Cisplatin, fluorouracil, and high-dose leucovorin for recurrent or metastatic head and neck cancer

Oxaliplatin, folinic acid and 5-fluorouracil (OFF) in patients with recurrent advanced head and neck cancer: A phase II feasibility study

The purpose of this phase II trial was to investigate the efficacy and toxicity of oxaliplatin combined with folinic acid (FA) and 5-FU in patients with recurrent squamous cell carcinoma of the head and neck (scchn) in advanced stage of disease. Thirty-six patients with recurrent/metastatic disease with median age of 59 years were enrolled. Patients received oxaliplatin (85mg/m(2)) and FA (200mg/m(2)) followed by 5-FU (2000mg/m(2)) as 24h continuous infusion on day 1 and 15 in a 4-week cycle. On day 8 and 22 FA (200mg/m(2)) and 5-FU (2000mg/m(2)) were administered without oxaliplatin followed by two weeks without cytotoxic treatment. Toxic effects, length of survival and tumour response were assessable in 33/36 patients. The overall response was 60.6% with 7 (21.2%) complete responders (CR) and 13 (39.4%) partial responders (PR). Eight patients (24.2%) showed stable disease (SD) and 5 (15.2%) progressed. The median time to progression (TTP) was 8.1 month (range 2-14) and median overall survival was 10.8 months (range 5-16). The 1-year survival rate was 43.2%. The incidence of haematological toxicity was low but mild paraesthesias occurred in all patients received more then 3 cycles of cytotoxic therapy and dose reduction was necessary in two patients due to diarrhoea grade 3. In this small phase II study the combination of oxaliplatin, FA and 5-FU (OFF) demonstrated relative to the standard regimen of cisplatin and 5-FU a high antitumoural activity in previously treated scchn with favourable toxicity profile.

Concurrent cisplatin, 5-fluorouracil, leucovorin, and radiotherapy for invasive bladder cancer

PURPOSE

To investigate the tolerance and efficacy of a modified concurrent chemoradiation (CCRT) protocol for patients with invasive bladder cancer "unfit" for radical cystectomy.

METHODS AND MATERIALS

Twenty-three muscle-invasive bladder cancer patients who were unfit for or unwilling to receive radical cystectomy were enrolled in this study. All patients had transitional cell carcinoma of bladder, and distribution of stage was 14 (61%), 1 (4%), and 8 (35%) for T3a, T3b, and T4, respectively. This study included a relatively old-age population, with the median age being 75 and 70% of patients over 70 years old. Patients were treated with maximal transurethral resection of the bladder tumor followed by curative CCRT. The chemotherapy (C/T) regimen was comprised of cisplatin, 50 mg/m(2) intravenously (i.v.) on Day 1; 5-fluorouracil (5-FU), 500 mg/m(2)/day by continuous i.v. infusion on Days 1-3; and leucovorin, 50 mg/day by continuous i.v. infusion on Days 1-3. Chemotherapy course was repeated at 21-day intervals. The radiation dose was 44-45 Gy to whole pelvis and 60-61.2 Gy to bladder, with a daily fraction of 1.8-2 Gy. The completeness of the CCRT protocol was defined as patients receiving at least 55 Gy of radiotherapy to the whole bladder and at least three courses C/T.

RESULTS

Seventy-four percent of patients (17/23) completed the CCRT protocol. Radiation Therapy Oncology Group (RTOG) Grade 3 acute toxicities were observed in 4 patients, which included leucopenia, vomiting, genitourinary (GU) tract infection, and diarrhea. No treatment-related deaths occurred during the CCRT period. RTOG Grade 3 or more late complications were observed in 3 patients; one of them died of radiation cystitis superimposed with GU infection. Of the 18 patients whose response to CCRT was evaluated, a complete tumor response was documented in 16 patients (89%). With a median follow-up of 3 years, the 3-year overall survival (OS) and disease-free survival (DFS) for all patients was 69% and 65% respectively. Meanwhile, the 3-year overall and DFS rates for patients who completed CCRT vs. those who did not complete CCRT were 82% vs. 33% and 75% vs. 33%, respectively (p = 0.18 for OS and p = 0.04 for DFS).

CONCLUSIONS

Concurrent cisplatin, 5-FU, leucovorin, and radiotherapy for treatment of invasive bladder cancer is a feasible and promising treatment even for relatively old patients. Our results are comparable to those in recent studies by using combined modality treatment or neoadjuvant chemotherapy plus radical cystectomy. Consequently, this novel protocol warrants a prospective clinical trial and may be a safe, effective alternative to radical cystectomy.

Prospective evaluation of preoperative chemotherapy in resectable squamous cell carcinoma of the thoracic esophagus

A prospective study was performed to clarify the surgical outcome of patients with esophageal carcinoma who would benefit from induction chemotherapy followed by surgery. Of 55 eligible patients, 42 (76.3%) agreed to randomization with either chemotherapy followed by surgery (n = 21) or surgery alone (n = 21). The other 13 refused. The chemotherapy consisted of cisplatin, 5-fluorouracil and leucovorin. All 55 patients underwent esophagectomy with two- or three-field resection, including two (3.6%) hospital mortalities. Of the 21 patients receiving chemotherapy, the response rate was 33.3% after the first course and 60% after the second course. A complete response was not obtained. Responders to the first course showed a prolonged survival, however time to treatment failure did not differ between patients treated with chemotherapy followed by surgery or surgery alone. This chemotherapy offered a worse surgical outcome for patients with pretreatment diagnosis of T3. Multivariate analysis identified a partial response to the first course of chemotherapy to be a favorable prognostic indicator. Preoperative chemotherapy does not give a survival benefit over surgery alone for patients with advanced tumor (T3). Initial response to the first dose of chemotherapy is deemed to be a prognostic factor for patients with less advanced tumor (T1/T2).

