ObjectiveTo investigate safety and explore efficacy of efgartigimod (ARGX-113), an anti-neonatal Fc receptor immunoglobulin G1 Fc fragment, in patients with generalized myasthenia gravis (gMG) with a history of anti-acetylcholine receptor (AChR) autoantibodies, who were on stable standard-of-care myasthenia gravis (MG) treatment.MethodsA phase 2, exploratory, randomized, double-blind, placebo-controlled, 15-center study is described. Eligible patients were randomly assigned (1:1) to receive 4 doses over a 3-week period of either 10 mg/kg IV efgartigimod or matched placebo combined with their standard-of-care therapy. Primary endpoints were safety and tolerability. Secondary endpoints included efficacy (change from baseline to week 11 of Myasthenia Gravis Activities of Daily Living, Quantitative Myasthenia Gravis, and Myasthenia Gravis Composite disease severity scores, and of the revised 15-item Myasthenia Gravis Quality of Life scale), pharmacokinetics, pharmacodynamics, and immunogenicity.ResultsOf the 35 screened patients, 24 were enrolled and randomized: 12 received efgartigimod and 12 placebo. Efgartigimod was well-tolerated in all patients, with no serious or severe adverse events reported, no relevant changes in vital signs or ECG findings observed, and no difference in adverse events between efgartigimod and placebo treatment. All patients treated with efgartigimod showed a rapid decrease in total immunoglobulin G (IgG) and anti-AChR autoantibody levels, and assessment using all 4 efficacy scales consistently demonstrated that 75% showed a rapid and long-lasting disease improvement.ConclusionsEfgartigimod was safe and well-tolerated. The correlation between reduction of levels of pathogenic IgG autoantibodies and disease improvement suggests that reducing pathogenic autoantibodies with efgartigimod may offer an innovative approach to treat MG.Classification of evidenceThis study provides Class I evidence that efgartigimod is safe and well-tolerated in patients with gMG.

Neutralizing the interaction of the platelet receptor gpIb with VWF is an attractive strategy to treat and prevent thrombotic complications. ALX-0081 is a bivalent Nanobody which specifically targets the gpIb-binding site of VWF and interacts avidly with VWF. Nanobodies are therapeutic proteins derived from naturally occurring heavy-chain-only Abs and combine a small molecular size with a high inherent stability. ALX-0081 exerts potent IntroductionThe successive adhesion, activation, and aggregation of platelets are key processes in arterial thrombus formation after endothelial damage. 1,2 Both rupture of atherosclerotic plaques as well as surgical interventions to treat atherosclerosis (eg, percutaneous coronary intervention [PCI]) may cause exposure of the subendothelium and subsequent clot formation. Eventually, this can result in the occlusion of arteries, leading to ischemia, myocardial infarcts, or stroke. Given the central role of platelets in thrombosis, a substantial number of currently marketed antithrombotic drugs, such as aspirin, clopidogrel, and abciximab, target different steps involved in platelet activation and aggregation. 1,2 Thanks to their complementary mechanisms of action, the combination of these agents inhibits platelet aggregation to a greater extent than either agent alone. 3 However, the use of these antiplatelet drugs is hampered by an increased bleeding risk 1,2 and the occurrence of treatment resistance in some patients. 4 Moreover, the irreversible nature of their action can complicate the staunching of bleeding. 1,2 Inhibition of the initial adhesion of platelets to subendothelial collagen provides an alternative strategy to prevent unwanted clot formation. The plasma glycoprotein VWF plays a pivotal role in this adhesion via binding to exposed collagen on the one hand, and the interaction of its A1 domain with the gpIb-IX-V receptor complex on the surface of platelets on the other hand. [5][6][7] Interestingly, the VWF A1 domain is only exposed under high-shear conditions, 8,9 so VWF only acts as a bridging molecule between collagen and platelets in small or stenosed arteries. Therefore, it is expected that drugs inhibiting this interaction between VWF and platelets show an improved safety profile with respect to bleeding tendency. Indeed, the antithrombotic effect of several compounds targeting the gpIb-VWF-A1-axis, like aurintricarboxylic acid, 10-12 recombinant VWF fragments, 10,13-16 a recombinant gpIb chimeric protein, 17,18 anti-VWF mAbs, [19][20][21][22][23][24][25][26][27] and an anti-VWF aptamer 28 has been demonstrated in vitro and in vivo, without increasing the bleeding risk. 13,[16][17][18]21,23,25,28,29 Nevertheless, until now only 3 drug candidates have been evaluated in humans, including ALX-0081. [30][31][32][33] We developed ALX-0081, a bivalent humanized Nanobody directed against the A1 domain of VWF. Nanobodies are therapeutic proteins derived from the heavy-chain variable domains (VHH) that occur naturally in heavy-chain-only Igs of Camelidae. 34,35 Here we...

