Fosigotifator

Fosigotifator emerged from medicinal-chemistry efforts to improve upon ISRIB, the prototype eIF2B activator, whose poor aqueous solubility limited absorption. According to the published discovery account, intermediate analogues such as 2BAct improved solubility but showed cardiovascular liabilities in higher species; a prodrug strategy ultimately produced fosigotifator with substantially improved solubility and drug-like properties suitable for clinical study ^[1].

The integrated stress response is increasingly implicated in neurodegeneration, where chronic activation reduces protein synthesis and remodels the transcriptome. Restoring translation by activating eIF2B is hypothesized to protect stressed neurons ^[2]. Fosigotifator was investigated clinically in ALS; however, a 2025 review of the ISR field reported that the ALS trials of ABBV-CLS-7262, alongside the related eIF2B activator DNL343, did not meet their objectives, underscoring the context-dependent and complex nature of ISR modulation in disease ^[2].

The compound is not an approved drug and is available only for laboratory research. It is discussed here for its mechanistic interest as a well-characterized eIF2B activator rather than as a validated therapeutic.

Fosigotifator is a research compound and is not approved for human use outside of registered clinical trials; it is offered strictly for laboratory research (RUO) and is not a dietary supplement. Earlier compounds in this chemical series showed cardiovascular effects in animals, a liability the fosigotifator prodrug was designed to reduce ^[1]. Human safety data are limited to sponsor-conducted trials, and the ALS program did not demonstrate clinical benefit ^[2]. No self-administration is advised.

Fosigotifator was developed through a collaboration between AbbVie and Calico Life Sciences as part of a program to translate eIF2B activation, first demonstrated with the tool compound ISRIB, into a clinically viable oral agent. Iterative optimization of the cyclohexyl core and side chains, followed by a prodrug approach, yielded the clinical candidate, which entered trials for ALS in the early 2020s ^[1].

Within neuroscience, eIF2B activators are viewed as an intellectually compelling approach to neurodegeneration, and fosigotifator is regarded as a well-optimized clinical-stage example. Enthusiasm has been tempered by the reported 2025 failure of the ALS trials of ABBV-CLS-7262 and the related DNL343, which reinforced that ISR modulation is context dependent and not straightforwardly beneficial in ALS ^[2]. It has no standing as a consumer nootropic.