Trofinetide (NNZ-2566) is a drug developed by Neuren Pharmaceuticals that acts as an analogue of the neuropeptide (1-3) IGF-1, which is a simple tripeptide with sequence Gly-Pro-Glu formed by enzymatic cleavage of the growth factor IGF-1 within the brain. Trofinetide has anti-inflammatory properties and was originally developed as a potential treatment for stroke, but has subsequently been developed for other applications and is now in Phase II clinical trials against Fragile X syndrome and Rett syndrome.