G-CSF biologic drugs (granulocyte-colony stimulating factors) were the sixth largest selling class of biological products, with total sales in 2005 estimated at $3.78 billion.

G-CSF is an haematopoietic growth factor that works by encouraging the bone marrow to produce more white blood cells.

A reduction in white blood cells, such as might occur as a result of chemotherapy, makes the body less able to fight infection.

In this situation, a G-CSF drug can be given to stimulate the bone marrow to produce new white cells, shortening the period during which a patient is at risk of developing a serious infection.

The leading G-CSF biologics at present are: