RF26 | PMON332 Safety and Efficacy of Treatment with Lonapegsomatropin in Children with Growth Hormone Deficiency at Week 130 in the enliGHten Trial

Background

Once-weekly lonapegsomatropin (TransCon hGH) is a long-acting prodrug of somatropin, recently approved for the treatment of pediatric growth hormone deficiency (GHD) by the US FDA. In the pivotal 52-week phase 3 heiGHt trial and the 26-week fliGHt trial, lonapegsomatropin demonstrated safety and efficacy in both treatment-naïve and treatment-experienced children with GHD.

Methods

Results are reported from Week 130 (data snapshot date: September 01, 2021) from the open-label extension trial enliGHten. Upon entry into enliGHten, all participants received lonapegsomatropin via vial/syringe, with subsequent switch to TransCon hGH Auto-Injector when available.

Results

A total of 298 participants (98% of parent trials) continued from the heiGHt or fliGHt trials into enliGHten. At Week 130, 36 participants had completed the trial and 248 participants remain enrolled. The height standard deviation score (SDS) mean (standard deviation [SD]) at Week 130 was -0.64 (0.85) compared with baseline value of -1.56 (0.88) at the start of enliGHten. Participants continued to approach the average parental height SDS mean (SD) of -0.39 (0.77). The annualized height velocity mean (SD) at Week 130 was 9.32 cm/year (0.45). Average IGF-1 SDS mean (SD) at Week 130 was 1.46 (1.18) compared with 0.52 (1.58) at enliGHten baseline. For the 36 participants who had completed the trial, 14 had reached bone age of >14 years (girls) or >16 years (boys), and 24 had completed the study based on investigator judgement that treatment for growth hormone deficiency was no longer necessary. The difference between mean (SD) height SDS at last visit and average parental height SDS was -0.05 (0.75) for the 36 completers, and 61.1% of these participants had met or exceeded the average parental height SDS. The mean (SD) total duration of hGH treatment for participants who completed the trial (including daily treatment and lonapegsomatropin) was 3.53 (0.88) years, and the mean (SD) duration of treatment with lonapegsomatropin was 2.20 (0.66). With continued lonapegsomatropin treatment, the AE profile remained consistent with what was observed in the parent trials, with no new safety signals.

Conclusions

Children and adolescents treated with lonapegsomatropin showed continued improvement of height SDS through their 3rd year of therapy. Lonapegsomatropin continued to demonstrate a safety profile comparable to that of daily somatropin therapy.

Presentation: Monday, June 13, 2022 12:30 p.m. - 12:35 p.m., Monday, June 13, 2022 12:30 p.m. - 2:30 p.m.

Efficacy and Safety of Weekly Somatrogon vs Daily Somatropin in Children With Growth Hormone Deficiency: A Phase 3 Study

CONTEXT

Somatrogon is a long-acting recombinant human growth hormone (rhGH) in development for once-weekly treatment of children with growth hormone deficiency (GHD).

OBJECTIVE

We aimed to compare the efficacy and safety of once-weekly somatrogon with once-daily somatropin in prepubertal children with GHD.

METHODS

In this 12-month, open-label, randomized, active-controlled, parallel-group, phase 3 study, participants were randomized 1:1 to receive once-weekly somatrogon (0.66 mg/kg/week) or once-daily somatropin (0.24 mg/kg/week) for 12 months. A total of 228 prepubertal children (boys aged 3-11 years, girls aged 3-10 years) with GHD, impaired height and height velocity (HV), and no prior rhGH treatment were randomized and 224 received ≥1 dose of study treatment (somatrogon: 109; somatropin: 115). The primary endpoint was annualized HV at month 12.

RESULTS

HV at month 12 was 10.10 cm/year for somatrogon-treated subjects and 9.78 cm/year for somatropin-treated subjects, with a treatment difference (somatrogon-somatropin) of 0.33 (95% CI: -0.24, 0.89). The lower bound of the 2-sided 95% CI was higher than the prespecified noninferiority margin (-1.8 cm/year), demonstrating noninferiority of once-weekly somatrogon vs daily somatropin. HV at month 6 and change in height standard deviation score at months 6 and 12 were similar between both treatment groups. Both treatments were well tolerated, with a similar percentage of subjects experiencing mild to moderate treatment-emergent adverse events in both groups (somatrogon: 78.9%, somatropin: 79.1%).

CONCLUSION

The efficacy of once-weekly somatrogon was noninferior to once-daily somatropin, with similar safety and tolerability profiles. (ClinicalTrials.gov no. NCT02968004).

Safety and Efficacy of Lonapegsomatropin in Children With Growth Hormone Deficiency: enliGHten Trial 2-Year Results

PURPOSE

The objectives of the ongoing, Phase 3, open-label extension trial enliGHten are to assess the long-term safety and efficacy of weekly administered long-acting growth hormone lonapegsomatropin in children with growth hormone deficiency.

