Biochemical modulation of fluorouracil with leucovorin: confirmatory evidence of improved therapeutic efficacy in advanced colorectal cancer

Differential growth inhibition by 5-fluorouracil in human colorectal carcinoma cell lines

The effects of 5-fluorouracil (5-FU) on cell growth were investigated using a primary culture of human fibroblasts, MRC-5, and three established human colon cancer cell lines, DLD-1, LoVo and SW620. Detailed flow cytometric analyses revealed differential growth inhibition among these cell lines including three modes of cell growth modulation: (a) loss or accumulation of S phase cells; (b) G2/M block; and (c) G1-S arrest. From analyses on the amount of 5-FU incorporated into cellular RNA and the activity of thymidylate synthase (TS), suppression of TS and depletion of dTTP, a possible consequence of the former, was considered to be the major action of 5-FU in these cells. Differences in the cellular responses to the nucleotide pool imbalance appeared to make the cell growth modulation diverse. Loss of S phase cells and G1-S phase arrest were evident in p53 wild-type cells, MRC-5 and LoVo. Cells proficient in DNA mismatch repair, SW620 and MRC-5, showed marked modulations in S-G2/M progression. These findings suggest that multiple factors, including p53 and DNA mismatch repair, participate in diverse cell growth modulations in cells treated with 5-FU. Cellular resistance to 5-FU correlated well with a loss of modulations in S-G2/M progression, rather than with a defect of G1-S arrest, which suggests the significance of DNA mismatch repair as a factor affecting the sensitivity of cells to 5-FU.

Risk factors determining chemotherapeutic toxicity in patients with advanced colorectal cancer

Antitumour therapy in advanced colorectal cancer has limited efficacy. For decades, fluorouracil has been the main anticancer drug for the treatment of colorectal cancer. Recently, however, new agents have been introduced: raltitrexed, irinotecan and oxaliplatin. Currently, the dosage for an individual patient is calculated from the estimated body surface area of the patient. Toxicity, however, frequently necessitates decreasing the dosage, extending the dose interval or even discontinuing treatment. Risk factors with predictive value for toxicity have been identified in several studies. These risk factors are often determined by the pharmacokinetic and pharmacodynamic properties of the drug. In this review, the risk factors for toxicity of the cytotoxic agents used in the treatment of advanced colorectal cancer are considered. For fluorouracil, age, gender, performance status, genetic polymorphism of dihydropyridine dehydrogenase, drug administration schedule, circadian rhythm of plasma concentrations, history of previous chemotherapy-related diarrhoea, xerostomia, low neutrophil levels, and drug-drug interactions have been identified as affecting chemotherapeutic toxicity. For raltitrexed, gender and renal and hepatic impairment, and for oxaliplatin, renal impairment and circadian rhythm of plasma concentrations, respectively, can be considered as risk factors for toxicity. In addition, age, performance status, bilirubinaemia, genetic polymorphism of uridine 5'-diphosphate-glucuronyltransferase-1A1 and drug administration schedule have been shown to be related to irinotecan toxicity. The available literature suggests that dose adjustment based on these risk factors can be used to individualise the dose in order to decrease toxicity and to improve the therapeutic index. This also applies to therapeutic drug monitoring, which has been shown to be effective controlling the toxicity of fluorouracil in some studies. Future research is warranted to assess the potential advantage of dose individualisation of chemotherapy founded on risk factors, over direct dose calculation from the estimated body surface area, with regard to toxicity, therapeutic index, and quality of life, in patients with advanced colorectal cancer.

Progress in colorectal cancer chemotherapy: how far have we come, how far to go?

Fluorouracil has been the mainstay of treatment for colorectal cancer (CRC) for almost 40 years. Various schedules and biochemical modulators have been investigated in an attempt to improve the therapeutic efficacy of fluorouracil. To date, fluorouracil plus folinic acid represents the standard therapy in CRC for the adjuvant treatment of patients at high risk for relapse and for the first-line treatment of metastatic disease. To gain clinical acceptance, however, oral fluoropyrimidines must confer at least the same survival advantages associated with the optimal intravenous fluorouracil regimens. Irinotecan and oxaliplatin are 2 other novel agents that have mechanisms of action that are uniquely different from those of fluorouracil, with demonstrated activity in patients with fluorouracil-refractory disease. Recent randomised trials comparing fluorouracil plus folinic acid with combinations of either irinotecan or oxaliplatin and fluorouracil plus folinic acid have shown that response rates are improved and time to progression is increased in patients receiving the combination regimens. These regimens are being rapidly introduced in the adjuvant setting, and the role and acceptance of these combination regimens as first-line therapy needs to be defined. Other novel agents being evaluated in the treatment of patients with advanced CRC include oral edrecolomab (monoclonal antibody 17-1A) and tumour vaccines. Future research is focused on enabling clinicians to individualise treatment strategies in patients with CRC, so as to improve clinical outcomes and reduce drug toxicity.

Basis for effective combination cancer chemotherapy with antimetabolites

Most current chemotherapy regimens for cancer consist of empirically designed combinations, based on efficacy and lack of overlapping toxicity. In the development of combinations, several aspects are often overlooked: (1) possible metabolic and biological interactions between drugs, (2) scheduling, and (3) different pharmacokinetic profiles. Antimetabolites are used widely in chemotherapy combinations for treatment of various leukemias and solid tumors. Ideally, the combination of two or more agents should be more effective than each agent separately (synergism), although additive and even antagonistic combinations may result in a higher therapeutic efficacy in the clinic. The median-drug effect analysis method is one of the most widely used methods for in vitro evaluation of combinations. Several examples of classical effective antimetabolite-(anti)metabolite combinations are discussed, such as that of methotrexate with 6-mercaptopurine or leucovorin in (childhood) leukemia and 5-fluorouracil (5FU) with leucovorin in colon cancer. More recent combinations include treatment of acute-myeloid leukemia with fludarabine and arabinosylcytosine. Other combinations, currently frequently used in the treatment of solid malignancies, include an antimetabolite with a DNA-damaging agent, such as gemcitabine with cisplatin and 5FU with the cisplatin analog oxaliplatin. The combination of 5FU and the topoisomerase inhibitor irinotecan is based on decreased repair of irinotecan-induced DNA damage. These combinations may increase induction of apoptosis. The latter combinations have dramatically changed the treatment of incurable cancers, such as lung and colon cancer, and have demonstrated that rationally designed drug combinations offer new possibilities to treat solid malignancies.

