Abstract. The leucovorin (FOL) and fluorouracil (5-FU) plus oxaliplatin (l-OHP; FOLFOX) or FOL and 5-FU plus irinotecan (SN-38; FOLFIRI) regimens with or without molecularly-targeted drugs are widely used as first-line chemotherapy in the treatment of advanced colorectal cancer (CRC). Whether FOLFOX or FOLFIRI is administered first is not significant, however, it is essential that full administration of the targeted dosages of all 3 drugs, 5-FU, l-OHP and SN-38, is achieved. However, this is not always possible and second-line chemotherapy must be abandoned in certain cases. Where possible, the most effective regimen should be selected as the first line of treatment. The aim of this study was to determine whether first-line chemotherapy may be individualized using the collagen gel droplet-embedded drug sensitivity test (CD-DST). Specimens of primary tumors were obtained from 43 CRC patients who had received no preoperative chemotherapy. Informed consent to measure drug sensitivity was obtained from all patients. The CD-DST allows evaluation of drug sensitivity using isolated, 3-dimensionally cultured tumor cells in a small collagen gel droplet. The CD-DST was performed and the growth inhibition rate (IR) was obtained under incubation conditions (5-FU with l-OHP at 6.0 and 3.0 µg/ml, or 5-FU with SN-38 at 6.0 and 0.2 µg/ml, respectively, for 24 h). The cumulative distributions of the growth IRs under each condition were evaluated based on the evidence that the clinical response rates to FOLFOX and FOLFIRI were almost the same. Individualization of first-line treatment was possible in all patients, with FOLFOX and FOLFIRI showing higher efficacy in 26 and 15 patients, respectively, and equal efficacy in 2 cases. This method has the potential to facilitate the establishment of individualized first-line chemotherapy for CRC and improve the prognosis in such patients.

Abstract. Leucovorin (FOL) and fluorouracil (5-FU) plus oxaliplatin (l-OHP; FOLFOX) or FOL and 5-FU plus irinotecan FOLFIRI) are widely used as first-line chemotherapy regimens in the treatment of advanced colorectal cancer (CRC). However, second-line chemotherapy must be abandoned in certain cases due to disease progression, adverse effects or high medical cost. Therefore, the most effective regimen should be selected as first-line chemotherapy. We reported that individualization of first-line treatment (FOLFOX/FOLFIRI/Dual/Poor responder) was possible using the collagen gel droplet-embedded culture drug sensitivity test (CD-DST) and that individualized first-line chemotherapy with CD-DST may improve the prognosis of patients with unresectable CRC. The aim of the present prospective cohort study was to evaluate the individualization of first-line chemotherapy using CD-DST, with a focus on prognosis. Between March 2008 and December 2015, tumor specimens were obtained from 120 patients with CRC who had not received preoperative chemotherapy. CD-DST was performed and the growth inhibition rate (IR) was determined by exposure for 24 h with 5-FU and l-OHP (6.0 and 3.0 µg/ml, respectively) and 5-FU and SN-38 (6.0 and 0.2 µg/ml, respectively). The cumulative distribution of IR values under each condition was evaluated on the basis that the clinical response to FOLFOX and FOLFIRI is equivalent (~50%). The prognosis of dual responder was improved compared with that of poor responders, however this difference was identified to be significant. There was no different prognosis between patients treated with an appropriate first-line regimen and patients treated with an inappropriate first-line regimen in dual responders. However, in poor responders, there were significant differences of prognosis between patients treated with an appropriate first-line regimen and patients treated with an inappropriate first-line regimen (P= 0.036). In conclusion, the results from the present study suggest that administration of the recommended first-line regimen using CD-DST for patients with unresectable CRC is important for the improvement of prognosis, particularly in poor responders.

