Experimental study on CPT-11 intraperitoneal chemotherapy--metabolism of CPT-11 in malignant ascites

The metabolism of CPT-11 in malignant ascites of gastric cancer patients with peritoneal seedings was studied in advance of the intraperitoneal chemotherapy of CPT-11 in humans. Malignant ascites and blood were drawn from gastric cancer patients. CPT-11 solution (20 mg/ml; 0.2 ml) was added into 3.8 ml ascites or plasma under 37 degrees C and CPT-11, SN-38 and SN-38GLU concentrations were measured with HPLC at times of 5, 30 and 60 minutes after addition of CPT-11. The change from CPT-11 to SN-38 was minimal not only in plasma, but also in malignant ascites. SN-38 GLU concentration was below the limit of measurement. This study showed that in malignant ascites, the enzymes such as carboxyesterase that convert CPT-11 to SN-38 were not present or minimal.