Prospective randomized comparison of fluorouracil versus fluorouracil and high-dose continuous infusion leucovorin calcium for the treatment of advanced measurable colorectal cancer in patients previously unexposed to chemotherapy

Phase II trial of 5-fluorouracil and the natural l isomer of folinic acid in the treatment of advanced colorectal carcinoma

Between February 1991 and July 1992, 79 previously untreated patients with metastatic colorectal carcinoma were enrolled in a phase II study of combined 5-fluorouracil (5-FU) and l-folinic acid (FA). 5-FU 370 mg/m2/day was administered for 5 consecutive days as an intravenous (i.v.) bolus injection preceded by l-FA 100 mg/m2/day with the same administration modality. Treatment was given every 4 weeks until progression. 79 patients were evaluable for toxicity and 64 for response. 2 patients (3%) achieved a complete remission and 8 (12.5%) a partial remission, 33 (52%) had stable disease and 21 patients (33%) had progressive disease. Median duration of remission was 32.5 weeks and median survival for all evaluable patients was 64.5 weeks. Substantial to severe side-effects occurred in 39% of patients. Dose-limiting toxicity (grade 3-4) was mainly diarrhoea (18%) and mucositis (15%). Nausea/vomiting, cutaneous toxicity, leucopenia, alopecia and conjunctivitis of grade 3-4 occurred respectively in 6, 4, 2.5, 1 and 1% of cases. Toxicity appeared to be substantially similar to that characteristic of combined 5-FU and the chiral mixture of d,l-FA. Efficacy was within the range of that observed with the 5-FU/d,l-FA combination, although at the lower level.

Nonsurgical management of recurrent colorectal cancer

Most patients with colorectal carcinoma undergo attempts at curative surgery. However, some present with metastatic disease and many others ultimately relapse. Most recurrences of colorectal cancer are not resectable and require nonsurgical approaches such as chemotherapy and radiation therapy directed against local recurrences, hepatic metastases, and widely disseminated disease. Nonsurgical therapy for locoregional recurrence of rectal cancer can offer significant palliation. Intraarterial chemotherapy for liver metastases increases the likelihood of response compared to systemic treatments, but has little effect on survival. Extrahepatic progression and hepatic toxicity are important limitations to this regional therapy. 5-fluorouracil (5-FU) is the mainstay of systemic chemotherapy, and efforts to modulate biochemically the cytotoxic effects of 5-FU with folinic acid, phosphonacetyl-L-aspartate, interferon, and other agents have resulted in promising response rates. The different approaches to biochemical modulation are being studied in ongoing cooperative group trials. Novel approaches, including monoclonal antibody therapy, biologic modifier therapy, and gene therapy, are under investigation.

The efficacy of preoperative 5-fluorouracil, high-dose leucovorin, and sequential radiation therapy for unresectable rectal cancer

BACKGROUND

The encouraging results seen in patients who received postoperative combined modality therapy in the adjuvant setting have prompted increased interest in preoperative combined modality therapy for patients with unresectable rectal cancer. The authors report the local control and survival of a previously reported Phase I dose escalation trial of combined preoperative 5-fluorouracil (5-FU), high-dose leucovorin (LV), and sequential radiation therapy followed by postoperative LV-5 FU for the treatment of patients with unresectable rectal cancer.

METHODS

Twenty patients (13, primary and 7, recurrent disease) received LV-5-FU for one cycle. Radiation therapy (5040 cGy) began on day 8. A second cycle of LV-5-FU was given concurrently with week 4 of radiation. Six patients received intraoperative brachytherapy. Postoperatively, the patients received LV-5-FU. The pathologic complete response rate was 20%, and 89% underwent a complete resection with negative margins.

RESULTS

The crude local failure rate was 26%, and the 3-year actuarial local failure rate was 29% (95% confidence interval [CI], +/- 8.94%). The crude abdominal and distant failure rates were 40% and 30%, respectively. The 3-year actuarial disease-free survival was 64% (95% CI, +/- 6.75%), and the overall survival was 69% (95% CI, +/- 7.65%).

CONCLUSIONS

These preliminary data revealed encouraging local control and survival rates. Preoperative combined modality therapy is an attractive approach in patients with unresectable rectal cancer.

Pre-operative combined 5-FU, low dose leucovorin, and sequential radiation therapy for unresectable rectal cancer

PURPOSE

We performed a Phase I trial to determine the maximum tolerated dose of combined pre-operative radiation (5040 cGy) and 2 cycles (bolus daily x 5) of 5-FU and low dose LV (20 mg/m2), followed by surgery and 10 cycles of post-operative LV/5-FU in patients with unresectable primary or recurrent rectal cancer.

METHODS AND MATERIALS

Twelve patients were entered. The initial dose of 5-FU was 325 mg/m2. 5-FU was to be escalated while the LV remained constant at 20 mg/m2. Chemotherapy began on day 1 and radiation on day 8. The post-operative chemotherapy, was not dose escalated; 5-FU: 425 mg/m2 and LV: 20 mg/m2. The median follow-up was 14 months (7-16 months).

RESULTS

Following pre-operative therapy, the resectability rate with negative margins was 91% and the pathologic complete response rate was 9%. For the combined modality segment (preoperative) the incidence of any grade 3+ toxicity was diarrhea: 17%, dysuria: 8%, mucositis: 8%, and erythema: 8%. The median nadir counts were WBC: 3.1, HGB: 8.8, and PLT: 153,000. The maximum tolerated dose of 5-FU for pre-operative combined LV/5-FU/RT was 325 mg/m2 with no escalation possible. Therefore, the recommended dose was less than 325 mg/m2.

