Biomodulation of Fluorouracil in colorectal cancer

The Role of Fluoropirimidines in Gastrointestinal Tumours: from the Bench to the Bed

PURPOSE

Gastrointestinal tumours are one of the most common types of cancer. Therapeutic options include surgery, radiotherapy, local ablation techniques, targeted agents, and chemotherapy. Fluoroprimidines are one of the most active drug families in digestive tumours and remains the cornerstone of the most commonly used chemotherapy schemes.

METHODS

We review the molecular basis of thymidylate synthase inhibition and the mechanisms of action of 5-fluorouracil, next generation oral fluoropyrimidines (capecitabine, tegafur and the latest S-1 and TAS-102) and antifolates.

RESULTS

In addition, mechanisms and biomarkers of resistance and toxicity are explored. Finally, new fluoropyrimidines development and clinical trials ongoing in digestive tumours are reviewed.

CONCLUSIONS

Further research is necessary to avoid resistance mechanisms, improve clinical outcomes and continue reducing toxicities. Until new drugs become available, the optimization of current therapies should be a priority.

A DFT study on the interaction between 5-fluorouracil and B12N12 nanocluster

The most stable interaction of 5-FU drug molecule from its nitrogen head (di-enol form) over B₁₂N₁₂ nano-cage is determined using density functional theory calculations.

Molecular Modeling Studies of Some Uracil and New Deoxyuridine Derivatives

Molecular modeling results reported in this paper are crucial in highlighting the quantitative relationship between the optimized structure and computed molecular properties related to four newly synthesized uracil derivatives with promising biological potential as anticancer bioactive agents. Moreover, 5-fluorouracil (5-FU) and its tautomers and thiouracils molecular properties are studied and correlated with their biological activities. The great medical importance of these and similar molecular systems requires research on their quantitative structure-activity relationships (QSAR) in order to further improve our knowledge about how receptor binding, selectivity, and pharmacological effects are achieved. Modeling is performed in the ground and the first singlet excited states using density functional theory (DFT) and its time-dependent extension (TD-DFT), respectively.

In the war against solid tumors arsenic trioxide needs partners

In the past decade, the therapeutic potential of arsenic trioxide (ATO) in the treatment of acute promyelocytic leukemia (APL) was recognized. This encouraged other investigators to test the efficacy of ATO in the management of other hematological and solid tumor malignancies. Notably, as a single agent, arsenic trioxide did not benefit patients diagnosed with solid tumors. However, when it was combined with other agents, treatment benefit emerged. In this article, we have summarized the outcome of clinical trials that used arsenic trioxide as a single agent as well as in combination settings in patients diagnosed with solid tumors. We have also reviewed possible additional mechanisms by which ATO may be useful as a chemosensitizer in combination therapy. We hope that our review will encourage clinical investigators to rationally combine ATO with additional chemotherapeutic agents in treating patients diagnosed with solid tumors.

Cancer prevention as biomodulation: targeting the initiating stimulus and secondary adaptations

In a medical sense, biomodulation could be considered a biochemical or cellular response to a disease or therapeutic stimulus. In cancer pathophysiology, the initial oncogenic stimulus leads to cellular and biochemical changes that allow cells, tissue, and organism to accommodate and accept the oncogenic insult. In epithelial cell cancer development, the process of carcinogenesis is frequently characterized by sequential cellular and biochemical adaptations as cells transition through hyperplasia, dysplasia, atypical dysplasia, carcinoma in situ, and invasive cancer. In some cases, the adaptations may persist after the initial oncogenic stimulus is gone in a type of “hit-and-run” oncogenesis. These pathophysiological changes may interfere with cancer prevention therapies targeted solely to the initial oncogenic insult, perhaps contributing to resistance development. Characterization of these accommodating adaptations could provide insight for the development of cancer preventive regimens that might more effectively biomodulate preneoplastic cells toward a more normal state.

Photochemistry and electrochemistry of anticancer uracils

The redox mechanism and electronic absorption behavior of a commercial anticancer drug, 5-fluorouracil (5-FU) and two potential anticancer drugs, 2-thiouracil (2-TU) and dithiouracil (DTU) have been investigated in a wide pH range by UV-Vis spectroscopy, cyclic voltammetry and differential pulse voltammetry. The effect of electrolytes, substituents, successive sweeps and potential scan rate on the voltammetric response of uracils was examined. Organized structure-activity relationships of these drugs were established on the basis of the results obtained from electronic absorption spectroscopy and cyclic voltammetry. The electrode reaction mechanism was suggested using the experimentally determined electrochemical parameters. The DNA binding propensity of uracils was found greater than the classical intercalator, proflavin and clinically used drug, epirubicin. Moreover, the results obtained through ab initio calculations for the oxidation potential of the three uracil derivatives were found in good agreement with the electrochemical results.

