Ascendis TransCon CNP sustains leg alignment gains at two years

Week 104 data from the ApproaCH trial show tibial-femoral angle continued improving in children with achondroplasia, with greater gains in those with preexisting leg

The Biotech Times Editorial Team By The Biotech Times Editorial Team
A bright office desk features a white monitor displaying a skeletal diagram of a human leg with measurements, alongside medical tools, scissors, and potted plants, all illuminated by natural light from large windows with white curtains.

Ascendis Pharma has presented two-year radiographic data from the completed ApproaCH pivotal trial, showing that its once-weekly prodrug TransCon CNP (navepegritide) produced continued improvements in lower extremity alignment in children with achondroplasia through Week 104, building on gains already reported at the one-year mark.

The data were presented by Leanne Ward, Professor of Paediatrics at the University of Ottawa and Children's Hospital of Eastern Ontario, at the 12th International Conference on Children's Bone Health in Montreal on 30 June 2026.

Trial data

In children who received TransCon CNP throughout the double-blind period, mean tibial-femoral angle (TFA) fell from 9.1 degrees at baseline to 7.7 degrees at Week 52 and 6.9 degrees at Week 104, a mean absolute change of 2.2 degrees over two years. The effect was more pronounced in the subgroup with preexisting genu varum, defined as a baseline TFA of 5 degrees or greater: in that group, mean TFA fell from 13.4 degrees to 9.6 degrees, a 3.8-degree improvement over the same period.

Children who crossed over from placebo to active treatment at Week 52 also showed benefit during the open-label extension, with TFA falling from 11.8 degrees at Week 52 to 10.1 degrees at Week 104. In the genu varum subgroup, the drop was steeper, from 18.7 degrees to 14.9 degrees, matching the 3.8-degree change seen in the continuous-treatment arm over 52 weeks of active dosing.

TFA Z-scores, which normalise the measurement against a reference population, followed a similar trajectory. The fibula-to-tibia length ratio remained stable in the overall population during the open-label extension, suggesting proportional rather than disproportionate growth of the lower leg.

On safety, the compound was described as generally well tolerated over two years. Injection-site reactions were all mild, there was no symptomatic hypotension, and no acceleration of bone age was observed. No participant discontinued treatment because of an adverse event.

Regulatory and market context

TransCon CNP received US Food and Drug Administration approval in February 2026 under the trade name YUVIWEL for increasing linear growth in paediatric patients aged two years and older with achondroplasia and open epiphyses. A Marketing Authorisation Application is under review at the European Medicines Agency, with a regulatory decision anticipated in the fourth quarter of 2026, which would open a significant European commercial opportunity for Ascendis.

Achondroplasia is estimated to affect more than 250,000 people worldwide. The condition is caused by overactive FGFR3 signalling and carries a range of complications beyond short stature, including spinal abnormalities, hearing deficits, sleep-disordered breathing, leg bowing, and chronic pain. BioMarin's vosoritide, a daily CNP analogue approved under the name Voxzogo, is the established comparator in this space. TransCon CNP's once-weekly dosing and the emerging skeletal-alignment data give Ascendis a differentiation argument, though longer-term outcomes data and head-to-head comparisons will be needed before payers and clinicians can make a definitive judgement on relative clinical benefit. The EMA decision in Q4 2026 will be the next material catalyst for the programme.

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