Regional radiochemotherapy using in situ hydrogel

Purpose. To evaluate the feasibility of regional radiochemotherapy of mammary tumors using in situ hydrogel loaded with cisplatin ( CDDP) and rhenium-188 (Re-188). Methods. Sodium alginate ( SA) and calcium chloride were used to create a hydrogel for delivery of CDDP and 188Re. In vitro studies were performed to evaluate cytotoxic effects of Re-188-hydrogel and sustained-release ability of the CDDP-hydrogel. Tumor-bearing rats were injected with Re-188-hydrogel (0.5 - 1 mCi/rat), Re-188-perrhenate ( 0.5 - 1 mCi/rat, intratumoral, I. T.), CDDP-hydrogel ( 3 mg/kg), and Re-188-hydrogel loaded with CDDP ( 3 mg/kg body weight, 0.5 - 1 mCi/rat), respectively, and groups receiving Re-188 were imaged at 24 and 48 h postinjection. Tumor volume, body weight, imaging, and kidney function were assessed as required for each group. Results. Successful formation of the hydrogel was demonstrated by cytotoxic effects of Re-188-hydrogel and slow release of CDDP-hydrogel in vitro. Tumor volume measurements showed significant delay in tumor growth in treated vs. control groups with minimal variation in normal kidney function for the CDDP-hydrogel group. Scintigraphic images indicated localization of Re-188-hydrogel in the tumor site up to 48 h postinjection. Conclusions. Our data demonstrate the feasibility of using hydrogel for delivery of chemotherapeutics and radiation locally. This technique may have applications involving other contrast modalities as well as treatment in cases where tumors are inoperable.