A phase II study of UFT with leucovorin administered as a twice daily schedule in the treatment of patients with metastatic colorectal cancer

Prolonged infusions have been shown to be safer and potentially more effective than bolus regimens of 5-fluorouracil (5-FU) as treatment for metastatic colorectal cancer (mCRC). However, infusional 5-FU requires central venous access and costly infusion pumps. Oral fluoropyrimidines enable longer exposures to 5-FU with increased convenience. Tegafur–uracil (UFT) with leucovorin (LV) given thrice daily has improved safety plus comparable survival and response rates to bolus 5-FU/LV. We conducted a phase II clinical study in 98 patients with mCRC to evaluate if UFT with LV given twice daily provided comparable time to progression (TTP), efficacy and tolerability to that reported for thrice daily in two phase III clinical studies. Secondary objectives included overall response rate (ORR) and overall survival (OS). Median TTP was 3.8 months, when compared with 3.5 months for thrice daily. The ORR (11%) and median OS (12.8 months) with twice daily administration were similar to that of thrice daily administration (12% and 12.4 months). The incidence of grade 3/4 treatment-related diarrhoea was 30% on the twice daily and 21% on the thrice daily schedule. These results suggest that twice daily administration has similar efficacy and tolerability to thrice daily administration and is an acceptable alternative for patients who would benefit from UFT with LV therapy.

A phase II study of irinotecan, high-dose 24-h continuous intravenous infusion of floxuridine and leucovorin (IFLUX) for advanced, previously untreated colorectal cancer

Our objectives were to determine response rate, time to progression, overall survival and tolerability of novel combination chemotherapy, consisting of irinotecan, high-dose 24-h continuous intravenous infusion of floxuridine and leucovorin in advanced previously untreated colorectal cancer. Thirty-eight patients with advanced colorectal cancer were treated at Sylvester Comprehensive Cancer Center, University of Miami, from 2000 to 2004, and received weekly intravenous infusion of irinotecan at 110 mg/m with a combination of 120 mg/kg floxuridine and 500 mg/m leucovorin administered as a 24-h continuous intravenous infusion. The treatment cycle consisted of 4 weeks of consecutive therapy followed by 2 weeks of rest. Five (13%) patients achieved complete response, 10 (26%) patients achieved partial response, 17 (45%) patients attained stable disease and six (16%) patients progressed. The overall response rate was 39% in this study. This chemotherapy regiment was well tolerated; the most common grade 3 toxicities were neutropenia (16%), anemia (16%), vomiting (24%), diarrhea (16%), and hand-and-foot syndrome (26%). The median time to progression was 11.5 months (347.5 days) with 95% confidence intervals of 6.8-12.9 months (206-389 days). The time to progression ranged from 1.8 to 34 months. The median survival of the patients in this trial was 31.28 months (952 days) with a confidence interval of 20.9-38.0 months (629-1141 days). Intravenous infusion of floxuridine and leucovorin is beneficial as first-line therapy in advanced colorectal cancer, demonstrating a prolonged time to progression and overall survival with acceptable tolerability and manageable toxicity profile.

Phase II trial of combined irinotecan and oxaliplatin given every 3 weeks to patients with metastatic colorectal cancer

BACKGROUND

Both irinotecan and oxaliplatin are active agents in the treatment of patients with metastatic colorectal cancer, and there is a strong preclinical rationale for combining these 2 agents. Therefore, a Phase II trial was designed and conducted to determine the efficacy and tolerability of combined irinotecan and oxaliplatin given every 3 weeks to patients with metastatic colorectal cancer.

METHODS

Patients with previously untreated metastatic colorectal cancer received irinotecan at a dose of 175 mg/m2 and oxaliplatin at a dose of 130 mg/m2, both given intravenously every 3 weeks. Objective responses were evaluated every 2 courses and were confirmed at least 4 weeks after the initial determination.

RESULTS

Fifty-five patients were enrolled and treated in the current trial. Of the 53 patients whose responses were evaluable, 18 (34%) achieved a partial response, 27 (51%) had stable disease, and 8 (15%) developed disease progression as their best response to the treatment. The intent-to-treat median survival for all patients was 16.4 months and the time to progression was 4.8 months. All 55 patients were available for toxicity analysis (according to version 2.0 of the National Cancer Institute Common Toxicity Criteria). The most common Grade 3-4 toxic effect was neutropenia, which was reported to occur in 22 patients (40%).