CONCLUSIONS

Since adequate doses of 5-FU to treat systemic disease could not be delivered until at least 3 months (cycle 3) following the start of therapy, we do not recommend that this 5-FU, low dose LV, and sequential radiation therapy regimen be used as presently designed. However, given the 91% resectability rate we remain encouraged with this approach.

[Bone metastases of colorectal cancers: apropos of 8 cases]

Having found, in the same medical centre, an abnormally high (15%) frequency of bone metastases from colorectal carcinoma, the authors report a series of 8 cases and review what is now known of this reputed rare (4%) metastases. Their clinical and imaging features are not very different from secondary bone lesions of other origins. They usually appear approximately 5 years after the primary tumour has been diagnosed; and they are rarely isolated, being part of a diffuse metastatic disease; their prognosis is in fact conditioned by visceral metastases (liver, lung, peritoneum). Concerning treatment, pain relieving radiotherapy is crucial, as witnesses by the authors. Chemotherapy must always be prescribed for its proven effectiveness against visceral lesions. The other medicinal treatments (e.g. analgesics, bisphosphonates) are very useful. Surgery must be reserved to emergency situations (spinal cord compression) and to patients in good general condition. To our 8 patients these treatments brought comfort and increased survival. Survivals of at least 6 to 9 months were obtained, and one patient is still alive 14 months after the diagnosis of bone metastasis. These results compare favourably with the 4 months median survival observed in other series.

A pilot study of hepatic artery floxuridine combined with systemic 5-fluorouracil and leucovorin. A potential adjuvant program after resection of colorectal hepatic metastases

BACKGROUND

Most patients with colorectal carcinoma metastatic to the liver have relapses after surgical resection of hepatic metastases with failures divided equally between hepatic and extrahepatic sites. A pilot study was begun using a regimen combining intrahepatic floxuridine (FUDR) and systemic 5-fluorouracil (5-FU) and leucovorin (LV) to determine its safety and efficacy.

METHODS

Because this was a pilot study, 21 patients with unresectable hepatic metastases from colorectal carcinoma were treated to assess the regimen's toxicity. Eight patients had liver metastases that were resected completely; then they received treatment. FUDR was given by hepatic arterial pump through a 14-day continuous infusion at 0.25 mg/kg/day. Systemic therapy consisted of LV 200 mg/m2 and 5-FU 280 mg/m2 using a bolus dose of 5-FU for 5 days with escalation of the 5-FU dose in separate patient cohorts. The maximally tolerated 5-FU dose was 325 mg/m2.

RESULTS

The median survival in the 21 unresectable patients was 16 months with a partial response rate of 56% (10 of 18 evaluable patients; 95% confidence interval, 38-79%). The major systemic toxicity was diarrhea, Grade 3 or 4, in 54% of patients being treated in the 4-week regimen and 19%, in the 5-week regimen. The level of hepatic toxicity was similar to that in previous studies using intrahepatic chemotherapy alone, i.e., 48% of patients had a 200% increase in alkaline phosphatase levels and 10% had bilirubin elevations of more than 3.0 mg/dl (one patient had documented biliary sclerosis). All eight patients treated with adjuvant therapy were alive without disease after a median follow-up of 23 months.

CONCLUSIONS

Systemic 5-FU and LV can be combined safely with intraarterial FUDR without loss of efficacy or increased biliary toxicity. Eight patients treated with this regimen as adjuvant therapy after liver metastasis resection were alive and disease-free after a median follow-up of 23 months.

Biochemical modulation of 5-fluorouracil: a randomized comparison of sequential methotrexate, 5-fluorouracil and leucovorin versus sequential 5-fluorouracil and leucovorin in patients with advanced symptomatic colorectal cancer. The Nordic Gastrointestinal Tumor Adjuvant Therapy Group

BACKGROUND

The optimal chemotherapy for advanced colorectal carcinoma is not known. Two regimens, both based upon biochemical modulation of 5-FU, were compared in a randomized multicenter trial.

PATIENTS AND METHODS

A total of 202 symptomatic patients were randomly allocated to receive either sequential methotrexate, 250 mg/m2, during the first 2 hours and 5-FU, 500 mg/m2, at hours 3 and 23 followed by leucovorin rescue initiated at hour 24 (15 mg x 8) (MFL) or sequential 5-FU 500 mg/m2 followed by leucovorin 60 mg/m2 30-40 minutes later, on days 1 and 2 (FLv). Treatments were repeated every 14 days for eight courses and then every 3 to 4 weeks. Four patients were unevaluable.

RESULTS

The two treatments were equally effective with respect to objective response rates (complete (CR)+partial (PR), MFL 17%, FLv 21%), subjective response rates (symptom relief in the absence of severe adverse effects, 45% vs. 37%), and survival (median 7.5 vs. 9 months). All responses lasted at least 4 months. Overall, toxicity was low and comparable between the groups, but serious toxicity was more common in the MFL group.

CONCLUSIONS

Since FLv is easier to administer and carries less risk for serious toxicity, it should be recommended as a first-line treatment before MFL. On either regimen, about 40% of symptomatic patients can expect palliation, i.e., symptomatic relief without severe adverse effects, for at least 4 months.

What can we learn from a meta-analysis of trials testing the modulation of 5-FU by leucovorin? Advanced Colorectal Meta-analysis Project

BACKGROUND AND DESIGN

We previously reported a meta-analysis of all randomized clinical trials comparing 5-FU to 5-FU plus intravenous d.l. leucovorin (LV) in patients with advanced colorectal cancer.

