Long-term results of a prospective trial of mantle irradiation alone for early-stage Hodgkin's disease

Use of 18F FDG PET and the short temporal response of Hodgkin's disease to RIT

Radioimmunotherapy (RIT) has been available for some time to treat patients with non-Hodgkin's lymphoma, but its use in Hodgkin's lymphoma has been less available, partly because of the need to find an appropriate antibody. A new radioiodinated chimeric antibody directed against the CD25 epitope (¹³¹I basiliximab) seems promising, but assessment of response has been difficult. ¹⁸F-fluorodeoxyglucose-positron emission tomography (¹⁸F-FDG-PET) has become a standard method by which the response of Hodgkin's disease to chemotherapy is both predicted and assessed with well-understood criteria of response. The aim of this study is to determine ¹⁸F-FDG-PET can be used to assess response to RIT. Pre- and post-treatment ¹⁸F-FDG-PET imaging was performed in a series of 13 patients with advanced Hodgkin's disease who had failed conventional therapy and had been enrolled on a compassionate use program for treatment with ¹³¹I basiliximab. The ¹³¹I basiliximab was given at an activity of 1200MBq/m² with one patient receiving 2 cycles and the rest a single cycle. The ¹⁸F-FDG-PET studies were compared using the “Deauville” criteria and by comparing the maximum standardized uptake value (SUVmax) of target tumors before and 4 and 8 weeks after treatment. All patients survived long enough for their initial ¹⁸F-FDG-PET-computed tomography scan at 4 weeks after their ¹³¹I basiliximab therapy. One out of ten patients with “Deauville” Grade 4 or 5 response died during the 6-month follow-up period. Two out of three patients with a “Deauville” Grade 2 or 3 response died in the follow-up period. The mean SUVmax pretreatment was 11.9 (±4.7); at 4-week posttreatment, the mean SUVmax was significantly lower at 6.5 (±5.8) (P = 0.02). At 8 weeks, the mean SUVmax was 8.8 (±7.0), which was not significantly different from the pretreatment level. ¹⁸F-FDG-PET imaging is able to predict the short-term response to treatment of Hodgkin's disease by RIT, and an initial poor response appears to predict poor outcome. Early changes in ¹⁸F-FDG-PET uptake did not predict sustained response and by 8 weeks all but one patient had recurrent disease.