Longer Intervals Between Hematopoietic Stem Cell Transplantation and Subsequent 90Y-Ibritumomab Radioimmunotherapy May Correlate With Better Tolerance

Abstract

This study aimed to evaluate the efficacy and toxicity of radioimmunotherapy (RIT) in recurrent lymphoma after hematopoietic stem cell transplantation (HSCT). We reviewed 9 patients, 7 with follicular lymphoma (DLBCL), 1 with mantle cell lymphoma (MCL), and 1 with diffuse large B-cell lymphoma treated with 90Y-ibritumomab tiuxetan 6 to 140 months after HSCT. Patients underwent 111In-ibritumomab scintigraphy and were treated 1 week later with standard 14.8 MBq/kg (n = 4) or 11.1 MBq/kg (n = 4) 90Y-ibritumomab. One patient who had allo-HSCT had reduced activity (70%) treatment. Among the 7 FL patients, we observed complete response (CR) in 2 patients and partial response (PR) in 5 patients. One patient with CR relapsed after 15 months; the other persisted 43.5 months after RIT. Of 5 patients with PR, 3 relapsed between 13 and 17 months; 1 persisted until unrelated death at 11.5 months. The fifth patient with PR received adoptive immunotherapy and improved to metabolic (FDG-PET) CR that persists 45.5 and 41 months after 90Y-ibritumomab and immunotherapy, respectively. Patients with MCL and DLBCL progressed or experienced stabilization (5 months), respectively. Six patients had grade 1 to 3 bone marrow (BM) toxicity and recovered within 3 months. Three patients having 90Y-ibritumomab 6, 14, and 24 months after HSCT experienced grade 4 BM toxicity. One of them (RIT 24 months after HSCT) recovered after 3 months, another delayed after 9 months, and the third patient only partially recovered, eventually developed myelodysplasia, and was allografted. Radioimmunotherapy after HSCT is an effective rescue therapy in FL. However, BM toxicity may be important; 3 of 8 patients treated with standard 90Y-ibritumomab activity experienced grade 4 BM toxicity, with incomplete recovery 3 months after RIT in 2 patients, both treated early (6 and 14 months) after HSCT.