A theoretical dose-escalation study based on biological effective dose in radioimmunotherapy with (90)Y-ibritumomab tiuxetan (Zevalin).

Aim: To investigate the variation in biological effective dose (BED) produced by the uncertainty in absorbed dose and radiobiological parameters in Zevalin radioimmunotherapy.

Methods: Eight patients scheduled for treatment with standard administration of (90)Y-ibritumomab tiuxetan (Zevalin) were studied. Patient-specific pretherapy dosimetry was performed by injection of (111)In-ibritumomab tiuxetan.