Larimar Therapeutics' Nomlabofusp Secured US FDA Breakthrough Therapy Designation for Friedreich's Ataxia

# FDA Grants Nomlabofusp Breakthrough Therapy Designation for Friedreich's Ataxia as Larimar Therapeutics Targets June BLA Filing Larimar Therapeutics, Inc. (Nasdaq: LRMR), a clinical-stage biotechnology company headquartered in Bala Cynwyd, Pennsylvania, [announced](https://www.globenewswire.com/news-release/2026/02/24/3243356/0/en/Larimar-Therapeutics-Announces-FDA-Breakthrough-Therapy-Designation-for-Nomlabofusp-in-FA-and-Reiterates-Planned-BLA-Submission-in-June-2026.html) on February 24, 2026, that the U.S. Food and Drug Administration (FDA) has granted Breakthrough Therapy Designation (BTD) to nomlabofusp, a recombinant frataxin (FXN) protein replacement therapy, for the treatment of adults and children with Friedreich's ataxia (FA). The nomlabofusp breakthrough therapy designation, coupled with alignment from a recent FDA meeting on the use of skin frataxin as a surrogate endpoint, positions Larimar Therapeutics to submit a Biologics License Application (BLA) seeking accelerated approval in June 2026, with a U.S. launch targeted for the first half of 2027. ## What the Designation Means for the Larimar Therapeutics Nomlabofusp BLA Timeline Breakthrough Therapy Designation is reserved for drugs intended to treat a serious condition where preliminary clinical evidence indicates the candidate may demonstrate substantial improvement over available treatments on one or more clinically relevant endpoints. The designation carries all procedural benefits of Fast Track Designation — including eligibility for Rolling Review and Priority Review, as well as more frequent meetings and written communication with the FDA — and adds intensive guidance on efficient drug development, along with organizational commitment involving senior FDA managers. For Larimar Therapeutics, the practical consequence is a compressed and more collaborative regulatory pathway. The company already holds Fast Track Designation, Orphan Drug Designation, and Rare Pediatric Disease Designation for nomlabofusp. The BTD adds a layer of FDA engagement that could prove relevant as the agency evaluates the adequacy of the safety database and the use of a surrogate endpoint — skin FXN levels — that has not previously served as a basis for approval in any disease. ## Clinical Data Underpinning the Nomlabofusp Friedreich Ataxia Program The BTD was granted on the basis of preliminary clinical data from Larimar's ongoing open-label (OL) study evaluating nomlabofusp in adult and pediatric patients with FA. The data submitted to the FDA showed that nomlabofusp increased skin frataxin to levels expected in asymptomatic carriers of the FXN gene expansion — individuals who carry one mutated allele but do not develop disease. Across four clinical outcome measures assessed after one year of treatment — modified Friedreich Ataxia Rating Scale (mFARS), FARS-Activities of Daily Living (ADL), 9-Hole Peg Test (9-HPT), and Modified Fatigue Impact Scale (MFIS) — the company reported consistent directional improvement relative to a matched reference group drawn from the Friedreich's Ataxia Clinical Outcomes Measure Study (FACOMS) natural history database. The open-label study design, lacking a concurrent placebo arm, is a limitation that the company and the FDA appear to be managing through exposure-response analyses and the natural history comparator. The FDA confirmed during a recent Support for Clinical Trials Advancing Rare Disease Therapeutics (START) pilot program meeting that the proposed statistical approach — linking nomlabofusp exposure to clinical outcomes and comparing treated patients against FACOMS-matched controls — is the type of analysis that could support a BLA submission. The agency also offered to provide advance review and comment on the statistical plan, a degree of proactive engagement consistent with the BTD framework. Topline data from the open-label study to support the Larimar Therapeutics nomlabofusp BLA are expected in Q2 2026. Separately, a pediatric pharmacokinetic run-in study ([NCT06681766](https://clinicaltrials.gov/study/NCT06681766)) is active, and the company has begun dosing adolescents. ## Friedreich's Ataxia Treatment Landscape and the Surrogate Endpoint Question Friedreich's ataxia is a progressive, autosomal recessive neurodegenerative disorder caused by a GAA trinucleotide repeat expansion in the FXN gene, leading to deficiency of the mitochondrial protein frataxin. The disease affects an estimated 5,000 individuals in the United States. Onset typically occurs in childhood or adolescence, and the clinical course involves progressive ataxia, cardiomyopathy, scoliosis, and, in many cases, diabetes. No therapy has been approved that restores frataxin or modifies the underlying biology of the disease. The only FDA-approved disease-targeted therapy is omaveloxolone (Skyclarys), a