Sequential high dose methotrexate, 5-fluorouracil and folinic acid does not improve response rates in advanced colorectal cancer

27 patients with advanced colorectal cancer were treated in a phase-II trial with high dose sequential methotrexate (MTX), 5-fluorouracil (5-FU), and folinic acid (FA). Following a 4 h infusion of 800 mg/m2 MTX and a 4 h interval, 1,500 mg/m2 5-FU and 200 mg/m2 FA were given as a 24 h infusion. Out of 23 evaluable patients we observed one partial remission and 9 disease stabilizations. Median survival time of all patients was 10.4 months. Overall toxicity was low. In comparison to a previous trial we did not observe better treatment results by adding high dose FA to a sequential MTX/5-FU schedule.     

Docetaxel compared with sequential methotrexate and 5-fluorouracil in patients with advanced breast cancer after anthracycline failure: a randomised phase III study with crossover on progression by the Scandinavian Breast Group

The aim of this study was to compare the efficacy and tolerability of docetaxel to methotrexate and 5-fluorouracil in advanced breast cancer after anthracycline failure. A randomised multicentre trial was conducted in 283 patients with advanced breast cancer who had failed previous anthracycline treatment. Docetaxel at a dose of 100 mg/m2 every 3 weeks (n = 143) was compared with sequential methotrexate and 5-fluorouracil (MF; n = 139) given at day 1 and 8 every 3 weeks at dosages of 200 mg/ m2 and 600 mg/m2, respectively. After progression, crossover to the alternative treatment group was recommended. There was a significantly higher overall response rate in the docetaxel 42% (CR 8% + PR 34%) than in the MF arm 21% (CR 3% + PR 18%) (P < 0.001). The median time to progression (TTP) was 6.3 months in the docetaxel arm and 3.0 months in the MF arm (P < 0.001). Docetaxel also had a significantly higher response rate of 27% following crossover compared with MF (12%). Significantly more side-effects (leucopenia, infections, neuropathy, oedema, asthenia, skin, nail changes, alopecia) were seen in the docetaxel than in the MF group. However, grade 3 and 4 side-effects were infrequent with both drugs, with the exception of fatigue, alopecia and infections. Median overall survival (OS) including crossover phase was 10.4 months in the docetaxel and 11.1 months in the MF arm (P = 0.79). Based on the response rate and the primary endpoint of TTP, docetaxel is superior to sequential methotrexate and 5-fluorouracil in advanced breast cancer after anthracycline failure.     

High-dose methotrexate and 5-fluorouracil in patients with advanced colorectal carcinoma. A randomized study of two pretreatment intervals

Thirty-two patients with untreated advanced colorectal carcinoma received high-dose methotrexate pretreatment followed sequentially by 5-fluorouracil (5-FU). Patients were randomized to receive high-dose methotrexate pretreatment at one of two intervals (0 h or 3 h before 5-FU). There were 16 patients in each study arm. The median methotrexate dose was 1,000 mg/m2 (range, 600-1,200 mg/m2) and that of 5-FU was 1,000 mg/m2 (range, 800-1,200 mg/m2). Treatments were repeated every 21 days. Three patients achieved partial remission (1 in the 3-h interval arm and 2 in the 0-h interval arm). As the response rate using this regimen was noted to be 9% with a less than 5% chance of achieving a response rate higher than 20%, we terminated this study although the therapy resulted in mild-to-moderate but infrequent toxicity. We thus conclude that pretreatment with high-dose methotrexate given at short intervals followed by 5-FU has no significant activity against colorectal carcinoma.     

The Effect of Sequential Methotrexate and 5-Fluorouracil in Patients with Recurrent Head and Neck Cancer

Sequential methotrexate and 5-fluorouracil was given to 105 patients with recurrent head and neck cancer. All 105 patients had previously received radiotherapy in curative doses; 41 patients had also been surgically treated and 21 had received previous chemotherapy for recurrence. The treatment consisted of methotrexate 125 mg/m², followed by 5-fluorouracil 600 mg/m² after 1 h. Leucovorin rescue was administered after 24 h. A response was observed in 24 patients (23%), including 9 (9%) with complete response. The majority of the responders were patients with a good performance status and with primary tumour in the oropharynx. The toxicity was not negligible, as 5 patients (5%) died of treatment-related causes, mainly due to leukopenia, which was the most frequent and important complication. This sequential methotrexate/5-fluorouracil treatment-schedule cannot be recommended for recurrent head and neck cancer patients.     

