Ascendis reports first infant data for once weekly TransCon CNP in achondroplasia

Ascendis Pharma has reported 52 week findings from the open label sentinel cohort of its Phase 2 reACHin trial, showing that once weekly TransCon CNP, also known as navepegritide, was associated with stable or improved foramen magnum stenosis and increased linear growth in infants with achondroplasia.

The data were presented at ESPE 2026, the annual meeting of the European Society for Paediatric Endocrinology, by Geneviève Baujat, MD, a clinical geneticist at Necker Enfants Malades Hospital in Paris.

The sentinel cohort included seven treatment naive infants with genetically confirmed achondroplasia who were aged from birth to under two years. Their mean age at enrolment was 11.7 months.

After 52 weeks of treatment, the Achondroplasia Foramen Magnum Score remained stable or improved in every child. The mean increase in the sagittal diameter of the foramen magnum was 3.15 mm, and no decompression surgeries were required during the treatment period.

TransCon CNP was also associated with improvements in growth. The mean change from baseline in achondroplasia specific supine length Z score was +0.42, while mean annualised growth velocity reached 9.9 cm per year.

Pharmacokinetic results were comparable with those previously observed in older children, supporting use of the 100 μg/kg/week dose in this younger population.

Safety findings were also encouraging. No injection site reactions were reported during the 52 week period, and there were no deaths, fractures, bone related safety events or cases of symptomatic hypotension.

Investigators did not consider any adverse events to be related to treatment. No adverse events resulted in treatment interruption, discontinuation or withdrawal from the study.

Baujat said the findings suggest that starting TransCon CNP early could help address both medical complications and growth limitations associated with achondroplasia. She highlighted the stabilization or improvement in foramen magnum stenosis as particularly important because narrowing in this area can cause serious compression of the brain stem and spinal cord.

The reACHin study is a pivotal Phase 2 randomised, placebo controlled trial assessing the safety, tolerability and efficacy of once weekly TransCon CNP in at least 66 treatment naive infants aged from birth to under two years with genetically confirmed achondroplasia.

The main double blinded part of the study is now fully enrolled. Participants receive either TransCon CNP at 100 μg/kg/week or placebo, followed by a 52 week open label extension.

The seven infant sentinel participants were enrolled before recruitment began for the double blinded portion of the trial. This initial group was used to evaluate safety and pharmacokinetics in the younger age population.

Susana Noval, Director of Fundación ALPE Acondroplasia in Spain, said achondroplasia can influence many aspects of a child’s health and quality of life beyond height alone. She described the initial infant safety and tolerability findings as encouraging and said the organisation would continue to follow the study as additional results become available.

Achondroplasia is a genetic skeletal condition that affects bone growth and can lead to a range of complications. Foramen magnum stenosis is among the most serious concerns in infants because narrowing at the base of the skull can compress the brain stem and spinal cord.

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Achondroplasia, ascendispharma, clinical trials, Endocrinology, Growth disorder, Navepegritide, paediatric, pharma news, rare disease