Taldefgrobep alfa
An investigational treatment for Spinal Muscular Atrophy.
The same compound appears under different names depending on the context. Here is how to identify Taldefgrobep alfa wherever you encounter it, plus the key facts at a glance.
- Generic name
- Taldefgrobep alfa
- Development codes
- RO7239361, BHV-2000, BMS-986089
- Drug class
- Myostatin inhibitor
- Manufacturer
- Biohaven
- How it's taken
- Given as a weekly shot under the skin.
An investigational subcutaneous myostatin inhibitor from Biohaven designed as an add-on therapy to SMN-targeted treatments in spinal muscular atrophy (SMA). The pivotal Phase 3 RESILIENT trial missed its primary endpoint in November 2024, taldefgrobep alfa did not statistically separate from placebo on the overall MFM-32 change at Week 48, but prespecified subgroup analyses showed clinically meaningful improvements, particularly in the 87% Caucasian subgroup[2]. Biohaven is also testing taldefgrobep alfa in obesity; that Phase 2 study finished enrolling in early 2026, with topline results expected in the second half of 2026[1].
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How Taldefgrobep alfa works
Spinal muscular atrophy (SMA) is caused by the body not making enough of a protein called SMN. Without enough SMN, the motor nerve cells that tell muscles how to move slowly die, and the muscles they control get weaker and shrink over time. The SMN-restoring SMA drugs, Spinraza (nusinersen), Zolgensma and Itvisma (onasemnogene), and Evrysdi (risdiplam), all work by restoring SMN, which helps save the nerve cells.
These drugs don't do much for muscle that's already been lost. Taldefgrobep alfa is designed to help with that muscle side of the problem. The body naturally makes 2 proteins called myostatin and activin A that tell muscles to stop growing, useful for balance in a healthy body, but harmful when muscles are already weak.
Taldefgrobep is an engineered protein that sticks to myostatin and activin A in the bloodstream before they can reach muscle cells, freeing the muscles to grow and recover. The idea is that taldefgrobep works together with SMN drugs: one keeps the nerves alive, the other helps rebuild the muscles[5].
Mechanism: Anti-myostatin/activin receptor ligand trap, a fully human recombinant adnectin that binds and neutralizes myostatin and activin A, blocking muscle-wasting signals
Side effects and safety
Taldefgrobep was generally well tolerated in the main Phase 3 study. Biohaven reported no serious side effects related to the drug, and 97% of participants continued into the optional long-term extension[2].
Longer-term safety will continue to be tracked in the follow-up study.
This is not a complete list of side effects. Talk to your doctor or pharmacist about what to expect and when to seek medical attention.
Taking Taldefgrobep alfa
Given as a weekly shot under the skin. In the main Phase 3 study, SMA patients ages 4 to 21 got a dose once a week (calculated by body weight) in the arm, belly, or thigh, on top of their existing SMA medicine[4]. Once parents or caregivers are trained, the injection can be given at home.
Clinical trial results
The main Phase 3 study, called RESILIENT (NCT05337553), enrolled SMA patients ages 4 to 21 in 9 countries. Biohaven aimed for about 180, and ClinicalTrials.gov lists 269 enrolled[3][4]. Every patient stayed on their current SMA drug (Spinraza, Evrysdi, or prior Zolgensma) and was randomly assigned to add either taldefgrobep or a placebo injection each week for 48 weeks.
The main question was whether patients on taldefgrobep would improve more on a standard motor score called MFM-32, which measures things like sitting, standing, rolling, and arm use. In November 2024, Biohaven reported that across all patients in the study, taldefgrobep did not beat placebo by a statistically significant amount on that main score[2].
However, the drug did exactly what it was designed to do biologically, myostatin levels fell below detection in every patient who got it, and when researchers looked at smaller groups within the study, Caucasian patients (about 87% of the study) and certain other subgroups did show meaningful improvement[2]. In November 2024 Biohaven said it would discuss the full results with SMA experts and regulators, and its second quarter 2026 update gave no new SMA plan, only the obesity study[1]. ClinicalTrials.gov lists RESILIENT as active, not recruiting[4].
Main registered trial: NCT05337553 on ClinicalTrials.gov. Check it for the current status, sites and contacts before asking about enrollment.
Development history
Taldefgrobep was originally created by Bristol Myers Squibb under the code BMS-986089 and tested first in Duchenne muscular dystrophy, but that program was stopped. Biohaven then licensed the drug, renamed it BHV-2000, and decided to try it in SMA, where the goal of preserving muscle made sense alongside the newer SMN drugs. Biohaven started the Phase 3 RESILIENT trial in 2022 and finished enrolling patients in September 2023[3].