Combination chemotherapy and radiation for palliation of hepatocellular carcinoma.

Twenty seven patients with hepatocellular carcinoma were treated by sequential methotrexate (75 mg/m2) and 5-fluorouracil (5-FU) (750 mg/m2) on day 1 followed on days 8-36 by external beam radiotherapy (total dose 30 cGy). The response was assessed by liver size on clinical examination. One patient had complete response, and six patients had partial response. The overall response to the treatment was 25.9%. More than a 50% reduction in serum alfa-fetoprotein level was noted in 66.6% patients. Seventy-one percent of patients had palliation of pain following therapy. The median survival of responders was 11 months and of nonresponders, 2 months. Radiation was discontinued in two patients who developed radiation hepatitis. Additional trials with different dosages and schedules are needed to fully evaluate this form of therapy.     

Sequential therapy with methotrexate and 5-fluorouracil in the treatment of advanced colorectal carcinoma

Twenty-nine patients with advanced colorectal carcinoma were entered in this study to evaluate the efficacy and toxicity of a sequential chemotherapeutic schedule with methotrexate (MTX), 200 mg/m2 intravenously (IV) (push injection) and 5-fluorouracil (5-FU), 1,200 mg/m2 in continuous IV infusion, using a 20-hour time interval. All patients received calcium leucovorin (LV), 25 mg, intramuscularly (IM) every six hours for eight doses beginning 24 hours after methotrexate administration. Courses were administered every 15 days. Of the 24 patients evaluable for response, 11 (46%) had major objective regressions (one complete remission [CR] and ten partial remissions [PR]). The survival rate of patients who responded to treatment was 60% at 16 months, whereas patients with no change and those in whom the disease progressed had a median survival of 9 months and 3 months, respectively. The median duration of response has not yet been reached in patients who presented objective tumor regression, and was 7.5 months in those with no change. Significant differences were found between objective regression and no change (P less than .0005) and between no change and tumor progression (P less than .05). All patients were evaluable for toxicity. There were three toxic-related deaths (10%) because of severe myelosuppresion, sepsis, and hemorrhage. These promising results, despite important toxicity, reveal the synergism between the two chemotherapeutic agents and also indicate that the response rate achieved could be a consequence of the 20-hour interval and high dose of 5-FU. Further studies are necessary to determine the optimal time interval and the adequate 5-FU dose.     

Continuous-infusion cisplatin, 5-fluorouracil, and bolus methotrexate in the treatment of advanced non-small cell lung cancer.

BACKGROUND. Cisplatin and 5-fluorouracil have noted synergy in preclinical systems. The authors combined methotrexate with infusional cisplatin and 5-fluorouracil in an attempt to produce a regimen with improved activity in advanced NSCLC. METHODS. Twenty-six ambulatory patients with previously untreated non-small cell lung cancer were treated with continuous-infusion cisplatin (25 mg/m2/day for 5 days), 5-fluorouracil (800 mg/m2/day for 5 days), and intermediate-dose methotrexate (200 mg/m2 on days 15, 22), followed by leucovorin rescue (PFM regimen). RESULTS. Patients received a median of four cycles of therapy. Two patients had a complete response, and 10 had a partial response (overall response rate, 46.2% or 12 of 26). The median time to treatment failure was 22.5 weeks; the median survival was 55 weeks from the start of chemotherapy. There were no toxic deaths attributed to chemotherapy. Thrombocytopenia was the only Grade 4 toxicity (27%). Grade 1/4 and 2/4 peripheral neuropathy occurred in 17 of 26 patients (66%) and was associated with a cumulative cisplatin dose of more than 300 mg/m2. CONCLUSIONS. PFM (using continuous-infusion cisplatin) produced a high response rate but resulted in an high incidence of low-grade peripheral neuropathy.     

