Seattle Genetics hit by clinical holds in AML

Seattle Genetics Inc. (NASDAQ:SGEN) shed about $1.3 billion in market cap this week after FDA placed full and partial clinical holds on early stage trials of vadastuximab talirine (SGN-CD33A) to treat acute myelogenous leukemia. The company reported hepatotoxicity in six patients receiving the antibody drug conjugate (ADC) who had received allogeneic stem cell transplant before or after treatment. There were four deaths and "several" cases of veno-occlusive disease, the company said.

Seattle Genetics lost $9.09 (15%) to $52.77 during the week. It announced the news Tuesday before market hours...