CONCLUSIONS

The combination of irinotecan and oxaliplatin appears to be safe and active when used to treat patients with metastatic colorectal cancer. Treatment results with this regimen were similar to those reported for other combined frontline chemotherapy regimens for colorectal cancer. When this particular regimen wa used, neutropenia was found to be the predominant toxicity.

Amifostine, in a reduced dose, protects against severe diarrhea associated with weekly fluorouracil and folinic acid chemotherapy in advanced colorectal cancer: a pilot study

Fifty-two consecutive patients with advanced colorectal cancer who developed persistent diarrhea following chemotherapy with 5-fluorouracil despite dose reduction were treated with amifostine 800, 500 or 150 mg/m(2). The administered dose of 5-fluorouracil was significantly greater during amifostine treatment. Amifostine 800 mg/m(2) was associated with complete elimination of diarrhea, but 76.3% of patients developed infusion-related hypotension. At a dose of 500 mg/m(2), diarrhea was significantly reduced and milder compared with baseline and the incidence of hypotension was 54.2%. At the lowest dose of amifostine, 17.1% of patients developed Grade 1 diarrhea, a significant reduction over baseline, and hypotension occurred in 25.2% of patients. Treatment with amifostine also improved mucositis but had no effect on the relatively mild nausea and vomiting due to 5-fluorouracil. In this study, amifostine reduced the incidence and severity of diarrhea associated with 5-fluorouracil in patients with advanced colorectal cancer, with acceptable efficacy at a reduced dose that offered better tolerability.

Phase III study of cyclophosphamide, doxorubicin, and fluorouracil (CAF) plus leucovorin versus CAF for metastatic breast cancer: Cancer and Leukemia Group B 9140

PURPOSE

To determine whether biochemical modulation with LV (leucovorin) enhances the efficacy of CAF (cyclophosphamide, doxorubicin, and fluorouracil) against metastatic breast cancer.

PATIENTS AND METHODS

Women with histologically confirmed stage IV breast cancer, Cancer and Leukemia Group B (CALGB) performance status 0 to 2, and no prior chemotherapy for metastatic disease were randomly assigned to receive CAF (cyclophosphamide 500 mg/m2 day 1, doxorubicin 40 mg/m2 day 1, and fluorouracil [FU] 200 mg/m2 intravenous bolus days 1 to 5) with or without LV (LV 200 mg/m2 over 30 minutes days 1 to 5 given 1 hour before FU).

RESULTS

Two hundred forty-two patients were randomly assigned to treatment; 124 patients had visceral crisis and 40 patients had a CALGB performance status score of 2. The median follow-up was 6 years. The two study arms were similar with regard to serious adverse events; four patients died from treatment-related causes, two patients on each study arm. Predictive variables for time to treatment failure and survival were visceral disease and performance status. The overall response rate was 29% for CAF versus 28% for CAF plus LV. The median time to treatment failure (9 months) and median survival (1.7 years) did not differ by treatment arm.

CONCLUSION

Modulation of CAF with LV improved neither response rates nor survival among women with metastatic breast cancer, compared with CAF alone. Multivariate analyses confirmed the prognostic importance of performance status and visceral crisis. However, the overall and complete response rates, response durations, time to treatment failure, and survival were the same in the two treatment arms.

Transcatheter Arterial Chemoembolization with or without Radiofrequency Ablation in the Management of Patients with Advanced Hepatic Malignancy

Transcatheter arterial chemoembolization (TACE) is efficacious against hepatic malignancies by rendering tumors ischemic while delivering high-dose chemotherapy. The added benefit of radiofrequency ablation (RFA) has not been determined. We sought to review our experience with TACE with or without RFA in the treatment of hepatocellular carcinoma and colorectal liver metastases in patients not amenable to resection. TACE and RFA were undertaken in 13 patients with hepatocellular carcinoma (n = 7) or colorectal liver metastases (n = 6). Concurrently 24 patients underwent TACE alone for hepatocellular carcinoma (n = 15) or colorectal liver metastases (n = 9). Patients undergoing TACE with or without RFA were similar in age, gender, and diagnosis. Overall follow-up was 9.1 months ± 7.1. One-year survival was greater in patients undergoing TACE with RFA than with TACE alone (100% vs 67%, P = 0.04). Mean survival was longer after TACE with RFA compared with TACE alone (25.3 months ± 15.9 vs 11.4 months ± 7.3, P < 0.05). No patients suffered significant complications. The addition of RFA to TACE improves survival in patients with unresectable primary or metastatic hepatic malignancies. RFA with TACE should be in the armamentarium of surgeons caring for patients with malignant liver lesions.

