Batoclimab

Batoclimab is an investigational, unapproved anti-FcRn monoclonal antibody available only through clinical trials; it is not FDA-approved, not a dietary supplement, not a compounded product, and not a legitimate research chemical for personal use. Any 'batoclimab', 'IMVT-1401', 'RVT-1401' or 'HBM9161' offered by a research-chemical or peptide vendor is unverified, unsafe and should not be used. In the U.S. and Canada, Immunovant/Roivant have publicly stated they do NOT intend to file batoclimab for approval in myasthenia gravis or CIDP, redirecting the program to the next-generation FcRn antibody IMVT-1402; the FcRn mechanism itself is validated and marketed through the approved agents efgartigimod (Vyvgart), nipocalimab (Imaavy) and rozanolixizumab (Rystiggo). In China, Harbour BioMed filed batoclimab (HBM9161) with the NMPA for generalized myasthenia gravis (BLA accepted June 2023; resubmitted June 2024).

A self-administered, once-daily subcutaneous macrocyclic peptide that inhibits complement component 5 (C5), FDA- and EMA-approved for anti-AChR-positive generalized myasthenia gravis.

A first-in-class, intravenous immunomodulatory fusion peptide derived from histidyl-tRNA synthetase that selectively binds neuropilin-2 (NRP2) to dampen inflammation in the lung; in Phase 3 development for pulmonary sarcoidosis, an interstitial lung disease.

A PEGylated cyclic-peptide inhibitor of complement component 3 (C3) built from two compstatin (Cp05) peptide domains bridged by a 40-kDa PEG chain; marketed as Empaveli/Aspaveli (subcutaneous, for paroxysmal nocturnal hemoglobinuria and, since July 2025, C3 glomerulopathy and primary IC-MPGN) and Syfovre (intravitreal, for geographic atrophy in age-related macular degeneration). It is one of the few complement-targeting therapeutic peptides to reach the market.

Efgartigimod (efgartigimod alfa, brand names Vyvgart intravenous and Vyvgart Hytrulo subcutaneous) is a first-in-class antagonist of the neonatal Fc receptor (FcRn) developed by argenx as ARGX-113. It is not a small synthetic peptide but an engineered fragment of the human immunoglobulin G1 (IgG1) antibody - specifically the Fc portion that normally binds FcRn - modified with argenx's ABDEG technology to bind FcRn with much higher affinity than natural IgG at both neutral and acidic pH. FcRn is the salvage receptor that rescues circulating IgG from lysosomal degradation and recycles it back into the blood, giving antibodies their long half-life. By outcompeting endogenous IgG for FcRn, efgartigimod blocks that recycling and drives rapid clearance of IgG - including the pathogenic autoantibodies that cause many autoimmune diseases - typically lowering total IgG by roughly 60-70% within weeks, without reducing IgM, IgA, or albumin. It was the first FcRn blocker ever approved: FDA-approved in December 2021 (Vyvgart IV) for acetylcholine-receptor-antibody-positive generalized myasthenia gravis (gMG) on the strength of the Phase 3 ADAPT trial, followed by a subcutaneous co-formulation with recombinant hyaluronidase (Vyvgart Hytrulo) for gMG in 2023 and for chronic inflammatory demyelinating polyneuropathy (CIDP) in 2024. In May 2026 the FDA expanded the gMG label to all serotypes - including AChR-antibody-negative (seronegative) patients - based on the Phase 3 ADAPT SERON trial, making efgartigimod the first and only therapy approved across every gMG antibody subtype. It is being studied in a broad set of other IgG-driven autoimmune diseases, including primary immune thrombocytopenia, myositis, Sjogren's disease, bullous pemphigoid, and lupus nephritis.

