December 15, 2020, by NCI Staff Drugs called TKIs are extremely effective in people with chronic myelogenous leukemia (CML), but can also cause side effects, including fatigue and depression. Credit: iStock For many people with chronic myelogenous leukemia (CML), the drug imatinib (Gleevec) changed a once-fatal blood cancer into a manageable disease and allowed them to live a nearly normal lifespan. Until recently, imatinib and related drugs for CML, known as tyrosine kinase inhibitors (TKIs), had to be taken every day for life, and the drugs can cause fatigue, depression, disrupted sleep, diarrhea, and other side effects. In 2018, based on results of two international studies, the Food and Drug Administration (FDA) approved an update to the recommended use of the TKI nilotinib (Tasigna) for CML. The update states that some people with CML who have been in remission for at least 3 years on nilotinib can safely stop taking the drug, although they must be closely monitored to make sure the cancer has not come back, or recurred.