In recent studies, better clinical outcomes for patients with left-sided colon cancer (CC) compared with right-sided CC have been reported; however, in such investigations, the chemotherapy regimens included molecular-targeting agents. To the best of our knowledge, the impact of primary tumor location as a predictive factor in patients suffering from CC treated with cytotoxic anticancer agents alone has not been investigated. The aim of the present study was to determine the impact of the primary tumor location as a predictive factor of patients undergoing the following cytotoxic anticancer agent regimens: Leucovorin and fluorouracil + oxaliplatin (FOLFOX) or Leucovorin and fluorouracil + irinotecan (FOLFIRI), using the collagen gel droplet-embedded drug sensitivity test (CD-DST). Between March 2008 and April 2017, tumor specimens were obtained from 133 patients suffering from colorectal cancer (CRC) who had not received preoperative chemotherapy. CD-DST was performed and the growth inhibition rate (IR) was determined in FOLFOX and FOLFIRI regimens. The associations between tumor location and IR values for each condition were evaluated. In the present study, the prognosis of patients receiving palliative chemotherapy as well as treatment with molecularly-targeted agents was also investigated. There were no significant differences in the IRs (%) of the two regimens using CD-DST for right-sided tumors compared with left-sided tumors, including or excluding the rectum. The median survival times of patients with right CC and left CC who had received palliative chemotherapy and treatment with molecularly-targeted agents were 960 and 1,348 days, respectively. Primary tumor location did not represent a predictive factor for the efficacy of treatment with cytotoxic anticancer agent regimens using CD-DST. However, patients suffering from left-sided CC were revealed to exhibit better clinical outcomes compared with patients suffering from right-sided CC when molecularly-targeted agent regimens were administered. Therefore, the results of the present study suggested that molecularly-targeted agents rather than cytotoxic anticancer agents may result in improved clinical outcomes for patients with CRC suffering from left-sided tumors.

The purpose of this study was to determine the effect of the addition of oxaliplatin (l-OHP) or irinotecan (SN-38) to 5-fluorouracil (5-FU) using the collagen gel droplet embedded culture-drug sensitivity test (CD-DST) to establish whether leucovorin plus 5-FU should be administered in combination with l-OHP (FOLFOX) or SN-38 (FOLFIRI) in individualized first-line chemotherapy for the treatment of advanced colorectal cancer (CRC). Specimens of primary tumors were obtained from 24 CRC patients who had received no preoperative chemotherapy. CD-DST was performed, and the inhibition rate (IR) was obtained under multiple incubation conditions. The effects of addition of l-OHP or SN-38 were evaluated for the same area under the concentration curve (AUC) of 5-FU based on linear regression analysis. Approximate expression and correlation coefficients (5-FU vs. 5-FU + l-OHP, 5-FU vs. 5-FU + SN-38; AUC of 5-FU=72 and 5-FU vs. 5-FU + l-OHP, 5-FU vs. 5-FU + SN-38; AUC of 5-FU=144) were y=0.94x+8.53 (R(2)=0.95, p<0.0004), y=0.77x+26.18 (R(2)=0.76, p<0.0004) and y= 0.91x+10.90 (R(2)=0.94, p<0.0004), y=0.52x+44.61 (R(2)=0.60, p<0.0004), respectively. Approximate expression of 5-FU vs. 5-FU + l-OHP almost fit the regression line (y=x+b(1)). This suggests that addition of l-OHP yields a constant additive effect, independent of the IR of 5-FU. However, approximate expression of 5-FU vs. 5-FU + SN-38 fit the regression line (y=ax+b(2), a<1, b(2)≥b(1)). This suggests that addition of SN-38 yields a greater additive effect due to the lower IR of 5-FU. These results indicate that FOLFIRI should be selected as the first-line chemotherapy for the treatment of poor responders to 5-FU.

Abstract. In patients with advanced colorectal cancer (CRC), a transient significant increase of serum iron is observed during chemotherapy with leucovorin and fluorouracil plus oxaliplatin (FOLFOX) or leucovorin and fluorouracil plus irinotecan (FOLFIRI). Serum iron may be a useful and convenient predictor of the response to chemotherapy; however, the mechanism underlying its increase has not been fully elucidated. Accordingly, the mechanism underlying the elevation of serum iron during chemotherapy was investigated in 20 patients with advanced CRC who were treated between September, 2012 and July, 2013. The levels of iron, ferritin, aspartate aminotransferase (AST), alanine aminotransferase (ALT), hemoglobin (Hb), hepcidin-25, interleukin (IL)-6 and soluble transferrin receptor (sTfR) were measured before and 48 h after chemotherapy. The serum levels of iron and hepcidin-25 were found to be significantly increased after chemotherapy (P<0.0001), whereas those of IL-6 were significantly decreased (P=0.0057). There were no significant changes in any of the other parameters. The lack of significant changes in AST, ALT and Hb suggested that the elevation of serum iron was not due to the destruction of hepatocytes, whereas the stable sTfR level suggested no destruction of erythroblasts. Hepcidin-25 regulates iron metabolism and decreases serum iron levels; it is increased by an iron load and IL-6, but is decreased under anemic or hypoxic conditions. The suppression of erythropoiesis increases serum iron levels and chemotherapy suppresses erythropoiesis. As serum iron and hepcidin-25 were both significantly increased and IL-6 was significantly decreased, with no significant changes in sTfR, it appears that the elevation of serum iron during chemotherapy may be secondary to reduced iron consumption by erythropoiesis, leading to increased expression of hepcidin-25 and suppression of Il-6 via negative feedback.