nuclear factor erythroid 2-related factor 2 (Nrf2) activator developed by Reata Pharmaceuticals and now marketed by Biogen, which received [approval in February 2023](https://app.allsci.com/article/W4367692703) based on the Phase II/III MOXIe trial. Omaveloxolone acts downstream of the frataxin deficit, modulating oxidative stress pathways rather than replacing the deficient protein. Its approval represented a first for Friedreich's ataxia treatment, but the mechanism does not address the root molecular cause. Nomlabofusp, by contrast, is a recombinant fusion protein designed to deliver functional frataxin intracellularly, targeting the proximal deficiency. The concept originated in academic research on TAT-frataxin fusion constructs at Indiana University School of Medicine. The program was developed by Chondrial Therapeutics, which was acquired in 2020 by the company then known as Zafgen, Inc., subsequently renamed Larimar Therapeutics. Larimar retains all development and commercialization rights and has not entered into any co-development or out-licensing partnerships. The use of skin frataxin as a surrogate endpoint is central to the accelerated approval strategy and is, by the FDA's own framing, a matter that will be evaluated at the time of BLA review. The biological rationale — that restoring frataxin in peripheral tissue correlates with improvements in mitochondrial function and clinical outcomes — is supported by decades of research on the [role of frataxin deficiency in FA pathophysiology](https://app.allsci.com/article/W2896552860), though no prior regulatory decision has validated tissue FXN as a registrational biomarker. ## Research context The competitive landscape for frataxin-directed therapy in FA is narrow. Beyond nomlabofusp, the only other frataxin-restoration modalities in clinical development are gene therapies. Lexeo Therapeutics is conducting a Phase I/II trial ([NCT05445323](https://clinicaltrials.gov/study/NCT05445323)) of LX2006, an AAVrh10-based gene therapy delivering the FXN transgene, though the program is focused on the cardiac manifestations of FA rather than the full multisystem disease. Lacerta Therapeutics, now part of the Astellas gene therapy portfolio, has pursued intrathecal AAV delivery for central nervous system frataxin expression, but remains in early clinical or Investigational New Drug (IND)-enabling stages. Several other approaches have faltered. Design Therapeutics discontinued its GeneTAC program (DT-216), which sought to derepress FXN transcription at the GAA repeat, after Phase I data showed insufficient target engagement. Minoryx Therapeutics' leriglitazone, a peroxisome proliferator-activated receptor gamma (PPARγ) agonist, failed the primary endpoint in its Phase III FRAMES trial. Retrotope's RT001, a deuterated polyunsaturated fatty acid designed to resist lipid peroxidation, produced inconclusive Phase I/II results and has not advanced. PTC Therapeutics' vatiquinone, a 15-lipoxygenase inhibitor evaluated in the Phase III [MOVE-FA trial](https://clinicaltrials.gov/study/NCT04577352), delivered mixed results on its mFARS primary endpoint, and its regulatory trajectory remains uncertain. Unlike omaveloxolone, which modulates a downstream antioxidant pathway, and unlike gene therapies that seek to restore endogenous FXN transcription, nomlabofusp delivers exogenous frataxin protein directly. This mechanistic distinction — protein replacement rather than transcriptional modulation or gene addition — differentiates it from every other clinical-stage program. Whether that distinction translates into a differentiated clinical profile will depend on the totality of data presented in the BLA and, ultimately, on the Phase III confirmatory study that Larimar plans to initiate across the United States, France, the United Kingdom, Canada, and Australia. Clinical trial applications for that study are currently under review in France and Canada, with a U.K. submission to follow. Screening is expected to begin in Q2 2026, with first patient dosing targeted for mid-2026. The FDA has confirmed that change from baseline in the Upright Stability Score (USS), a subscale of mFARS, is a reasonable primary endpoint for that trial. The Larimar Therapeutics FDA interaction history — spanning Orphan Drug, Rare Pediatric Disease, Fast Track, and now Breakthrough Therapy Designation, along with participation in the START pilot program — reflects a regulatory relationship that has deepened as the clinical dataset has matured. The question now is whether the data package, built on an open-label study with a natural history comparator and a surrogate endpoint without regulatory precedent, will meet the evidentiary threshold for accelerated approval when the BLA lands at the agency in June. --- Spot something wrong? [Report an issue with this article](https://newsgen-prod.reframedata.com/feedback/nomlabofusp-breakthrough-therapy-larimar)