Adverse effects of hydroxyurea used for the treatment of myeloproliferative neoplasms

Abstract

Background: Hydroxyurea is administered to control elevated blood counts in patients with myeloproliferative neoplasms (MPNs) to reduce the risk of thrombosis and mortality. We reviewed the side effects of hydroxyurea, development of secondary malignancies, and drug resistance observed in some patients.Current Concepts: The low incidences of malformed births, intrauterine deaths, and spontaneous abortions associated with hydroxyurea therapy suggest that adverse pregnancy and fetal effects are unlikely. However, animal studies have reported malformations; therefore, the use of hydroxyurea during pregnancy is not recommended. Low-grade adverse events associated with hydroxyurea therapy include gastrointestinal symptoms such as nausea, upper gastrointestinal discomfort, and diarrhea. These symptoms are usually resolved by dose adjustment or temporary discontinuation. Approximately 10% of patients with MPNs are resistant to hydroxyurea, and another 10% are unable to tolerate it owing to side effects. Drug intolerance and resistance are the most common causes of inadequate cytoreductive control in patients with MPNs. Second-line cytoreductive agents should be considered to overcome the high risk of thrombosis and poor survival. The evolution to secondary hematologic cancers is related to the duration of the disease, not hydroxyurea administration.Discussion and Conclusion: In pregnant patients accidentally exposed to hydroxyurea, the risk should be discussed with the patient to determine whether to continue the pregnancy. Hydroxyurea administration increases the risk of skin cancer but does not affect the incidence of other secondary hematologic or solid cancers. Ropeginterferon or Janus kinase (JAK) inhibitors, including ruxolitinib, are recommended as alternative treatments if the patient is intolerant or resistant to hydroxyurea, as this is associated with poorer survival.