This study aimed at identifying clinical factors for predicting hematologic toxicity after radioimmunotherapy with 90Y-ibritumomab tiuxetan or 131I-tositumomab in clinical practice. Methods: Hematologic data were available from 14 non-Hodgkin lymphoma patients treated with 90Y-ibritumomab tiuxetan and 18 who received 131I- tositumomab. The percentage baseline at nadir and 4 wk post nadir and the time to nadir were selected as the toxicity indicators for both platelets and neutrophils. Multiple linear regression analysis was performed to identify significant predictors (P < 0.05) of each indicator. Results: For both platelets and neutrophils, pooled and separate analyses of 90Y- ibritumomab tiuxetan and 131I-tositumomab data yielded the time elapsed since the last chemotherapy as the only significant predictor of the percentage baseline at nadir. The extent of bone marrow involvement was not a significant factor in this study, possibly because of the short time elapsed since the last chemotherapy of the 7 patients with bone marrow involvement. Because both treatments were designed to deliver a comparable bone marrow dose, this factor also was not significant. None of the 14 factors considered was predictive of the time to nadir. The R2 value for the model predicting percentage baseline at nadir was 0.60 for platelets and 0.40 for neutrophils. This model predicted the platelet and neutrophil toxicity grade to within ±1 for 28 and 30 of the 32 patients, respectively. For the 7 patients predicted with grade I thrombocytopenia, 6 of whom had actual grade I-II, dosing might be increased to improve treatment efficacy. Conclusion: The elapsed time since the last chemotherapy can be used to predict hematologic toxicity and customize the current dosing method in radioimmunotherapy.
- Hematologic toxicity
- I- tositumomab
- Y-ibritumomab tiuxetan
ASJC Scopus subject areas
- Radiology Nuclear Medicine and imaging