Randomized comparison of prophylactic antidiarrheal treatment versus no prophylactic antidiarrheal treatment in patients receiving CPT-11 (irinotecan) for advanced 5-FU-resistant colorectal cancer: an open-label multicenter phase II study

Delayed diarrhea is the main toxicity of irinotecan at the currently recommended dose of 350 mg/m2 30-minute intravenous infusion, once every 3 weeks. This phase II, multicenter, open-label, randomized study was primarily designed to evaluate the effect of a 15-day Tiorfan (racecadotril) treatment on the incidence and severity of irinotecan-induced delayed diarrhea. One hundred thirty-six patients with metastatic colorectal cancer who failed to respond to a 5-fluorouracil-based treatment received 714 cycles of irinotecan. The patients were randomly allocated either to group A (68 patients) and received Tiorfan (300 mg/day) from D0 to D15 or to group B (68 patients) with no prophylactic treatment. Delayed diarrhea occurred in 197 of 355 cycles (55%) in Group A and 203 of 344 cycles (59%) in Group B. grade III-IV diarrhea was reported in 17 of 40 compliant patients (42%) in group A and 31 of 68 evaluable patients (45%) in group B. No difference was observed between the two groups for delayed diarrhea characteristics, incidence, or severity. The response rate in 99 evaluable patients was 12.1% (6.4%-20.2%). This study has shown that Tiorfan given prophylactically at 300 mg/day has no effect on delayed diarrhea.

Standard dose (Mayo regimen) 5-fluorouracil and low dose folinic acid: prohibitive toxicity?

Despite the perception that standard 5-fluorouracil/folinic acid (5-FU/FA) (425 mg/m2 per day and 20 mg/m2 per day intravenously once daily x 5 every 4 or 5 weeks) is well tolerated, we have been impressed by toxicity seen and frequent need for dose modification. We performed a retrospective analysis to quantitate the proportion of patients experiencing toxicity and attempted to identify associated clinical characteristics. One hundred thirty-four patients received 5-FU/FA at standard doses described by the Mayo regimen. Patient characteristics were as follows: female 35%, median age 66 years, Eastern Cooperative Oncology Group performance status less than or equal to 2, 96%. Sixty-eight percent received chemotherapy for metastatic disease. Forty-seven patients (35%+/-8%) experienced significant toxicity and were unable to receive the second cycle as scheduled: 76% required dose reduction, 11% discontinued therapy (including two toxic deaths), 11% discontinued therapy during the first cycle, and 2% required dose delay. Logistic regression was used to explore the following as predictors of toxicity: age, sex, performance status, adjuvant versus metastatic setting, prior chemotherapy, prior radiation, mean corpuscular volume, red blood cell distribution width, albumin, alkaline phosphatase, aspartate aminotransferase, bilirubin, and calculated creatinine clearance. No clinical characteristic was found to predict toxicity. Only high bilirubin approached statistical significance. We conclude that standard 5-FU/FA, when used in the general population, is associated with significant toxicity. Known clinical characteristics are not helpful in predicting toxicity. The lack of previous formal phase I evaluation of this regimen of 5-FU/FA raises concerns regarding its safety and generalizability in clinical practice.

A dose-escalation phase II clinical trial of infusional mitomycin C for 7 days in patients with advanced measurable colorectal cancer refractory or resistant to 5-fluorouracil

Chemotherapy for 5-fluorouracil (5-FU)-resistant colorectal cancer is largely ineffective with new and innovative therapeutic strategies needed to benefit patients developing progressive disease while receiving 5-FU or 5-FU-based programs. The tumor antibiotic mitomycin C is an alkylating agent with a broad range of clinical activity in a variety of gastrointestinal malignancies and is therefore a reasonable agent to test for clinical activity in the setting of 5-FU-resistant or -refractory colorectal cancer. The principal goal of this study is to investigate the logistical feasibility and clinical efficacy of a 7-day infusion of mitomycin C, delivering an equitoxic dose to the standard bolus delivery in patients with progressive disease while receiving 5-FU-based chemotherapy. Twenty-five patients with advanced measurable colorectal cancer, resistant or refractory to 5-FU-based chemotherapy, were treated with a 7-day intravenous infusion of mitomycin C. Doses ranged between 1.5 and 3.0 mg/M2/day for total cumulative mitomycin C, ranging between 10.5 and 21.0 mg/M2 per chemotherapy cycle. Forty-four courses of infusional mitomycin C were delivered to 25 patients via surgically implanted venous access devices. The median age of all patients was 63 years (range, 27-83); there were 11 men and 14 women. Eleven patients had received two or more prior chemotherapy combinations, with the average number of prior therapies before mitomycin C being 1.6. The median number of cycles of mitomycin C administered was two (range, one to six). Thirty-seven of 44 cycles were administered at the dose range of 2.0-3.0 mg/M2/day. Hematologic toxicity was mild, with only three courses associated with grade III thrombocytopenia and one course with grade III neutropenia. No extrahematologic toxicities were observed. No patient had a complete response; two patients (8%) showed partial responses that lasted for 145 and 190 days. One patient had stable disease for 180 days. Twenty-two of 25 patients (88%) developed progressive disease during mitomycin C administration. Infusional mitomycin C for 7 days, cycled every 42 days, is logistically feasible and associated with minimal clinical toxicity. Used on this schedule and with these doses in 5-FU-resistant/refractory colorectal cancer, however, there is no meaningful clinical activity for this agent, and it cannot be recommended as a salvage or second-line therapy in the treatment of metastatic colorectal cancer.

