Biomathematical approach of (188)Re radiopharmaceutical therapy characterization.
OBJECTIVE
In order to optimize radioimmunotherapy (RIT) as a cancer treatment modality, it is necessary to select the appropriate radionuclide and the biomolecule carrier. We have developed the radiolabeling with (188)Re (beta emitter) of anti-carcinoembryonic antigen (CEA) monoclonal antibody (Mab) for targeting CEA-producing tumors.


METHODS
Labeling was realized by the addition of Na(188)ReO(4) eluted from (188)W- (188)Re generator to a preformulated biomolecule in SH prereduction form in the presence of supplemental stannous ions. Wistar London rats were used for the biological studies. For the mathematical processing of the obtained results we used interpolation functions, as well as the different organs under investigation. Used were those interpolation functions for which the standard error is zero, correlation coefficient is the unit and the analytic expression emphasize generally exponential forms (the differential equations specific to the radioactive biodistribution have exponential integral curves as solutions).


RESULTS
The achieved radiochemical purity was 92-96%. The resulting solutions had a pH value 5-7 and were used for intravenous (i.v.) administration. The optimum field of interpolation functions was determined, comprising Hoerl, Modified Hoerl, Heart Capacity, Gaussian, Logistic, and Exponential type models. The optimum model existing in that field was also determined in the condition in which the ratio between absolute error of the biodistribution surface/the mean surface of the optimum biodistribution was minimal.


CONCLUSIONS
The obtained optimum model has a predictive character, allowing the identification of the moment to which the maximum percent value for every other time point in the considered time interval t(o)-t(f). This mathematical model can be used for every other pharmacokinetic paradigm.
Lungu
V
V
"Horia Hulubei" Institute for Physics and Nuclear Engineering, Bucharest, Romania.
Niculae
D
D
Mihailescu
G
G
Baiculescu
S
S
Turcu
I
I
Danaila
L
L