RESULTS

The meta-analysis confirmed the advantage of 5-FU/LV over 5-FU alone in terms of response rate: overall, the response rate was 11% with 5-FU alone vs 23% with 5-FU/LV (p < 10(-7)). At the same time, it was showed that tumor regression can not be considered a surrogate end point for survival in patients with advanced colorectal cancer: no significant survival advantage was observed for patients allocated to 5-FU/LV. The present paper focuses on the interest of meta-analysis to study the role of the biomodulation of 5-FU by LV. This approach is compared with the analysis of individual clinical trials in terms of power, bias and credibility. It is argued that for the meta-analysis to be reliable, individual patient data from all available studies must be used, rather than summary data extracted from published papers.

CONCLUSION

It is concluded that meta-analysis is very useful as a tool to explore and summarize available data on a given clinical problem, though its purpose is not to recommend any treatment modality. This meta-analysis has confirmed both the benefit of biomodulation of 5-FU by LV, and the limitations of the current modalities to impact significantly on overall patient survival. Further laboratory and clinical research is warranted on the biomodulation of 5-FU by LV.

5-Fluorouracil combined with the [6S]-stereoisomer of folinic acid in high doses for treatment of patients with advanced colorectal carcinoma. A phase I-II study of two consecutive regimens

BACKGROUND

Potentiation of the antitumor activity of 5-fluorouracil (5-FU) by folinic acid has been demonstrated in patients with colorectal adenocarcinoma. Modulation is due to the interaction of thymidylate synthase (TS), fluorodeoxyuridylate (FdUMP), and methylene tetrahydrofolate (5,10-CH2-FH4), which leads to the formation of a stable ternary complex with concomitant enzyme inactivation. Folinic acid consists of a mixture of equal parts of two stereoisomers differing in chirality at the C6 carbon of the pteridine ring. Only the levorotatory [6S]-folinic acid is transformed into active folate cofactors. However, the [6R]-stereoisomer is not inert; it was shown to interfere with the [6S] form at the cellular level. The possibility of a deleterious effect of the unnatural stereoisomer on the modulation of 5-FU led us to carry out 2 consecutive phase I-II studies of 5-FU combined with the [6S]-stereoisomer of folinic acid given in high doses for treatment of patients with advanced colorectal carcinoma.

PATIENTS AND METHODS

Treatment comprised 5-FU by i.v. infusion for 2 hours (the initial dose was 350 mg/m2/d; it was incremented by 25 mg/m2/d until a maximal dose of 550 mg/m2/d) and [6S]-folinic acid (100 mg/m2/d by rapid i.v. injection in Regimen 1, and 100 mg/m2 by rapid i.v. injection followed by a 2-hour infusion of 250 mg/m2 in Regimen 2) for 5 days, every 21 days. Twenty-five pts and 27 pts were assessed in Regimen 1 and in Regimen 2, respectively. They had had no prior chemotherapy. The median follow-up time was 9 months and 15.5 months for patients treated with Regimen 1 and Regimen 2, respectively. For pts treated with Regimen 1, the response rate was 52% (CR, 12%; PR, 40%). The median time to disease progression was 9.2 months. The probability of survival at 12 months was 73%. For pts treated with Regimen 2, the response rate was 37% (CR, 7%; PR, 30%). The median time to disease progression was 8.9 months. The probability of survival at 12 months was 67%. Improvement in quality of life was achieved in most patients who had symptoms due to the tumor before the start of treatment. The dose-limiting toxic effects (WHO grades > or = 3) were diarrhea, dermatitis, and mucositis. One single episode of grade 4 diarrhea occurred. After injection according to the schema in Regimen 1, [6S]-folinic acid was rapidly cleared from plasma (mean t 1/2 alpha and t 1/2 beta of 7.2 and 126 minutes, respectively). The mean concentration of the [6S]-stereoisomer two hours after injection was 5.8 mmol/L. After a rapid i.v. injection of 100 mg/m2 followed by a 2-hour infusion of 250 mg/m2, the mean concentration of [6S]-folinic acid two hours after the injection was 57.5 mmol/L. Pharmacokinetic data suggests saturation of the metabolic conversion of [6S]-folinic acid when large doses are administered.

CONCLUSION

The [6S]-form of folinic acid potentiates the antitumor effect of 5-FU given concomitantly. However, increase of the daily dose of the folate did not result in a therapeutic improvement. The present results justify a more complete exploration of the pure active stereoisomer as a modulator of the fluoropyrimidines.

The use of mitoxantrone, 5-fluorouracil and high-dose leucovorin in the treatment of advanced breast cancer

BACKGROUND

Metastatic breast cancer remains an incurable disease; therefore, both the efficacy and the toxicity of palliative chemotherapy are important considerations. Mitoxantrone and 5-fluorouracil (5-FU) with high dose leucovorin are active drugs in the treatment of breast cancer, and both can be given with relatively few side effects. We evaluated the efficacy and toxicity of these agents in a combination regimen for the treatment of metastatic breast cancer.

PATIENTS AND METHODS

In a phase II study, we treated 35 women with metastatic breast cancer with the following regimen: mitoxantrone 12 mg/m2 i.v. day 1; leucovorin 300 mg i.v. over 1 hour followed by 5-FU 350 mg/m2 i.v. push on days 1, 2 and 3; courses repeated every 21 days. Responding patients received a total of 6-8 courses. Most patients were receiving second-line chemotherapy for metastatic breast cancer, but some were receiving first-line therapy following failure of adjuvant chemotherapy.

