Addition of leucovorin in modulation of 5-fluorouracil with methotrexate: potentiating or reversing effect?

Concurrent Modulation of 5-Fluorouracil with Methotrexate and L-leucovorin: An Effective and Moderately Toxic Regimen for the Treatment of Advanced Colorectal Carcinoma a Multicenter Phase II Study of the Southern Italy Cooperative Oncology Group

Aims and Background

Methotrexate (MTX) and leucovorin (LV) can enhance the cytotoxicity of 5-fluorouracil (5FU) by modifying its metabolic pathway inside target cells. Some preclinical studies and clinical trials have suggested that the concurrent or sequential double modulation of 5FU by means of MTX and LV may give a higher activity than single biochemical modulations. The purpose of our phase II study was to assess the activity and toxicity of a biweekly regimen including MTX, levo-LV and 5FU in colorectal cancer patients.

Methods

From July 1994 to May 1997, 100 consecutive patients affected by advanced or metastatic colorectal carcinoma were given MTX, 750 mg/m2 iv (2-h infusion) on day 1, and levo-LV, 250 mg/m2 iv (2-h infusion) followed by 5FU, 800 mg/m2 iv bolus on day 2, every two weeks. Patients were treated until complete response or progressive disease was documented, or for a maximum of 16 courses.

Results

Among 97 eligible patients, 5 complete and 25 partial responses were obtained, giving an overall response rate of 31% (95% exact confidence limits, 22-41%). Response rate was significantly higher in patients with a good (ECOG scale 0) than with a poor (ECOG scale 1 or 2) performance status (40% versus 17%, P <0.02). Median time to treatment failure was 27 weeks, median survival time was 63 (95% confidence limits, 54-71) weeks, and 2- and 3-year probability of survival were 34% and 12%, respectively. Performance status was the only pretreatment characteristic significantly affecting the outcome of patients. Indeed, median survival time was 94 weeks for patients with a performance status = 0 and 37 weeks for patients with a performance status ≥ 1 (P < 0.05). Toxicity of the treatment was low and manageable; grade 3 to 4 leukopenia affected 8% of patients, whereas grade 3 diarrhea and mucositis occurred in 5% and 4%, respectively.

Conclusions

The double biochemical modulation of 5FU by MTX and levo-LV is at least as effective as, and probably more effective than, the single modulation by MTX or by LV. It may therefore represent a therapeutic option for the palliative treatment of patients with advanced colorectal carcinoma.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Biweekly irinotecan or raltitrexed plus 6S-leucovorin and bolus 5-fluorouracil in advanced colorectal carcinoma: a Southern Italy Cooperative Oncology Group phase II-III randomized trial

PURPOSE

The aim of this randomised trial was to evaluate the activity and toxicity of a biweekly regimen including 6S-leucovorin-modulated 5-fluorouracil (LFA-5-FU), combined with either irinotecan (CPT-11 + LFA 5-FU) or raltitrexed (Tomudex) (TOM + LFA-5-FU), in advanced colorectal cancer patients, and to make a preliminary comparison of both these experimental regimens with a biweekly administration of LFA-5-FU modulated by methotrexate (MTX + LFA-5-FU).

PATIENTS AND METHODS

One hundred fifty-nine patients with advanced colorectal carcinoma previously untreated for the metastatic disease (34 of them previously exposed to adjuvant 5-FU) were randomly allocated to receive: CPT-11, 200 mg/m2 i.v. on day 1, followed on day 2 by LFA, 250 mg/m2 i.v. infusion and 5-FU, 850 mg/m2 s i.v. bolus (arm A); TOM, 3 mg/m2 i.v. on day 1, followed on day 2 by LFA, 250 mg/m2 i.v. infusion and 5-FU, 1050 mg/m2 i.v. bolus (arm B); or MTX, 750 mg/m2 i.v. on day 1, followed on day 2 by LFA, 250 mg/m2 i.v. infusion and 5-FU, 800 mg/m2 i.v. bolus (arm C). Courses were repeated every two weeks in all arms of the trial. Response rate (RR) was evaluated after every four courses. The sample size was defined to have an 80% power to detect a 35% RR for each experimental treatment, and to show a difference of at least 4% in RR with the standard treatment if the true difference is 15% or more.

RESULTS

The RRs were: 34% (95% confidence interval (95%, CI): 21%-48%) in arm A, including 3 complete responses (CRs) and 15 partial responses (PRs), 24% (95% CI: 14%-38%) in arm B, including 2 CRs and 11 PRs, and 24% (95% CI: 14%-38%), with 2 CRs and 11 PRs, in arm C. After a median follow-up time of 62 (range 18-108) weeks, the median time to progression was 38, 25, and 27 weeks for arm A, B, and C, respectively. With 94 patients still alive, the one-year probability of survival was 61%, 54%, and 59%, respectively. WHO grade 3 or 4 neutropenia and diarrhoea affected 46% and 16%, respectively, of patients treated with CPT-11 + LFA 5-FU. Median relative dose intensity over eight cycles (DI8) was 78% for CPT-11 and 82% for 5-FU. Severe toxicities of TOM + LFA-5-FU were neutropenia (16%) and diarrhoea (16%), but median relative DI8 was 93% for TOM, and 82% for 5-FU.

