Bimagrumab anti-ActRII antibody (150 mg vial)

In brief: ALTA PEPTIDES supplies Bimagrumab (Anti-activin type II receptor monoclonal antibody, BYM338) as a 150 mg vial of research-grade antibody for £17,999.00 (£119.99/mg), with the certificate for the current lot pending publication, held in UK stock and dispatched the same working day before 1pm. Supplied for laboratory research only, not for human consumption.

New to Bimagrumab? Read our guide, Bimagrumab: what it is, the BELIEVE results, side effects, price and when it could reach the UK, for what it is, what the research covers and how it is handled.

What is bimagrumab?

Bimagrumab, formerly Novartis's BYM338, is a fully human monoclonal antibody that binds the activin type IIA and IIB receptors (ActRIIA and ActRIIB). Most myostatin inhibitors bind a single ligand; bimagrumab blocks the receptor, so it cuts off myostatin, activin A and related ligands at once. That breadth gives it a larger effect on body composition than the single-ligand antibodies. Eli Lilly acquired it when it bought Versanis Bio in 2023.

What the research covers

Novartis trials in inclusion body myositis and sarcopenia produced muscle gains without functional benefit. A 2021 phase 2 trial in 75 adults with type 2 diabetes and obesity then reported a 20.5% fall in fat mass with lean mass rising. In the 72-week BELIEVE trial in 507 adults, weight fell 10.8% on bimagrumab alone, 15.7% on semaglutide 2.4 mg and 22.1% on the high-level combination, with fat making up 100%, 71.8% and 92.8% of the loss. Reported adverse events included muscle spasms, diarrhoea and acne, with transient rises in ALT and lipase. Our bimagrumab article sets out the data.

Research-grade antibody, not the originator product

The vial is a research-grade antibody: a recombinant monoclonal antibody produced by a third-party manufacturer for laboratory use, not the originator company's product and not an approved biosimilar; the originator product is not sold outside clinical trials or prescription supply. It is supplied with the manufacturer's certificate of analysis for the lot, and identity and purity for an antibody are shown by methods such as SEC-HPLC and SDS-PAGE rather than the reversed-phase HPLC used for peptides. Check the certificate against the lot number on your vial before any work begins.

Bimagrumab price and buying in the UK

Bimagrumab price: £17,999 for a 150 mg vial, which is £120 per mg, including VAT, with free tracked UK delivery.

Bimagrumab is investigational and has no regulatory approval anywhere. It is not a licensed medicine in the UK and is not a controlled substance. %BRAND% supplies it strictly as a laboratory reagent for in-vitro research; it is not for human or veterinary use, and nothing on this page is guidance on using it in a person. At 150 mg per vial it is a specialist reagent priced accordingly; the stack discount does not apply to antibodies.

Bimagrumab price (UK)

Prices include VAT. Shipping is £4.95 by Royal Mail Tracked 48, free on orders over £75, and sealed items can be returned within 14 days. Ships from UK stock with the lot certificate for the vial you receive.

Quality and testing

Every lot of Bimagrumab is released with its certificate of analysis published on our certificates page against the lot number on the vial label. The certificate for the current lot is pending publication, and ALTA's own independent third-party test of the lot is pending; both are added to the certificates page as they arrive. Specification: Per lot certificate of analysis (identity, purity by SEC-HPLC or SDS-PAGE), supplied as research-grade monoclonal antibody, 150 mg per vial.

Handling a monoclonal antibody

Bimagrumab is a monoclonal antibody, a folded protein of roughly 150 kDa, and is far less robust than a small synthetic peptide. Keep the vial at the temperature stated on the manufacturer's label and certificate, protected from light, and avoid repeated freezing and thawing. Never shake or vortex: agitation and air-liquid interfaces cause antibodies to aggregate. Use low-protein-binding plasticware, work aseptically, and if the vial is supplied lyophilised, reconstitute it only with the diluent and volume given on the manufacturer's certificate (for antibodies this is normally sterile water, not bacteriostatic water), swirling gently until dissolved. Aliquot for single use rather than re-entering the vial. As stated on the manufacturer's label and certificate; antibodies are normally held at 2 to 8 °C, protected from light and not frozen. Do not shake.

Lot traceability

Every Bimagrumab vial carries a printed lot number and expiry. The same lot number appears on the certificate of analysis for that lot on our certificates page, which names who issued it (the manufacturer's QC laboratory for a batch certificate, or the outside laboratory for a third-party report) so it can be checked directly. ALTA's own independent test of each lot is published on the same row as it arrives. If the number on your vial does not match a certificate on our site, contact support before using it. Certificates are kept online for the life of the product plus two years.

Related products

Trevogrumab, Garetosmab, Apitegromab, and everything else in Myostatin Antibodies or the full range.

Related reading in the Journal

• Bimagrumab: what it is, the BELIEVE results, side effects, price and when it could reach the UKBimagrumab is a monoclonal antibody that blocks the activin type II receptors, owned by Eli Lilly since its 2023 purchase of Versanis. In the phase 2b BELIEVE trial with semaglutide it produced 22.1% weight loss at 72 weeks with 92.8% of it from fat, and on its own it lost fat while adding lean mass. Its history at Novartis, the tirzepatide trials, and a plain statement for anyone searching 'bimagrumab buy'.
• Myostatin inhibitors explained: the pathway, the antibodies and why muscle matters in GLP-1 weight lossA myostatin inhibitor is anything that blocks the signal telling muscle to stay small. Four monoclonal antibodies are now in trials alongside GLP-1 drugs to stop the muscle loss that comes with rapid weight loss. What the pathway is, what each antibody does, what came before, and why none of them is available outside a clinical trial.
• Apitegromab explained: the first approved muscle-protecting antibody, and what it means for weight lossApitegromab is Scholar Rock's antibody that stops the body's main muscle brake, myostatin, from switching on. It became the first drug of its kind ever approved, for the muscle-wasting disease SMA in the US in September 2026. In obesity it doesn't add weight loss: with tirzepatide, it made more of the weight lost come from fat and less from muscle. What it is, what the trials show, and whether you can get it.
• Muscle loss on GLP-1 peptides: what the DXA substudies say for semaglutide, tirzepatide and retatrutideIn the DXA substudies of their own trials, semaglutide lost 9.7% of lean body mass alongside 19.3% of fat, tirzepatide lost 10.9% of lean mass alongside 33.9% of fat, and retatrutide's lean share was reported as consistent with other treatments. Across trials, a quarter to a third of the weight lost on these drugs is lean tissue. The figures per drug, what lean mass is and is not, and the antibody trials built to change the ratio.
• Trevogrumab and garetosmab: the COURAGE results, side effects, and when they could be availableTrevogrumab (REGN1033) is Regeneron's fully human antibody against myostatin (GDF8). In the phase 2 COURAGE trial it prevented about half of the lean mass lost on semaglutide, and with garetosmab added it prevented more, at the cost of far more discontinuations and two deaths in the triplet arm. The figures, the safety record and where it stands.

Handling and buying guides: How to reconstitute peptides: a laboratory guide, How to store peptides, and how long lyophilised peptides last at room temperature, How to read a peptide certificate of analysis.

Handling and storage

As stated on the manufacturer's label and certificate; antibodies are normally held at 2 to 8 °C, protected from light and not frozen. Do not shake.