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.

The role of chemotherapy in head and neck cancer

We studied the effect of cytoreductive chemotherapy in head and neck cancer and analyzed it in terms of efficacy, remission rates, and duration, as well effect on survival. Single-agent chemotherapy, which formerly was used as a palliative therapy in recurrent and metastatic disease, had little affect on survival. More recently, multi-agent chemotherapy trials have shown significantly higher response rates, but this success has not translated into an added survival benefit. These findings led to the introduction of multi-agent chemotherapy into the induction (neoadjuvant) clinical setting. In these clinical circumstances, better objective response rates were found, particularly in the previously untreated patient. Although this therapy has resulted in better control of local disease, the impact on survival is not yet clear. Adjuvant chemotherapy is most useful in patients who have a high risk of relapse. Therapy appears to decrease its incidence, particularly at distant sites. Finally, chemoradiation trials have shown that this treatment provides a survival advantage, but at the cost of a significant increase in toxicity.

Phase I trial of uracil-tegafur (UFT) plus oral leucovorin: 14-day schedule

We previously reported results of a Phase II trial of UFT [Taiho Pharmaceutical Ltd., Tokyo, Japan; (BMS-200604) Bristol-Myers Squibb, Princeton, NJ], an oral 4:1 molar concentration of uracil and tegafur, plus oral leucovorin for metastatic colorectal carcinoma (Pazdur et al., J. Clin. Oncol. 12:2296-2300, 1994]. Our results demonstrated that a 28-day schedule of this combination produced a response rate similar to that obtained with conventional intravenous fluorouracil (5-FU)-plus-leucovorin regimens but without the severe or life-threatening neutropenia or oral mucositis that complicates intravenous 5-FU regimens. The current Phase I trial examines the dose-limiting toxic effects and maximum tolerated dose of a 14-consecutive-day schedule of UFT plus oral leucovorin in 14 patients who had histologically proven cancer and had received prior chemotherapy. The daily UFT plus leucovorin dose was divided into three doses administered orally every 8 hours. In this study, the UFT dose was escalated while the leucovorin dose remained at 150 mg/day. Of the 14 patients, 4 were initially treated at the 350-mg/m2/day UFT level for 14 days without any dose-limiting toxic reactions. Subsequently, another 7 patients were treated at the 400-mg/m2/day level; grade 3 diarrhea developed in 3 of these 7 (with severe abdominal cramping in 2 cases and severe nausea and vomiting unresponsive to antiemetics in the third). To better define the starting dose for phase II studies, an additional 3 patients were treated at the 350-mg/m2/day dose level. Of the total 7 patients treated at 350 mg/m2/day, grade 3 toxic events (diarrhea) developed in 2 patients. Grade 1-2 toxic effects noted at this level included fatigue, stomatitis, skin rash, abdominal pain, nausea, and vomiting. Neither partial nor complete responses were observed in this trial. The maximum tolerated dose of this schedule is 350 mg/m2/day UFT plus 150 mg/day oral leucovorin. However, because of this schedule's inferior dose intensity compared with that of the 28-day schedule of UFT plus leucovorin, subsequent development of UFT in the United States has focused on the 28-day regimen.

Management for patients with advanced T4 epidermoid carcinoma of the esophagus

Available data concerning the treatment of patients with advanced T4 esophageal carcinoma are limited. A consecutive series of 42 patients with advanced T4M0 epidermoid carcinoma of the esophagus were studied from June 1987 to July 1992. The aim of this study was to evaluate the efficacy of various therapeutic modalities, and further evaluate the therapeutic options. The various therapeutic modalities included the following: Group I, feeding jejunostomy or endoesophageal intubation, 6 patients; Group II, palliative subtotal esophagectomy only, 8 patients; Group III, bypass procedures without tumor resection, 9 patients; Group IV, nutritional support and then treatment with irradiation (n=8) or concurrent radio-chemotherapy (n=4), 12 patients; Group V, subtotal esophagectomy, followed by aggressive concurrent radiochemotherapy, 7 patients. The total prescribed irradiation dose was 60 Gy (10 Gy/5 fractions/week). A combination regimen of chemotherapy consisted of cisplatin, 5-fluorouracil, and leucovorin (PFL regimen). For the patients undergoing esophagectomy or bypass procedures (n=24), the rates of operative complication and mortality were 45.8% and 25%, respectively. Side effects of adjuvant therapy (n=24) consisted of main airway irritation (100%), mucositis or gastrointestinal symptoms (83.3%), hematologic toxicity (79.2%), esophagitis or gastric ulcer (62.5%), alopecia (37.5%), and pneumonia (20.8%). The mortality due to toxicity of adjuvant therapy was 21.1% (4/19 patients). The mean survival times for each of the different groups was 1.9+/-0.5 months for Group I, 4.8+/-1.6 months for Group II, 5.2+/-1.2 months for Group III, 7.3+/-2.0 months for Group IV, and 20.3+/-2.5 months for Group V, respectively. Compared with patients of Groups I--IV, the Group V patients had a significantly superior one-year survival rate (P<0.01). Our results demonstrated that esophagectomy followed by concurrent irradiation and PFL combination chemotherapy may provide a significant improvement in the quality of life and survival for appropriate patients with advanced T4M0 epidermoid carcinoma of the esophagus. Furthermore, more than one cycle of PFL regimen chemotherapy may result in a better prognosis. During the performance of such an aggressive treatment, the utmost care must be taken with the patient's nutrition and to prevent pulmonary complications.

