Poster Presentation ESA-SRB-APEG-NZSE 2022

Efficacy of once-weekly somatrogon vs once-daily Genotropin in subjects stratified by peak stimulated growth hormone values (≤3, >3 to ≤6.7, and >6.7 ng/mL): post hoc analysis of the pivotal phase 3 trial (#449)

Moshe Phillip 1 , Cheri L Deal 2 , Lawrence A Silverman 3 , Robin Henocque 4 , Monica Nijher 5 , Michael P Wajnrajch 6 7 , Ronnie Wang 8 , Jose F Cara 6 , Roy Gomez 9
  1. Schneider Children’s Medical Center of Israel, Petah Tikva, and Sackler Faculty of Medicine, Tel-Aviv University, Tel-Aviv, Israel
  2. Centre de recherche CHU Ste-Justine, Université de Montréal, Montréal, Canada
  3. Goryeb Children’s Hospital, Morristown, NJ, USA
  4. Pfizer SAS (France), Paris, France
  5. Pfizer Ltd., Tadworth, UK
  6. Pfizer Inc, New York, NY, USA
  7. New York University Grossman School of Medicine, New York, NY, USA
  8. Pfizer Inc, Groton, CT, USA
  9. Pfizer Pte Ltd, Singapore

Somatrogon, a long-acting recombinant human growth hormone (GH), is approved in several countries as a once-weekly treatment for children with GH deficiency (GHD). The peak stimulated GH cut-off value for diagnosis of GHD varies according to country-specific guidelines. This post hoc subgroup analysis of the pivotal phase 3 study evaluated efficacy outcomes for subjects stratified by their baseline peak GH values: ≤3, >3 to ≤6.7, and >6.7 ng/mL.

The phase 3 study randomized 224 subjects (peak stimulated GH<10 ng/mL) 1:1 to receive either once-weekly somatrogon (0.66mg/kg/week) or once-daily Genotropin (0.24mg/kg/week) for 12 months. Randomization was stratified by peak GH level, age, and geographic region; the same stratification was used in this post-hoc analysis. Subjects were subdivided into 1 of 3 subgroups based on their peak GH values and then further stratified. The primary endpoint was height velocity (HV) at month 12.

There were 43, 92, and 89 subjects in the ≤3, >3–≤6.7, and >6.7 ng/mL groups, respectively. The least-squares mean HV at month 12 was similar between somatrogon- and Genotropin-treated subjects across all 3 peak GH subgroups (Table). This finding was consistent with the overall study population (peak GH <10 ng/mL), wherein mean HV at month 12 was 10.10 and 9.78 cm/year for somatrogon- and Genotropin-treated subjects, respectively, with a treatment difference of 0.33 favoring somatrogon. Efficacy results are presented below (Table). The increase in IGF-1 SDS from baseline to month 12 was higher in somatrogon-treated subjects compared with Genotropin-treated subjects across all 3 subgroups. Mean bone maturation at 12 months was similar between somatrogon- and Genotropin-treated subjects across all 3 subgroups.

This post-hoc analysis showed that somatrogon- and Genotropin-treated subjects had similar growth parameters. These findings are consistent with those from the overall study population, in which non-inferiority of once-weekly somatrogon to once-daily Genotropin was statistically demonstrated.

Clinicaltrials.gov:NCT02968004

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