Enhanced renal toxicity of total body irradiation combined with radioimmunotherapy.

PURPOSE: Total body irradiation (TBI) with and without additional radioimmunotherapy (RIT) was examined for renal toxicity after stem cell transplantation.

PATIENTS AND METHODS: Serum creatinine levels of 35 patients (15 female, 20 male, median age 40.5 years, range 17-60 years) after TBI alone and of 23 patients (eight female, 15 male, median age 47, range 16-58 years) after TBI with additional RIT were determined between 10/1997 and 11/1999. TBI was performed by external-beam radiotherapy in six fractions over 3 days with renal doses of 12 Gy in the TBI-alone group and 6 Gy in the group with additional RIT. The mean kidney dose due to the (188)Re-radiolabeled antibody was estimated to be 8.3 Gy (2.3-11.6 Gy).

RESULTS: Within 12 months after treatment, creatinine levels increased from 77 mmol/l (SD +/- 11) to 89 mmol/l (SD +/- 20) for TBI alone and from 78 mmol/l (SD +/- 13) to 144 mmol/l (SD +/- 52) for combined TBI and RIT.

CONCLUSION: Despite a 50% reduction of the external-beam contribution to the kidney dose, the application of approximately 10 GBq (188)Re-labeled anti-CD66 monoclonal antibody with a calculated renal dose of 8.3 Gy (range 2.3-11.5 Gy) led to renal toxicity, as reported previously. In the absence of a positive dose-response relationship for the (188)Re-labeled antibody, the observation may be explained by an underestimation of the biologically effective dose and the inaccuracy of the dose determination at the glomerular level.