Cisplatin, 5-fluorouracil, and high-dose folinic acid in patients with advanced unresectable head and neck cancer

For patients with advanced, unresectable head and neck (HN) cancer, surgery and/or radiotherapy are the standard treatments but have poor results. A phase II trial of a continuous infusion of cisplatin, 5-FU, and high dose folinic acid (PFL) as induction chemotherapy in patients with previously untreated, locally advanced HN cancer was performed in an attempt to confirm the encouraging results reported by Dana Farber investigators using an identical regimen. Forty-five consecutive patients with unresectable HN cancer were treated every 28 days with a continuous infusion of cisplatin 25 mg/m(2)/day (days 1-5), 5-FU 800 mg/m(2)/day (days 2-6), and folinic acid 500 mg/m(2)/day (days 1-6). After three courses of chemotherapy, patients were treated with surgery and/or radiotherapy. Objective responses were observed in 26 of 38(69%) evaluable patients with 14(37%) clinical complete responses. Grade III-IV toxicity was important and consisted mainly of mucositis and neutropenia that were found in 47 and 18%, respectively , of patients after the first course. There was one toxic death. PFL is an active, toxic induction regimen for far-advanced HN cancer, yielding a response rate in the range of the widely used cisplatin and 5-FU (PF) schedule; a comparative trial is warranted before concluding that PFL is superior to the latter combination.

Evaluation of in vitro chemosensitivity using human lung cancer cell lines

The use of well-characterized human lung cancer cell lines has allowed for new opportunities in preclinical and clinical drug evaluation. Development of semiautomated tests of in vitro cytotoxicity such as the MTT assay, which utilizes the formazan salt 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), has allowed for preclinical evaluation of novel chemotherapeutic agents and drug combinations. In addition, techniques such as this make possible the testing of sufficient data sets to allow determination of true biochemical drug synergy. Assessment of drug combinations which possess in vitro synergy or supraadditive effects can suggest chemotherapeutic regimens for further clinical testing. Using the MTT assay in conjunction with isobolographic analysis, it is possible to test commonly used regimens which are based on presumed or apparent in vivo drug synergy, such as the combination of etoposide and cis-platinum. This frequently prescribed combination was found to lack in vitro biochemical synergy when tested with human lung cancer cell lines, indicating that the observed clinical benefits of this drug combination may be due to factors in the tumor microenvironment, drug metabolism, or non-overlapping toxicities. Finally, although it remains to be determined if a significant role for in vitro drug testing will be found in direct clinical applications, preclinical drug evaluation during the drug development process using cultured tumor cell lines may ultimately allow for disease or patient specific therapies for testing.

Chemotherapy of squamous cell carcinoma of head and neck: the future is now

In 1996, there is an established role for chemotherapy in head and neck cancer. Patients with recurrent disease will be offered combination chemotherapy. In this setting, investigations of new drugs or combinations and the pursuit of concomitant chemo-reirradiation are of interest. In patients with locoregionally advanced disease, induction chemotherapy can be used with the goal of larynx preservation. In addition, a role for chemotherapy in nasopharyngeal cancer appears to be emerging with increased survival as therapeutic goal. The combination of cisplatin and 5-FU does not need to be tested further, however, a more definitive evaluation of a biochemically modulated PF regimen might be of interest. Furthermore, induction chemotherapy represents an ideal investigational tool in which to further evaluate the activity of several new drugs in head and neck cancer patients. Finally, concomitant chemoradiotherapy has resulted in increased survival in several randomized clinical studies. Given the poor outcome of standard radiotherapy in patients with unresectable disease, we favor the administration of concomitant chemoradiotherapy in this group of patients as a standard therapy. In our opinion, the use of radiation therapy alone in this group of patients should be restricted to patients with poor performance status or other high medical risks that render the administration of chemotherapy unadvisable. Finally, given the high incidence of second malignancies and general medical complications in cured head and neck cancer patients, studies of chemoprevention and good preventive medical care by a medical oncologist should be made available to all patients.

Elimination of dose limiting toxicities of cisplatin, 5-fluorouracil, and leucovorin using a weekly 24-hour infusion schedule for the treatment of patients with nasopharyngeal carcinoma

BACKGROUND

Cisplatin, 5-flourouracil (5-FU), and leucovorin (PFL) chemotherapy has been reported to be effective in the treatment of cancers but severe mucositis or neutropenia are dose limiting toxicities. This Phase II study evaluated the anticancer effect and the toxicities of a new weekly 24-hour infusional PFL chemotherapy in patients with nasopharyngeal carcinoma (NPC).

