A study for establishment of individualized chemotherapy for colorectal cancer based on the individual 50% inhibitory area under the concentration curve (AUCIR50) using the collagen gel droplet embedded culture-drug sensitivity test (CD- DST)

Abstract

14553 Background: The drug sensitivity of tumor cells is one of the key issues to explore in individualized 5-fluorouracil (5-FU) based chemotherapy for colorectal cancer patients. We reported that growth inhibition rate (IR) and area under the concentration curve (AUC) approximated to a logarithmic curve using the collagen gel droplet embedded culture-drug sensitivity test (CD-DST) in ASCO 2003 (#1283). We also reported that the individual 50% inhibitory area under the concentration curve (AUC IR50) could be obtained using the individual AUC-IR curve in ASCO 2006 (#13560). The aim of this study was to evaluate the achievement of the individual AUCIR50 in 5-FU based adjuvant chemotherapy for the establishment of individualized chemotherapy. Methods: Surgical specimen was obtained from resectable 33 CRC patients without any preoperative chemotherapy during 2001 to 2005. 5-FU based adjuvant chemotherapy was administered in all patients. CD-DST was performed under 6–9 different conditions. The individual AUCIR50 was obtained from the individual AUC-IR curve. The patients were divided into 2 groups, the achieved group and the non-achieved group. In the achieved group, total administered AUC was more than the individual AUCIR50 and in non-achieved group, the total administered AUC was less than the individual AUCIR50. Recurrence rates were evaluated from the 2 groups. Results: In all patients, the recurrence rates were 6.7% (1/15) in the achieved group and 27.8% (5/18) in the non-achieved group. In the colon cancer patients, the recurrence rates were 8.3% (1/12) in the achieved group and 10.0% (1/10) in the non-achieved group. In the rectal cancer patients, the recurrence rates were 0% (0/3) in the achieved group and 50.0% (4/8) in the non-achieved group. Conclusions: The recurrence rate of the achieved group was lower than that of the non-achieved group. Therefore, this study demonstrated that the achievement of the individual AUCIR50 could be a prerequisite of individualized 5-FU based adjuvant chemotherapy. No significant financial relationships to disclose.