Complex sentence: Omalizumab, sold under the trade name Xolair, is a humanized antibody originally designed to reduce sensitivity to inhaled or ingested allergens, especially in the control of moderate to severe allergic asthma, which does not respond to high doses of corticosteroids.
Split into simpler sentences: Omalizumab, sold under the trade name Xolair, is a medication originally designed to reduce sensitivity to allergens. It has been used to try to control severe allergic asthma, which does not respond to high doses of corticosteroids.