| ORIGINAL ARTICLE |
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| Year : 2013 | Volume
: 12
| Issue : 1 | Page : 27-32 |
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Labeling and Biological Evaluation of 99m Tc-HYNIC-Trastuzumab as a Potential Radiopharmaceutical for In Vivo Evaluation of HER2 Expression in Breast Cancer
Victoria Calzada1, Fernanda Garcia1, Marcelo Fernández1, Williams Porcal2, Thomas Quinn3, Omar Alonso4, Juan Pablo Gambini4, Pablo Cabral1
1 Centro de Investigaciones Nucleares, Facultad de Ciencias, Universidad de la Republica, Montevideo, Uruguay
2 Laboratorio de Química Orgánica, Facultad de Ciencias-Facultad de Química, Universidad de la Republica, Montevideo, Uruguay
3 Department of Biochemistry, University of Missouri, Columbia, USA
4 Centro de Medicina Nuclear, Hospital de Clinicas, Facultad de Medicina, Universidad de la Republica, Montevideo, Uruguay
Correspondence Address:
Pablo Cabral
Centro de Investigaciones Nucleares, Mataojo 2055, Montevideo 11400
Uruguay
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DOI: 10.4103/1450-1147.113953 PMID: 23961253 
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The amplification of HER2 gene has been described in several tumor types, mainly breast cancer with a subsequent increase in HER2 protein expression. Trastuzumab is a humanized monoclonal antibody that recognizes selectively the HER2 extracellular domain. The objective of the present work was to standardize the conjugation of Trastuzumab with Succinimidyl-hydrazinonicotinamide (HYNIC) and labeling with 99m Tc to obtain 99m Tc-HYNIC-Trastuzumab for use as in vivo tracer of the HER2 expression in breast cancer. The labeling procedure involved derivatization of 0.067 μmol of Trastuzumab with 0.33 μmols of HYNIC in dimethyl sulfoxide (DMSO). The mixture was incubated for 30 min. A mixture of Tricine and SnCl 2 .2H 2 O was prepared by add a solution of 44.6 μmols Tricine in 0.05 mL HCl 2.0 M and a similar volume of another solution containing 44.3 μmols SnCl 2 .2H 2 O in 0.5 mL HCl 2.0 M. Then, 0.05 mL of this mixed was added to the conjugated with 296 MBq of 99mTcO-4. The final mixture was incubated at room temperature (18-25°C) for 30 min. Radiochemical purity of the labeled solution was studied by chromatography, to evaluate 99m Tc-Tricine, 99m TcO 2 .H 2 O, and free 99m TcO 4 − . Radiochemical purity was also evaluated by HPLC. Stability studies were tested in solution at 4°C and lyophilized at 4°C. Biodistribution studies were performed in healthy CD-1 female mice at 2, 5, and 24 h (n0 = 3) and CD-1 female mice spontaneous breast adenocarcinoma (n = 3). Scintigraphic images of spontaneous breast adenocarcinoma in female CD-1 mice were acquired in a gamma camera at 2, 5, and 24 h post-injection. Labeling was easily performed with high yields (>90%) and radiopharmaceutical stability for 24 h post-labeling. Stability studies revealed that antibody derivative must be lyophilized for undamaged storage. Biodistribution studies and imaging revealed excellent uptake in the tumor. Based on the results it was concluded that 99m Tc-HYNIC-Trastuzumab could be a promising radiopharmaceutical for in vivo diagnosis of the HER2 status in breast with impact on treatment planning. |
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