Phase II study of Adriamycin with sequential methotrexate and 5-fluorouracil (AMF) in gastric carcinoma

Summary The purpose of this study was to evaluate the response rate, methotrexate plasma levels, and toxicity of a three-drug regimen in patients with gastric carcinoma. A total of 37 patients with advanced measurable adenocarcinoma of the stomach were treated with Adriamycin, methotrexate, and 5-fluorouracil (AMF). Adriamycin and methotrexate were given as i.v. infusions on day 1; 24 h following methotrexate administration, patients received an i.v. infusion of 5-fluorouracil concomitantly with oral leukovorin factor (given over 48 h). Methotrexate levels were monitored regularly in all patients, and courses were repeated every 3 weeks. The median dose levels per course were 50 mg/m² (range, 40–60 mg/m²) for Adriamycin, 1,000 mg/m² (range, 650–1,250 mg/m²) for 5-fluorouracil, and 500 mg/m² (range, 160–625 mg/m²) for methotrexate. Of 36 evaluable patients, 8 (22%) achieved an objective response, including 1 complete remission. Stable disease was noted in 11 patients and a minor tumor regression occurred in 1. The median survival duration of all patients was 6 months (range, 2–31 + months). AMF was well tolerated; toxicities were mild to moderate, most frequently involving nausea and vomiting, mucositis, and neutropenia with or without fever. There was no death directly attributable to chemotherapy. Although the AMF regimen used a well-documented preclinical concept of synergism between methotrexate and 5-fluorouracil, response and survival results suggest a modest activity of this combination in patients with gastric cancer. Better preclinical models are necessary for the development of effective combination chemotherapy.     

Chemotherapy of advanced colorectal cancer. A randomized trial of sequential methotrexate and 5-fluorouracil

Fifty-five patients with advanced colorectal cancer were entered into a randomized controlled clinical trial to evaluate order of administration and sequential methotrexate (MTX) and 5-fluorouracil (5-FU) therapy. Patients were randomized to receive either MTX, 250 mg/m2, followed 1 h later by 5-FU, 600 mg/m2, or 5-FU followed 1 h later by MTX in the same doses. Fifty-four patients were evaluable for response, of whom 15 (28%) achieved objective partial tumor response. There were no significant differences between the two sequences in response rate, time to treatment failure, or survival duration. The results of this study do not indicate a clinically significant difference between the two sequences tested, in which MTX preceded or followed 5-FU by 1 h. Determination of the value of these drugs given sequentially at longer intervals must await appropriate controlled trials.     

5-Fluorouracil infusion and mitomycin combination chemotherapy in the management of patients with advanced non-small-cell lung cancer

We have carried out a phase II study evaluating the activity of a 5-fluorouracil drug combination in patients with advanced non-small-cell lung cancer. Patients were given 60 mg/m2 of methotrexate i.v. on day 1. On day 2, 750 mg/m2 of 5-fluorouracil was administered as a 24-h infusion daily for 3 days. Also on day 3, 10 mg/m2 of mitomycin was given i.v. along with folinic acid. Folinic acid was started on day 3 initially at a dose of 25 mg/m2 intravenously every 6 h for three doses, followed by a 2-h infusion of 200 mg/m2 daily on days 3 and 4. Therapy was repeated every 28 days. Fourteen of 35 patients (40%) experienced a partial response to chemotherapy. The median survival of the entire group was 19 weeks. Mucositis was a common side effect but severe leukopenia, anemia, renal insufficiency, and skin ulceration were rare. This study demonstrated that 5-fluorouracil infusion therapy has activity in advanced non-small-cell lung cancer but the responses are not durable. Further studies evaluating differing dose schedules and alternate 5-fluorouracil infusion-based drug combinations seems warranted.     

Double-modulation of 5-Fluorouracil by methotrexate and leucovorin in advanced colorectal-carcinoma

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 leucovorin (LV) as first line chemotherapy in advanced colorectal carcinoma. Between January 1990, and April 1992, 42 patients with metastatic or advanced recurrent (inoperable) colorectal cancer were entered into the study. Therapy consisted of a sequential combination of MTX, LV and 5-FU. MTX was administered at a dose of 150 mg/m2 over 20 minutes I.V. infusion at hour (h) 0, followed 19 h later by LV 50 mg/m2 over 2 h infusion. 5-FU 900 mg/m2 was given by I.V. push injection at h 20. Starting 24 h after MTX administration all patients received LV 15 mg/m2 intramuscularly every 6 h for six doses. Treatment was repeated every 15 days until progressive disease, severe toxicity, or death. Four patients were considered not evaluable for response. Objective regression (OR) was observed in 14 of 38 patients (37%, 95% confidence interval 23-53%). Two patients (5%) obtained complete response (CR) and 12 (32%) partial response (PR). Median time to treatment failure was 6 months (range 1-21). Median survival for the whole group of patients was 13 months (range 1-27). Toxicity was within acceptable limits but one therapy-related death due to severe leukopenia and sepsis was observed. Double modulation of 5-FU with MTX and low dose of LV is an active regimen against advanced colorectal carcinoma and represents a promising strategy that should be further explored.     

