Radiolabeling and preclinical animal model evaluation of DTPA coupled 99mTc-labelled flutamide complex ([99mTc]DTPA-FLUT) as a potential radiotracer for cancer imaging.

Background: Advances in molecular imaging strategies have had an effect on precise diagnosis and treatment. Research has been intensified to develop more effective and versatile radiopharmaceuticals to uplift diagnostic efficiency and, consequently, the treatment.

Purpose: To label the flutamide (FLUT) coupled with diethylenetriamine pentaacetate (DTPA) with technetium-99 m (^99mTc) and to evaluate its binding efficiency with rhabdomyosarcoma (RMS) cancer cells.

Material and methods: Radiolabeling of FLUT with 185 MBq freshly eluted ^99mTcO₄^-1 was carried out via DTPA bifunctional chelating agent using stannous chloride reducing agent at pH 5. The labeled compound was assessed for its purity using chromatography analysis, stability in saline and blood serum, AND charge using paper electrophoresis. Normal biodistribution was studied using a mouse model, while binding affinity with RMS cancer cells was studied using an internalization assay. The in vivo accumulation of RMS cancer cells in a rabbit model was monitored using a SPECT gamma camera.

Results: Radiolabeling reaction displayed a pharmaceutical yield of 97% and a stability assay showed >95% intact radiopharmaceutical up to 6 h in saline and blood serum. In vitro internalization studies showed the potential of [^99mTc]DTPA-FLUT to enter into cancer cells. This biodistribution study showed rapid blood clearance and minimum uptake by body organs, and scintigraphy displayed the [^99mTc]DTPA-FLUT uptake by lesion, induced by RMS cancer cell lines in rabbit.

Conclusion: Stable, newly developed [^99mTc]DTPA-FLUT seeks its way to internalize into RMS cancer cells, indicating it could be a potential candidate for the diagnosis of RMS cancer.