CONCLUSIONS

CPT-11 + LFA-5-FU compares favorably in term of activity and toxicity with other combination regimens including CPT-11 and continuous infusional 5-FU. The hypothesis of a RR 15% higher than the MTX + LFA-5-FU treatment can not be ruled out after this interim analysis. The TOM + LFA 5-FU regimen showed a RR and a toxicity profile very close to the MTX + LFA 5-FU combination, and dose not deserve further evaluation in advanced colorectal cancer patients.

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.

Relation between thymidylate synthase expression and survival in colon carcinoma, and determination of appropriate application of 5-fluorouracil by immunohistochemical method

BACKGROUND

Thymidylate synthase (TS) is regarded as a parameter of 5-fluorouracil (5-FU) chemosensitivity for colorectal carcinoma. Recent researchers indicate that the chemosensitivity of 5-FU for colorectal carcinoma with low expression of TS is better than tumors with high expression of TS. But the relation between TS expression and overall survival of curatively resected colorectal cancer patients has been less studied.

METHODS

Specimens of curatively resected colon carcinoma from 148 patients were included in this study. TS expression in the tumor was assessed by immunohistochemical staining technique, and the patients were categorized into TS-(+) and TS-(-) groups. First, the relation between TS expression and survival of patients was examined. Next, for each group, we compared survival between the chemotherapy-(+) and the chemotherapy-(-) subgroup.

RESULTS

Overall survival was significantly better in the TS-(-) group (n = 107) than in the TS-(+) group (n = 41) (P = .0003). In the TS-(-) group, there was little difference between the chemotherapy-(+) and the chemotherapy-(-) subgroup. In the TS-(+) group, the survival of the chemotherapy-(+) subgroup was significantly better than the chemotherapy-(-) subgroup (P = .0439).

CONCLUSIONS

TS, itself, may be a prognostic factor for colon carcinoma; and 5-FU adjuvant chemotherapy may be appropriate for colon carcinoma with high expression of TS.

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.

Biochemical mechanisms of interferon modulation of 5-fluorouracil activity in colon cancer cells

The antiproliferative effect of 5-fluorouracil (5-FU) in colon cancer can be enhanced by interferons (IFN-alpha and IFN-gamma). The mechanisms by which IFNs modulate 5-FU activity are not completely elucidated. IFN-alpha may elevate the levels of the active 5-FU metabolite 5-fluoro-2'-deoxyuridine-5'-monophosphate (FdUMP) in the cell, possibly leading to increased inhibition of the target enzyme thymidylate synthase (TS), which might enhance DNA damage. It has been shown that IFN-gamma can prevent 5-FU induced overexpression of TS. We studied IFN modulation in three colon cancer cell lines (SW948, WiDr, human; C26-10, murine) and the sublines WiDr/F and C26-10/F, which were adapted to low folate levels. A 1.5-fold increase in 5-FU sensitivity was observed in C26-10 and C26-10/F (by murine IFN-alpha, beta); in SW948, WiDr and WiDr/F (by human IFN-gamma) and in SW948 and WiDr/ F (by human IFN-alpha). In none of the cell lines did human IFN-alpha, IFN-gamma or murine IFN-alpha, beta increase FdUMP levels after exposure to 5-FU. TS activity, indirectly measured by incorporation of [6-3H]-deoxyuridine into DNA, was inhibited by 5-FU, but the IFNs did not enhance inhibition. DNA damage was measured as a drug-induced decrease of double-stranded (dss) DNA compared to control cells. After 5-FU exposure, dss DNA decreased to 60-75% in WiDr, WiDr/F and SW948 cells. Human IFN-alpha alone caused minimal DNA damage (95% dss DNA), but increased 5-FU-induced effects to 35-50% dss DNA. IFN-gamma did not cause DNA damage and did not enhance 5-FU-mediated DNA damage. Expression of TS protein, analysed by ELISA, was increased after 5-FU exposure of SW948 cells, but this increase was not affected by addition of either IFN-alpha or IFN-gamma. It is concluded that one of the mechanisms involved in modulation of 5-FU activity is the effect of IFN-alpha on 5-FU-mediated DNA damage, but for IFN-gamma no mechanism of action was found.

Thymidylate synthase and drug resistance

Thymidylate synthase is an important target for both fluorinated pyrimidines and for new folate analogues. Resistance to 5-fluorouracil (5FU) can be related to insufficient inhibition of thymidylate synthase. The 5FU-nucleotide FdUMP induces inhibition of thymidylate synthase which is enhanced and retained for longer in the presence of increased folate pools, for which leucovorin is a precursor. In a murine model system, 5FU treatment caused a 4-fold induction of thymidylate synthase levels which may have contributed to resistance. Addition of leucovorin to this treatment prevented this induction and increased the antitumour effect 2-3-fold. In the clinical setting, 5FU administration to patients resulted in approximately 50% inhibition of TS after 48 h. The combination with leucovorin resulted in a more pronounced inhibition after 48 h (approximately 70%). A significant relationship was observed with outcome of treatment; when thymidylate synthase levels were high and inhibition was low, no response was observed. A separate study showed that low thymidylate synthase levels appeared to be an independent prognostic factor for adjuvant therapy.