RESULTS

Twenty of 31 assessable patients (65%) had objective responses; in addition, 2 of 4 patients with bone-only metastases had sustained symptomatic responses. Toxicity was mild and the regimen was well tolerated. The activity of this drug combination has been verified in several other phase II studies.

CONCLUSIONS

The combination of mitoxantrone, 5-FU and high-dose leucovorin provides an attractive option for second-line chemotherapy of metastatic breast cancer. The efficacy of this combination in first-line therapy is currently being compared to cyclophosphamide, methotrexate and 5-FU (CMF) in a randomized trial.

Five-day infusional fluorodeoxyuridine with oral leucovorin and escalating doses of interferon alpha-2b: a phase I study

In a previous phase I study we identified the maximally tolerated dose (MTD) of a continuous intravenous infusion of fluorodeoxyuridine (FUdR) to be 0.3 mg/kg daily for 5 days when combined with oral leucovorin (LV) given at 100 mg q4h. In an attempt to modulate FUdR further, we added escalating doses of interferon alpha-2b (IFN) to FUdR/LV in a phase I cohort study. A total of 36 patients with refractory solid tumor were treated at two dose levels of FUdR and five dose levels of IFN. Although the initial patient cohort was treated with a dose of FUdR lower than that previously identified as the MTD [FUdR at 0.2 mg/kg daily with LV at 100 mg q4h and IFN at 2 million units (MU)/m2 daily], three of six patients developed grade 3 mucositis, indicating that the toxicity of FUdR/LV was increased in the presence of low doses of IFN. After decreasing the FUdR dose to 0.1 mg/kg daily, we could increase the dose of IFN from 2 to 30 MU/m2 daily in five additional cohorts of patients. With increasing IFN doses, no increase in mucositis or dermatitis was observed, indicating no further potentiation of FUdR/LV toxicity with higher IFN doses. However, known toxicities of IFN, including transient myelosuppression and hepatic transaminase elevation, were observed more frequently at IFN doses of 15 and 30 MU/m2 daily, where they became dose-limiting. We conclude that IFN modulates FUdR/LV at low doses, resulting in increased FUdR toxicity. When the dose of IFN is increased, this FUdR/LV toxicity does not appear to be potentiated further and IFN-related toxicities become dose-limiting.

Recent advances in the treatment of advanced colorectal cancer

The treatment of advanced colorectal cancer has improved in recent years. Prospective randomized trials comparing innovative therapies with the "standard" bolus dose of 5-fluorouracil (5-FU) found increased response rates after biochemical modification of the drug, infusion administration of 5-FU, and direct intrahepatic arterial infusion. Although the impact on survival of these techniques has been minimal, it is possible that these innovative approaches provide an incremental survival advantage for certain subgroups of patients that may be the foundation for additional therapeutic improvements in the future.

Phase I trial of a 5-day infusion of L-leucovorin plus daily bolus 5-fluorouracil in patients with advanced gastrointestinal malignancies

The combination of leucovorin [(6d,l)-5-formyl-tetrahydrofolate] and 5-fluorouracil (5-FU) has increased efficacy compared to 5-FU alone as treatment of advanced colorectal cancer. Leucovorin is metabolized to methylene tetrahydrofolate, which potentiates the antitumor actions of 5-FU by forming a ternary complex of thymidylate synthase, fluorodeoxyuridine and methylene tetrahydrofolate. Only l-leucovorin is metabolized to methylene tetrahydrofolate and forms this ternary complex. However, d-leucovorin may not be inert. d-Leucovorin may impair cellular uptake and metabolism of l-leucovorin, thereby inhibiting the actions of l-leucovorin. Because of this possible limitation to the effectiveness of racemic leucovorin, we have begun to explore the effects of the pure, biologically active isomer, l-leucovorin. In this phase I trial, patients with advanced gastrointestinal malignancies were treated with a 5-day continuous infusion of l-leucovorin and daily intravenous boluses of 5-FU at 370 mg/m2. The dose of l-leucovorin was escalated in groups of three patients at four doses, 200 mg/m2 per day, 400 mg/m2 per day, 700 mg/m2 per day and 1000 mg/m2 per day. Treatment was repeated every 28 days. Seventeen patients with advanced gastrointestinal cancers entered the trial. Sixteen patients were evaluable for toxicity. Toxicity was similar to that expected for leucovorin plus 5-FU. The most common severe toxicities (and the number of patents affected) were: diarrhea (2), mucositis (2), nausea/vomiting (1), and abdominal/rectal pain (2). The maximum tolerated dose of l-leucovorin was 700 mg/m2 per day. Twelve patients were evaluable for response. One complete, one partial and one minor response were observed. All responses occurred among the nine patients with colorectal carcinomas. The combination of l-leucovorin and 5-FU is well tolerated by patients and appears active for treatment of advanced colorectal carcinomas. Additional clinical trials are necessary to determine if l-leucovorin is more effective than d,l-leucovorin for modulating the effectiveness of 5-FU.

