Ascendis Pharma Reports Positive Week 52 Phase 2 COACH Trial Results For TransCon CNP And hGH In Achondroplasia

Ascendis Pharma has reported positive topline results from Week 52 of the COACH Phase 2 trial, the first study to evaluate a once-weekly combination of TransCon CNP (navepegritide) and TransCon hGH (lonapegsomatropin) in children with achondroplasia. The results showed durable improvements in growth while maintaining a favorable safety and tolerability profile. Beyond linear growth, the combination therapy also delivered meaningful benefits in body proportionality and arm span, reinforcing its potential to address broader disease manifestations.

“Once-weekly TransCon CNP, designed to provide continuous exposure to CNP, has demonstrated its potential to transform the treatment of achondroplasia, positioning it as a potential long-term foundation of care,” said Jan Møller Mikkelsen, President and Chief Executive Officer at Ascendis Pharma. “The Week 52 COACH Trial results show that combination therapy with TransCon CNP and TransCon hGH further unlocks the transformative potential in children with achondroplasia and may set new treatment standards with clinically meaningful improvements in growth, body proportionality, and arm span with a safety and tolerability profile essential for long-term use in children.”

The findings suggest that TransCon CNP could serve as a foundational therapy targeting the underlying biology of achondroplasia, with TransCon hGH providing complementary growth benefits. Safety outcomes with the combination were consistent with those seen for each therapy as monotherapy, with treatment generally well tolerated and adverse events mostly mild in nature.

“The COACH Trial has demonstrated unmatched improvements in growth and benefits beyond linear growth without compromising safety or tolerability compared to historical data,” said Dr. Ciara McDonnell, MD FRCPI, Consultant in Pediatric Endocrinology & Diabetes at Children's Health Ireland in Dublin. “Seeing the additive effects of these complementary once-weekly therapies, where TransCon CNP makes the growth plates receptive to the growth-promoting effects of TransCon hGH, suggests we may be entering an era where rational dual-agent regimens such as this become a new standard of care in achondroplasia and other growth disorders.”

COACH is an ongoing open-label Phase 2 proof-of-concept study evaluating once-weekly TransCon CNP at 100 µg/kg alongside once-weekly TransCon hGH starting at 0.30 mg/kg in children aged 2 to 11 years. The trial includes both treatment-naïve patients and children previously treated with TransCon CNP, reflecting a representative achondroplasia population. At 52 weeks, children across both cohorts achieved annualized growth velocities exceeding the 97th percentile of average-stature peers, with improvements in height Z-scores, body proportionality, and arm span, while bone age remained aligned with chronological age.

“The dwarfism community has long emphasized the importance of research that honors dwarf and disability pride while also deepening understanding of outcomes that matter most in achondroplasia,” said Michael Hughes, Chair of the Biotech Industry Liaison Committee at Little People of America. “Although the COACH findings are still early, it is encouraging to see meaningful improvements in arm span and body proportionality alongside changes in linear height, as these endpoints provide important context beyond height alone. Given the diversity of healthcare goals within the dwarfism community, data like these may help expand the range of options individuals and families consider as they weigh what matters most to them.”

TransCon CNP is currently under priority review by the U.S. FDA and the European Medicines Agency as a monotherapy for pediatric achondroplasia, with a U.S. regulatory decision expected in February 2026. TransCon hGH, marketed as SKYTROFA® for growth hormone deficiency, remains investigational in achondroplasia. Following these encouraging Phase 2 results, Ascendis has already engaged with the FDA in preparation for a Phase 3 trial of the combination therapy.