METHODS

Forty-two patients with stage IV NPC were studied. Cisplatin 25 mg/m2/d, 5-FU 2200 mg/m2/d, and leucovorin 120 mg/m2/d were adminstered weekly by 24-hour intravenous continuous infusion in an outpatient setting. Clinical response and toxicity were evaluated weekly.

RESULTS

The complete response rate (CR) was 30% and the partial response (PR) rate 60% in the localized previously untreated group. The CR rate was 22.7% and PR rate 45.5% in local recurrent/metastatic group. The overall response rate was 79%. Eighty-one percent of patients who had no previous chemotherapy and 67% of patients who had previous chemotherapy responded to weekly PFL. There were no dose limiting toxicities. No patient had grade 3 or 4 mucositis or neutropenia. Thirty-two patients (76%) had no oral mucositis. Seven patients (17%) had grade 1 mucositis and 3 patients (7%) had grade 2 mucositis.

CONCLUSIONS

Elimination of dose limiting toxicities is possible using a weekly 24-hour infusion schedule of PFL chemotherapy while retaining significant anticancer activity as demonstrated in these patients with advanced NPC. To discover whether this schedule is superior to cisplatin and 5-FU or other PFL chemotherapy regimens requires further investigation.

Interferons and other cytokines in head and neck cancer

The use of cytokines in head and neck cancer is increasingly under investigation. Clinical trials have tested the interferons, interleukin-2 and other cytokines as single agents and in various combinations. The addition of interferon to the cisplatin and 5-fluorouracil (5-FU) regimens (with and without leucovorin) has been explored. A randomized international trial comparing cisplatin and 5-FU with cisplatin, 5-FU and interferon-alpha 2b is in progress.

Leucovorin and folic acid regimens for selective expansion of murine 5,10-methylenetetrahydrofolate pools

Mice bearing subcutaneously implanted EMT6 mammary adenocarcinoma were treated with leucovorin or folic acid by continuous subcutaneous infusion or bolus intraperitoneal injection. (6R)-5,10-Methylenetetrahydrofolate pools in cytosolic extracts of the tumor, marrow, and gut were measured by analysis of the ternary complex with thymidylate synthase (5,10-methylenetetrahydrofolate: dUMP C-methyltransferase, EC 2.1.1.45) and 5-fluoro-2'-deoxyuridylate, and the polyglutamate distribution in the (6R)-5,10-methylenetetrahydrofolate pool was analyzed by native gel electrophoresis. Bolus intraperitoneal administration of either leucovorin or folic acid caused dose-dependent expansion of the (6R)-5,10-methylenetetrahydrofolate pool in the tumor, but not in the marrow or gut. For example, the AUC (0-5 hr) in the tumor increased from a baseline value of 8.2 to 20 nmol/mg protein.hr after a bolus dose of 1.5 mmol/kg of leucovorin or folic acid, whereas the increase in marrow and gut was 2- to 4-fold lower. Continuous subcutaneous infusion at the same total dosage over 3 days gave AUC (0-96 hr) values of 134 nmol/mg protein.hr for controls as compared with 347 nmol/mg protein.hr for the leucovorin group and 254 nmol/mg protein.hr for the folic acid group. In contrast to bolus treatment, the increase in (6R)-5,10-methylenetetrahydrofolate in the marrow and small intestine with both leucovorin and folic acid infusion was similar to the increase in the tumor. Thus, intraperitoneal bolus injection was tumor selective, but subcutaneous continuous infusion was not. Longer-chain polyglutamates of (6R)-5,10-methylenetetrahydrofolate in the tumor after bolus treatment with 0.375 and 0.75 mmol/kg of leucovorin or folic acid increased relative to controls. At higher doses of 1.5 and 2.25 mmol/kg, an increase was observed only in the mono/diglutamate fraction. In marrow, on the other hand, the mono/diglutamate fraction, but not the longer-chain polyglutamates, increased at all doses. In the constant infusion regimen, longer-chain polyglutamates increased in all three tissues, though in gut and marrow the mono/diglutamate fraction increased more than in tumor. Leucovorin and folic acid were converted to (6R)-5,10-methylenetetrahydrofolate more efficiently but less selectively during a 3-day subcutaneous infusion than after an intraperitoneal bolus. Longer-chain polyglutamates were selectively increased in tumor by both regimens of leucovorin administration.

Head and neck cancer: present status and future prospects of adjuvant chemotherapy

For more than 15 years, active clinical research and continuing efforts in the field of CT in head and neck cancer have produced a modest but definite progress and achievements in this disease. We are a long way away from producing more definitive and acceptable results and higher cure rates in this disease. The achievements of systemic CT in patients with head and neck cancers are summarized in this review. Continuing efforts and investigation are needed to study the efficacy of systemic CT in patients with resectable head and neck cancer. We are continuing to investigate the best timing and sequence of CT as part of CMT and then the efficacy of such treatment in patients with resectable cancer. Efforts are underway to improve on the results in patients with NPC and patients with unresectable disease with the use of chemotherapy as part of CMT. Efforts are also underway to consolidate and improve on the results obtained with systemic CT to preserve laryngeal function. We strongly believe that with continuation of these serious efforts further achievement and impact can be obtained with systemic CT as part of other modalities in these patients.