Schedule-selective biochemical modulation of 5-fluorouracil in advanced colorectal cancer--a phase II study

BACKGROUND

5-fluorouracil remains the standard therapy for patients with advanced/metastatic colorectal cancer. Pre-clinical studies have demonstrated the biological modulation of 5-fluorouracil by methotrexate and leucovorin. This phase II study was initiated to determine the activity and toxicity of sequential methotrexate--leucovorin and 5-fluorouracil chemotherapy in patients with advanced colorectal cancer.

METHODS

Ninety-seven patients with metastatic colorectal cancer were enrolled onto the study. Methotrexate--30 mg/m2 was administered every 6 hours for 6 doses followed by a 2 hour infusion of LV--500 mg/m2. Midway through the leucovorin infusion, patients received 5-fluorouracil--600 mg/m2. This constituted a cycle of therapy and was repeated every 2 weeks until progression.

RESULTS

The median age was 64 yrs (34-84) and the Eastern Cooperative Group Oncology performance score was 0 in 37%, 1 in 55% and 2 in 8% of patients. Partial and complete responses were seen in 31% of patients with a median duration of response of 6.4 months. The overall median survival was 13.0 months. The estimated 1-year survival was 53.7%. Grade III and IV toxic effects were modest and included mucositis, nausea and vomiting.

CONCLUSIONS

This phase II study supports previously reported data demonstrating the modest clinical benefit of 5-FU modulation utilizing methotrexate and leucovorin in patients with metastatic colorectal cancer. Ongoing studies evaluating 5-fluorouracil modulation with more novel agents (Irinotecan and/or oxaliplatin) are in progress and may prove encouraging.

Enhancement of fluorouracil uptake in human colorectal and gastric cancers by interferon or by high-dose methotrexate: An in vivo human study using noninvasive (19)F-magnetic resonance spectroscopy

PURPOSE

To study whether two modulators, high-dose methotrexate (MTX) and interferon alfa-2a (IFNalpha-2a) will alter the intratumoral pharmacokinetics of fluorouracil (5-FU).

PATIENTS AND METHODS

Five patients, two with gastric cancer and three with colorectal cancer, who had metastatic tumor nodules in their livers were studied dynamically in vivo after 5-FU injection. In a magnetic resonance imaging unit, noninvasive (19)F-magnetic resonance spectroscopy (MRS) was used to detect (19)F signals from 5-FU and its metabolites.

RESULTS

The intratumoral half-life (t(1/2)) of 5-FU in these tumors ranged from 18.8 minutes to 42.3 minutes. Four of the five patients exhibited increases in the t(1/2) of 5-FU after intravenous (IV) administration of MTX or IFNalpha-2a. In the two patients with gastric cancer who received IV high-dose MTX followed by IV 5-FU, increases were seen in either the total t(1/2) of 5-FU (41.8%) or in the t(1/2) of the alpha phase (150%). In the three patients with colorectal cancer who received IV IFNalpha-2a followed by IV 5-FU, the two patients with partial responses had increases in the t(1/2) of 5-FU of 41% and 30.2%, whereas the nonresponder had a nonsignificant increase (5.6%) in the t(1/2) of 5-FU.

CONCLUSIONS

These results document that the in vivo modulation of the tumoral pharmacokinetics of 5-FU can be measured noninvasively by (19)F-MRS and suggest that such information correlates with subsequent clinical outcomes. The findings also indicate that IFNalpha-2a and high-dose MTX can increase the intratumoral 5-FU in some patients. Such information, obtained prospectively in vivo, may assist in better individual cancer patient management and in developing novel drug combinations.

Sequential biochemical modulation of fluorouracil with folinic acid, N-phosphonacetyl-L-aspartic acid, and interferon alfa-2a in advanced colorectal cancer

PURPOSE

Several agents have been evaluated for their effect as biochemical modulators of fluorouracil (5-FU) in the treatment of metastatic colorectal carcinoma. In this study, we used folinic acid (FA), N-phosphonacetyl-L-aspartic acid (PALA), and recombinant interferon alfa-2a (IFNalpha-2a) in a sequential order to assess the efficacy of this approach in patients with metastatic colorectal carcinoma.