Oral fluoropyrimidines: a closer look at their toxicities

Patient preferences, quality of life issues, and economic considerations are driving the development of orally administered chemotherapy. Oral fluorinated pyrimidines, which have been used in Japan, are attracting increasing interest as a means to provide convenient, less toxic treatment without compromising efficacy. The oral fluoropyrimidines provide prolonged 5-fluorouracil (5-FU) exposure at lower peak concentrations than those observed with bolus intravenous administration. Moreover, depending on the dose schedule, the pharmacokinetics of the oral fluoropyrimidines may mimic the pharmacokinetics of continuous-infusion 5-FU. This review focuses on the toxicity profiles of five emerging oral fluoropyrimidine antineoplastic drugs: combined uracil and tegafur (UFT), capecitabine, eniluracil, S-1, and emitefur (BOF-A2). Different patterns of toxicities emerge from an analysis of the clinical trials of these agents relative to 5-FU administered as an intermittent intravenous bolus or as continuous infusion. The results of ongoing phase III trials comparing the oral fluoropyrimidines with conventional regimens of 5-FU plus leucovorin and 5-FU by continuous intravenous infusion are necessary before their therapeutic role in the management of colorectal carcinoma can be defined.

5-fluorouracil-induced small bowel toxicity in patients with colorectal carcinoma

BACKGROUND

Diarrhea and oral mucositis are the most frequently reported gastrointestinal side effects caused by 5-fluorouracil (5-FU). Diarrhea may be severe in 10-30% of patients and is schedule-dependent. 5-FU-induced gastrointestinal toxicity predominantly affects the upper and the lower gastrointestinal tract. The current study describes 5-FU-induced small bowel toxicity as an entity that to the authors' knowledge has not been reported previously in patients with colon carcinoma receiving 5-FU-based therapy.

METHODS

The authors report a series of six patients with colorectal carcinoma who developed acute small bowel toxicity after treatment with 5-FU and leucovorin.

RESULTS

Six patients developed a clinical picture of acute abdominal pain and diarrhea. Small bowel damage was documented by laparotomy in two patients, by colonoscopy in one patient, and by abdominal computed tomography scan in three patients. The course was complicated by recurrence of symptoms in one patient who was rechallenged with 5-FU and leucovorin, but the remaining four patients were rechallenged safely with lower doses of 5-FU and leucovorin after the acute toxicity episode. A possible explanation for this toxicity is 5-FU-induced vasospasm and/or decrease in fibrinolytic activity that results in decreased mucosal blood flow.

CONCLUSIONS

5-FU-induced small bowel toxicity is a potentially severe toxicity that may occur in patients with colon carcinoma or other malignancies who are receiving 5-FU-based therapy. [See editorial on pages 1099-100, this issue.]

Phase II study of radiochemotherapy with UFT and low-dose oral leucovorin in patients with unresectable rectal cancer

PURPOSE

To determine the activity and evaluate the toxicity of uracil and tegafur in a 4:1 molar concentration (UFT) plus low-dose leucovorin administered concomitantly with pelvic irradiation in patients with unresectable or recurrent rectal cancer.

METHODS AND MATERIALS

Thirty-five patients (22 with primary unresectable tumors and 13 with locally recurrent tumors) were enrolled in the trial. Thirty-five patients were evaluable for toxicity and 32 of these were evaluable for clinical response. Patients received 300 mg/m2/day UFT and 30 mg/day leucovorin on days 8-35 concomitantly with pelvic radiotherapy, to a total dose of 45 Gy.

RESULTS

Eight of the 35 (23%) patients developed Grade 3 diarrhea and were treated with radiotherapy alone after this event. Of the 22 patients with unresectable primary tumors, 17 underwent surgery, and resection was feasible in 15 cases (88%). Of the 32 patients evaluable for clinical response, 4 (13%) had a complete clinical response (CR) and 22 (69%) a partial response (PR). A complete pathologic response was observed in 3 cases (18%) and, a PR in 11 cases (65%).

CONCLUSION

The response rates achieved with this schedule seem comparable to those obtained with 5-FU and radiotherapy. These results warrant further evaluation of this combination in patients with unresectable or locally advanced tumors.

Raltitrexed (Tomudex) in combination with 5-fluorouracil for the treatment of patients with advanced colorectal cancer: preliminary results from phase I clinical trials

The potential of raltitrexed (Tomudex) in combination with 5-fluorouracil (5-FU) as treatment for advanced colorectal cancer has been investigated in two phase I clinical trials. In the first study, raltitrexed was combined with bolus 5-FU; patients received raltitrexed as a 15-min infusion followed 24 h later by bolus 5-FU every 3 weeks. In the second study, 5-FU was administered as a weekly 24-h infusion for 5 weeks of a 6-week cycle and raltitrexed was given 15-min prior to 5-FU on days 8 and 29. The recommended dose for bolus 5-FU in combination with raltitrexed is likely to be 1200 mg/m2 as dose-limiting toxicity (DLT) of febrile neutropenia was observed at 1350 mg/m2, but escalation of raltitrexed above the dose used for single-agent use (3.0 mg/m2) continues. In the raltitrexed/infusional 5-FU study, dose escalation is also still continuing, but only in men as no DLT has been observed in men; 2 of 3 female patients had DLT of myelosuppression and diarrhoea at raltitrexed 3.0 mg/m2 and infusional 5-FU 2400 mg/m2. Raltitrexed had a significant effect on the pharmacokinetics of 5-FU irrespective of 5-FU regimen. Preliminary response data is encouraging with 53% of patients receiving raltitrexed/infusional 5-FU showing a partial response. In addition, significant disease stabilisation was observed in patients receiving raltitrexed combined with bolus 5-FU who had previously failed 5-FU therapy. Recruitment has recently commenced in two studies in which raltitrexed is combined with oral derivatives of 5-FU. In conclusion, preliminary data from these phase I studies indicate that the combination of raltitrexed and 5-FU is well tolerated and has encouraging clinical activity.