Primary immune thrombocytopenia (ITP) is an acquired autoimmune bleeding disorder, characterized by a low platelet count (<100 × 10 9 /L) in the absence of other causes associated with thrombocytopenia. In most patients, IgG autoantibodies directed against platelet receptors can be detected. They accelerate platelet clearance and destruction, inhibit platelet production, and impair platelet function,

8 March 2012.

Background Primary immune thrombocytopenia (ITP) is an acquired autoimmune bleeding disorder, characterized by a low platelet count (&lt;100×109/L) in the absence of other causes. In most patients, IgG autoantibodies are detected which accelerate platelet clearance, inhibit platelet production, induce platelet apoptosis or complement-dependent lysis, and may alter platelet function, resulting in increased risk of bleeding and impaired quality of life. Efgartigimod is a human IgG1 antibody Fc-fragment, a natural ligand of the neonatal Fc receptor (FcRn), engineered for increased affinity to FcRn whilst preserving characteristic pH-dependent binding. Efgartigimod blocks FcRn, preventing IgG recycling, causing targeted IgG degradation. In healthy volunteers (NCT03457649), efgartigimod was well tolerated and induced a rapid reduction of total IgG and all IgG subtypes. Targeted reduction of autoantibodies through FcRn blockade may prevent their pathogenic actions and represents a novel treatment modality in ITP. We investigated the safety and efficacy of efgartigimod in adult patients with primary ITP in a randomized, double-blinded, placebo-controlled Phase 2 study (NCT03102593). Methods After a 2-week screening period, patients were randomized 1:1:1 to receive 4 weekly intravenous infusions of either placebo or efgartigimod at a dose of 5 mg/kg or 10 mg/kg. Following periods included 8-week follow-up, up to 13 weeks extended follow-up, and a 1-year open-label extension (OLE) where patients could be treated with efgartigimod 10 mg/kg (Figure 1). Patients aged 18 to 85 years with confirmed primary ITP, and an average of 2 platelet counts ˂30×109/L during screening (with no single reading &gt;35×109/L), were recruited. Oral corticosteroids, oral immunosuppressants, and/or thrombopoietin receptor agonists at stable doses were permitted. The primary endpoint was safety. Secondary endpoints included pharmacodynamic (PD) markers, pharmacokinetic (PK) parameters, presence of anti-drug antibodies (ADA) and autoantibodies, and efficacy. Data for all endpoints were summarized by group using descriptive statistics. Data until the last visit of the first treatment cycle of the OLE period are reported. Results Thirty-eight patients (placebo [N=12], efgartigimod at a dose of 5 mg/kg [N=13] or 10 mg/kg [N=13]), mostly with longstanding ITP (median disease duration 4.8 [0.1-47.8] years) who had insufficient response to prior ITP therapy or failed splenectomy (N=6), were randomized. Twenty (52.6%) patients had a baseline platelet count &lt;15×109/L. Efgartigimod was well tolerated with no dose-related safety observations and the safety profile was consistent with previous observations in healthy volunteers. No increased risk of infection was apparent. Low positive pre- and post-dose ADA titers were measured in all groups and did not have an apparent effect on PK/PD parameters. Treatment with efgartigimod resulted in a rapid reduction of total IgG (up to 63.7% mean change from baseline) and all IgG subtypes in all treated patients. Autoantibodies were identified in all patients and were reduced following efgartigimod treatment. Efgartigimod-treated groups achieved a higher maximum mean platelet count change from baseline compared to the placebo group. A higher proportion of efgartigimod-treated patients achieved a platelet count of ≥50×109/L and ≥100×109/L at any time compared to the placebo group (Figure 2). Forty-six percent patients on efgartigimod vs. 25% on placebo achieved a platelet count of ≥50×109/L on at least 2 occasions and 38% vs. 0% achieved ≥50×109/L for at least 10 cumulative days. A decreased incidence of bleeding, measured using WHO and ITP-BAT scales, was observed in both efgartigimod-treated groups. In the OLE period, in which 12 