Chemoembolization of rat liver metastasis with microspheres and gemcitabine followed by evaluation of tumor cell load by chemiluminescence

An orthotopic, isogenic rat model was used to determine the potential of chemoembolization (CHE) for reducing the tumor cell load of a diffusely metastatic liver. Seven days after injecting CC531-lac-Z cells intraportally to male WAG/Rij rats, tumor positive animals were treated by injection into the hepatic artery with solvent (n=17), degradable starch microspheres (DSM, 30 mg/kg; n=16), DSM plus 5-fluorouracil (5-FU, dosages: 90, 60, and 40 mg/kg) or DSM plus gemcitabine (Gem, dosages: 100, 80, 50, and 10 mg/kg). After 3 more weeks the experiment was terminated, the livers were weighted and the number of CC531-lac-Z cells per liver was determined. Injection of DSM reduced the tumor cell load by 21% (T/C%=79), the combination with 5-FU caused a stimulation of growth at 40 mg/kg (T/C%=291; n=10), but effected dose-dependent reductions in tumor cell number at 60 mg/kg (T/C%=86; n=16), and 90 mg/kg (T/C=19; n=17). None of these effects was significantly different from controls. The combination of DSM plus Gem was toxic at the highest dose (100 mg/kg), but well tolerated and highly effective at 80 mg/kg (T/C%= 16; n=12), 50 mg/kg (T/C%=9; n=12), and 10 mg/kg (T/C%=26; n=14). These results were significantly different from controls (p<0.05), respectively. In summary, the comparison of CHE with 5-FU or Gem shows that the efficacy of Gem in reducing the hepatic tumor cell load was significantly higher and its therapeutic ratio was greater than that of 5-FU.