Chemotherapy for metastatic colorectal cancer

The systemic management of patients with colorectal cancer continues to focus on the use of 5-fluorouracil (5-FU). In the setting of metastatic disease, parenteral 5-FU has been shown to be superior to oral 5-FU; however, survival duration seems similar whether such parenteral 5-FU is administered in a "loading," weekly, or continuous infusion manner. The addition of other cytotoxic agents such as semustine, mitomycin C, or cisplatin to 5-FU does not appear to increase the response rate or prolong survival. The results of five randomized trials assessing the value of intraarterial hepatic infusions of 5-FU or floxuridine show that such regional chemotherapy increases the likelihood of hepatic response compared with systemic treatment but has little effect on survival and is associated with significant toxicity. Recent efforts in the management of patients with advanced disease have been directed at optimizing the activity of 5-FU by (1) enhancing the inhibition of DNA synthesis through the concomitant administration of folinic acid; (2) increasing drug incorporation into RNA through pretreatment with methotrexate or phosphonacetyl-L-aspartate; and (3) improving the drug's activity through the synergistic action of alpha-2a-interferon. Although the results of some of these investigations have been promising, only the 5-FU and folinic acid combination consistently has appeared to be superior to single-agent 5-FU. These different approaches to biochemical modulation are being compared in ongoing cooperative group trials.

Alpha-interferon in combination with 5-fluorouracil and leucovorin in metastatic colorectal cancer: a phase I study

A high rate of response to 5-fluorouracil (5FU) and alpha-interferon (alpha IFN) combination therapy has been reported in metastatic colorectal cancer patients. Therefore, designed a trial of high-dose continuous-infusion 5FU, oral leucovorin (LV), and alpha IFN in this group of patients. Because this combination has not previously been tested and severe toxicity has been reported for 5FU and alpha IFN combination therapy, we conducted a phase I trial in which 11 patients presenting with previously untreated metastatic colorectal cancer were treated with escalating doses of alpha IFN together with fixed doses of 5FU and LV. WHO grade III toxicity consisting mainly of oral mucositis was noted in four patients. No grade IV toxicity occurred. Although alpha IFN may enhance the toxicity of 5FU, the toxicity of this regimen remained manageable. Three partial responses were noted.

Factors that influence the therapeutic activity of 5-fluorouracil [6RS]leucovorin combinations in colon adenocarcinoma xenografts

The therapeutic activity of FUra alone or combined with [6RS]LV doses ranging from 50 to 1,000 mg/m2 was examined in eight colon adenocarcinoma xenografts, of which five were established from adult neoplasms (HxELC2, HxGC3, HxVRC5, HxHC1, and HxGC3/c1TK-c3 selected for TK deficiency) and three were derived from adolescent tumors (HxSJC3A, HxSJC3B, and HxSJC2). The growth-inhibitory effects of FUra were potentiated by higher doses of [6RS]LV (500-1,000 mg/m2) in three lines (HxGC3/c1TK-c3, HxSJC3A, and HxSJC3B) and by a low dose of [6RS]LV in only one tumor (HxVRC5). Expansion of pools of CH2-H4PteGlun+H4PteGlun (greater than or equal to 2.4-fold) in response to higher doses of [6RS]LV was obtained in all lines except HxHC1. Metabolism of [6RS]LV was high in HxVRC5, with high levels of 5-CH3-H4PteGlu being detected, but not in HxHC1, in which levels of 5-CH3-H4PteGlu and CH = H4PteGlu+10-CHO-H4PteGlu remained relatively low. In the adolescent tumors, levels of CH = H4PteGlu+10-CHO-H4PteGlu were consistently higher than those of 5-CH3-H4PteGlu following [6RS]LV administration, and in HxSJC3A, in which pools of CH2-H4PteGlun+H4PteGlun were significantly expanded, 5-CH3-H4PteGlu concentrations were lower than those observed in the other two lines. The sensitivity of tumors to FUra +/- [6RS]LV and the characteristics of [6S]LV metabolism did not correlate with the activity of CH = H4PteGlu synthetase, the enzyme responsible for the initial cellular metabolism of [6S]LV to CH = H4PteGlu. Thus, no single metabolic phenotype correlated with the [6RS]LV-induced expansion of CH2-H4PteGlun+H4PteGlun pools. Potentiation of the therapeutic efficacy of FUra by [6RS]LV was observed in HxGC3/c1TK-c3 xenografts but not in parent HxGC3 tumors, demonstrating the influence of dThd salvage capability in the response to FUra-[6RS]LV combinations. Plasma dThd concentrations in CBA/CaJ mice were high (1.1 microM). The present data therefore demonstrate the importance of (1) higher doses of [6RS]LV, (2) expansion of pools of CH2-H4PteGlun+H4PteGlun, and (3) dThd salvage capability in potentiation of the therapeutic efficacy of FUra in colon adenocarcinoma xenografts. The plasma levels of FUra achieved in mice are presented.

Phase I trial of postoperative 5-FU, radiation therapy, and high dose leucovorin for resectable rectal cancer

