in radionuclide therapies with 90Y-conjugates: the IEO experience
Cremonesi M, Ferrari M, Chinol M, Bartolomei M, Stabin MG, Sacco E,
Fiorenza M, Tosi G, Paganelli G
Medical Physics, European Institute of Oncology (IEO), Milan, Italy.
The basis for a successful radionuclide therapy is a high and stable uptake of
the radiopharmaceutical in the target tissue along with low activity
concentration in other normal organs.
The contribution of dosimetry in radionuclide therapy is to predict before the
treatment the absorbed doses in tumor and normal organs, to identify the
critical organs, to minimize any possible toxicity and to evaluate the maximum
We report our experience concerning pharmacokinetics and dosimetry of two
90Y-therapeutic protocols: 3-step pretargeting radioimmunotherapy (RIT)
according to the biotin-avidin system and receptor mediated radionuclide therapy
with the somatostatin analogue [DOTA-D-Phe1-Tyr3] octreotide named
For the dosimetric analysis, analogous approaches for the two radiolabeled
compounds due to the similar pharmacokinetic characteristics were adopted; the
MIRD formalism was applied, taking into account both the physical and the
biological characteristics of the radioconjugate and patients' metabolism.
In order to determine biological clearance, serial blood samples and complete
urine collection were obtained up to 48 hours after injection; to evaluate
biodistribution, several whole body scans were acquired.
Both therapies showed the advantageous characteristics of a fast blood clearance
and a predominantly renal excretion of the radiopharmaceuticals thus lowering
the irradiation of the total body.
Although pharmacokinetic characteristis were similar, different critical organs
were found for the two therapies; in particular, some considerations regarding
red marrow, spleen and kidneys were required.
The results of our studies indicate that high activities of 90Y-biotin (3-step
RIT) and 90Y-DOTATOC can be administered with acceptable radiation doses to
PMID: 11302260 [PubMed - indexed for MEDLINE]