patients received efgartigimod 10 mg/kg, 8 (66.7%) patients achieved platelet count ≥50×109/L on at least 2 occasions. Conclusion A short 3-week treatment cycle of efgartigimod in patients with ITP predominantly refractory to previous lines of ITP therapy was well tolerated, markedly reduced IgG levels, was associated with clinically relevant increases in platelet counts, and reduced the proportion of patients with bleeding (Figure 3). This suggests that targeted IgG reduction with efgartigimod is a potential new treatment modality in primary ITP, and warrants evaluation of longer-term treatment in a larger Phase 3 study. Disclosures Newland: Novartis: Consultancy, Honoraria, Research Funding; Angle: Consultancy, Honoraria; Amgen: Consultancy, Honoraria, Research Funding; Ono: Consultancy, Honoraria; Shionogi: Consultancy, Honoraria; Rigel: Consultancy, Honoraria, Research Funding; Argenx: Consultancy, Honoraria; Dova: Consultancy, Honoraria. Sánchez-González:Amgen: Consultancy, Speakers Bureau; Gilead: Speakers Bureau; Navartis: Consultancy, Speakers Bureau; Shire: Speakers Bureau; Takeda: Consultancy, Speakers Bureau. Godar:Argenx: Employment. Verschueren:Argenx: Consultancy. Gandini:Argenx: Employment, Equity Ownership. Ulrichts:Argenx: Employment. Beauchamp:Argenx: Employment. Dreier:Argenx: Employment. Ward:Argenx: Equity Ownership, Honoraria, Research Funding. Michel:Rigel: Consultancy; Amgen: Consultancy; Novartis: Consultancy. Liebman:Pfizer: Consultancy; Dova: Consultancy; Bristol-Myers: Research Funding; Argenx: Consultancy; Rigel: Consultancy; Janssen: Research Funding; Novartis: Consultancy. De Haard:Argenx: Employment, Equity Ownership, Patents & Royalties. Leupin:Argenx: Employment, Equity Ownership, Patents & Royalties. Kuter:Dova: Consultancy, Honoraria; Pfizer: Consultancy, Honoraria; UCB: Consultancy, Honoraria; Momenta: Consultancy, Honoraria; Caremark: Consultancy, Honoraria; Novartis: Consultancy, Honoraria; Protalix: Consultancy, Honoraria; Principia: Consultancy, Honoraria, Research Funding; Platelet Disorder Support Association: Consultancy, Honoraria; Shire: Consultancy, Honoraria; Amgen: Consultancy, Honoraria, Research Funding; Principia: Consultancy, Honoraria, Research Funding; Daiichi Sankyo: Consultancy, Honoraria; Kyowa-Kirin: Consultancy, Honoraria; Kyowa-Kirin: Consultancy, Honoraria; Merck Sharp Dohme: Consultancy, Honoraria; Genzyme: Consultancy, Honoraria; Genzyme: Consultancy, Honoraria; Pfizer: Consultancy, Honoraria; Merck Sharp Dohme: Consultancy, Honoraria; Protalix: Consultancy, Honoraria; Rigel: Consultancy, Honoraria, Research Funding; Rigel: Consultancy, Honoraria, Research Funding; Sanofi: Consultancy, Honoraria; Sanofi: Consultancy, Honoraria; Bristol Myers Squibb (BMS): Consultancy, Honoraria, Research Funding; Alnylam: Consultancy, Honoraria, Research Funding; Daiichi Sankyo: Consultancy, Honoraria; Protalex: Consultancy, Honoraria, Research Funding; Dova: Consultancy, Honoraria; Protalex: Consultancy, Honoraria, Research Funding; Amgen: Consultancy, Honoraria, Research Funding; Up-to-Date: Consultancy, Honoraria, Patents & Royalties: 3 Up-to-Date chapters; Up-to-Date: Consultancy, Honoraria, Patents & Royalties: 3 Up-to-Date chapters; Zafgen: Consultancy, Honoraria; Takeda (Bioverativ): Consultancy, Honoraria, Research Funding; Platelet Disorder Support Association: Consultancy, Honoraria; Shinogi: Consultancy, Honoraria; Agios: Consultancy, Honoraria, Research Funding; Actelion (Syntimmune): Consultancy, Honoraria, Research Funding; Takeda (Bioverativ): Consultancy, Honoraria, Research Funding; Caremark: Consultancy, Honoraria; Kezar: Research Funding; Kezar: Research Funding; Shire: Consultancy, Honoraria; Argenx: Consultancy, Honoraria, Research Funding; Alnylam: Consultancy, Honoraria, Research Funding; Agios: Consultancy, Honoraria, Research Funding; Bristol Myers Squibb (BMS): Consultancy, Honoraria, Research Funding; Argenx: Consultancy, Honoraria, Research Funding; Novartis: Consultancy, Honoraria; Actelion (Syntimmune): Consultancy, Honoraria, Research Funding; Shinogi: Consultancy, Honoraria; Zafgen: Consultancy, Honoraria; Momenta: Consultancy, Honoraria; UCB: Consultancy, Honoraria.