By September 2023 the FDA had given it Fast Track and Orphan Drug designations, which can speed up review[3]. After the November 2024 results showed the main goal wasn't met, Biohaven announced it would also test taldefgrobep in obesity, because blocking myostatin may help people keep their muscle while losing weight on newer drugs like GLP-1 medications[2].
Explore Spinal Muscular Atrophy trials
Other Spinal Muscular Atrophy treatments
The 3 approved SMA therapies, nusinersen (Spinraza, 2016), onasemnogene abeparvovec (Zolgensma, 2019 IV and Itvisma 2025 intrathecal), and risdiplam (Evrysdi, 2020), all work by restoring SMN protein, either by modulating SMN2 splicing or replacing the SMN1 gene. Together they have dramatically changed SMA outcomes, especially when started pre-symptomatically or in infancy.
What these therapies do not directly address is muscle that has already atrophied or motor neurons that have already been lost, which leaves residual disability most prominent in later-onset patients and those treated after symptom onset. Muscle-directed therapies are the next logical layer: taldefgrobep alfa (myostatin/activin-A neutralization, Biohaven, subcutaneous weekly) and apitegromab (anti-pro/latent myostatin, Scholar Rock, IV every 4 weeks, approved September 11, 2026 as Isembyld for SMA in patients 2 and older who are already on an SMN2-targeted treatment) both sit in this adjunctive muscle-preservation category.
Apitegromab's positive Phase 3 SAPPHIRE readout and subsequent approval set the evidentiary bar that taldefgrobep's subgroup-only RESILIENT result did not clear in the overall population, which is why taldefgrobep's near-term regulatory path in SMA is uncertain while apitegromab has moved to market.
Common questions about Taldefgrobep alfa
▸What is Taldefgrobep alfa?
An investigational subcutaneous myostatin inhibitor from Biohaven designed as an add-on therapy to SMN-targeted treatments in spinal muscular atrophy (SMA). The pivotal Phase 3 RESILIENT trial missed its primary endpoint in November 2024, taldefgrobep alfa did not statistically separate from placebo on the overall MFM-32 change at Week 48, but prespecified subgroup analyses showed clinically meaningful improvements, particularly in the 87% Caucasian subgroup[2]. Biohaven is also testing taldefgrobep alfa in obesity; that Phase 2 study finished enrolling in early 2026, with topline results expected in the second half of 2026[1].
▸How does Taldefgrobep alfa work?
Spinal muscular atrophy (SMA) is caused by the body not making enough of a protein called SMN. Without enough SMN, the motor nerve cells that tell muscles how to move slowly die, and the muscles they control get weaker and shrink over time. The SMN-restoring SMA drugs, Spinraza (nusinersen), Zolgensma and Itvisma (onasemnogene), and Evrysdi (risdiplam), all work by restoring SMN, which helps save the nerve cells.
These drugs don't do much for muscle that's already been lost. Taldefgrobep alfa is designed to help with that muscle side of the problem. The body naturally makes 2 proteins called myostatin and activin A that tell muscles to stop growing, useful for balance in a healthy body, but harmful when muscles are already weak.
Taldefgrobep is an engineered protein that sticks to myostatin and activin A in the bloodstream before they can reach muscle cells, freeing the muscles to grow and recover. The idea is that taldefgrobep works together with SMN drugs: one keeps the nerves alive, the other helps rebuild the muscles[5].
▸What are the side effects of Taldefgrobep alfa?
Taldefgrobep was generally well tolerated in the main Phase 3 study. Biohaven reported no serious side effects related to the drug, and 97% of participants continued into the optional long-term extension[2].
Longer-term safety will continue to be tracked in the follow-up study.
▸How is Taldefgrobep alfa taken?
Given as a weekly shot under the skin. In the main Phase 3 study, SMA patients ages 4 to 21 got a dose once a week (calculated by body weight) in the arm, belly, or thigh, on top of their existing SMA medicine[4]. Once parents or caregivers are trained, the injection can be given at home.
▸Is Taldefgrobep alfa FDA approved?
Taldefgrobep alfa is currently in trial failed clinical trials for Spinal Muscular Atrophy. It has not yet received FDA approval.
▸Did taldefgrobep alfa work in the RESILIENT trial or not?
