Lack of effect of oral 4-phenylbutyrate on serum alpha-1-antitrypsin in patients with α-1-antitrypsin deficiency:: A preliminary study

Objective: In homozygotes with ZZ genotype alpha-1-antitrypsin (alpha1AT) deficiency, mutant alpha1ATZ protein (alpha1ATZ) accumulates in hepatocytes, rather than being secreted into the blood. Homozygous individuals experience emphysema as a result of reduced levels of circulating alpha1AT in the lung with which to inhibit connective tissue breakdown. Homozygotes may also experience liver disease from the accumulation of alpha1ATZ within hepatocytes, which causes liver damage. A previous study indicated that the compound 4-phenylbutyrate (4-PBA) mediated a significant increase in release of alpha1ATZ from cells in tissue culture and in a mouse model of alpha1AT deficiency. The authors hypothesized that 4-PBA could be used to treat both the liver and lung disease of humans with alpha1AT deficiency. Methods: In this preliminary, open label study the authors evaluated the effect of 14 days of oral 4-PBA therapy on alpha1AT blood levels in 10 patients with alpha1AT deficiency. Results: There was no significant increase in alpha1AT blood level associated with 4-PBA administration. Symptomatic and metabolic side effects were significant. Conclusion: 4-PBA did not increase alpha1AT blood levels in humans with alpha1AT deficiency in this preliminary trial.