Following surgery for Stages T3-4N0-2M0 primary and recurrent resectable rectal cancer limited to the pelvis, 25 patients have been entered on a Phase I trial of pelvic radiation therapy (RT) [5040 cGy] and 12 cycles of postoperative 5-FU and high dose Leucovorin (LV) chemotherapy. 5-FU was escalated 50 mg/m2 while the LV remained constant at 200 mg/m2. The initial doses of 5-FU were: combined-RT/chemotherapy = 200 mg/m2 and post-RT chemotherapy = 325 mg/m2. The median F/U was 25 months (range: 13-36). Two maximum tolerated doses (MTD's) have been determined, one for combined-RT/chemotherapy and one for post-RT chemotherapy. The MTD for combined-RT/chemotherapy was 250 mg/m2; therefore, the recommended dose of 5-FU is 200 mg/m2. The MTD for post-RT chemotherapy was 375 mg/m2; therefore, the recommended dose of 5-FU is 325 mg/m2. The dose limiting toxicities were diarrhea, tenesmus, frequent bowel movements, dysuria, and myelosuppression. For the nine patients who received 5-FU at the recommended dose level the median low counts were WBC 3.5 (2.2-4.0), HGB 10.3 (9.0-12.3), and PLT (x 1000) 167 (133-280), and the incidence of any grade greater than or equal to 3 toxicity was 22% diarrhea, 17% tenesmus, and 22% frequent bowel movements. The recommended dose of combined-RT/chemotherapy as used in this protocol was relatively well tolerated. However, optimal doses of 5-FU cannot be delivered until the fourth postoperative month. Therefore, despite the encouraging results reported with high dose LV in patients with advanced disease, we do not recommend that high dose LV be used with combined RT and 5-FU in the treatment regimen as presently designed.

A phase I trial of 5-fluorouracil, leucovorin, and dipyridamole given by concurrent 120-h continuous infusions

A phase I trial of 5-fluorouracil (FUra) and leucovorin (LV) given with and without dipyridamole (DP) by concurrent 120-h continuous infusion was performed in 27 patients with advanced solid malignancies, 8 of whom had previously received FUra. The LV and DP doses were fixed at 500 mg/m2 daily and 7.7 mg/kg daily, respectively, whereas the FUra dose was escalated. Level 3 (450 mg/m2 FUra daily) represented the maximum tolerated dose for both FUra/LV+DP and FUra/LV. Dose-limiting stomatitis (greater than or equal to grade 3 or grade 2 occurring during the infusion) was encountered in 75% of the first courses given at level 4 (600 mg/m2 daily). Stomatitis was observed in 44/78 (56%) courses. Diarrhea was infrequent and mild. DP infusions were complicated by mild to moderate headache, which was controlled with narcotic analgesics, and mild to moderate nausea/vomiting. FUra-related toxicity was not enhanced by DP administration. Limited pharmacokinetic sampling at levels 3 and 4 revealed mean steady-state FUra concentrations of around 1.0 microM with infusions of FUra/LV+DP. Among three paired courses given with and without DP, no statistically significant difference was found in the total body clearance of FUra (P = 0.44). One partial response was seen in a patient with metastatic gastric carcinoma. For phase II trials, we recommend that concurrent 120-h continuous infusions of FUra (450 mg/m2 daily) and LV (500 mg/m2 daily) be given with and without DP (7.7 mg/kg daily) every 21 days.

In vitro enhancement of fluoropyrimidine-induced cytotoxicity by leucovorin in colorectal and gastric carcinoma cell lines but not in non-small-cell lung carcinoma cell lines

Leucovorin (LV) increases the cytotoxic effect of fluorouracil (FUra) and 5-fluoro-2'-deoxyuridine (FdUrd) by enhancing the formation of the fluorodeoxyuridine monophosphate (FdUMP) thymidylate synthase (TS) 5,10-methylenetetrahydrofolate (mTHF) ternary complex. To study the difference in the efficacy of this combination against different tumors, we compared the effect of LV (20 microM) on the cytotoxicity of FUra, FdUrd, and 5-fluorouridine (FUrd) in vitro against cell lines of five colorectal carcinomas (CC), five gastric carcinomas (GC), and four non-small-cell lung carcinomas (NSCLC) using the colony-forming assay. At the concentration used in the experiments, LV alone failed to inhibit colony formation in any of the cell lines tested. The NSCLC cell lines were more resistant to FdUrd than were the CC and GC lines. LV modulated the cytotoxicity of FdUrd in all five CC lines and in three of the five GC lines but failed to do so in any of the NSCLC lines. In addition, following 20 h treatment with 1 microM [3H]-FdUrd, formation of the FdUMP/TS/mTHF ternary complex was enhanced by LV in the LV-sensitized CC and GC cell lines but not in the LV-refractory NSCLC lines. These in vitro data corresponded well to the results of clinical trials. Therefore, the colony-forming assay may be useful for the identification of the sensitivity of tumors according to phenotype.

5-Fluorouracil (5FU) with or without folinic acid (LV) in human colorectal cancer? Multivariate meta-analysis of the literature

This meta-analysis is based on 106 evaluations of response from 77 clinical studies about 5-fluorouracil (5FU) treatment with or without leucovorin (LV) in metastatic colorectal carcinoma. Overall, in naive patients, LV is associated with a median response rate of 31% as compared with a 12% figure with 5FU alone. Using a forward stepwise multilinear regression analysis, it is shown that as much as 44% of the variance in the reported response rates in naive patients can be accounted for by treatment-related variables (P less than 0.001). The significant parameters are LV adjunction (partial R = 0.636), cumulative total 5FU dose (R = 0.344), and 5FU weekly schedule (R = 0.246). In pretreated patients, the latter parameter is the only significant one (R = 0.443). Unexpectedly, LV administration behaves like an all-or-nothing governor, without any obvious dose-effect relationship. Protracted 5FU infusion over weeks allows a mean cumulative drug delivery, 3 times higher than bolus regimens (21.3 vs 7.02 g m-2, P less than 0.001) and may represent the best clinical approach to influence the 5FU-related variables. Accordingly, it is suggested that 5FU protracted infusion, titrated to the highest tolerable doses and potentiated with low doses of leucovorin, could represent the most efficacious way for using 5FU in colorectal disseminated cancer. This hypothesis and its eventual impact on survival should be tested in randomized trials.

