Somatrogon
A long-acting recombinant GH fusion protein approved for pediatric GH deficiency, allowing once-weekly instead of daily injection. It fuses human GH to C-terminal peptide domains of hCG beta to extend half-life.
01 Overview
Somatrogon (brand Ngenla) is a long-acting growth hormone consisting of human GH fused to three copies of the C-terminal peptide of the beta subunit of hCG, which slows clearance and extends the half-life enough for weekly dosing. It was approved for pediatric GH deficiency in the EU, Canada, Japan and later the US.
Phase 3 trials showed non-inferior annual height velocity versus daily somatropin, with the convenience advantage of once-weekly injection. It is a well-characterised modern biologic.
02 Mechanism
Activates the GH receptor like native GH; the fused CTP domains prolong circulating half-life for weekly dosing.
03 Dosing
| Tier | Dose | Route | Notes |
|---|---|---|---|
| Pediatric GHD | 0.66 mg/kg/wk | SubQ | Once weekly, as studied in phase 3 pediatric trials. |
04 Effects
| Effect | Magnitude | Evidence | |
|---|---|---|---|
| Increased height velocityComparable annualised growth to daily somatropin in pediatric GHD. | ~10 cm/yr, non-inferior to daily GH | Clinical | |
| Reduced injection burdenWeekly dosing improved treatment burden versus daily GH. | 7 to 1 injections/week | Clinical |
05 Side effects
| Effect | Severity | Frequency | Evidence | Countermeasures |
|---|---|---|---|---|
| Injection-site reactionsLocal pain, redness or itching, somewhat more frequent than daily GH. | Mild | Common | Clinical | |
| Transient hyperglycaemiaGH-related mild glucose elevation. | Mild | Uncommon | Clinical |