Intratumoral injection of radioactive Astatine (211At) microspheres for the treatment of tumors

Our aims were to prepare microspheres labelled with radioactive astatine as brachytherapy seeds and to confirm the antitumor ability of these microspheres.

Chitosan-collagen composite microspheres (CCMs) were synthesized through an emulsification crosslink reaction and radiolabelled with 211At using the chloramine-T method. Radiation stability was assessed in both phosphate-buffered saline and blood serum. The in vivo distribution and therapeutic effects were evaluated in BALB/c nude mice with implanted tumours.

CCMs showed ideal morphological characteristics (diameter of 7.5-15 μm) and acceptable radiation stability (73.99% in PBS and 72.56% in serum after 16 hours). The in vivo biodistribution analysis demonstrated that 211At-CCMs were highly localized in tumour tissue. The therapeutic efficacy of 211At-CCMs when intratumorally injected into a cervical tumour model was assessed. Fourteen days after a single-dose treatment with 211At-CCMs, significantly retarded tumour volume growth was observed.

211At-CCM brachytherapy has the potential to provide an alternative solution for tumour treatment.