Adverse effects at adjuvant treatment of liver metastases in rat with RSU-1069 + microspheres, or liposomal MTP-PE.

UNLABELLED: Rats were inoculated via the portal vein with a suspension of tumor cells from a transplantable dimethylhydrazine-induced adenocarcinoma of rat colon. In one set of experiments, the bioreductive drug RSU-1069 was injected once via the portal vein with or without degradable starch microspheres (DSM) 10 mins after tumour cell inoculation. In another set the immunostimulator liposomal-encapsulated muramyl tripeptide phosphatidyl-ethanolamine (MTP-PE) was injected via the portal vein or penile vein 1 day before tumour-cell inoculation and then twice a week. The experiments were finished after 2 to 3 weeks. Tumour take, numbers and volumes were measured.

RESULTS: RSU-1069 enhanced tumour growth when combined with DSM. Liposomal MTP-PE also increased tumour growth.

CONCLUSION: A bioreductive drug combined with microspheres, known to suppress the growth of an established tumour, may enhance its growth in the adjuvant setting. An accepted immunostimulator may enhance tumour take. Drugs used for the treatment of tumours must be carefully employed, if applied in an adjuvant setting. The effect on the normal immune system should be further studied.