METHODS

Eligible subjects completing a prior Phase 3 lonapegsomatropin parent trial (heiGHt or fliGHt) were invited to participate. All subjects were treated with lonapegsomatropin. Subjects in the United States switched to the TransCon hGH Auto-Injector when available. Endpoints were long-term safety, annualized height velocity, pharmacodynamics [insulin-like growth factor-1 SD score (SDS) values], and patient- and caregiver-reported assessments of convenience and tolerability.

RESULTS

Lonapegsomatropin treatment during enliGHten was associated with continued improvements in height SDS through week 104 in treatment-naïve subjects from the heiGHt trial (-2.89 to -1.37 for the lonapegsomatropin group; -3.0 to -1.52 for the daily somatropin group). Height SDS also continued to improve among switch subjects from the fliGHt trial (-1.42 at fliGHt baseline to -0.69 at week 78). After 104 weeks, the average bone age/chronological age ratio for each treatment group was 0.8 (0.1), showing only minimal advancement of bone age relative to chronological age with continued lonapegsomatropin treatment among heiGHt subjects. Fewer local tolerability reactions were reported with the TransCon hGH Auto-Injector compared with syringe/needle.

CONCLUSIONS

Treatment with lonapegsomatropin continued to be safe and well-tolerated, with no new safety signals identified. Children treated with once-weekly lonapegsomatropin showed continued improvement of height SDS through the second year of therapy without excess advancement of bone age.

Switch Data From the Open-Label Extension of the Pivotal Phase 3 Study of Once Weekly Somatrogon Compared to Daily Somatropin in Pediatric Patients With Growth Hormone Deficiency (pGHD)

Objectives: Somatrogon (hGH-CTP) is a long acting recombinant human growth hormone, consisting of the amino acid sequence of hGH and three copies of the carboxy-terminal peptide (CTP) of human chorionic gonadotropin (hCG) being developed as a once weekly treatment for children with pGHD. This report summarizes data from the first year of the optional open-label extension (OLE) of the pivotal phase 3 global trial (ClinicalTrials. gov: NCT02968004), comparing the efficacy and safety of children switched from Genotropin (rhGH; somatropin) to somatrogon (Geno/Soma) and children maintained on somatrogon (Soma/Soma).

Methods: During the main study, 224 children were randomized to receive either once weekly somatrogon (0.66 mg/kg, n=109) or once daily Genotropin (0.24 mg/kg/wk, n=115) for 12 months. Of these, 222 completed the 12-month main study, and 212 chose to enter the OLE study. By Sept 30, 2020, 161 children (including 76 Geno/Soma) had complete auxological data at month 12 of the OLE.

Results: At the end of the main study, mean height velocity and gain in height SDS for the somatrogon cohort were 10.10 cm/year and 0.92; for the Genotropin cohort these were 9.78 cm/year and 0.87. Baseline values for the OLE (Soma/Soma group and Geno/Soma group, respectively): height SDS was -1.95 and -1.84, BMI was 17.03 and 15.48 kg/m2 while bone age was 6.54 and 6.40 years. At month 12 (of the OLE), the mean height velocity and the change in height SDS was 8.04 cm/year and 0.41 (Soma/Soma group) and 8.21 cm/year and 0.47 (Geno/Soma group); BMI was 18.07 and 17.49 kg/m2 and bone age was 8.48 and 8.41 years. IGF-1 SDS values were 1.15, and 1.28, while the IGFBP-3 SDS were 0.29 and 0.42, respectively. Dose reductions were required in 16.3% and 20.4% of patients due to IGF-1 SDS >2. Pubertal status changed from Tanner 1 (at OLE baseline) for 13.6% of Soma/Soma patients and 14.6% of Geno/Soma patients. Mean glucose, HbA1c, thyroid function (free T4 and TSH) and cholesterol (total, LDL and HDL) values remained similar to baseline in both groups across the 12 months OLE. The majority of adverse events in both cohorts were mild to moderate (Soma/Soma 94.2%, Geno/Soma 93.5%) and there were no clinically concerning safety observations. During the first 12 months of the OLE six patients discontinued in the Geno/Soma group due to AEs vs zero in the Soma/Soma group.

Conclusions: Height velocities and change in height SDS in the OLE were similar between the Geno/Soma and Soma/Soma cohorts. The main phase of the global pivotal phase 3 trial demonstrated that somatrogon (hGH-CTP) given once weekly is non-inferior to Genotropin (hGH) while the OLE demonstrated that catch-up growth continued into the second year of treatment, with ‘switch’ from Genotropin to somatrogon non-inferior to somatrogon given for two years. Metabolic (glycemic, lipid and thyroid) parameters were similar between groups and not meaningfully different from the main study.

