FDA Grants Priority Review to Ascendis Pharma’s NDA for TransCon® CNP in Achondroplasia Treatment
Ascendis Pharma A/S a biopharmaceutical company focused on developing innovative therapies for patients with serious rare diseases, announced a significant regulatory milestone today. The U.S. Food and Drug Administration (FDA) has officially accepted the company’s New Drug Application (NDA) for TransCon® CNP (navepegritide), an investigational therapy intended for the treatment of children diagnosed with achondroplasia, the most common form of dwarfism. Importantly, the FDA granted priority review status to the application, signifying the agency’s recognition of the drug’s potential to address a serious condition where current treatment options remain limited.
As part of the priority review designation, the FDA has set a Prescription Drug User Fee Act (PDUFA) goal date of November 30, 2025. This is the date by which the agency aims to complete its evaluation of the application. The FDA also indicated that it does not currently plan to convene an advisory committee meeting to review the application, a decision that could reflect confidence in the data provided by Ascendis.
TransCon CNP is designed as a long-acting prodrug of C-type natriuretic peptide (CNP), formulated to deliver continuous exposure to active CNP throughout the body. It is administered via once-weekly subcutaneous injection, and its unique design enables sustained inhibition of the fibroblast growth factor receptor 3 (FGFR3) pathway, which is known to be overactive in individuals with achondroplasia. By targeting this biological pathway, the investigational therapy aims to address the underlying causes of many of the complications associated with the disorder—not just height growth, but also issues involving bone alignment, spinal dimensions, and muscle strength.
Achondroplasia: A Complex and Underserved Condition
Achondroplasia is a rare genetic bone growth disorder caused by mutations in the FGFR3 gene. It leads to disproportionate short stature and a range of health complications that can impact a child’s quality of life, including spinal stenosis, bowed legs, sleep apnea, recurrent ear infections, and delays in motor development. The condition occurs in approximately one in every 20,000 live births, affecting people of all ethnic backgrounds.
Despite its serious clinical implications, treatment options for achondroplasia remain limited. Currently, the primary FDA-approved pharmacological therapy is vosoritide (brand name Voxzogo®), developed by BioMarin, which has demonstrated efficacy in improving growth velocity. However, there remains a substantial unmet need for therapies that address the broader clinical spectrum of achondroplasia beyond growth metrics alone.
A New Era of Treatment Innovation
The FDA’s priority review of TransCon CNP is being viewed as a potentially transformative moment for the achondroplasia community. Advocacy leaders and medical professionals alike have welcomed the news, emphasizing the importance of addressing the medical complexities that children with achondroplasia face.
“Too many profound medical needs endure for people living with achondroplasia,” said Chandler Crews, Founder of The Chandler Project, a nonprofit organization dedicated to improving the lives of people with skeletal dysplasias. “Therapies that could address some of the underlying, serious complications of achondroplasia offer welcome potential to improve health outcomes beyond what currently approved therapies and interventions offer.”
The Chandler Project has been a vocal advocate for more holistic treatment approaches, especially therapies that can improve daily functionality, reduce the need for invasive surgeries, and support long-term health. Crews, who has lived experience with achondroplasia herself, is among a growing chorus of patient advocates pushing for treatments that focus not only on height but also on quality of life and mobility.
Clinical Evidence Supporting TransCon CNP
The NDA submission for TransCon CNP was supported by a robust clinical development program, including data from global, randomized, placebo-controlled Phase 2 and 3 trials. According to Ascendis Pharma, these trials demonstrated that TransCon CNP delivers consistent and sustained exposure to CNP, which translated into meaningful clinical benefits over the course of a 52-week treatment period.
“TransCon CNP is designed to provide sustained exposure to CNP, resulting in continuous inhibition of the FGFR3 pathway that is overactive in achondroplasia,” explained Dr. Janet Legare, Professor of Pediatrics at the University of Wisconsin School of Medicine and Public Health, who has served as an investigator in clinical trials evaluating the therapy. “In clinical trials, these pharmacological effects have been associated with improvements in lower limb alignment, spinal canal dimensions, muscle strength, and growth compared to placebo.”
Dr. Legare noted that while linear growth is an important metric, physicians treating children with achondroplasia are increasingly focused on functional outcomes that affect mobility, posture, and independence. “As a practicing physician, I am encouraged to see the FDA designating priority review for TransCon CNP as a potential new treatment option for children with achondroplasia,” she said.
A New Benchmark in Achondroplasia Research
The clinical data presented by Ascendis also mark a significant scientific advancement in the field of rare bone diseases. According to Dr. Aimee Shu, Executive Vice President of Endocrine & Rare Disease Medical Sciences and Chief Medical Officer at Ascendis Pharma, the TransCon CNP trials are the first in the field to show improvements beyond linear growth at the one-year mark.
“Our clinical trials of TransCon CNP are the first ever to demonstrate improvements beyond linear growth at 52 weeks compared to placebo,” Dr. Shu stated. “People living with achondroplasia and their physicians have expressed an urgent need for a meaningful treatment option to address the complications of achondroplasia. We look forward to working with the FDA during its review to make TransCon CNP available as quickly as possible.”
The company emphasized that it is actively preparing for potential commercial launch pending FDA approval, and it remains committed to engaging with patient advocacy groups, healthcare professionals, and insurers to ensure equitable access if TransCon CNP is approved.
As Ascendis Pharma awaits the FDA’s final decision later this year, the priority review designation signals that TransCon CNP may soon offer a novel, once-weekly treatment option capable of delivering multi-dimensional health benefits for children with achondroplasia. If approved, TransCon CNP could redefine the standard of care for a condition long underserved by traditional therapeutic development.
This regulatory milestone is also expected to further bolster Ascendis Pharma’s position in the rare disease space, reinforcing its commitment to developing targeted, disease-modifying therapies that address serious unmet needs. The company is concurrently advancing a pipeline that includes other endocrine and rare disease programs, all built upon its proprietary TransCon technology platform, which allows for the sustained and controlled release of active molecules.
For families affected by achondroplasia, physicians treating this condition, and the broader rare disease community, the FDA’s review of TransCon CNP represents more than just a potential drug approval—it symbolizes a continued shift toward treatments that address the full spectrum of disease burden, not just symptoms visible on a growth chart.