Combination of raltitrexed with other cytotoxic agents: rationale and preclinical observations

Agents for use in combination therapy should be effective as monotherapy in the tumour type of interest, have different mechanisms of action or pharmacology, and preferably non-overlapping toxicity profiles. Raltitrexed is effective as monotherapy in a number of tumour types, but it is hoped that combining it with other cytotoxic agents will lead to enhanced efficacy. Raltitrexed and 5-fluorouracil (5-FU) are specific and non-specific inhibitors, respectively, of thymidylate synthase, a critical enzyme in the de novo synthesis of DNA. Preclinical studies have indicated that raltitrexed and 5-FU have an incompletely overlapping spectrum of antitumour activity and may have additive or synergistic effects on colon carcinoma cells. These interactions are schedule-dependent (raltitrexed should precede 5-FU). Pre-treatment of colon carcinoma cells with raltitrexed has also been shown to increase intracellular levels of phosphoribosyl pyrophosphate resulting in increased incorporation of 5-FU nucleotides into RNA. Raltitrexed has a different mechanism of action from two other new agents active in colorectal cancer, irinotecan and oxaliplatin, and tumours are therefore not necessarily cross-resistant. Short pre-exposure of colon carcinoma cells to the irinotecan active metabolite, 7-ethyl-10-hydroxy-camptothecin (SN-38), prior to exposure to raltitrexed has consistently resulted in synergistic cell kill, whereas the reverse sequence is antagonistic. Preliminary results indicate that equitoxic doses of raltitrexed and cisplatin, or oxaliplatin, are antagonistic in two colon carcinoma cell lines. However, because there are major difficulties in translating preclinical drug combination results to the clinical settings, these results should be interpreted with caution.

Treatment of colorectal liver metastases

BACKGROUND

Surgical resection is the only potentially curative treatment for colorectal liver metastases, with 5-year survival rates approaching 40 per cent. However, at present only 20-25 per cent of such lesions are deemed resectable. This review examines developments in neoadjuvant and adjuvant treatments of colorectal liver metastases that aim to improve the results of surgical management of this disease.

METHODS

A literature review was undertaken based on a Medline search from 1970 to May 1998.

RESULTS

Further evolution in surgical technique is unlikely to lead to a dramatic increase in the resectability rate of colorectal liver metastases. Recent developments in neoadjuvant and adjuvant chemotherapy schedules, together with a range of interventional radiological procedures and interstitial lytic techniques, show promise in terms of extending the limits of resectability and decreasing recurrence rates associated with these lesions. Using multimodality regimens 5-year survival rates of 40 per cent are now being reported for lesions that were initially considered irresectable.

CONCLUSION

Patients with colorectal liver metastases should be assessed in units that can offer all the specialist techniques necessary to deliver optimum care. Incorporation of newer neoadjuvant and adjuvant treatments into management strategies should occur in the setting of randomized trials.

Haematological and non-haematological toxicity after 5-fluorouracil and leucovorin in patients with advanced colorectal cancer is significantly associated with gender, increasing age and cycle number. Tomudex International Study Group

5-Fluorouracil (5-FU) has been widely used for over 30 years. Recently, investigators have described interactions between toxicity with 5-FU and age and gender. Pharmacokinetics of infusional 5-FU are known to be gender dependent, with drug clearance being lower in females. The full impact of age and gender on both toxicity and response has not been fully explored and is worthy of further investigation. 439 patients were entered into a phase III trial comparing a novel thymidylate synthase (TS) inhibitor Tomudex (raltitrexed, formerly ZD1694) with 5-FU and leucovorin (LV) for the treatment of advanced colorectal cancer. Approximately 20-24% of patients in each treatment group were aged 70 years or older and 41% of the patients were female. In a multiple regression analysis, female patients receiving 5-FU + LV experienced significantly more grade 3/4 leucopenia, whilst those receiving raltitrexed had more rises in transaminase levels. Grade 3/4 leucopenia and mucositis were significantly correlated with age (especially > 70 years) only in patients receiving 5-FU + LV. Patients receiving 5-FU + LV were significantly more at risk of experiencing grade 3/4 haematological and non-haematological toxicity in the first three cycles than patients receiving raltitrexed. Female gender and increased age predict for increased grade 3/4 toxicity in patients receiving modulated 5-FU. Further studies with modulated 5-FU which utilise a modified dose reduction schema for female patients, or patients aged 70 years or over, may be appropriate.

Resection of both hepatic and pulmonary metastases in patients with colorectal carcinoma

BACKGROUND

More than 40% of patients who undergo curative resection of advanced colorectal carcinoma can be expected to have recurrence of the disease. The most frequent sites of recurrence are the liver (33% of patients) and lung (22%). Interest has therefore focused on treating hepatic or pulmonary metastases, or both, to improve the outcomes of these patients. Although surgical resection has become an increasingly accepted treatment for resectable localized hepatic or localized pulmonary metastases from colorectal carcinoma, the value of aggressive surgery for the removal of both hepatic and pulmonary metastases from patients with primary colorectal carcinoma remains to be clarified.

METHODS

Data on 30 patients who had undergone resection of both hepatic and pulmonary metastases from colorectal carcinoma were included in the study.

RESULTS

Independent, significant prognostic features were found to be the time that hepatic or pulmonary metastases occurred and the distribution of pulmonary metastases. Median survival times were 30 months (range, 7-108 months) after resection of both hepatic and pulmonary metastases and 48.5 months (range, 11-149 months) after excision of the primary colorectal tumor. Actuarial 1-, 3-, and 5-year survival after resection of both hepatic and pulmonary metastases was 86.7%, 49.3%, and 43.8%, respectively. No perioperative mortality occurred. There were three cases of minor morbidity, which the authors considered acceptable.

CONCLUSIONS

Resection of both hepatic and pulmonary metastases from colorectal carcinoma may help to prolong the survival of a small group of patients with these metastases.

Randomized trial comparing monthly low-dose leucovorin and fluorouracil bolus with weekly high-dose 48-hour continuous-infusion fluorouracil for advanced colorectal cancer: a Spanish Cooperative Group for Gastrointestinal Tumor Therapy (TTD) study

PURPOSE

The objective of this multicenter study was to compare the efficacy and toxicity profiles of a combination of 5-fluorouracil (5-FU) given by bolus injection together with intravenous leucovorin (LV) versus high-dose 5-FU in continuous infusion (CI) in the treatment of advanced colorectal cancer.

