Safety of ⁹⁰Y-ibritumomab Tiuxetan Treatment for Japanese Patients in Real-world Clinical Practice

When undergoing ⁹⁰Y-ibritumomab tiuxetan (90Y-IT) treatment, patients are discharged from hospital soon after initiation of treatment and followed up as outpatients. Thus it is important to apprise patients of the safety information regarding 90Y-IT treatment. However, studies investigating the safety of 90Y-IT in real-world clinical practice are lacking. We sought to investigate the adverse events arising from 90Y-IT administration to patients in our hospital. Patients who received 90Y-IT treatment at Hiroshima University Hospital from April 2010 to December 2014 were eligible for this study. The medical records of the patients were reviewed retrospectively. Eleven patients (median age, 65 years) were enrolled. Patients were classified into 3 groups according to the number of prior regimens: 1, 2-3, or >3, consisting of 5, 4, and 2 patients, respectively. The number of patients with induced grade 3 and 4 hematotoxicity, respectively, was 5 and 0 for leukocytopenia, 3 and 2 for neutropenia, and 3 and 2 for thrombocytopenia. The median nadir time was 37 d for leukocytopenia, 37 d for neutropenia, 36 d for thrombocytopenia, and 43 d for anemia. Patients with 2 or more prior regimens tended to experience grade 3 or 4 hematotoxicity more frequently than those with 1 prior regimen. In conclusion, we showed that hematotoxicity is a major adverse event of 90Y-IT treatment and that the nadir time is later than that with conventional anticancer agents. Medical staff, including pharmacists, should direct attention to the initial symptoms of hematotoxicity, especially in those patients who have received several prior regimens.