Hypoxia, the deprivation of oxygen from living tissue, has been recognized as a serious problem since the beginnings of medical science. Practical and safe solutions to dealing with oxygen deprivation long proved elusive. But during the 20th century, technologies that restore oxygen through the transfusion of blood, or by improving tissue perfusion, have provided some of the success stories of modern medicine. However, there are many conditions of tissue hypoxia where blood transfusion isn't beneficial.

Allos Therapeutics is working to address that challenge with technology that aims to mimic the body's own internal response to blood loss and hypoxia. The approach uses a class of small molecules known as synthetic hemoglobin allosteric modifiers. These molecules decrease the chemical affinity for oxygen shown by hemoglobin, the molecular carrier of oxygen that is found in all red blood cells (RBCs). By making RBCs less "attached" to their oxygen, more is released to tissues.