PATIENTS AND METHODS

A total of 306 patients were randomized to receive either 5-FU 425 mg/m2 given by bolus injection on days 1-5 plus intravenous (i.v.) LV 20 mg/m2 every four to five weeks or 5-FU 3.5 g/m2/week in a 48-hour CI. Therapy was continued until disease progression. Second-line chemotherapy was allowed in both arms.

RESULTS

The response rates in 306 patients with measurable lesions were 19.2% (modulated arm) and 30.3% (CI arm, P < 0.05). The median progression-free survival times were 23.5 weeks (modulated arm) and 25 weeks (CI arm, P = NS). Median survival times were 42.5 weeks (modulated arm) and 48 weeks (CI arm, P = NS). There were no significant differences in grade 3-4 toxicity profiles but if we consider all grades we observed more mucositis in the modulated arm and more hand-foot syndrome in the CI arm.

CONCLUSIONS

In terms of response rate, the continuous infusion regimen was more effective than the modulated regimen. There was no significant difference in survival and time to progression, and none in grade 3-4 toxicity.

A prospective randomized study comparing high- and low-dose leucovorin combined with same-dose 5-fluorouracil in advanced colorectal cancer

Although the efficacy of 5-fluorouracil (5-FU) modulated by leucovorin is well established for advanced colorectal cancer, the question of the most effective regimen and optimal dose of leucovorin remains unanswered. This prospective randomized trial compares low-dose (group 1) and high-dose (group 2) leucovorin, combined with the same dose of 5-FU to determine whether high-dose leucovorin was more beneficial than low-dose on overall survival. Inclusion criteria were: unresectable metastatic colorectal carcinoma, with or without evaluable tumor response; a performance status of less than grade 3 (World Health Organization classification); and no previous chemotherapy for metastases. Forty-two patients were randomized in group 1 (leucovorin, 20 mg/m2/day, days 1 through 5) and 41 patients in group 2 (leucovorin, 200 mg/m2/day, days 1-5). All the patients in the two groups received a 1-hour infusion of 400 mg/m2/day 5-FU every 4 weeks. The two groups were matched with no statistically significant differences in gender ratio, site of primary tumor, performance status, and tumor extent. Toxicity in the two regimens was low and not significantly different between the two groups. Overall median survival was 346 days in group 1 and 323 days in group 2 and was not significantly different between the two groups. At 1 year, the test of equivalence was significant (p < 0.01), demonstrating an absence of more than 20% benefit in 1-year survival for the high-dose regimen. The use of high-dose leucovorin combined with 5-FU in the 5-day regimen does not significantly improve overall survival for patients who have metastatic colorectal cancer.

Biomodulation of Fluorouracil in colorectal cancer

5-Fluorouracil (5-FU) remains the agent of choice for the treatment of colorectal cancer. Research has focused on the biomodulation of 5-FU in order to attempt to improve the cytotoxity and therapeutic effectiveness of this drug in the treatment of advanced colorectal cancer. Modulation of 5-FU by methotrexate (MTX), trimetrexate (TMTX), interferon-alpha (IFN-alpha), leucovorin (LV), or N-(phosphonacetyl)-L-asparte acid (PALA) has produced higher response rates than those observed with 5-FU alone. Methotrexate may improve the durability of response to or survival with 5-FU, but with inferior results compared with those in trials of 5-FU and leucovorin. Trimetrexate produces a number of responses, and further phase III trials are in progress to confirm the results of promising phase II trials with this drug. IFN-alpha has shown therapeutic efficiency when combined with 5-FU alone or with 5-FU and leucovorin, but latest studies with these combinations have shown increased toxicity. Initial single-institution phase I trials with 5-FU and PALA reported promising responses, but the latter responses with PALA were not substantiated in randomized multicenter trials. Leucovorin enhances the cytotoxic activity of 5-FU in vitro and in vivo, and several clinical trials have shown improved response rates and possible trends in improved survival when such therapy is compared with the use of 5-FU as a single-agent. More recent randomized trials have focused their attention on determining the optimal dose and schedule with this combination for producing a better clinical response with minimal toxicity. Schedules using infusional 5-FU appear to be the most active regimens when 5-FU is used as a single agent, as demonstrated by recent randomized trials. The Southwest Oncology Group (SWOG) and the Eastern Cooperative Oncology Group (ECOG) have performed separate randomized trials and have shown that the optimal regimens employ infusional 5-FU as a single agent, and that these are the least toxic regimens, perhaps more effective, and associated with a better quality of life. Future studies will focus on infusional regimens involving either short-term, high-dose protracted or long-term, low-dose protracted infusion of 5-FU, since these regimens have shown the most favorable toxicity spectrum and produced the longest survival times. Future research will also focus on the evaluation of various methods of delivery of 5-FU, including oral administration of the drug in combination with compounds that can modify its catabolism.

The impact of adding low-dose leucovorin to monthly 5-fluorouracil in advanced colorectal carcinoma: results of a phase III trial. Swiss Group for Clinical Cancer Research (SAKK)

PURPOSE

A wide variety of fluorouracil (FU)-plus-leucovorin (LV) dose schedules are in clinical use for the treatment of advanced colorectal cancer. Only the monthly low-dose LV-plus-FU regimen, as used by the North Central Cancer Treatment Group, has demonstrated a lasting survival benefit as opposed to FU alone (J Clin Oncol 1989; 7: 1407-1417). The Swiss Cancer Group adopted this regimen for a confirmatory phase III trial but used the same dose-intensity of fluorouracil in both treatment arms.

PATIENTS AND METHODS

Patients with inoperable or metastatic colorectal cancer were randomized to receive monthly FU 400 mg/m2/day plus LV 20 mg/m2/day as intravenous push daily for five days, or FU alone.

RESULTS

Three hundred nine of the 310 patients randomized were eligible and included in the analysis. The objective response rate for patients with measurable disease was 9% with FU alone and 22% with FU-plus-LV (P = 0.0001). The median progression-free survival was 3.9 versus 6.2 months (P = 0.003) and the overall survival 10 versus 12.4 months (P = 0.02). The major prognostic factors for survival were performance status, weight loss, and disease symptoms. WHO > 2 toxicity, consisting of stomatitis (P = 0.001), diarrhea (P = 0.001), and nausea (P = 0.001), was more pronounced for FU-plus-LV, without fatal events.

