If approved, BridgeBio Pharma’s BBP-418—which, according to one Jefferies analyst, boasts “pretty darn compelling” data—would be the first therapy for limb-girdle muscular dystrophy. The FDA has an action date of Nov. 27.
As far as regulatory shots on goal go, BridgeBio Pharma has a fairly clear view to the back of the net for a potential November approval for its limb-girdle muscular dystrophy Type 2I/R9 (LGMD2I/R9) drug candidate. If approved, it would be the first disease-modifying therapy for this rare neuromuscular condition.
With an FDA action date slated for Nov. 27, propelled by priority review and no scheduled advisory committee meeting, BridgeBio leadership and advisors alike are confident that the FDA will give the go-ahead due to compelling evidence and unmet medical need.
“This is a profound opportunity to change the course of disease,” Christine Siu, CEO of BridgeBio’s neuromuscular division, told BioSpace, “since our drug demonstrated meaningful improvements in both the ability to walk faster and breathe better.”
Siu explained that patients with the chronic progressive disease lose function over time, becoming wheelchair bound between their 20s and 40s, depending on the aggressiveness of their disease. The condition also causes cardiac and respiratory disease, which can be fatal, she said.
There are over 30 subtypes of limb girdle muscular dystrophy, according to Siu. LGMD2I/R9 is caused by a mutation in the fukutin-related protein (FKRP) gene that results in reduced levels of the encoded protein, impairing a cellular process called glycosylation and ultimately destabilizing and damaging muscles. An oral glycosylation substrate therapy, BBP-418 is designed to increase FKRP, which in turn leads to higher levels of glycosylated alpha-dystroglycan (αDG) , a common biomarker for the disease.
Jefferies analyst Andrew Tsai gave BBP-418 higher than 90% odds of approval by the FDA’s deadline, given results from the Phase 3 FORTIFY study, which enrolled 112 patients 12 to 60 years of age with LGMD2I/R9. FORTIFY met its primary interim analysis endpoint, demonstrating a statistically significant increase in glycosylated αDG in patients treated with the drug compared to “approximately no change” in the placebo group from baseline to three months, according to an October 2025 press release. BBP-418 also met the trial’s secondary endpoints, showing an increase in glycosylated αDG and a reduction in serum CK, a biomarker for muscle damage.
Exploratory data from the 12-month interim analysis last month suggest cardiac benefits as well, with 100% of patients treated with BBP-418 returning to normal range for the blood biomarker HS troponin I, an indicator of heart muscle injury.
Not only is BBP-418 slowing the decline of the disease, “you’re actually getting improvement,” Tsai said. “It feels pretty darn compelling.”
‘A real difference’
Presenting clear evidence of improvement means showing that treated patients deviate significantly from the natural history of the disease, Siu said—adding that BBP-418 has succeeded in this goal. The therapy led to a 31-second difference compared to placebo during a 100-meter time test—designed to measure the functional status of muscles involved in the respiratory system—after 12 months.
“That is a real difference for patients between being able to ambulate independently in the community versus being limited to the house,” Siu said. She told the story of one trial participant who was able to walk during her high school graduation, having previously been confined to a wheelchair. “Our drug can make the difference between walking across the stage and being pushed,” Siu said.
Tsai added that the lack of an advisory committee ahead of the FDA’s target date is probably a good thing.
“It’s likely the FDA doesn’t see something in the dataset to tease out, and that it may be straightforward to the agency because it is pretty convincing,” Tsai said, adding that a potential approval could bring BridgeBio to profitability by the fourth quarter of 2027.
The company is now focused on BBP-418’s launch—which would be its second. BridgeBio’s only commercial asset, the transthyretin amyloid cardiomyopathy (ATTR-CM) drug Attruby, found widespread success after its 2024 approval, and the company has built a similar market force to do the same for BBP-418 for patients with LGMD2I/R9.
“We’ve built out our commercial infrastructure. We have our sales force. We have our medical science liaisons, our field reimbursement managers, and they’re all trained and in the field already speaking with physicians,” Siu said. “Having identified the initial patients who have a genetically confirmed diagnosis, it’s a concentrated market for us at about 150 Muscular Dystrophy Association centers, and we’ve seen a very positive reaction.”
BridgeBio has identified more than 500 prospective patients in the U.S. while guiding toward potentially thousands more given adequate genetic testing and diagnosis. This could make the market opportunity greater than $1 billion annually at peak sales, Tsai said.
Beyond the beachhead, BridgeBio is looking to the horizon with more than 7,000 patients worldwide, approximately 3,000 of whom are in the U.S., with between 4,000 and 5,000 in Europe, specifically in Scandinavia where the causative FKRP mutation has genetic roots, Siu said. BBP-418 holds orphan drug designation from the European Medicines Agency.
Improving access
Pricing for rare disease drugs can be a sticking point, and Tsai noted BridgeBio’s “pricing power” as the potential owner of the first and only treatment in the space. The analyst modeled about $400,000 as an annual list price, “but people ultimately would not be surprised if it were priced at $1 million plus,” he said.
The company has not yet disclosed pricing, but Siu said she and her team are in active discussions with payers, whom market research has indicated are quite receptive to the functional data BridgeBio has shared, along with the unmet need.
Siu said she believes BBP-418 will be priced in line with or comparable to other rare neuromuscular drugs.
Payers will also likely require genetic testing in order to grant coverage, as BridgeBio did before a patient could be admitted to its Phase 3 trial, and Siu expects that to be included in the label. She does not, however, anticipate that it will be an issue.
“Based on the therapeutic hypothesis and the mechanism of disease, there are already two sponsored genetic tests that are broad neuromuscular panels, accessed for free, that can identify not only LGMD but also subtypes that can shorten the diagnostic journey,” she said.
Longer term, BridgeBio is looking to broaden BBP-418’s eventual label to other subtypes of LGMD, including autosomal recessive limb-girdle muscular dystrophy types 2M and 2U, as well as to pediatric patients under 12 with the 2I/R9 subtype.
Other players are also searching for disease-modifying treatments for limb-girdle muscular dystrophy. Industry pioneer Sarepta Therapeutics, which gained approval for the gene therapy Elevidys in 2023 for Duchenne muscular dystrophy, is developing its only remaining investigational gene therapy, SRP-9003, for LGMD2E/R4. In October 2025, the company reported results from a Phase 3 trial showing that SRP-9003 increased expression of the beta-sarcoglycan protein biomarker—a transmembrane protein involved in the αDG complex—by 23.9% among non-ambulatory patients and by 43.4% in those who were able to walk.
Bayer’s AskBio is another contender in the space, with its gene therapy AB-1003 targeting the same 2I/R9 subtype of LGMD as BridgeBio’s BBP-418. AB-1003 demonstrated an acceptable safety profile in a Phase 1/2 trial last October.
However, Tsai said, with a decision date just weeks away, BridgeBio sits comfortably in pole position.