The pharmacokinetics of reduced folates after intraperitoneal and intravenous administration of racemic [6S,R]-folinic acid

We investigated the pharmacokinetics of tetrahydrofolates following the administration of [6S,R]-folinic acid and 5-flurouracil delivered i.v., i.p., and by a combination of both routes in patients with colon cancer. The concentrations of the biologically active tetrahydrofolates ([6S]-folinic acid and 5-methyltetrahydrofolate) and the relatively inert diastereomer [6R]-folinic acid were monitored using a selective on-line coupled achiral-chiral high-performance liquid chromatographic method. In plasma, a target concentration of 5 microM active tetrahydrofolates, which is considered necessary for an optimal synergistic effect, could be achieved after i.v. or combined i.v. and i.p. administration but was not reached in a patient receiving i.p. [6S,R]-folinic acid alone. In three patients receiving i.p. [6S,R]-folinic acid a high level of [6S]-folinic acid was observed in ascites, suggesting that the peritoneal cavity may act as a storage site for tetrahydrofolates after i.p. administration. In these patients, only a trace level of the active metabolite 5-methyltetrahydrofolate was detected in ascites, which may indicate that tetrahydrofolate derivatives penetrate only minimally, if at all, into the peritoneal cavity from the central compartment. These data would indicate that a combination of i.p. and i.v. administration may, from the pharmacological point of view, indeed contribute to an improved treatment of minimal residual disease persisting in the peritoneal cavity.

Cisplatin, 5-fluorouracil and interferon alpha 2b for recurrent or metastatic head and neck cancer

On the basis of preclinical data suggesting the possibility of maximising the efficacy of 5-fluorouracil and cisplatin by interferon, a pilot clinical trial was initiated in recurrent and/or metastatic head and neck cancer. Thirty-four patients were treated with cisplatin at 100 mg m-2, followed by 5-fluorouracil at 1,000 mg m-2 by continuous infusion for 5 days. Interferon alpha 2b was administered at the dose of 3 million U i.m. daily for 7 days, beginning the day before chemotherapy. Courses were repeated every 3 weeks. Two patients achieved a complete remission, six a partial response, 14 had stable disease and 12 progressed on therapy, for an overall response rate of 23% (95% confidence interval 10-36%). Median survival time was 5 months. Toxicity was severe. Stomatitis, diarrhoea and myelosuppression were the most common side-effects. Because of the poor response rate and the presence of severe toxicity, in our opinion further clinical trials in head and neck cancer should be attempted only after a better definition in preclinical studies of interactions among 5-fluorouracil, cisplatin and interferon.

Continuous infusion of high-dose 5-fluorouracil in combination with leucovorin and recombinant interferon-alpha-2b in patients with advanced colorectal cancer. A Multicenter Phase II study

BACKGROUND

5-Fluorouracil (5-FU), when combined with leucovorin (LV) or interferon-alpha (IFN-alpha), may result in improved response rates compared with 5-FU alone in patients with advanced colorectal cancer. The authors investigated the clinical efficacy of combining these three agents for patients in this group.

METHODS

Forty-five patients were administered outpatient high-dose 5-FU, 60 mg/kg/48 hours (2400 mg/m2/48 hours) continuous intravenous infusion on days 1 and 2; LV, 90 mg orally every 6 hour, 8 times during 5FU infusion; and recombinant IFN-alpha-2b, 10 x 10(6) IU/dose subcutaneously on days 1, 3, and 5. Cycles were repeated weekly for 4 weeks and every 2 weeks thereafter.

RESULTS

Forty-four patients were evaluable for response, and 11 patients (25%; 95% confidence interval, 12-38%) achieved a partial response with a median duration of 11 months. Median survival time for all patients was 11 months. Grade 3 and Grade 4 toxicities occurred in 21 patients (47%), which necessitated discontinuation of treatment in 2 patients (4%); permanent dose reductions were necessary in 11 patients (24%). The addition of IFN-alpha produced more 5-FU-related toxicity compared with a previous study in which the same dosage and schedule of 5-FU plus LV was used.

CONCLUSIONS

The efficacy of 5-FU continuous infusion combined with LV and IFN-alpha does not appear to differ significantly from earlier reports on treatment using 5-FU plus LV or 5-FU plus IFN-alpha for patients with colorectal cancer. However, this schedule of 5-FU combined with LV and IFN-alpha produces less toxicity compared with previous trials using bolus 5-FU plus IFN-alpha.

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.