CONCLUSIONS

This is the largest published randomized trial to compare FU-plus-LV to FU alone in advanced colorectal cancer. It confirms the survival benefit obtained from biomodulating monthly FU with low-dose LV. The toxic effects of FU-plus-LV were acceptable to most patients, and they responded well to FU dose reductions. In the absence of an ideal dose-intense FU monotherapy regimen, monthly FU with low-dose LV provides a simple and economical means by which to achieve adequate FU efficacy in the treatment of advanced colorectal cancer.

Phase I trial of uracil-tegafur (UFT) plus oral leucovorin: 28-day schedule

UFT [Taiho Pharmaceutical Co. Ltd., Tokyo, Japan; (BMS-200604), Bristol-Myers Squibb, Princeton, NJ], a fluorouracil prodrug, is an oral 4:1 molar concentration of uracil plus tegafur. This study examined the dose-limiting toxic effects and maximum tolerated dose of UFT plus leucovorin administered for 28 consecutive days followed by a 7-day rest period. A course of therapy was repeated every 35 days. UFT dose levels examined were 200 mg/m2/day, with planned escalations to 250, 300, 350, and 400 mg/m2/day; the leucovorin dose remained at 150 mg/day. Three patients were initially enrolled at each UFT dose level. The total daily doses of both UFT and leucovorin were divided into three doses administered every 8 hr. Diarrhea became the dose-limiting toxicity at 400 mg/m2/day UFT, with grade 3 diarrhea noted in 2 of the 3 patients receiving that dose. To further define a phase II UFT starting dose, 3 additional patients were entered at the 350 mg/m2 level; 3 of the 6 patients treated at this level developed grade 3 nonhematological toxic effects. No partial or complete responses were observed. The recommended phase II UFT starting dose is 300 mg/m2/day plus 150 mg/day leucovorin. Since neutropenia, significant mucositis, and "hand-foot syndrome" were not observed with UFT plus leucovorin, the toxicity profile of this regimen appears favorable compared with that of intravenous regimens of fluorouracil plus leucovorin. This phase I trial of UFT served as the basis for a phase II trial, current phase III trials, and a national adjuvant therapy trial of UFT for high-risk colon cancer patients.

Bolus injection (2-4 min) versus short-term (10-20 min) infusion of 5-fluorouracil in patients with advanced colorectal cancer: a prospective randomised trial. Nordic Gastrointestinal Tumour Adjuvant Therapy Group

The use of bolus 5-fluorouracil (5-FU) as a short-term infusion over 10-30 min is increasing at the cost of a push injection, mainly due to practical advantages. Since even a short prolongation of the administration time results in lower 5-FU peak and area under the curve (AUC) levels, there might be a risk of decreased efficacy. The aim of this study was to compare a rapid intravenous (i.v.) 5-FU injection and a short-term 5-FU infusion with respect to objective responses and toxicity in patients with advanced colorectal cancer. 203 patients with measurable advanced colorectal cancer were randomised to bolus 5-FU either as an injection for 2-4 min or as a short-term infusion lasting 10-20 min. In both groups, the 5-FU dose was 500 mg/m2 and leucovorin 60 mg/m2 was given 40 min after the start of 5-FU. Treatment was given on two successive days every other week until progression. Objective tumour regression was seen in 27/100 (27%) in the injection group and in 13/103 (13%) in the infusion group (P = 0.02). Severe toxicity was rare and did not differ significantly between the groups. Progression-free survival tended to be longer in the injection group (P = 0.07), but overall survival did not differ between the groups. Bolus 5-FU should be administered as a rapid i.v. injection rather than as a short-term infusion, since the former rate of administration results in a higher response rate without being significantly more toxic.

A review of GERCOD trials of bimonthly leucovorin plus 5-fluorouracil 48-h continuous infusion in advanced colorectal cancer: evolution of a regimen. Groupe d'Etude et de Recherche sur les Cancers de l'Ovaire et Digestifs (GERCOD)

The addition of leucovorin (LV) to 5-fluorouracil (5-FU) in advanced colorectal cancer has shown improved tumour response rates in many trials, but the optimal LV/5-FU regimen has yet to be determined. Seven studies carried out over the last 12 years to evaluate the safety and efficacy of various LV/5-FU regimens are reviewed. The initial bimonthly high-dose LV/5-FU regimen consisted of high-dose LV as a 2-h infusion followed by 5-FU as an intravenous (i.v.) bolus plus a 22-h continuous infusion (CI), repeated for two consecutive days every 2 weeks. A randomised comparison of this bimonthly high-dose LV/5-FU regimen and the NCCTG-Mayo Clinic regimen (LV [20 mg/m2/day] followed by 5-FU bolus [425 mg/m2/day] daily x 5, every 4 weeks) showed that the bimonthly high-dose LV/5-FU regimen was superior to the NCCTG-Mayo Clinic regimen in response rate and progression-free survival, but showed no difference in overall survival. In addition, toxicity was less with the bimonthly high-dose LV/5-FU regimen. These promising results led to a phase II trial of a simplified bimonthly high-dose LV/5-FU regimen consisting of LV (500 mg/m2/day) and a 48-h CI of 5-FU (1.5-2 g/m2/day) which has been administered alone or in combination. In summary, GERCOD-sponsored studies have further demonstrated that high doses of both LV and 5-FU given as a CI can improve response rates still more with acceptable toxicity. Further studies are focused on the effectiveness of combination with oxaliplatin or CPT-11 in metastatic disease and the use of high-dose LV/5-FU regimens for colorectal cancer in the adjuvant setting.

