Asthma is a disease of the lungs characterized by intense inflammation of the airways. Recent research has shown that the bright red cells, eosinophils cause much of the damage to the lungs in severe asthma.
Eosinophils are made in the bone marrow and travel throughout the body via the blood. The only known normal role for eosinophils is to kill invading parasites.
If the eosibophil could be prevented from entering the lung, or prevented from causing damage, asthma should be much less severe. Recently, a drug has been developed to do just that.
Eosinophils depend on a hormone called IL-5 for growth, development, and survival in tissues. Nucala is an antibody that binds to IL-5 and blocks the effects of IL-5 on eosinophils.
The drug is entered subcutaneously once a month.
Blocking IL-5 with Nucala reduces the risk of a flare of asthma by an average of about 50%. Nucala also reduces the need for systemic steroids by an average of about 50%.
This drug is approved for use in asthmatics 12 years of age and older, with severe asthma with a prominent role for eosinophils. This means having 150 or more eosinophils/mm3 in a blood sample.
Adverse effects of Nucala include rare allergic reactions to the drug, and injection site reactions (8%). There may be a slight increased risk of Herpes Zoster. There are no known adverse effects on pregnancy or during lactation, but there are few human data. In monkeys, no adverse effect were observed.