Xiamen Amoytop opens dosing in adult growth hormone deficiency PK study
The Phase 2 trial of long-acting Inpegsomatropin moves to recruiting, entering a Growth Hormone Receptor field where 14 direct comparators are already in clinical testing.
Executive Summary
- A Phase 2 trial of Xiamen Amoytop's long-acting growth hormone agonist Inpegsomatropin began recruiting adult patients, moving the study from planned to active status with its enrollment target unchanged.
- The trial extends a therapy already in late-stage testing for pediatric short stature into adult growth hormone deficiency, a second indication that would broaden the drug's addressable population if the safety and pharmacokinetic profile holds.
- The trial enters a growth hormone receptor field where more than a dozen direct comparators, including marketed pegylated somatropins and long-acting agonists from Novo Nordisk, Pfizer, and Ascendis Pharma, are already in clinical use or late-stage testing, so differentiation will rest on dosing interval and tolerability rather than a novel mechanism.
- With a primary completion date set roughly a year and a half out, the near-term signal to track is whether the trial keeps pace with that stated timeline as it works through pharmacokinetic, safety, and body-composition measures in adults.
The status change
NCT07551804 moved from Not yet recruiting to Recruiting on July 22, 2026, according to its registry update, with enrollment held flat at its original target of 36 adults. The trial, titled "Safety, Pharmacokinetic (PK) Profile and Efficacy of Inpegsomatropin Injection in Adults With Growth Hormone Deficiency," started dosing on June 10, 2026, and carries a primary completion date of December 31, 2027. It runs in China across six arms under a randomized, quadruple-masked, placebo-controlled design. NCT07551804Safety, Pharmacokinetic (PK) Profile and Efficacy of Inpegsomatropin Injection in Adults With Growth Hormone DeficiencyNCT07551804
Probability of SuccessBased on the AppliedXL Probability of Success model. For more information about the methodology, read the research here.
What the trial tests
The Phase 2 study is a safety and pharmacokinetic trial, not an efficacy-defining readout. Its 39 primary measures span immunogenicity (anti-drug antibodies and neutralizing antibodies), pharmacokinetic parameters (AUC, Cmax, half-life), and safety and tolerability endpoints including adverse events, vital signs, ECG intervals, bone mineral density, and body composition. That breadth is typical of an early adult dose-and-safety study designed to characterize the drug's pharmacokinetic profile and tolerability before a larger efficacy trial, rather than to establish a clinical benefit. NCT07551804Safety, Pharmacokinetic (PK) Profile and Efficacy of Inpegsomatropin Injection in Adults With Growth Hormone DeficiencyNCT07551804
Operational read
The enrollment target held at 36 with no change from the anticipated figure, which the operational model classifies as a typical, routine signal rather than a deviation. No protocol amendments beyond the status update, and no shift in the primary completion date, have registered since the trial's initial posting in April 2026. The trial's own history shows two events on record: its initial registration and this recruitment start, consistent with a stable early-stage program rather than one showing signs of operational strain. NCT07551804Safety, Pharmacokinetic (PK) Profile and Efficacy of Inpegsomatropin Injection in Adults With Growth Hormone DeficiencyNCT07551804
The competitive field
Inpegsomatropin is a pegylated, long-acting growth hormone receptor agonist, and the growth hormone deficiency and short stature space already carries a deep bench of similar mechanisms. The closest direct comparator is Changchun GeneScience Pharmaceutical Co., Ltd.'s PEG-Somatropin, a pegylated somatropin in Phase 4 testing for growth hormone deficiency. Other direct comparators sharing the same target and modality include Ascendis Pharma A/S's Lonapegsomatropin and Novo Nordisk A/S's Somapacitan, both in Phase 3 testing for short stature, and Pfizer's Somatrogon, in Phase 3 for growth hormone deficiency. Xiamen Amoytop itself already runs Inpegsomatropin in a Phase 3 short-stature trial, meaning this adult study extends an existing asset into a new population rather than introducing a new mechanism.
The field's shape
The growth hormone receptor x growth hormone deficiency class has accumulated 98 trials across 28 sponsors reaching as far as Phase 4, and 16 of 19 Phase 2 trials in this target-indication pair have completed against 3 terminations, an 16% termination rate. Field activity has declined sharply, with a 0.06 ratio of recent to older trials in the broader growth hormone receptor space, reflecting a mechanism class that matured decades ago rather than one still generating fresh clinical interest. Against that backdrop, the informative result from this study is less about proving the mechanism, which is already validated by multiple approved agents, and more about whether Inpegsomatropin's pharmacokinetic and safety profile in adults supports moving forward without a tolerability signal that would separate it unfavorably from the established long-acting comparators.
This analysis was produced using AI-assisted reporting systems, AppliedXL data, and official public records. These systems undergo editorial review, quality checks, and regular audits by human experts. Errors may still occur, as with any automated system. Always consult the linked primary sources. Read our AI Editorial Policy.