[Oxaliplatin, folinic acid and 5-fluorouracil (folfox) in pretreated patients with metastatic advanced cancer. The GERCOD]

Preliminary studies suggest synergy between oxaliplatin and fluorouracil (5-FU). To assess this issue, we performed a study in pretreated patients with advanced colorectal cancer (CRC) resistant to leucovorin and 5-FU. Regimen consisted of oxaliplatin day 1, 130 mg/m2 every two cycles (folfox 1) or 100 mg/m2/cycle (folfox 2) or 85 mg/m2/cycle (folfox 3) and leucovorin 500 mg/m2 as a 2-hour infusion, followed by 5-FU 22 h infusion 1.5-2 g/m2 for two consecutive days every 2 weeks. One hundred and thirteen patients have been treated. One complete response (CR) and 32 partial responses (PRs) were observed for an overall response rate of 29.2%. Sixty-seven patients had prior documented progression while receiving the same schedule of leucovorin and 5-FU than the one used in the folfox regimens, among them 18 had PRs (26.9%). The best response rate was observed in patients treated with the folfox 2 regimen: 41.7%. From start of folfox, median progression-free survival was 6 months and median survival 13 months. Limiting toxicities were peripheral neuropathy and neutropenia. Fifty-four percent of the patients experienced WHO toxicity > or = grade 3 with the folfox1 regimen, 45% with the folfox2 and 40% with the folfox3. The folfox regimens achieve a high response rate in pretreated patients with CRC. Further studies are needed to determine the best oxaliplatin dose-intensity.

Double modulation of 5-fluorouracil by methotrexate and high-dose L-leucovorin in advanced colorectal cancer

A phase II trial was performed to evaluate the efficacy and toxicity of a double modulation of 5-fluorouracil (5-FU) by methotrexate (MTX) and L-leucovorin (L-LV) in patients with advanced recurrent (inoperable) or metastatic colorectal carcinoma (ACC). Between July 1993 and October 1995, 41 patients with ACC received a regimen that consisted of MTX 150 mg/m2 i.v., infused over a 20-minute period at hour 0, followed 19 hours later by L-LV 250 mg/m2 in a 2-hour i.v. infusion. 5-FU, 900 mg/m2, was administered by i.v. push injection at hour 20. Beginning 24 hours after MTX administration, all patients received four doses of L-LV, 15 mg/m2 i.m., every 6 hours. Cycles were repeated every 15 days. Two patients were not assessable for response. Objective regression was observed in 11 of 39 (28%) patients, [95% confidence interval (CI), 14-42%]. One (2%) patient achieved complete response (CR) and 10 (26%) partial response (PR). No change was recorded in 15 (39%) patients and progressive disease was noted in 13 (33%) patients. The median time to treatment failure was 6 months and the median survival time was 10 months. Toxicity was within acceptable limits, but one therapy-related death due to severe leukopenia was observed. The dose-limiting toxicity was mucositis. Eight episodes of grade 3 or 4 stomatitis were observed, and were responsible for dosage modifications of MTX and 5-FU. In conclusion, further in experimental and clinical studies are clearly necessary in order to design the best modulatory strategy of 5-FU.

Phase II trial of 5-fluorouracil and high-dose leucovorin in recurrent adenocarcinoma of the cervix: a Gynecologic Oncology Group study

OBJECTIVE

The objective of the study was to determine the response rate and associated toxicity of 5-fluorouracil and high-dose leucovorin in patients with recurrent adenocarcinoma of the cervix.

METHODS

Between December 1993 and October 1995, 53 patients with recurrent adenocarcinoma of the cervix were entered into a Phase II trial utilizing 200 mg/m2 of intravenous (iv) leucovorin with 370 mg/m2 of i.v. 5-fluorouracil daily for 5 days every 4 weeks for two courses, then every 5 weeks until disease progression. Eligibility criteria were a Gynecologic Oncology Group (GOG) performance status of 0-2, adequate bone marrow reserve, adequate liver function with bilirubin < or = 1.5 x normal and SGOT and alkaline phosphatase < or = 3 x normal, serum creatinine < or = 2 mg%, and signed informed consent. Standard GOG toxicity and response criteria were employed.

RESULTS

Six patients were ineligible because of wrong cell type (N = 3), insufficient pathology materials (N = 2), or a second primary (N = 1); therefore 45 were evaluable for toxicity. Two patients did not have adequate response assessment; thus, 43 were evaluable for response. The median age was 50 (range, 28-79). Prior chemotherapy had been administered to 16 patients and radiotherapy to 40 patients. The median number of courses delivered was three (range, 1-22). The site of evaluable disease was pelvic in 25 patients and extra-pelvic in 18. Grade 3 neutropenia was seen in 17.8% (8/45) patients and 35.5% (16/45) developed grade 4 neutropenia. Grade 3 or 4 thrombocytopenia was seen in 1 patient each (2.1%). Grade 3 gastrointestinal toxicity with nausea, vomiting, diarrhea, dehydration, or stomatitis was of grade 3 severity in 11.1% (5/45) and grade 4 in 6.7% (3/45). There were four partial responses and two complete responses for an overall response rate of 14%. The duration of the complete responses was 17.3 and 8.8+ months. None of the patients with responses had previously received chemotherapy.

CONCLUSION

The schedule of 5-fluorouracil and leucovorin exhibits moderate activity in patients with previously treated adenocarcinoma of the cervix and should be considered for a trial in chemotherapy-naive patients.

[Modulation of 5-fluorouracil with folinic acid in advanced colorectal cancers. Groupe d'étude et de recherche sur les cancers de l'ovaire et digestifs (GERCOD)]

The rational of leucovorin modulation of 5-fluorouracil and the clinical results in colorectal cancer are reviewed with special emphasis on the monthly schedule of low dose leucovorin and 5FU bolus for 5 consecutive days (NCCTG-Mayo Clinic regimen) and the bimonthly schedule of high-dose leucovorin and 5FU bolus plus continuous infusion for two consecutive days (LV5FU2) which is now considered as a new standard.

9-Aminocamptothecin by 72-hour continuous intravenous infusion is inactive in the treatment of patients with 5-fluorouracil-refractory colorectal carcinoma

BACKGROUND

9-Aminocamptothecin (9AC) and its parent compound, camptothecin, have shown outstanding preclinical activity against colorectal carcinoma. Irinotecan (CPT-11), another camptothecin derivative, has demonstrated clinical activity in patients with 5-fluorouracil (5-FU)-refractory colorectal carcinoma.

