Thymosin alpha 1: past clinical experience and future promise.

Thymosin alpha 1, originally isolated as the compound responsible for reconstitution of immune function in thymectomized animal models, has enjoyed a wide-ranging clinical development program over the past decades, extending across multiple companies, indications, countries, and continents. This paper provides an overview of this complex picture. The extensive clinical studies began with small studies conducted with an impure mixture of peptides under the aegis of physician-sponsored INDs submitted to the US FDA, in subjects with primary immune deficiency such as DiGeorge syndrome. Subsequent studies ranged all the way to large phase-3 trials conducted with synthetically produced thymosin alpha 1 and hundreds of patients, in many countries including the United States, Italy, and China.