Doxorubicin versus methotrexate both combined with cyclophosphamide, 5-fluorouracil and tamoxifen in postmenopausal patients with advanced breast cancer--a randomised study with more than 10 years follow-up from the Danish Breast Cancer Cooperative Group. Danish Breast Cancer Cooperative Group (DBCG)

To evaluate the substitution of methotrexate with doxorubicin (Dox) in CMF-(cyclophosphamide, methotrexate, 5-fluorouracil) containing regimen for advanced breast cancer, 415 postmenopausal patients below the age of 66 years, na?ve to chemotherapy, were accrued from 1980 to 1984 and followed-up until 1995. They received tamoxifen 30 mg daily orally and by randomisation either 400 mg/m2, cyclophosphamide, 25 mg/m2 doxorubicin and 500 mg/m2 5-fluorouracil (CAF) or 40 mg/m2 methotrexate instead of Dox (CMF) intravenously (i.v.) days 1 + 8 repeated every 4 weeks. Dox was substituted by methotrexate at a cumulative dose of 550 mg/m2. Among 341 eligible patients the response rate and median time to progression was significantly in favour of CAF: 53% CAF versus 36% CMF (P = 0.002) and 11.8 months CAF versus 6.5 months CMF (P = 0.001). Median duration of response was 19.5 CAF versus 18.0 CMF months, and survival 20.8 CAF versus 17.4 CMF months (non-significant). The two regimens were equimyelotoxic. There were no treatment-related fatalities but 1 patient with congestive heart failure on CAF was reported. Nausea/vomiting, stomatitis and infections were modest in both groups, whilst alopecia was more common with CAF. Regression analysis showed that long recurrence free interval, good performance status, and no visceral involvement was significantly related to long-term survival, whilst the treatment regimen was not. It is concluded that in chemotherapy-na?ve patients with advanced breast cancer Dox-containing regimens are superior and remain the first choice of chemotherapy, especially in patients with visceral metastases, until newer drugs and combinations have been proven to be superior.     

Combined intraarterial 5-fluorouracil and subcutaneous interferon-alpha therapy for advanced hepatocellular carcinoma with tumor thrombi in the major portal branches

BACKGROUND: The prognosis of hepatocellular carcinoma (HCC) invading into the major branches of the portal vein (Vp3) is extremely poor. METHODS: Eleven consecutive patients with HCC and Vp3 were treated with 2-6 cycles of a "basic" combination therapy consisting of continuous arterial infusion of 5-fluorouracil (450-500 mg/day, for the initial 2 weeks) and subcutaneous injection of interferon-alpha (5 million international units, 3 times/week, 4 weeks). In the first 3 patients, methotrexate (90 mg/day 1 of every week), cisplatin (10 mg/day), and leucovorin (30 mg/days 2 and 3 of every week) also were administered for the initial 2 weeks ("full" regimen). RESULTS: In 8 (73%) of 11 patients, an objective response (complete response [CR] or partial response [PR]) was observed with marked regression of tumor and decrease in tumor markers. The use of the full regimen was associated with objective response in all patients; instead, they developed thrombocytopenia or leukopenia. In the subsequent 8 patients with basic regimen, 5 patients showed CR (2 cases) or PR (3 cases; objective response rate, 63%), and leukopenia was observed only in 1 patient. CONCLUSIONS: Simple combination therapy with subcutaneous interferon-alpha and intraarterial 5-fluorouracil therefore is a promising treatment modality for intractable HCC with Vp3.     

Sequential combination chemotherapy with methotrexate and 5-fluorouracil in advanced colorectal carcinoma

Twenty patients bearing advanced colorectal carcinoma, confirmed by histology, were evaluated after undergoing a sequential chemotherapeutic schedule which consisted of methotrexate, 200 mg/m2 in intravenous infusion during 4 h followed 1 h later by 5-fluorouracil, 600 mg/m2 in intravenous bolus. Twenty hours after ending the MTX administration, leucovorine, 14 mg/m2, was given intramuscularly every 6 h, in 8 doses. Courses were repeated every 15 days. Of 20 patients, 3 bearing colon carcinoma, without previous radiotherapy or chemotherapy, had a partial response. No change was registered in 6 cases. There was no significant difference in the survival of responders, those with stable illness and those with progression. Results were no better than those obtained with 5-fluorouracil used as a single drug and are in agreement with studies that established a 1-h interval between the administration of both drugs.     