METHODS

The authors performed a Phase II trial of 9AC involving patients with measurable metastatic colorectal carcinoma who had progressed through only one prior regimen of 5-FU-based chemotherapy. 9AC was given initially at a dose of 59 microg/m2/hour by continuous intravenous infusion for 72 hours, with treatments repeated every 14 days. Granulocyte-colony stimulating factor was given on Days 5-12.

RESULTS

Sixteen patients were treated on this trial. Fourteen were evaluable for response. Contrary to expectations, no major objective antitumor responses were observed. Eight patients experienced stable disease for a median of 4.1 months (range, 2.2-9.5 months). Toxicities, especially myelosuppression, were severe and necessitated a 15% reduction in the initial dose after the first 9 patients. Toxicities at this reduced dose remained unacceptable.

CONCLUSIONS

9AC did not demonstrate substantial activity against 5-FU-refractory colorectal carcinoma on the schedule studied. Toxicities at the doses and schedule studied were unacceptable in this patient population. Based on their results, the authors consider it unlikely that 9AC administered as a 72-hour continuous intravenous infusion will play a major role in the treatment of colorectal carcinoma.

Management of hepatic metastases from colorectal cancer: systemic chemotherapy

The current phase III studies of chemotherapy in advanced colorectal cancer include 60% to 85% of patients with the liver as a site of metastatic disease. Within the past 10 years, various modulatory combinations of 5-fluorouracil (5-FU) with agents such as leucovorin, interferon, N-(phosphonacetyl)-L-aspartate (PALA), and methotrexate have produced higher response rates than 5-FU alone. A major seven-arm study, conducted by the Southwestern Oncology Group and reported in 1995, suggested that single-agent, continuous-infusion 5-FU demonstrated the most encouraging results. Nine of 12 reported randomized studies comparing the combination of 5-FU and leucovorin with 5-FU alone report significant increases in response rates; two studies reported significant increases in survival. The meta-analysis project involving 1381 patients confirmed the increase in response rate with the combination (23%) vs. 5-FU alone (11%) but did not demonstrate any significant difference in median survival. The current issues involving 5-FU administration largely concentrate on the best approach (modulation vs. scheduling) and comprehensive evaluation of end points (quality of life, survival, and pharmacoeconomics). The current literature examining quality-of-life issues suggests that 5-FU and low-dose leucovorin produce the best overall improvement in symptoms. Others argue that continuous-infusion scheduling is also associated with a very good quality of life (although the increased cost and morbidity of continuous-infusion administration has to be factored into this consideration). An important phase III study is currently being conducted by the National Cancer Institute of Canada comparing immediate vs. delayed (until symptomatic) chemotherapy in patients with advanced colorectal cancer. Of the new approaches to therapy, perhaps the most immediately applicable are the new thymidylate synthase inhibitors (in particular, Tomudex, which produces a response rate equivalent to that of 5-FU plus leucovorin with less toxicity and a more convenient schedule).

The need for a multidisciplinary approach in the treatment of advanced colorectal cancer: a critical review from a medical oncologist and surgeon

Over the last 10 years important advances have been made in the treatment of patients with advanced colorectal cancer, particularly with surgery either alone or in combination with radiotherapy. Furthermore, despite early scepticism, several chemotherapy studies have now reported significant clinical benefits with 5-FU-based regimens and promising results have also been reported with newer agents such as raltitrexed and irinotecan. Taken together these advances now enable a significant proportion of patients to undergo treatment which will improve their quality of life, prolong survival and even result in cure in certain cases. Patients with advanced colorectal cancer can only benefit from these important advances, however, if a truly multidisciplinary approach to patient care is adopted which requires integration of the roles of the surgeon, medical oncologist and radiotherapist.

A comprehensive review of 5-fluorouracil and leucovorin in patients with metastatic colorectal carcinoma

BACKGROUND

Colorectal carcinoma is the third leading cause of cancer-related death. The primary treatment for patients with metastatic colorectal carcinoma is systemic chemotherapy with 5-fluorouracil (5-FU) and leucovorin (LV), a biomodulator of 5-FU that has been shown to enhance its activity. Optimal dosing and administration strategies remain to be determined.

METHODS

This article is a review of recent studies reporting on the use of high dose and low dose LV as a biomodulator of 5-FU in patients with advanced colorectal carcinoma.

RESULTS

Studies of LV plus 5-FU demonstrated response rates of 7-58% in patients who had not received prior chemotherapy. A survival advantage was recorded in some trials. LV plus 5-FU produces mild and transient hematologic toxicity. The most common toxicities from LV plus 5-FU were gastrointestinal and schedule-dependent, but generally resolved within a few days.

CONCLUSIONS

The combination of LV and 5-FU provides a favorable treatment regimen for patients with metastatic colorectal carcinoma. Growing evidence suggests that altering the dose and schedule of both LV and 5-FU can impact positively on the response rate. However, controversy remains regarding the optimal dosing regimen. Therefore, continued study of LV plus 5-FU is urged and a favorable impact on survival is requisite before definitive conclusions are drawn, particularly in relation to LV dosage.

Gastrointestinal Tract Cancer Liaison Office: an attempt to organise clinical research in Europe

The Gastrointestinal Tract Cancer Liaison Office (GITCLO) was developed in an attempt to organise the increasing body of clinical research in gastrointestinal tumours in Europe. This paper represents an analysis, by tumour localisation, of the trials collected for the second edition of the GITCLO booklet. The list of cooperative groups, chairmen and study coordinators is given with their respective telephone and telefax numbers. A total of 84 trials were collected, conducted by 46 co-operative groups in 14 countries. For each organ and stage of disease, a summary of concepts investigated is given with the references of the study co-ordinator. Obviously, too many questions are raised at the same time. In colorectal cancer, for example, a total of 41 trials exploring 22 concepts are currently open for patients' registration. We hope that the present attempt to clarify the situation of clinical research in the field of gastrointestinal cancers in Europe will speed up therapeutic progress in the best interest of the patients.