Sotatercept

Winrevair (sotatercept-csrk) for injection, 45 mg and 60 mg, was first approved by the FDA in March 2024 based on the Phase 3 STELLAR trial. On October 27, 2025 the FDA approved an updated indication based on the Phase 3 ZENITH trial: treatment of adults with pulmonary arterial hypertension (PAH, WHO Group 1) to improve exercise capacity and WHO functional class and to reduce the risk of clinical worsening events, including hospitalization for PAH, lung transplantation and death. It is a prescription biologic administered by subcutaneous injection every 3 weeks with mandatory hemoglobin and platelet monitoring; it is not a research chemical, supplement, or over-the-counter product.

Effective: October 2025

An anti-activin type II receptor antibody that promotes fat loss while preserving lean muscle mass, studied in combination with GLP-1 agonists for obesity.

A novel myostatin-activin pathway inhibitor targeting fat reduction and lean mass gain, with Phase 2 results in obesity expected H2 2026.

A once-daily subcutaneous peptide (a 39-amino-acid analog of C-type natriuretic peptide, CNP) that is the first approved medicine to increase linear growth in children with achondroplasia. Marketed by BioMarin as Voxzogo, it works one step downstream of the overactive FGFR3 receptor that causes achondroplasia: by binding natriuretic peptide receptor-B (NPR-B), it dampens FGFR3's braking signal on the growth plate and lets cartilage cells proliferate and mature normally. First FDA-approved in November 2021 for children 5 and older with open growth plates, its label was expanded in 2023 to cover children under 5 (all ages with open growth plates). In 2026 BioMarin reported new long-term and early-treatment data and advanced a once-weekly successor CNP peptide, BMN 333.

Apitegromab (SRK-015) is an investigational, fully human IgG4 monoclonal antibody developed by Scholar Rock that inhibits myostatin - the muscle-produced growth factor that limits skeletal-muscle mass - through a novel, muscle-selective mechanism. Rather than neutralizing mature, active myostatin (the approach of earlier failed inhibitors), apitegromab binds only the inactive precursor forms of the protein - promyostatin and latent myostatin - stored locally in muscle, and blocks their proteolytic conversion into the active ligand. Because it spares the closely related growth factors activin A, BMP9/10, and TGF-beta1, it aims to avoid the off-target effects (such as bleeding and vascular changes) that sank broad ActRII-pathway drugs. Apitegromab is the first muscle-targeted therapy to succeed in a pivotal Phase 3 trial in spinal muscular atrophy (SMA): in the 156-patient SAPPHIRE study of nonambulatory Type 2/3 patients aged 2-12 already on an SMN-directed therapy (nusinersen or risdiplam), adding apitegromab (10 or 20 mg/kg IV every 4 weeks) improved motor function by a pooled 1.8 points on the Hammersmith Functional Motor Scale Expanded (HFMSE) versus placebo at 12 months (p=0.019). Scholar Rock's initial Biologics License Application received an FDA Complete Response Letter in September 2025 tied solely to a third-party (Catalent Indiana) fill-finish manufacturing inspection - not to the drug's efficacy or safety - and the company resubmitted the BLA on March 31, 2026, with a PDUFA target action date of September 30, 2026. In parallel, apitegromab produced positive Phase 2 obesity data (EMBRAZE): added to tirzepatide over 24 weeks it preserved about 55% more lean mass (roughly 1.9 kg / 4.2 lb) than tirzepatide alone, positioning myostatin inhibition as a potential lean-mass-sparing partner for GLP-1-based weight loss.

Trevogrumab (REGN1033) is an investigational fully human anti-myostatin (anti-GDF8) monoclonal antibody from Regeneron being tested as a lean-mass-sparing add-on to semaglutide in the Phase 2 COURAGE obesity trial; adding it to semaglutide prevented roughly half of the ~33% of GLP-1-induced weight loss that normally comes from muscle, and the semaglutide + trevogrumab + garetosmab triplet reached 13.4% weight loss at 26 weeks with only ~7.4% of that loss from lean mass.

Garetosmab (REGN2477) is Regeneron's investigational fully human anti-activin A monoclonal antibody. In the Phase 3 OPTIMA trial in adults with the ultra-rare bone disease fibrodysplasia ossificans progressiva (FOP), it cut new heterotopic bone lesions by ~90-94% and reduced new-lesion volume by >99% versus placebo; its BLA was accepted for FDA Priority Review with an August 2026 target action date. The same activin A blockade also makes garetosmab the muscle-preserving partner to trevogrumab and semaglutide in the Phase 2 COURAGE obesity program.

Abaloparatide (Tymlos) is a synthetic 34-amino-acid analog of parathyroid hormone-related protein, PTHrP(1-34), engineered to bind the PTH1 receptor with a strong preference for its transient RG conformation rather than the long-lived R0 conformation favored by teriparatide. That receptor bias produces a shorter burst of signaling per injection - enough to drive osteoblast activity, but short enough to limit the bone resorption and calcium mobilization that follow a prolonged signal. In the 18-month Phase 3 ACTIVE trial in 2,463 postmenopausal women, abaloparatide 80 mcg daily reduced new morphometric vertebral fractures by 86% versus placebo, alongside significant reductions in nonvertebral, major osteoporotic and clinical fractures. The FDA approved Tymlos in April 2017; in December 2021 the osteosarcoma boxed warning and the two-year cumulative lifetime limit were both removed from the label.

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.

A first-in-class, once-monthly injectable antisense oligonucleotide (ASO) from Ionis and Novartis that lowers lipoprotein(a) [Lp(a)] by shutting down apolipoprotein(a) production in the liver. Its pivotal Lp(a)HORIZON trial (8,323 patients) is the first-ever cardiovascular outcomes trial for any Lp(a)-lowering drug, with a landmark topline readout due in 2026.