Intravenous 6-thioguanine or cisplatin, fluorouracil and leucovorin for advanced non-small cell lung cancer: a randomized phase II study of the cancer and leukemia group B

This randomized phase II study was designed to evaluate the activity of intravenous 6-thioguanine (6-TG) as a single agent and the combination of cisplatin and 5-fluorouracil (5-Fu) modulated by oral leucovorin (PFL) in patients with advanced non-small cell lung cancer (NSCLC). Eligible patients had measurable or evaluable stage III B or IV NSCLC, had no received prior chemotherapy and had a performance status of 0-2. Patients were randomized to treatment with intravenous 6-TG at 55 mg/m2 administered over 30 minutes for 5 consecutive days and repeated every 35 days, or PFL chemotherapy with cisplatin 100 mg/m2 on day 1, 5-FU 800 mg/m2/day as a continuous intravenous infusion over 5 days and oral leucovorin administered at 100 mg every 4 hours during the entire duration of the cisplatin and 5-FU infusions. PFL was repeated every three weeks. Ninety-five eligible patients were randomized, 46 to 6-TG and 49 to PFL. Response rates were 4% for 6-TG (95% confidence interval 0.5%-14.8%, 1 partial, and 1 complete response) and 29% (16.6%-43.3%) for PFL (all partial). The median time to treatment failure was 2 and 4 months, respectively, and the median survival times were 6 and 10 months, respectively. Toxicities with 6-TG were, generally, mild to moderate but severe or life-threatening granulocytopenia was observed in 21% of patients. With PFL, mucositis was dose-limiting, and 78% of patients had severe or life-threatening mucositis. This led to dose reduction of 5-FU and leucovorin during subsequent cycles or treatment termination in 82% of patients.(ABSTRACT TRUNCATED AT 250 WORDS)

5-Fluorouracil, leucovorin, hydroxyurea, and escalating doses of continuous-infusion cisplatin with concomitant radiotherapy: a clinical and pharmacologic study

Cisplatin (CDDP), 5-fluorouracil (5-FU), and hydroxyurea (HU) have individually demonstrated activity against several solid tumors, act synergistically with each other in vitro, and may act as radiation sensitizers. Therefore, we designed a phase I study to determine the maximally tolerated dose of cisplatin as given in addition to our previously described combination of 5-FU, HU, and concomitant radiotherapy (XRT). Patients exhibiting advanced solid tumors requiring palliative XRT were eligible. The regimen consisted of 1 g HU given p.o.b.i.d. on days 1-5, 600 mg/m2 5-FU given i.v. daily by continuous infusion (c.i.) on days 1-5, escalating doses of cisplatin starting at 10 mg/m2 daily given by c.i. on days 1-5, and involved-field XRT carried out on days 1-5. The cycle was repeated every 14 days until the target XRT dose had been reached. In all, 19 patients were entered at the first dose level, and cumulative grade 3-4 myelosuppression was seen in 16 subjects. As no dose escalation was feasible, the chemotherapy was subsequently altered by using the above regimen for cycles 1, 3, 5, and 7 and substituting the less myelosuppressive regimen of 1 g HU given p.o.b.i.d. on days 1-5, 400 mg/m2 5-FU given i.v. daily by c.i., and 100 mg leucovorin given p.o.4 h on days 1-5 for cycles 2, 4, and 6. On this alternating program, 28 patients were treated with escalating doses of CDDP. The dose-limiting toxicity was again myelosuppression, which was prohibitive at a CDDP dose of 20 mg/m2 daily. In the final phase of the protocol, 30 subjects were treated with the above alternating-cycle regimen at a CDDP dose of 20 mg/m2 daily and a decreased HU dose of 500 mg p.o.b.i.d. in an attempt to circumvent the myelosuppression associated with this dose of CDDP. Although severe acute toxicity (cycles 1 and 2) was observed less frequently, cumulative toxicity (all cycles) remained pronounced. The other major toxicity encountered was mucositis, which was particularly pronounced in patients receiving radiation to the head and neck and following leucovorin-containing cycles. Plasma concentrations of free platinum did not correlate with the CDDP dose, possibly due to the narrow range of doses given. Pharmacodynamic modeling demonstrated that the CDDP dose and the HU dose were associated with leukopenia. Antitumor activity was demonstrated in a number of solid tumors particularly non-small-cell lung cancer and head and neck cancer.(ABSTRACT TRUNCATED AT 400 WORDS)

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.

Current chemotherapy of head and neck cancer

This article reviews the results of over 50 published trials testing the use of chemotherapy in patients with squamous cell carcinoma of the head and neck. Among the trials using chemotherapy before standard surgery and/or radiotherapy in stage III and IV disease, none has shown an improvement in survival compared with surgery and/or radiotherapy alone. In these studies, the survival at 3 to 5 years has been generally 40% to 50%. Several trials using chemotherapy after standard therapy, however, have reported survival benefits of 10% to 20%, suggested that further evaluation of classic adjuvant chemotherapy in this disease is warranted. Among studies in recurrent head and neck cancer, the most effective chemotherapy regimens appear to be variations of the program consisting of cisplatin followed by a 5-day infusion of 5-fluorouracil. Nevertheless, median survivals in recurrent disease remain short, generally 5 to 10 months.

5-fluorouracil + folinic acid with cisplatinum and bleomycin in the treatment of advanced head and neck squamous cell carcinoma

Thirty-six patients with advanced squamous cell carcinoma of the head and neck (SCCHN) were treated with a regimen including cisplatinum (CP) 30 mg/m2 i.v., 5-fluorouracil (5-FU) 500 mg/m2 i.v. bolus, folinic acid (FA) 200 mg/m2 i.v. in a continuous one-hour infusion, and bleomycin (B) 15 mg i.m. on the first and second days and repeated every 28 days. Thirty-three patients (25 with recurrent disease and 8 untreated) are evaluable for objective response. Of these, 4 (12%) achieved CR and 15 (45%) PR. All of the untreated patients responded. The mean duration of response in the patients with recurrent or metastatic disease was 5.5 months (range 2-10+). Remission of symptoms, such as pain and dysphagia, was obtained in 58% and in 44%, respectively. Subjective remission occurred almost exclusively in objectively responsive patients. The major side effects were leukopenia (55%) and nausea/vomiting (58%). This regimen is active in the treatment of advanced SCCHN. The quality of life may be improved in responsive patients.

