⁹⁰Y-Ibritumomab Therapy in Refractory Non-Hodgkin's Lymphoma: Observations from ¹¹¹In-Ibritumomab Pretreatment Imaging

Abstract

Radioimmunotherapy is an effective treatment for non-Hodgkin's lymphoma (NHL). ⁹⁰Y-ibritumomab is an antibody targeting CD20 receptors on the surface of lymphocytes. We present observations from our clinical experience with ⁹⁰Y-ibritumomab in the management of NHL. Methods: This was a retrospective study of 28 NHL patients treated with ⁹⁰Y-ibritumomab. There were 21 men and 7 women, 36–85 y old. A diagnostic dose of ¹¹¹In-ibritumomab was administered on day 0, and imaging followed immediately and at 24, 48, and 72 h. The doses of ⁹⁰Y-ibritumomab ranged from 629 to 1,258 MBq (17–34 mCi). Outcomes were compared with the findings of the ¹¹¹In-ibritumomab scans. Results: ⁹⁰Y-ibritumomab induced objective responses in 22 of 28 patients. A complete response was noted in 9 patients, a partial response in 9 patients, and a mixed response in 4 patients. Three patients had stable disease, and 3 patients had disease progression. ¹¹¹In-ibritumomab findings were positive in 19 patients and negative in 9 patients. A complete response was noted in 2 of 19 patients with positive findings and 7 of 9 with negative findings. A partial response was seen in 7 of 19 patients with positive findings and 1 of 9 with negative findings. Disease progression was observed in 3 of 19 patients with positive findings and 0 of 9 with negative findings. The remaining patients had a mixed response or no changes. Conclusion: A higher rate of complete response after ⁹⁰Y-ibritumomab treatment was seen in patients with negative ¹¹¹In-ibritumomab findings, whereas a higher rate of disease progression despite therapy was noted in patients with positive ¹¹¹In-ibritumomab findings. This observation suggests that patients with bulky disease may require more aggressive management.