5-Fluorouracil dose intensity increase in 5-fluorouracil and leucovorin combination: results of a phase II study

It was our intention to verify if in the combination of 5-fluorouracil and leucovorin, the fluoropyrimidine dose intensity is an important determinant of response as noted by Hryniuk when 5-fluorouracil was given alone. By employing the Machover regimen but with cycles repeated every three weeks, a 5-fluorouracil projected dose intensity of 616 mg/m2/wk was obtained. It approximates the maximum tolerated dose for this drug when used alone by i.v. bolus. 50 patients entered this study and 48 were evaluable for response and toxicity. The overall response rate was 29% (five complete responses and nine partial responses). The dose limiting toxicity was gastrointestinal rather than myelosuppression. 5-fluorouracil dose reduction was needed in seven patients. The mean delivered dose intensity of 5-fluorouracil was 610 mg/m2/wk (582 mg/m2/wk in patients in whom 5-fluorouracil was reduced for toxicity and 616 mg/m2/wk in the others). Our results do not seem to show any advantage in the maximization of 5-fluorouracil dose intensity. Furthermore, in an analysis of data from the literature we did not find any difference in response rate in relation to dose intensity in the 5-fluorouracil/leucovorin combination.     

Intra-arterial and intravenous use of 4' epidoxorubicin combined with 5-fluorouracil in primary hepatocellular carcinoma. A randomized comparison.

Between October, 1986, and March, 1990, 20 consecutive untreated and noncirrhotic patients with measurable and histologically and/or cytologically confirmed unresectable primary liver cancer were randomly assigned to intravenous (10 patients) or intra-arterial (10 patients) therapy. Patients were treated every 4 weeks with a combination chemotherapy regimen containing 4' epidoxorubicin and 5-fluorouracil. A 3-min bolus injection of 4' epidoxorubicin was followed by 5-fluorouracil given in a 90-min infusion. The dose of 4' epidoxorubicin was escalated: the starting dose was 40 mg/m2, the second dose was 50 mg/m2, and thereafter 60 mg/m2 during subsequent cycles. The dose of 5-fluorouracil was always 800 mg/m2. Objective response rates (20%) were similar in both treatments; two patients had partial responses in the intra-arterially treated group and one complete and one partial response were recorded in the intravenously treated group. The median survival time was 15.2 months for the patients treated intra-arterially and 13.8 months for the patients treated intravenously. Toxicity was mainly mild in both groups with less hematopoietic toxicity in the I.A.-treated group. 4' epidoxorubicin combined with 5-fluorouracil given intra-arterially is not superior to the intravenous therapy, but it may diminish systemic toxicity.     

Advanced colorectal carcinoma. A prospective randomized trial of sequential methotrexate, 5-fluorouracil, and leucovorin versus 5-fluorouracil alone

One hundred and twenty-five previously untreated patients bearing metastatic or advanced recurrent (inoperable) colorectal carcinoma and measurable disease were prospectively randomized. Those in arm A received 5-fluorouracil (5-FU), 1,200 mg/m2 i.v. infusion over 2 h, while those in arm B received methotrexate (MTX), 200 mg/m2 i.v. (push injection), followed 20 h later by 5-FU, 1,200 mg/m2 i.v. infusion over 2 h, plus calcium leucovorin (LV), 25 mg i.m. every 6 h for eight doses beginning 24 h after MTX administration. Cycles were repeated every 15 days. All patients receiving treatment were evaluable for toxicity and survival, and 118 patients were evaluable for response. The objective regression rate (complete plus partial response) was 12% (7 of 58) in arm A and 28% (17 of 60) in arm B (p = 0.049). No change was observed in 24% (14 of 58) in arm A and in 35% (21 of 60) in arm B (p = 0.28), while progressive disease was registered in 64% (37 of 58) and 37% (22 of 60) in arms A and B, respectively (p = 0.006). Median duration of response was 3 months in arm A and 5 months in arm B (p = 0.39). The median survival was 8.3 months in arm A and 11.2 months in arm B (p = 0.25). No statistically significant differences were found when objective regression and survival were related to site of primary tumor, performance status, and number of involved organs. There were two drug-related deaths in arm B due to severe myelosuppression followed by mucositis and sepsis. Of nonhematologic toxicities, diarrhea was more frequently observed in arm B, as were mucositis and infectious complications. Our results indicate that the sequential schedule MTX-5-FU-LV with 20-h intervals between MTX and 5-FU is superior in terms of objective regression to 5-FU alone given at the dose and schedule used in the present study. However, MTX-5-FU-LV did not have a significant impact on survival.     