Nipocalimab (brand name Imaavy, development code M281) is a fully human, aglycosylated, 'effectorless' IgG1 monoclonal antibody that blocks the neonatal Fc receptor (FcRn), developed by Johnson & Johnson (Janssen). Like efgartigimod it lowers circulating immunoglobulin G (IgG) - including the pathogenic autoantibodies that drive many autoimmune diseases - by occupying FcRn and preventing it from recycling IgG back into the blood, so unrescued IgG is routed to the lysosome and degraded, typically cutting total IgG by roughly 65-75% while sparing IgM, IgA, complement, and albumin. Unlike efgartigimod's engineered Fc fragment, nipocalimab is a full-length monoclonal antibody engineered to be aglycosylated and effectorless (it does not trigger ADCC or complement-dependent cytotoxicity), and it is dosed as a maintenance intravenous infusion for continuous IgG suppression rather than in short cycles. The FDA approved Imaavy on April 30, 2025 for generalized myasthenia gravis (gMG) in anti-AChR-antibody-positive and anti-MuSK-antibody-positive patients aged 12 and older - making it the first FcRn blocker approved for adolescents and the first to explicitly cover MuSK-positive disease - on the strength of the Phase 3 Vivacity-MG3 trial. It has since generated positive data across a striking breadth of IgG-mediated conditions: Sjogren's disease (Phase 2 DAHLIAS), rheumatoid arthritis, warm autoimmune hemolytic anemia (wAIHA), and - uniquely among FcRn blockers - maternal-fetal alloimmune disease, where it is being developed to treat hemolytic disease of the fetus and newborn (HDFN) by crossing the placenta to protect the fetus. In April 2026 the FDA granted Priority Review to nipocalimab for wAIHA, positioning it as a potential first approved therapy for that condition.

Rozanolixizumab (brand name Rystiggo, development code UCB7665) is a humanized IgG4 monoclonal antibody that blocks the neonatal Fc receptor (FcRn), developed by UCB. Like efgartigimod and nipocalimab it lowers circulating immunoglobulin G (IgG) - including the pathogenic autoantibodies that drive many autoimmune diseases - by binding FcRn and preventing it from recycling IgG back into the blood, so unrescued IgG is routed to the lysosome and degraded, typically cutting total IgG by roughly 70-80% while sparing IgM, IgA, complement, and albumin. Unlike efgartigimod's engineered Fc fragment, rozanolixizumab is a full-length humanized antibody, and unlike nipocalimab's intravenous infusion it is given as a rapid subcutaneous infusion (including via an on-body delivery device), typically in weekly cycles that are repeated based on clinical response rather than continuously. The FDA approved Rystiggo on June 27, 2023 for generalized myasthenia gravis (gMG) in adults who are anti-acetylcholine-receptor (AChR) antibody-positive or anti-muscle-specific-tyrosine-kinase (MuSK) antibody-positive - making it the first therapy ever approved to treat both of those gMG subtypes - on the strength of the Phase 3 MycarinG trial. It has since been studied across other IgG-mediated diseases, including chronic inflammatory demyelinating polyneuropathy (CIDP), where it did not show meaningful benefit and was not advanced to Phase 3, and myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD), primary immune thrombocytopenia (ITP), and other autoantibody conditions where development continues. The European Medicines Agency approved rozanolixizumab in January 2024 and the UK MHRA in March 2024.

IMVT-1402 (international nonproprietary name imeroprubart; originally HL161ANS) is Immunovant/Roivant's investigational, next-generation, fully human IgG1 monoclonal antibody that blocks the neonatal Fc receptor (FcRn). It is a re-engineered successor to batoclimab, built to keep batoclimab's deep IgG-lowering while removing that molecule's defining liability: because FcRn recycles serum albumin as well as IgG, first-generation FcRn blockers reproducibly lowered albumin and raised LDL cholesterol, and IMVT-1402 was specifically designed to spare albumin and lipids. Like the approved FcRn blockers efgartigimod, nipocalimab and rozanolixizumab it lowers circulating IgG - including pathogenic autoantibodies - but it is distinguished by two things: a low-volume subcutaneous autoinjector for at-home self-administration, and Phase 1 data showing 60-80% IgG reduction with no albumin drop and no LDL rise. It is now Immunovant's lead pipeline asset, advancing across roughly six autoimmune indications with potentially registrational Graves' disease and myasthenia gravis readouts expected in 2027.