NNZ-2591Investigational compound
NNZ-2591 is an oral investigational compound related to cyclic glycine-proline and the IGF-1 signalling system. Researchers have explored it in rare neurodevelopmental syndromes.
What is NNZ-2591?
NNZ-2591 is an oral investigational compound related to cyclic glycine-proline and IGF-1 signalling. It has been explored in rare neurodevelopmental syndromes.
How it works
The development rationale concerns growth-factor signalling and communication within brain circuits. NNZ-2591 is a different compound from trofinetide.
Effects studied
Phelan–McDermid syndrome outcomes
An open-label study followed children and adolescents during treatment. Such observations can identify promising changes and tolerability issues but cannot cleanly separate drug effects from development, other support and expectations. A published correction accompanies the report. 1 2
Evidence: Early open-label clinical study
What does the evidence show?
The archived reading includes an open-label Phelan–McDermid syndrome study and its correction. Current trial recruitment and approval status have not been independently established for this draft.
Why this pathway attracted attention
IGF-1 is involved in growth and communication between cells. NNZ-2591 was developed around a small cyclic molecule connected to that system, with the aim of influencing signalling in brain circuits. It is not the same compound as trofinetide, even though the programmes share a broader biological theme.
The early human question
The retained Phelan–McDermid study followed children and adolescents during treatment. Studies of this kind can identify tolerability issues, help choose outcomes for a larger trial and reveal changes worth testing. The published correction needs to be read alongside the original report. 1 2
Why a comparison group matters
Development, day-to-day variation, concurrent support and expectations can all affect observations. When everyone receives the experimental treatment, those influences cannot be cleanly separated from a drug effect. A blinded comparison and prespecified outcomes are therefore particularly important before claiming broad improvement across abilities.
Keeping the syndromes separate
Phelan–McDermid, Angelman, Rett and Pitt–Hopkins syndromes are distinct diagnoses. A signal in one does not establish benefit in another. Families need results for the relevant condition, including side effects and treatment burden, before broad claims of neurological recovery can be assessed. Participation in research also does not establish routine availability.
Safety & status
Small early studies do not establish the long-term risk profile. Tolerability and treatment burden must be assessed separately for each syndrome and population.
Country and product status
This introduction describes the molecule and its research context. Product availability, approved indications and eligibility in Germany and Switzerland require a current local product check; they are not established by an overseas study or an online listing.
Frequently asked questions
Is it trofinetide under another name?
No. They are separate compounds with a related broader research theme.
Can results in one syndrome predict results in another?
Not reliably. Phelan–McDermid, Angelman, Rett and Pitt–Hopkins syndromes have distinct clinical features and require condition-specific evidence.
Sources
This entry was rewritten from our research archive. References below are reading leads unless a completed check is explicitly noted; a full independent evidence and regulatory review is still pending.
- NNZ-2591: paper 10.1212/NXG.0000000000200338 Research reference · Retained archive reference; not independently checked for this draft.
- NNZ-2591: paper 10.1212/NXG.0000000000200405 Research reference · Retained archive reference; not independently checked for this draft.
Research provenance
This name was discovered in the Superpower peptide index, archived 26 October 2026. Its ratings and reviewer attribution have not been adopted as our own. The archive informed this original editorial draft; independent source review is still pending.