A phase II study of piritrexim in combination with methotrexate in recurrent and metastatic head and neck cancer

Thirty patients with recurrent and/or metastatic head and neck cancer were treated with sequentially administered methotrexate (MTX) and piritrexim (PTX). The treatment schedule consisted of intravenous (IV) MTX (50 mg/m2) administered on day 1 and oral PTX (75 mg/m2) administered twice daily on days 8 to 12. Courses were repeated every 21 days with dose escalation in subsequent courses aimed at achieving Grade 1 toxicity. Two patients were not evaluable for response, 5 (17%; 95% confidence interval, 4% to 30%) had a partial response (PR), 10 had stable disease, and 13 had progressive disease. All five responses were seen in patients with regional lymph nodes as measurable disease. The median time to progression for all patients was 1.4 months, and the median survival was 6.7 months. Generally, this regimen was well tolerated with only mild toxicity seen during cycle 1 in the majority of patients. Dose escalation in subsequent cycles was possible in a high percentage of patients. Although the overall response rate and survival figures in this Phase II trial were disappointing, the doses and schedule used in this trial may have been suboptimal as reflected by the low incidence of moderate to severe toxicity. Additional evaluation of this combination of drugs in a more aggressive schedule may be warranted.

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.

Induction chemotherapy with a new regimen alternating cisplatin, fluorouracil with mitomycin, hydroxyurea and bleomycin in carcinomas of nasopharynx or other sites of the head and neck region

Sixty-six patients with locally advanced (Stages III and IV) carcinoma of the head and neck were treated with three cycles of induction chemotherapy, consisting of cisplatin, fluorouracil (FU) infusion, bleomycin, mitomycin, and hydroxyurea, followed by radiotherapy and/or surgery. There were 48 men and 18 women with a median age of 55 years (range, 18 to 75 years) and Karnofsky performance status of 80 (range, 40 to 90). Primary site was nasopharynx (28 patients), followed by larynx (12) and others (26). Forty-one (62%) patients were presented with Stage IV disease. The response rate to induction chemotherapy was 27% complete response, 50% partial response, 20% stable disease, and 3% progressive disease. There was no significant difference in response rate between patients with cancer of nasopharynx or other sites (P greater than 0.1). Survival was 61% at 24 months. Patients with cancer of nasopharynx had a better survival than those with other primaries (P = 0.033). Toxicities from chemotherapy included alopecia (73%), nausea/vomiting (66%), leukopenia (54%), stomatitis (36%), anemia (32%), thrombocytopenia (16%), and diarrhea (9%). Grade IV toxicity was not observed. Induction chemotherapy with this new regimen resulted in a high response rate but may not be superior to cisplatin and FU alone. It can be safely combined with radiotherapy as a potentially curative therapy in squamous cell carcinoma of the head and neck. Chemotherapy followed by radiation therapy may yield survival similar to radical surgery in laryngeal and other head and neck cancers.

5-Fluorouracil with oral leucovorin and hydroxyurea and concomitant radiotherapy for stage III non-small cell lung cancer

Twenty-three patients with regionally advanced non-small cell lung cancer (NSCLC) (Stage III) were treated with continuous infusion 5-fluorouracil (5-FU) augmented by high-dose oral leucovorin and hydroxyurea and concomitant radiotherapy. This chemoradiotherapy regimen was administered during 5 days of every other week for six cycles (total radiation dose, 6000 cGy). Three patients (13%) had stable disease, 13 patients (57%) had a partial response (PR), and 1 patient (4%) had a complete response (CR). The overall response rate was 61% (95% confidence interval, 41% to 81%). At a median follow-up time of 19 months, the median survival time for all 23 patients was 12 months. The median time to disease progression was 6 months. Twelve patients have had disease progression outside of the chest, and only 3 patients have had intrathoracic disease progression as the site of first failure. The toxicities of this regimen consisted of mild to moderate myelosuppression and moderate degree dermatitis and mucositis. It was concluded that concomitant chemoradiotherapy with this regimen results in high local activity at acceptable toxicity. However, the systemic activity of this regimen was low, resulting in a high distant recurrence rate and a median survival time that was not different from that achieved with standard therapy. Therefore, its use, as defined in this study, cannot be recommended.

Phase I clinical trial of cisplatin given i.v. with 5-fluorouracil and high-dose folinic acid

We report the results of a phase I study of intravenously administered cisplatin, 5-fluorouracil and high-dose folinic acid. This trial was designed to exploit potential biochemical interactions between these three agents. The maximum tolerated doses were cisplatin, 75 mg/m2, day 1; 5-fluorouracil, 375 mg/m2, days 1-5 and leucovorin 500 mg/m2, days 1-5. The dose-limiting toxic effect of this regimen was myelosuppression. Mild non-hematologic toxic effects were also observed and included nausea, vomiting, stomatitis, and diarrhea. Phase II trial of this regimen are underway, however randomized studies will eventually be necessary to establish whether cisplatin contributes clinically significant activity to this regimen.