'Neo-FAC' (5-fluorouracil, doxorubicin, and cyclophosphamide) for poor-prognosis stage IV breast cancer: a Southwest Oncology Group Phase II Study.

The authors report a phase II pilot investigation in the Southwest Oncology Group examining a combination of 5-fluorouracil, doxorubicin, and cyclophosphamide (FAC) incorporating modulated 5-FU in patients with poor-prognosis stage IV breast cancer. Patients with poor-prognosis stage IV breast cancer were treated with this "neo-FAC" as front-line therapy. The regimen consisted of 5-fluorouracil by continuous ambulatory infusion pump at 200 mg/m2/day for 42 days, repeated at 56-day intervals; doxorubicin at 20 mg/m2/week intravenously to a maximum cumulative total dose (including adjuvant therapy, if any) of 500 mg/m2; cyclophosphamide 60 mg/m2/day taken orally; methotrexate 15 mg/m2/week intravenously beginning 1 week after termination of doxorubicin; and oral prednisone decreasing from 60 mg/day on a tapering schedule for a total of 7 weeks of treatment. Treatment was continued until progression, unacceptable toxicity, or patient refusal. Twenty-four patients were accrued to this study. Of these, two were ineligible, and the remaining 22 were evaluable for response. Ten patients experienced grade 3 toxicity, and six had grade 4. There were no treatment-associated deaths. Best responses were a complete response in one patient (5%) and partial responses in 6, for an overall response rate of 32% (7/22 evaluable patients). Overall survival in five pilot studies in the Southwest Oncology Group in this poor-prognosis population are relatively superimposable. The present regimen, with its relatively poor outcome and the expense and inconvenience of administering chemotherapy by ambulatory infusion pump, will not be pursued further.     

Sequential administration of methotrexate, cisplatin, and 5-fluorouracil in multimodal therapy for locally advanced head and neck cancer

Thirty-eight previously untreated patients with locally advanced head and neck cancer received three cycles of induction chemotherapy with methotrexate (120 mg/m2) followed by cisplatin (100 mg/m2) and a 5-day continuous infusion of 5-fluorouracil (1,000 mg/m2 per day). The response rate in 34 evaluable patients was 94%, with a complete response rate of 26%. Thirty-one patients underwent local therapy following induction chemotherapy, and 25 (81%) were rendered free of disease: 14 of 15 treated with surgery and radiotherapy and 11 of 16 treated with radiotherapy alone. At a median follow-up of 11 months, 8 patients have relapsed while the remaining 17 patients continue free of disease. The dose-limiting toxicity of chemotherapy was mucositis resulting in reduction of the 5-fluorouracil dose in 28 patients. This regimen is highly effective in inducing responses in patients with locally advanced head and neck cancer; 81% of the patients who complete local therapy are rendered free of disease with this multimodal approach. Due to short follow-up, the relapse rate, overall survival, and disease-free survival cannot yet be determined.     

Sequential trimetrexate, 5-fluorouracil and folinic acid are effective and well tolerated in metastatic colorectal carcinoma. The phase II study group of the AIO

Trimetrexate (TMTX) is a new antifolate which avoids competition for cellular uptake with folinic acid (FA). A regimen of sequential TMTX, FA and 5-fluorouracil (5-FU) has shown efficacy in patients with colorectal cancer. Therefore, we treated 34 previously untreated patients with metastatic colorectal cancer with a weekly chemotherapy regimen consisting of 110 mg/m(2) of TMTX intravenously, then 24 h later 200 mg/m(2) of FA (i.v.) and 500 mg/m(2) of 5-FU (i. v.). Thereafter, 7 doses of oral FA (15 mg) were given at 6-hourly intervals. A treatment cycle consisted of 6 weeks of treatment, then 2 weeks of rest. All patients were treated as outpatients unless complications arose. Thirty-three patients were assessable for tumor response, and all 34 patients were assessable for toxicity. Twelve patients (36%; 95% confidence interval: 25-49%) achieved a partial response. The median duration of response was 8.5 months, and median survival was 14 months. The most common toxicity was diarrhea of grade 3/4, observed in 22% of treatment cycles; this decreased to 8% with early loperamide treatment. Hematologic toxicity was mild. The sequential administration of TMTX, FA and 5-FU is an active regimen in the first-line treatment of metastatic colorectal cancer and warrants further studies.