment period of 52 weeks of all treated patients compared to placebo. Prespecified analyses evaluated the combined IMNM and DM population and each subtype separately. ALKIVIA was conducted globally across North America, Europe, the Middle East, and Asia-Pacific, including China and Japan. Argenx has an exclusive license agreement with Zai Lab for the development and commercialization of VYVGART and VYVGART Hytrulo in Greater China. Through this agreement, Zai Lab recruited Chinese patients into the ALKIVIA trial. Autoimmune myositis is a heterogenous disease spectrum with autoimmune-mediated pathophysiology, characterized by chronic inflammation and progressive muscle weakness, and in some subtypes by skin involvement and other extramuscular manifestations. Proximal muscle weakness is a hallmark clinical feature across subtypes. Approximately 100,000 people in the United States live with autoimmune myositis, including approximately 20,000 with IMNM and approximately 40,000 with DM. Up to 80% of patients report long-term disability despite treatment. There are currently no targeted treatments available, and care and treatment relies primarily on corticosteroids and broad immunosuppressants, which are associated with significant cumulative toxicity, including metabolic, cardiovascular, musculoskeletal and infectious complications. Advances in the understanding of autoimmune myositis biology have highlighted the central role of antibody-mediated immunity, with pathogenic IgG autoantibodies contributing to muscle fiber damage and extramuscular manifestations across subtypes. FcRn maintains circulating IgG levels by recycling IgG antibodies, including pathogenic autoantibodies. Efgartigimod is designed to selectively block FcRn, reducing pathogenic IgG autoantibodies while preserving other aspects of immune function. VYVGART (efgartigimod alfa fcab) is a first-in-class human IgG1 antibody fragment that binds to the neonatal Fc receptor (FcRn), resulting in the reduction of circulating IgG autoantibodies. VYVGART Hytrulo is a subcutaneous combination of efgartigimod alfa (VYVGART) and recombinant human hyaluronidase PH20 (rHuPH20), Halozyme’s ENHANZE drug delivery technology to facilitate subcutaneous injection delivery of biologics. VYVGART is approved for generalized myasthenia gravis (gMG) and immune thrombocytopenia (Japan only). VYVGART Hytrulo is approved for gMG and chronic inflammatory demyelinating polyneuropathy (CIDP). VYVGART Hytrulo may be marketed under different proprietary names in other regions.

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