Impact of the individualization of the first-line chemotherapy for advanced colorectal cancer based on collagen gel droplet-embedded drug sensitivity test.

Leucovorin (FOL) and fluorouracil (5-FU) plus oxaliplatin (l-OHP; FOLFOX) or FOL and 5-FU plus irinotecan (SN-38; 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.

Mechanism underlying the transient increase of serum iron during FOLFOX/FOLFIRI therapy.

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.

Serum iron levels as a new biomarker in chemotherapy with leucovorin and fluorouracil plus oxaliplatin or leucovorin and fluorouracil plus irinotecan, with or without molecularly-targeted drugs.

Serum iron levels have been reported to increase following the administration of various anticancer drugs. An increase in serum iron levels during therapy with leucovorin and fluorouracil plus oxaliplatin (FOLFOX) or leucovorin and fluorouracil plus irinotecan (FOLFIRI) was also observed. The aim of this study was to investigate the correlation between serum iron levels and prognosis in advanced colorectal cancer (CRC) patients treated with FOLFOX/FOLFIRI ± molecularly-targeted drugs. Serum iron levels were measured prior to and at 48 h after treatment with FOLFOX/FOLFIRI ± molecularly-targeted drugs in 72 advanced CRC patients, all of whom succumbed to the disease between December, 2005 and February, 2012. No patients received radiotherapy. Taking the median rate of increase in serum iron levels as the cut-off value in each therapy, the patients were divided into cohort I (increase rate greater than the cut-off value in at least one therapy) or cohort II (increase rate less than the cut-off value in all therapies). The χ2 test and the t-test were used to compare patient characteristics between the two cohorts. Prognosis was evaluated between the two cohorts using the Kaplan-Meier method, the log-rank test and the Cox proportional hazards regression analysis. No significant bias in patient characteristics (including the frequency of chemotherapy or number of patients treated with molecularly-targeted drugs) was observed between the two cohorts. Serum iron levels were transiently elevated following treatment (P<0.001), returning to baseline within 2 weeks. Median survival time (MST) in cohort I (n=44) and cohort II (n=28) was 430 and 377 days, respectively. The MST was significantly higher in cohort I (P=0.0382). The multivariate analysis identified a small increase in serum iron levels as an independent risk factor for overall survival (OS). These results suggest that serum iron levels may be used as a new predictive factor in FOLFOX/FOLFIRI ± molecularly-targeted drug therapy. Serum iron levels may therefore prove to be a useful and convenient biomarker for OS in CRC patients.

Individualized chemotherapy for colorectal cancer based on the collagen gel droplet-embedded drug sensitivity test.

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.

Good response to leucovorin and fluorouracil plus oxaliplatin and cetuximab therapy in a patient with metastatic ascending colon cancer harboring a KRAS p.G13D mutation.

The effectiveness of cetuximab (Cmab) against KRAS p.G13D mutant-type tumors has been reported. In this study, we report a case of metastatic ascending colon cancer harboring a KRAS p.G13D mutation in a 65-year-old female. Considering the absence of symptoms and the post-operative risk of respiratory system complications due to multiple lung metastases, particularly at the entrance to the left main bronchus, anticancer drug therapy was selected as first-line therapy. With informed consent, FOLFOX4 [folinic acid (FOL), fluorouracil (F) plus oxaliplatin (OX)] + Cmab therapy was administered as preoperative chemotherapy. A good preoperative response was obtained to the chemotherapy, with a metastatic lesion disappearing from the entrance to the left main bronchus. Subsequent resection was performed successfully with no post-operative complications. Although a histopathological examination of the resected tissue specimen revealed residual cancer cells, it also showed the marked efficacy of the chemotherapy regimen used. In this study, we describe a case of metastatic ascending colon cancer harboring a KRAS p.G13D mutation in which the patient responded well to first-line therapy with FOLFOX4 + Cmab.

Evaluation of serum iron levels during FOLFOX4 and FOLFIRI therapies.

FOLFOX4 and FOLFIRI are effective regimens for the treatment of advanced colorectal cancer, and their use together with molecular targeting drugs has recently become more common. In the present study, we evaluated the changes in the serum iron levels of patients undergoing FOLFOX4 or FOLFIRI therapy alone or in combination with bevacizumab (BV). The serum iron level was increased 48 h after therapy and was restored to baseline 2 weeks afterwards in colorectal cancer patients who received FOLFOX4 or FOLFIRI alone or in combination with BV. This transient increase in serum iron was observed repeatedly during chemotherapy. The serum iron level was 71.66±28.96 µg/dl (mean ± standard deviation) before treatment and significantly increased to 186.82±83.17 µg/dl (p<0.001) 48 h after therapy. A transient increase in serum iron levels was also observed when FOLFIRI was administered to a patient after tumor resection. In contrast, no decrease in blood hemoglobin, no increase in liver enzymes and no increase in urinary iron excretion were observed. Based on these results, it can be concluded that an increase in serum iron may be induced by a transient change in iron distribution within the body after FOLFOX4/FOLFIRI therapy with or without BV.

Evaluation of the individual 50% inhibitory area under the concentration curve of 5-fluorouracil based on the collagen gel droplet embedded culture drug sensitivity test in colorectal cancer.

We have previously reported the 5-fluorouracil (5-FU) sensitivity of cancer cells from colorectal cancer (CRC) patients using the collagen gel droplet embedded culture-drug sensitivity test (CD-DST) under multiple drug concentrations and contact durations. Moreover, the area under the concentration curve (AUC) and growth inhibition rate (IR) were combined, resulting in the AUC-IR curve, which was approximated to the logarithmic curve. In the present study, we used the AUC-IR curve to calculate the individualized AUCIR50, the AUC value that imparts 50% growth inhibition. Individual AUCIR50 was calculated in CRC patients, and its distribution was evaluated. The cumulative distribution of individual AUCIR50 was regressed over two lines (logarithmic scale). Among the 45 resectable CRC patients, those who achieved more than the individual AUCIR50 during post-operative 5-FU-based chemotherapy demonstrated a trend towards better disease-free survival compared to those who did not achieve AUCIR50. Of the Dukes' D patients (n=10), those who achieved more than twice the individual AUCIR50 during post-operative 5-FU-based chemotherapy demonstrated significantly better survival rates (p=0.05) than those who did not. In this study, the distribution of the individual AUCIR50 suggested that approximately 6% of patients demonstrated very low 5-FU sensitivity. Therefore, the individual AUCIR50 was useful in classifying good, intermediate and poor 5-FU response. Achievement of the individual AUCIR50 may be a prerequisite for individualized 5-FU-based adjuvant chemotherapy. As well, the early achievement of twice the individual AUCIR50 may indicate an improved prognosis in Dukes' D patients. The individual AUCIR50 using CD-DST is useful in determining the individualized chemotherapy of CRC patients, thus CD-DST has the potential to facilitate the establishment of individualized chemotherapy for CRC.