Estimated human absorbed dose for 68Ga-ECC based on mice data: comparison with 67Ga-ECC

Human Dose Assessment of 68Ga-NODAGA-RGD-BBN Heterodimer Peptide based on Animal Data

Aims

Calculation of the absorbed dose in human organs is one of the first steps for developing new radiopharmaceuticals. The aim of this study is to estimate the human absorbed dose of a newly developed 68Ga-NODAGA-RGD-BBN radiolabeled compound.

Materials and Methods

68Ga-NODAGA-RGD-BBN was prepared by varying different parameters at optimized conditions. The stability of the radiolabeled peptide in phosphate-buffered saline (PBS) and in human serum was evaluated for 120 min. Afterward, the biodistribution of the complex was assessed in normal and tumor-bearing mice, at least for 120 min postinjection. Finally, the human absorbed dose of 68Ga-NODAGA-RGD-BBN was estimated based on mice data using Radiation Dose Assessment Resource and Spark method.

Results

68Ga-NODAGA-RGD-BBN was produced with radiochemical purity of more than 98% (high-performance liquid chromatography/ radio thin layer chromatography (RTLC)) with high stability in PBS buffer and in human serum at least for 2 h. The complex demonstrated high uptake in gastrin-releasing peptide receptor-expressing tumors compared to other nontarget organs. Furthermore, the dose assessment for the complex showed that the kidneys receive the highest absorbed dose in comparison with other organs.

Conclusion

The result of this study showed that 68Ga-NODAGA-RGD-BBN is an effective and radiolabeled ligand for tumor detection, however more studies are still needed.

Optimized production, quality control, biological evaluation and PET/CT imaging of 68Ga-PSMA-617 in breast adenocarcinoma model

Optimized production, quality control and preclinical evaluation of 68Ga-PSMA-617 as a PET radiotracer for PSMA-positive malignancies as well as successful application in imaging of breast adenocarcinomas are reported. 68Ga-PSMA-617 radiolabeling and QC optimization, stability, log P, biodistribution in breast adenocarcinomas-bearing mice (direct and blockade studies) and also PET/CT imaging was performed. 68Ga-PSMA-617 complex was prepared in high radiochemical purity (>96%, ITLC, HPLC) and specific activity of 300–310 GBq/mM at 95 °C using 2–4 micrograms of the peptide in 10 min followed by solid phase purification. The tracer was stable in serum and final formulation for at least 120 min. The log P was −1.98. Western blot test on the tumor cell homogenates demonstrated distinct existence of the PSMA on the surface. The biodistribution of the tracer demonstrated specific kidney and tumor significant uptake using blocking study. Significant tumor:blood and tumor:muscle ratio uptake observed at 30 min post-injection (2.69 and 19.1, respectively). A reduction of 40–80% off tumor uptake in the study time period observed using blocking test. 68Ga-PSMA-617 can be proposing a possible tracer for PET imaging of breast adenocarcinomas and other breast malignancies.