Sogroya ISS Opinion: Regulatory First-Mover Secured, EU Payer Pathway Uncharted

CHMP Recommends Once-Weekly Sogroya for Idiopathic Short Stature in EU

Novo Nordisk has received a positive opinion from the Committee for Medicinal Products for Human Use (CHMP) of the European Medicines Agency (EMA) for once-weekly Sogroya® (somapacitan) for children in Europe with idiopathic short stature (ISS) with persistent growth disturbance. If approved by the European Commission, Sogroya would be the first and only growth hormone treatment for ISS in the EU, a condition affecting up to 3% of children worldwide. This recommendation follows previous positive CHMP opinions for Sogroya in children born Small for Gestational Age (SGA) and with Noonan Syndrome (NS) in May 2026. The European Commission's decision on marketing authorisation, covering all three indications, is expected later this year, supported by Phase 3 REAL8 clinical trial data demonstrating non-inferiority to once-daily growth hormone treatment.

• The positive CHMP opinion for Sogroya in idiopathic short stature (ISS) marks a significant regulatory milestone for Novo Nordisk. If approved by the European Commission, Sogroya would become the first and only once-weekly growth hormone treatment specifically for ISS in the EU. This addresses a critical unmet need, as ISS affects up to 3% of children worldwide and currently has limited approved treatment options, potentially transforming care for affected children and their families.
• The CHMP's recommendation is supported by robust data from the Phase 3 REAL8 clinical trial. This study demonstrated that once-weekly Sogroya (somapacitan) was non-inferior to once-daily growth hormone treatment in achieving mean annualised height velocity at Week 52 in children with idiopathic short stature, as well as those born small for gestational age and with Noonan Syndrome. This clinical evidence underscores Sogroya's efficacy and convenience as a long-acting growth hormone analogue.
• This positive opinion expands Sogroya's potential utility, building on previous CHMP recommendations in May 2026 for short stature in children born Small for Gestational Age (SGA) and with Noonan Syndrome (NS). The anticipated marketing authorisation from the European Commission will cover all three indications, offering a comprehensive treatment solution for various growth disorders. This multi-indication approval highlights Novo Nordisk's commitment to addressing diverse paediatric growth challenges and improving patient quality of life.

Addressing the Unmet Needs in Pediatric Idiopathic Short Stature

Despite established therapeutic options, managing ISS with persistent growth disturbance remains complex, with efficacy constrained by biological, pharmacological, and safety-related factors that limit the extent of achievable height gain across patient subgroups.

• Bone age acceleration limits the therapeutic window. The relentless tempo of bone age advancement driven by sex steroids — particularly estrogen, which principally modulates epiphyseal fusion in both females and males — significantly hinders the impact of GH therapy by restricting the time available for growth.

• Predictive models explain only a fraction of height outcome variability. In GH-treated children with ISS, adult height correlates positively with height at GH start, mid-parental height, and first-year GH responsiveness, and negatively with age — yet this model explains only 64% (R² = 0.64) of the variance in adult height, with the first-year prediction model accounting for just 39% (error SD 1.2 cm) of variability in height gain.

• Peak stimulated GH levels are a poor predictor of treatment response. The correlation between peak stimulated GH and first-year height velocity is small (r = −0.12) and not clinically relevant in defining GH resistance; no GH cut-off level could be determined to enhance the usefulness of this measure. Baseline age was the only clinically significant predictor, with an R-squared of 6.4%.

• Dose escalation raises safety concerns. At dosages ≥ 0.3 mg/kg/week, a dose-dependent increase in mean fasting and stimulated insulin levels is observed. A continuing trend toward dose escalation to achieve greater height-promoting effects raises concerns about the possibility of delayed post-treatment effects of hyperinsulinemia and heightened GH and insulin-like growth factor I exposure on cancer risk, warranting caution and ongoing scrutiny of risks versus benefits.

• Adjunct therapies carry their own limitations and unresolved safety signals. Two years of letrozole therapy did not increase predicted adult height in pre- and peripubertal boys with ISS when re-assessed 4 years after the treatment period, and letrozole-treated boys were noted to have more vertebral abnormalities than a placebo group. GnRHa use renders adolescents temporarily hypogonadal at a critical time in development, and both GnRHa and aromatase inhibitor treatment to delay puberty remain controversial, with augmentation of adult height more likely only when combined with rhGH in children already receiving rhGH.

• Adherence to daily injection regimens remains suboptimal. Treatment adherence with daily rhGH is suboptimal owing to the burden of daily injections, and long-acting formulations introduce their own adverse event profile — including localized lipoatrophy, observed in 14.5% of patients receiving daily rhGH and also reported with long-acting preparations — underscoring the need for vigilant monitoring and proper injection site rotation.