SAT-LB15 24-Month Efficacy and Safety of Once Weekly and Every Other Week Administration of GX-H9, Hybrid FC-Fused Long-Acting Human Growth Hormone: A Phase 2 Study in Children With Growth Hormone Deficiency

Objectives GX-H9 is a long-acting form of recombinant human GH under clinical development for both adults and children with GHD. In this report, 24-month efficacy and safety of once weekly and every other week (EOW) administration of GX-H9 were evaluated, in addition to Genotropin^® switch-ability to GX-H9 after 12-month of treatment. Methods Subjects were randomly assigned to receive either one of three doses of GX-H9 (0.8 mg/kg/week, 1.2 mg/kg/week or 2.4 mg/kg every other week) or 0.03 mg/kg/day of Genotropin^®. Treatment duration is 24-month for all patients in GX-H9 arms while patients in Genotropin^® arm were re-randomized to one of three doses of GX-H9 at the completion of the first 12-month of treatment. Doses of GX-H9 were adjusted throughout the treatment period whenever necessary, based on IGF-1 levels. Results Out of 56 randomized, 54 received either GX-H9 or Genotropin^®. Fifty subjects completed the 12-month treatment period. Of 50, 45 subjects completed the next 12-month, comprising 33 patients from GX-H9 and 12 patients who switched from Genotropin^®. First year/second year mean±SD annualized height velocity (aHV) for 0.8 mg/kg/week, 1.2 mg/kg/week or 2.4 mg/kg every other week of GX-H9 were 10.50±2.54/9.14±1.96, 11.76±1.96/9.88±1.92 and 11.03±2.92/9.72±1.90 cm/year, respectively. First year mean±SD aHV for Genotropin^® was 9.14±3.09 cm/year. Patients switched to one of the three doses of GX-H9 in the second year showed comparable aHV in the second year (8.73±2.69/7.60±0.90/9.13±1.07 cm/year for 0.8 mg/kg/week, 1.2 mg/kg/week and 2.4 mg/kg/EOW GX-H9, respectively). No significant slow-down of the growth was observed in the second year from patients who received GX-H9 throughout and patients who switched from Genotropin^®. Mean change in height SDS after 12 months/24 months of GX-H9 treatment throughout from baseline treatment improved continuously (+1.10/+1.61 and +1.31/+1.89 and +1.15/+1.69 for 0.8 mg/kg/week, 1.2 mg/kg/week and 2.4 mg/kg EOW GX-H9, respectively). First year mean change in height SDS for Genotropin^® was +0.92 SDS, and showed comparable improvement in height SDS after switching to GX-H9 weekly arms (+0.76 and +0.79 SDS for 0.8 mg/kg/week and 1.2 mg/kg/week, respectively). Most treatment-emergent adverse events were evaluated as unrelated to the study drug and were mild or moderate in severity. No new safety concerns were observed throughout 24 months of long-term GX-H9 treatment or after switching to GX-H9 from Genotropin^®.Conclusions Growth response and safety profile of GX-H9 in children with GHD is comparable to those of daily GH, achieving robust growth rates after 24-month treatment. Subjects switched from Genotropin^® in the second year, also showed substantial catch-up growth indicated by improvement in height SDS. GX-H9 has a unique potential to be a convenient long-term GH providing not only weekly but also twice-monthly treatment.

A Randomized Phase 2 Study of Long-Acting TransCon GH vs Daily GH in Childhood GH Deficiency

CONTEXT

TransCon Growth Hormone (GH) (Ascendis Pharma) is a long-acting recombinant sustained-release human GH prodrug in development for children with GH deficiency (GHD).

OBJECTIVE

To compare the pharmacokinetics, pharmacodynamics, safety, and efficacy of weekly TransCon GH to that of daily GH in prepubertal children with GHD.

DESIGN

Randomized, open-label, active-controlled study of three doses of weekly TransCon GH versus daily Genotropin (Pfizer).

SETTING

Thirty-eight centers in 14 European countries and Egypt.

PATIENTS

Prepubertal male and female treatment-naïve children with GHD (n = 53).

INTERVENTIONS

Subjects received one of three TransCon GH doses (0.14, 0.21, or 0.30 mg GH/kg/wk) or Genotropin 0.03 mg GH/kg/d for 26 weeks.

MAIN OUTCOME MEASURES

GH and insulinlike growth factor-1 (IGF-1) levels, growth, adverse events, and immunogenicity.

RESULTS

Both GH maximum concentration and area under the curve were similar following TransCon GH or Genotropin administration at comparable doses. A dose response was observed, with IGF-1 standard deviation scores increasing into the normal range for all three TransCon GH doses. Annualized mean height velocity for the three TransCon GH doses ranged from 11.9 cm to 13.9 cm, which was not statistically different from 11.6 cm for Genotropin. Adverse events were mild to moderate, and most were unrelated to the study drug. Injection site tolerance was good. One TransCon GH subject developed a low-titer, nonneutralizing antibody response to GH.

CONCLUSIONS

The results suggest that long-acting TransCon GH is comparable to daily Genotropin for GH (pharmacokinetics) and IGF-1 (pharmacodynamics) levels, safety, and efficacy and support advancement into phase 3 development.