Folinic acid + 5-fluorouracil (5-FU) versus equidose 5-FU in advanced colorectal cancer. Phase III study of 'GISCAD' (Italian Group for the Study of Digestive Tract Cancer)

In a multicentre Phase III trial, 182 patients were randomized to either folinic acid (FA) (200 mg/sqm i.v. x 5 days) + 5-fluorouracil (5-FU) (400 mg/sqm i.v. in 15' x 5 days) every 4 weeks (Arm A), or to 5-FU alone at the same dosage (Arm B). Response rates were 20.6% (Arm A) and 10% (Arm B) with a significant (p = 0.046) advantage for FA + 5-FU. Median time to progression (6 and 6 months) and overall survival (11.5 and 11 months) were similar in the 2 groups of patients, while neither treatment was effective in reducing pain or improving performance status. Univariate analysis showed that no prognostic factors other than treatment influenced response, although survival was affected by the number and site of metastases, performance status, and the presence and degree of pain. Toxicity was acceptable and lower in comparison with other Phase II-III trials, with no significant difference between the 2 arms. However, in individual patients, grade 3-4 side effects (mainly stomatitis and diarrhoea) were observed, particularly in patients receiving FA: this led to interruption of the treatment in 7 cases. The superiority, in terms of objective response, of FA + 5-FU over 5-FU alone would seem to justify a large-scale evaluation of this combination in the adjuvant setting. Further improvements in relation to advanced disease (i.e., modifications to the schedule and/or introduction of other modulators) are warranted.

Fluorouracil and recombinant interferon alfa-2a in advanced gastrointestinal neoplasms

Based on preclinical studies which demonstrated synergy between recombinant interferon alfa-2a (rIFN alpha-2a) and 5-fluorouracil (5FU), clinical studies have been initiated to investigate this combination. The initial study conducted by investigators from the Albert Einstein Cancer Center reported a response rate of 76% with 13/17 patients with advanced colorectal carcinoma responding. To further evaluate this regimen, two clinical trials have been conducted in previously untreated advanced colorectal carcinoma patients with measurable disease. The regimen consisted of 5FU administered as a continuous infusion, 750 mg/m2/d for 5 consecutive days. Intravenous bolus administration of 5FU 750 mg/m2 was given weekly for 7 weeks starting 1 week after completion of the continuous infusion. rIFN alpha-2a, 9 MU, was administered subcutaneously three times weekly. In The University of Texas M.D. Anderson Cancer Center trial, 15/45 evaluable patients experienced partial response, and one patient achieved a complete response for an overall response rate of 35%. Another trial of this regimen conducted by Memorial Sloan-Kettering has reported a 26% response rate with 9/34 evaluable patients experiencing a partial response. Current randomized trials comparing this schedule of 5FU with rIFN alpha-2a to 5FU plus folinic acid or single-agent 5FU may clarify its role in the treatment of advanced colorectal carcinomas.

A phase II study of epidoxorubicin in colorectal cancer and the use of cyclosporin-A in an attempt to reverse multidrug resistance

We determined the ability of the multidrug resistance (MDR) reversal agent cyclosporin-A to increase anthracycline drug accumulation in colorectal tumour cells in vitro, using the technique of on-line flow cytometry. Data of four previously untreated patients showed that cyclosporin-A can increase intracellular net-uptake of daunorubicin. A phase II study was initiated in 24 colorectal cancer patients. They received cyclosporin-A at a dose of 3 mg kg-1 over 1 h as i.v. infusion, at 7 h and at 1 h preceding cytotoxic drug administration. At the end of the second cyclosporin-A administration epidoxorubicin 90 mg m-2 was administered as i.v. bolus. Cycles were repeated every 3 weeks. Median cyclosporin-A peak blood levels and levels at 18 h after cytotoxic drug administration appeared to be 6248 ng ml-1 and 1012 ng ml-1 respectively. Only one partial response was observed, despite these high cyclosporin-A levels. Cyclosporin-A did not cause major toxicity, only a 29% incidence of hot flushes was observed. Epidoxorubicin toxicities were as expected but the frequency of severe leucocytopenia was striking. This treatment schedule can not be considered active in colorectal cancer.

Preoperative high-dose leucovorin/5-fluorouracil and radiation therapy for unresectable rectal cancer

Twenty patients with primary or recurrent unresectable rectal cancer limited to the pelvis were entered on a Phase I trial of preoperative pelvic radiation therapy (RT) (5040 cGy) and two cycles of combined high-dose leucovorin (LV) and 5-fluorouracil (5-FU), followed by surgery and ten cycles of postoperative LV/5-FU (sequential). Maximum tolerated doses (MTD) were determined for preoperative combined LV/5-FU and RT and for postoperative sequential LV/5-FU. 5-FU was escalated 50 mg/m2 while the LV remained constant at 200 mg/m2. The initial doses of 5-FU were combined LV/5-FU and RT (200 mg/m2) and sequential LV/5-FU (325 mg/m2). The median follow-up time was 14 months. The resectability rate was 89%, and the pathologic complete response rate was 21%. The MTD for combined LV/5-FU and RT was 300 mg/m2; therefore, the recommended dose of 5-FU is 250 mg/m2. The recommended dose of 5-FU for sequential LV/5-FU is 375 mg/m2. The dose-limiting toxicities in this trial were diarrhea, tenesmus, increased bowel movements, dysuria, and myelosuppression. For the six patients who received 5-FU at the recommended dose level, the median low counts were leukocyte count, 3.7/microliters (range, 2.4 to 4.9/microliters); hemoglobin, 9.0 g/dl (range, 8.2 to 11.9 g/dl); and platelet count (X1000), 146/microliters (range, 89 to 182/microliters). The incidence rate of any Grade 3 toxicity was 17% (diarrhea and frequent bowel movements). The recommended doses of 5-FU used in this protocol were well tolerated. Because there was a long delay before optimal doses of 5-FU could be delivered, the authors do not recommend that high-dose LV be used in conjunction with combined 5-FU and RT with the treatment regimen as currently designed. However, because the resectability and complete response rates were higher than those previously reported for preoperative RT alone, the authors are encouraged by the combined technique approach. New trials are currently being undertaken to determine if the use of a low-dose LV regimen is more tolerable.

