At last check Vertex shares were trading off 13% at $188.50. They closed regular Thursday trading up 1.5% at $216.77.
AATD is an inherited disorder. Cincinnati Children's Hospital says it is the most common genetic disease that leads to liver transplant in children.
Alpha-1 antitrypsin is a protein made by the liver and released into the bloodstream. This protein protects the lungs and allows them to work normally, the hospital says.
The deficiency occurs if not enough alpha-1-antitrypsin is available in the body. With the deficiency, the body makes an incorrect form of the protein.
The lack of the protein in the lungs leads to lung disease. The buildup of the abnormal protein in the liver leads to liver disease, the hospital explains.
Vertex said that a Phase 2 study focused on AATD patients with the PiZZ genotype. Three dosing groups participated. VX-864 was measured against placebo.
VX-864 met its primary endpoint and was well tolerated, the study went ahead with no interruptions due to adverse effects, and the drug's mechanism was proved to work.
But the "magnitude of the treatment effect observed [was] unlikely to translate into substantial clinical benefit," the company said.
The Boston company plans to continue research to develop treatments for AATD, using the information it gained from this study, Carmen Bozic, a physician who is executive vice president for global medicine development and medical affairs and chief medical officer at Vertex, said in the company statement.