PATIENTS AND METHODS

Forty-four patients with metastatic colorectal carcinoma were enrolled onto the study. The treatment course consisted of three cycles: (cycle 1) FA 20 mg/m(2) followed by 5-FU 425 mg/m(2) on days 1 to 5; (cycle 2) PALA 250 mg/m(2) on days 29, 36, 43, and 50 and 5-FU 2,600 mg/m(2) as a 24-hour infusion on days 30, 37, 44, and 51; and (cycle 3) IFNalpha-2a 9 million units (MU) three times a week for 5 weeks beginning on day 57, with a continuous infusion of 5-FU 750 mg/m(2) on days 57 to 61, and then weekly bolus of 5-FU 750 mg/m(2)/wk on days 71, 78, and 85. Response was determined after cycle 3.

RESULTS

All patients had a Zubrod performance status >/= 2, measurable disease, and had received no prior chemotherapy for their metastatic disease. A total of 212 cycles were given. Thirty-six patients were assessable for response. No complete responses were seen. Seven patients had a partial response, eight had stable disease, and 15 had progressive disease. The median duration of response was 25 weeks, and the median survival was 53 weeks. Grade 3 and 4 toxic effects included granulocytopenia, stomatitis, diarrhea, rash, nausea, and fatigue.

CONCLUSION

This trial provided no evidence that sequential biochemical modulation of 5-FU in patients with metastatic colorectal carcinoma had any therapeutic advantage over conventional treatment regimens of 5-FU plus FA.

Prevention by chitosan of myelotoxicity, gastrointestinal toxicity and immunocompetent organic toxicity induced by 5-fluorouracil without loss of antitumor activity in mice

We examined the antitumor activity and side effects (myelotoxicity, immunocompetent organic toxicity and gastrointestinal toxicity) of combined treatment with the cancer chemotherapy drug 5-fluorouracil (5-FU) and dietary fiber chitosan in sarcoma 180-bearing mice. 5-FU (12.5 mg/kg x 2/day) plus chitosan (150, 375 and 750 mg/kg x 2/day) inhibited the tumor growth as well as 5-FU alone. Chitosan (150 and 750 mg/kg x 2/day) blocked the reduction of blood leukocyte number caused by 5-FU administration, and it prevented the injury of the small intestinal mucosa membrane and delayed the onset of diarrhea induced by 5-FU. Furthermore, chitosan (750 mg/kg x 2/day) prevented the reduction of spleen weight induced by 5-FU in sarcoma 180-bearing mice, and the reduction of lymphocyte and CD8+ T cell numbers induced by 5-FU was also prevented by the oral administration of chitosan (750 mg/kg x 2/day) in C57BL/6 mice. Chitosan (150 and/or 750 mg/kg x 2/day) reduced the 5-FU incorporation into RNA fractions of small intestine and spleen without affecting the 5-FU incorporation into the tumor in sarcoma 180-bearing mice. These findings suggest that prevention of the 5-FU side effects by chitosan might be partly due to the selective inhibition of 5-FU uptake into the small intestine and spleen, resulting in the reduction of immune function toxicity, myelotoxicity and gastrointestinal toxicity of 5-FU. Therefore, it is concluded that the combination of chitosan and 5-FU might be useful for the prevention of side effects such as gastrointestinal toxicity, immunotoxicity and myelotoxicity caused by 5-FU.

Raltitrexed (Tomudex) in combination treatment for colorectal cancer: new perspectives

In recent years, significant advances have been achieved in the treatment of colorectal cancer, including the use of adjuvant chemotherapy following surgery in patients with colon cancer and the use of palliative chemotherapy for metastatic disease. Further potential for improvements in outcome for patients with colorectal cancer is provided by the introduction of new agents in combined treatment modalities. Although some of these new agents, such as raltitrexed, oxaliplatin and irinotecan, are active in colorectal cancer, single-agent therapy as first-line treatment has failed to demonstrate a substantial increase in survival. However, preclinical studies have indicated that combination treatments have the potential benefit of enhanced response rates. One such agent, raltitrexed, is currently under investigation in combination with 5-FU (bolus and infusional), oxaliplatin, cisplatin, irinotecan and anthracyclines, principally in patients with advanced colorectal cancer, but also in patients with other tumours. Similarly, combinations of adjuvant or neo-adjuvant radiotherapy and chemotherapy are being investigated and can offer a benefit in the treatment of rectal, oesophageal, pancreatic and gastric cancer. Promise for the future, therefore, appears to lie in combined treatment modalities which are expected to provide superior alternatives to current standard treatments.