Perspectives in colorectal cancer

This paper presents an overview of recent developments pertaining to colorectal adenocarcinoma. It is aimed toward the practicing clinician. Topics discussed include epidemiologic observations; genetic predispositions; molecular biology findings; screening and early detection programs; endoscopy; principles of surgical resection; laser and radioimmunoguided surgery; staging; selection of patients for adjuvant chemotherapy; and considerations regarding biologic response modifiers and pain control in the advanced-disease setting.

5-Fluorouracil by protracted venous infusion: a review of recent clinical studies

The pharmacokinetics of continuous infusion 5-fluorouracil make it an ideal drug to administer as a protracted infusion (continuous infusion more than 30 days). During the last decade numerous clinical studies have been conducted to evaluate the efficacy of 5-fluorouracil (5FU) administered as a protracted venous infusion. Phase II studies in metastatic colorectal cancer in 345 patients have demonstrated an average response rate of 36% (range 15-59%) and a prospective randomized study performed by the Mid-Atlantic Oncology Program (MAOP) has confirmed a higher response rate with 5FU infusion compared with a bolus schedule. Phase II studies in refractory carcinoma of the breast in 177 patients have demonstrated a 30% response rate (range 17-50%); studies in pancreatic, gastric, and refractory prostate cancer have also demonstrated clinical utility. The major toxicities of 5FU infusion are mucositis and hand-foot syndrome; life-threatening myelosuppression is rare and treatment-related deaths have not been reported. 5FU infusion is a useful palliative treatment for many adult patients with advanced malignancies.

Five-day infusion of fluorodeoxyuridine with high-dose oral leucovorin: a phase I study

Fluorodeoxyuridine (FUdR) interferes with cellular metabolism by inhibiting thymidylate synthase. Therefore, we sought to modulate its activity with leucovorin (LV) and to identify the maximally tolerated dose given as a 5-day continuous intravenous infusion in combination with oral administration of LV at a dose of 100 mg every hour for four doses immediately preceding the start of the FUdR infusion and then every 4 h for the entire duration of FUdR treatment. Patients were evaluated at six FUdR dose levels ranging from 0.1 to 0.375 mg/kg per day. Severe or life-threatening mucositis was first observed in two of six patients treated at 0.25 mg/kg daily. Further escalation of the dose to 0.3 mg/kg per day resulted in grade 2 mucositis in four of six patients and in grade 3 mucositis in two cases. A dose of 0.375 mg/kg daily resulted in grade 3 toxicity in all three patients treated. Other types of toxicities included skin rash and hand-foot syndrome, but no hematologic toxicities were observed. Stable disease was observed in 11 of 24 evaluable patients, including 3 subjects with renal cell carcinoma. Our recommended dose for phase II trials is 0.3 mg/kg FUdR per day.

Modulation of fluoropyrimidines by leucovorin: rationale and status

In recent years the concept of metabolic modulation of fluoropyrimidines by leucovorin has been introduced clinically in patients with advanced colorectal cancer, breast cancer, gastric cancer and head and neck cancer among others. The concept of metabolic modulation was developed in the laboratory and employed clinically. Leucovorin is a noncytotoxic compound used to increase the therapeutic efficacy of 5-fluorouracil. Following 5-fluorouracil activation to 5-fluorodeoxyuridine monophosphates, its binding to thymidylate synthase is stabilized by the active cofactor, 5,10 methylene tetrahydrofolate and its polyglutamate forms. Under these conditions, both the extent and duration of inhibition of thymidylate synthase and consequently, DNA synthesis are more pronounced. The results of clinical trials (phase II and III) indicate that the response rates to 5-fluorouracil/leucovorin modulation are significantly higher than that of fluorouridine alone.

A prospective randomized comparison of protracted infusional 5-fluorouracil with or without weekly bolus cisplatin in metastatic colorectal carcinoma. A Mid-Atlantic Oncology Program study

One hundred eighty-four patients with advanced measurable colorectal cancer not previously treated with chemotherapy were entered into a prospective randomized clinical trial by the Mid-Atlantic Oncology Program (MAOP) to assess the value of weekly cisplatin (20 mg/m2) when added to a protracted schedule of 5-fluorouracil (5-FU) infusion (PIF) at 300 mg/m2/d for 10 weeks of every 12 weeks. The liver was the primary indicator lesion in approximately 75% of the study group. All tumor measurements required radiographic confirmation. The response rate in the PIF alone arm was 35% (29 of 83; 95% confidence interval [CI], 25% to 46%) compared with 33% (28 of 85; 95% CI, 23% to 44%) for the arm in which weekly cisplatin was added to PIF. The median survival times were 11.8 and 11.2 months in the two groups. Weekly cisplatin does not appear to add to the effectiveness of PIF in colorectal carcinoma.