It depends on which analysis you look at. On the prespecified primary endpoint, change from baseline in the 32-item Motor Function Measure (MFM-32) at Week 48 in the overall study population, taldefgrobep did not statistically separate from placebo. That is the result the FDA and payers will weight most heavily. However, the drug did demonstrate complete target engagement, reducing circulating myostatin to undetectable levels in all treated patients, and prespecified subgroup analyses did show statistically significant MFM-32 improvements in the Caucasian subgroup (the largest subgroup at roughly 87% of enrollment) and in several biomarker-defined subgroups. Positive subgroup analyses on a failed primary endpoint are hypothesis-generating, not approval-grade, which is why the regulatory path is now unclear.
▸What's the difference between taldefgrobep alfa and apitegromab?
Both are anti-myostatin biologics being developed as add-on therapies for SMA patients already on SMN-targeted treatment, but they differ in molecule class, target, and dosing. Taldefgrobep alfa is a fully human adnectin (a small engineered protein based on the fibronectin scaffold) that neutralizes both mature myostatin and activin A, given subcutaneously once weekly. Apitegromab (Scholar Rock) is a monoclonal antibody that selectively targets the pro-form and latent form of myostatin, sparing mature myostatin and activin A, given intravenously every 4 weeks. Apitegromab's Phase 3 SAPPHIRE trial met its primary endpoint and the drug was FDA-approved as Isembyld on September 11, 2026 for SMA patients 2 and older who are currently receiving an SMN2-targeted treatment, while taldefgrobep's RESILIENT trial missed its primary endpoint in November 2024. Every patient in SAPPHIRE was nonambulatory at baseline, even though the approved label does not restrict use by walking status. Which selectivity profile, broader (taldefgrobep) or pro/latent-specific (apitegromab), is clinically optimal remains an open question.
▸Will taldefgrobep alfa ever be approved for SMA?
The path is uncertain. A failed primary endpoint in a well-powered Phase 3 trial is a significant setback, and the FDA does not typically approve drugs based on post hoc subgroup analyses alone. Biohaven would likely need either (1) a second prospective trial enriched for the subgroups that responded, which is expensive and slow, or (2) a regulatory pathway that uses biomarker data, the open-label extension, and the subgroup analyses to support conditional approval, which the FDA has been reluctant to grant in this setting. In the meantime, Biohaven has expanded the taldefgrobep program into obesity, where myostatin inhibition is being explored as a way to preserve lean muscle mass during GLP-1-driven weight loss. Biohaven has not given an SMA timeline since November 2024, and its August 2026 update listed only the obesity study for taldefgrobep.
▸Can SMA patients currently access taldefgrobep alfa?
Outside of the RESILIENT open-label extension, which 97% of trial completers chose to enter, the drug is not broadly available. It is not FDA-approved, and Biohaven has not opened a general expanded-access program. Patients interested in muscle-directed add-on therapy for SMA should discuss apitegromab (Scholar Rock's recently approved anti-pro/latent-myostatin monoclonal antibody) with their neuromuscular specialist; that is currently the only approved muscle-directed adjunctive therapy for SMA.
Sources and references
Every factual claim on this page is drawn from the public sources listed below. Click any reference to open the original document.
- Biohaven (Investor Relations) · 2026-08-10. Biohaven Reports Second Quarter 2026 Financial Results and Recent Business Developments. https://ir.biohaven.com/news-releases/news-release-details/biohaven-reports-recent-business-developments-and-second-quarter
- Biohaven (Investor Relations) · November 2024. Biohaven Provides Update on Taldefgrobep Alfa Development Program for Spinal Muscular Atrophy and Obesity. https://ir.biohaven.com/news-releases/news-release-details/biohaven-provides-update-taldefgrobep-alfa-development-program
- Biohaven (Investor Relations) · September 2023. Biohaven Completes Enrollment in Pivotal Phase 3 Study of Taldefgrobep Alfa in Spinal Muscular Atrophy. https://ir.biohaven.com/news-releases/news-release-details/biohaven-completes-enrollment-pivotal-phase-3-study-taldefgrobep
- U.S. National Library of Medicine, ClinicalTrials.gov. A Study of Taldefgrobep Alfa (BMS-986089) in Participants With Spinal Muscular Atrophy. https://clinicaltrials.gov/study/NCT05337553
- NIH / National Library of Medicine. Taldefgrobep Alfa and the Phase 3 RESILIENT Trial in Spinal Muscular Atrophy. https://pubmed.ncbi.nlm.nih.gov/39408601/
- Cure SMA. Biohaven Provides Update on Taldefgrobep Alfa Development Program for Spinal Muscular Atrophy. https://www.curesma.org/biohaven-provides-update-on-taldefgrobep-alfa-development-program/