Calico Life Sciences Announces Fosigotifator (ABBV-CLS-7262) Chosen for FDA START Pilot Program for Vanishing White Matter Disease

10 June 2024

Calico Life Sciences LLC, a biotechnology company co-founded by Alphabet and Arthur D. Levinson, Ph.D., has announced that their investigational drug fosigotifator has been accepted into the FDA's START Pilot Program. This program, initiated by the FDA's Center for Biologics Evaluation and Research (CBER) and Center for Drug Evaluation and Research (CDER), aims to accelerate the development of new treatments for rare diseases. Fosigotifator, developed in collaboration with AbbVie, is being evaluated as a potential treatment for Vanishing White Matter (VWM) disease.

Calico, expressed gratitude for fosigotifator's selection in the program, emphasizing its potential to address the needs of patients and families affected by VWM disease. He also commended the FDA for its dedication to advancing rare disease treatments.

VWM disease is an exceptionally rare progressive brain disorder affecting the white matter, caused by mutations in the eIF2B enzyme, critical for protein synthesis and the integrated stress response. This condition leads to degeneration of the brain's white matter, resulting in symptoms such as impaired motor function, cognitive decline, and seizures. Currently, there are no approved treatments for VWM disease.

Fosigotifator targets eIF2B to reduce the chronic activation of the stress response observed in VWM, as demonstrated in preclinical studies using a mouse model. These studies showed improvements in motor coordination.

Calico and AbbVie are currently conducting a Phase 1b/2 trial to evaluate fosigotifator's safety, tolerability, and pharmacokinetics in individuals with VWM disease. This trial represents the first human testing of an eIF2B activator for this condition. More information can be found under study NCT05757141 on

Additionally, fosigotifator is being investigated as a potential treatment for amyotrophic lateral sclerosis (ALS) in ongoing studies.

It's important to note that fosigotifator is still under investigation and has not been approved for use in any country.