Sogroya's Potential to Redefine ISS Treatment in Europe

Recombinant human growth hormone (rhGH) is the established pharmacological intervention for idiopathic short stature (ISS) with persistent growth disturbance. Daily subcutaneous administration of somatropin at 0.05 mg/kg/day over 52 weeks has demonstrated statistically significant improvements across key growth endpoints, including height standard deviation score (HT-SDS), height velocity, and IGF-1 SDS, relative to untreated controls. At dosages of 0.24–0.37 mg/kg/week, rhGH treatment does not adversely affect blood glucose levels, though a dose-dependent increase in mean fasting and stimulated insulin levels is observed at dosages ≥ 0.3 mg/kg/week. The frequencies of targeted adverse events — including scoliosis, slipped capital femoral epiphysis, intracranial hypertension, and pancreatitis — are similar to or lower than rates observed in other rhGH-treated conditions, supporting a favorable safety profile at approved dose ranges.

Emerging evidence supports once-weekly PEGylated rhGH (PEG-rhGH) as a clinically meaningful alternative to daily rhGH in prepubertal children with ISS. In a 2-year real-world retrospective cohort study, children receiving PEG-rhGH at 0.2–0.3 mg/kg weekly achieved height velocities of 10.59 ± 1.37 cm/year and 8.75 ± 0.86 cm/year in the first and second years, respectively — significantly greater than those receiving daily rhGH (9.80 ± 1.05 cm/year, P = 0.002, and 8.03 ± 0.89 cm/year, P < 0.001). Height SDS improvement at the end of year two was also superior in the PEG-rhGH group (1.65 ± 0.38 vs. 1.50 ± 0.36, P = 0.001), alongside markedly lower missed doses (0.75 ± 1.06 vs. 4.4 ± 2.0, P < 0.001), with no serious adverse events observed in either group.

Beyond monotherapy, combination strategies are under active clinical consideration. Gonadotropin-releasing hormone analogs (GnRHas) suppress physiologic puberty and, when combined with GH, can meaningfully increase height potential in both males and females, though they render adolescents temporarily hypogonadal during a critical developmental window. Aromatase inhibitors (AIs) represent a time-limited alternative — particularly in pubertal males — by blocking androgen-to-estrogen conversion to slow growth plate fusion while permitting normal virilization. However, a meta-analysis of combined GnRHa and rhGH therapy in girls with idiopathic central precocious puberty or early puberty found no statistically significant differences in final adult height SDS versus monotherapy or no treatment, with the overall analysis failing to indicate a benefit of combined therapy, though individual reports suggested potential benefit in specific instances. Diagnostic stratification also informs treatment selection: primary IGF-1 deficiency is identified in 28% of children with ISS, representing a distinct subpopulation whose management may warrant differentiated therapeutic approaches.

Unpacking the REAL8 Data Supporting Sogroya for ISS

Several controlled and observational trials have examined growth hormone therapy in children with idiopathic short stature (ISS), evaluating design parameters ranging from randomized controlled frameworks to real-world cohort studies. The trials span a range of populations, dosing regimens, and endpoints, with adult or final height standard deviation score (SDS) as the primary measure of efficacy.

Once-Weekly Somapacitan: A New Horizon for Pediatric Short Stature

The recent positive opinion from the CHMP for once-weekly Sogroya (somapacitan) marks a pivotal moment for children in Europe living with idiopathic short stature (ISS), Noonan Syndrome (NS), and those born Small for Gestational Age (SGA). This recommendation paves the way for Sogroya to become the first and only once-weekly growth hormone treatment specifically for ISS in the EU, addressing a significant unmet need for a condition affecting millions of children globally.

The core appeal of somapacitan lies in its once-weekly administration, a substantial improvement over the daily injections that have long been the standard. This reduced treatment burden is not merely a convenience; it is a critical factor in improving patient adherence and, consequently, the overall effectiveness of therapy. For families managing chronic conditions like short stature, simplifying the regimen can profoundly enhance their quality of life.

Clinical evidence from the Phase 3 REAL8 program underpins this optimism. In children with ISS, somapacitan demonstrated non-inferiority to daily growth hormone, achieving comparable height velocity. Even more compelling, the trial showed superiority for somapacitan in children with Noonan Syndrome, alongside a similar safety profile to daily GH across all studied indications, including Turner syndrome where non-inferiority was also confirmed. This robust clinical profile positions somapacitan as a highly effective and well-tolerated option.

However, the path forward is not without considerations. While somapacitan offers a clear advantage in dosing frequency, the broader landscape of long-acting growth hormone therapies is becoming increasingly competitive. Other LAGH products are already approved for different pediatric growth disorders, meaning Novo Nordisk will need to clearly articulate somapacitan's unique benefits and clinical differentiation. Furthermore, while the 52-week data are strong, the long-term real-world effectiveness and safety data, particularly regarding final adult height and rare adverse events, will be vital for solidifying its position and building sustained confidence among clinicians and patients. This approval, if finalized, represents a significant step towards more patient-friendly and effective growth hormone therapy, but ongoing data generation and strategic positioning will be key to its long-term success.