A phase II trial of cisplatin and 5-fluorouracil with allopurinol for recurrent or metastatic carcinoma of the uterine cervix: a Southwest Oncology Group trial

On the strength of recent evidence of the activity of the combination of cisplatin and 5-fluorouracil against squamous malignancies of the esophagus and head and neck, this regimen was evaluated in a phase II trial against metastatic or recurrent squamous carcinoma of the uterine cervix. Cisplatin was administered at a dosage of 100 mg/m2 iv bolus and 5-fluorouracil was continuously infused iv at a dosage of 1000 mg/m2/day for 4 days. In an effort to determine whether the toxicities of 5-fluorouracil could be ameliorated by coadministration of allopurinol, patients were randomized to receive allopurinol, 900 mg orally, an odd or even courses of therapy beginning 5 days before 5-fluorouracil administration and continuing until conclusion of the infusion. Fifty-two eligible patients received 177 evaluable courses of treatment. The overall response rate was 28% (8 complete responses and 6 partial responses). Toxicity was confined to nausea and vomiting (81% of courses), anemia (47%), leukopenia (37%), oral mucositis (15%), diarrhea (6%), and thrombocytopenia (4%). Allopurinol produced no improvement in treatment-related toxicities. Allopurinol did not permit substantial increases in 5-fluorouracil dosage.

Cisplatin and tegafur in recurrent head and neck cancer. A phase II study

A phase II study of cisplatin and tegafur in recurrent epidermoid head and neck cancer is presented. All patients were treated with cisplatin 100 mg/m2 every 4 weeks. Twenty-nine received tegafur 750 mg/m2 days 2-28 orally and 18 patients, who were unable to take tegafur orally, were treated with tegafur 1,500 mg/m2 intravenously days 2-5. The response rate in the oral group was 28.5% and the median survival 29 weeks. The response rate in the intravenous group was 6% and the median survival was 17 weeks. We conclude that cisplatin and oral tegafur is active against head and neck cancer.

Enhancement of the antitumor effects of 5-fluorouracil by folinic acid

Although 5-fluorouracil (FUra) is one of the most effective cytotoxic agents in the treatment of various solid tumors (carcinomas of the gastro-intestinal tract, breast, head and neck), remissions occur in only 20-30% of cases and usually are of short duration. Recently, preclinical studies have shown that the antitumor activity of FUra can be potentiated by modulating the metabolism of this drug by using other substances, in particular 5-formyltetrahydrofolate (folinate, LV). Reduced folates (LV and 5-methyltetrahydrofolate) at concentrations greater than or equal to 1 microM can, by raising the intracellular levels of 5,10-methylenetetrahydrofolate, increase and prolong the inhibition of the target enzyme, thymidylate synthase, with formation of a stable ternary complex formed by the enzyme, the folate coenzyme and the fluoropyrimidine inhibitor (5-fluorodeoxyuridylate). After phase II clinical trials reported encouraging results with the combination LV-FUra in the treatment of patients with various solid tumors, randomized controlled studies in patients with colorectal carcinoma have documented an increase in the response rate of the combination compared to treatment with FUra alone. The integration of the LV-FUra combination into multidrug regimens is now under investigation for the treatment of carcinomas of the breast, stomach, and head and neck.

Phase I trial of 5-fluorouracil, leucovorin, and cisplatin in combination

The ongoing evaluation of combination chemotherapy with 5-fluorouracil (5-FU) and cisplatin in several tumors prompted a phase I clinical trial of cisplatin with 5-FU modulated by leucovorin. A total of 26 patients were treated with varying doses of 5-FU by continuous i.v. infusion for 5 days; 200 mg/m2 leucovorin was given by daily bolus injection for 5 days; and 20 mg/m2 cisplatin was infused over 2 h on each day of treatment. Courses were repeated every 21-28 days. The starting dose of 5-FU was 300 mg/m2. Poor-risk patients (extensive prior radiation, performance status of 2 or worse) did not tolerate the initial dose; the maximum tolerated dose of 5-FU in this group was 200 mg/m2 daily. Good-risk patients tolerated 300 mg/m2, but a majority had excessive toxicity at higher doses. The dose-limiting toxicity was gastrointestinal (mucositis/diarrhea) and/or myelosuppression; additional side effects included were nausea and vomiting (less than or equal to grade 2) and ataxia (one patient). Among 13 patients with colorectal cancer, 4 partial responses were observed. The marked reduction in the tolerable dose of 5-FU occasioned by the addition of modulating doses of leucovorin is noteworthy. The responses observed support further investigation of this regimen in phase II trials.

The emerging role of 5-fluorouracil and leucovorin in the treatment of advanced breast cancer. A review

Considerable interest has been generated by the clinical experience with 5-fluorouracil + leucovorin based regimens in colorectal cancer. Consequently, this combination was tested in other tumors in which 5-fluorouracil has some activity (gastric, pancreatic, head and neck and breast cancer). This review summarizes the interesting results reported so far in advanced breast cancer. Up to now, more than 300 patients have been treated with chemotherapeutic regimens based on this attempt at biochemical modulation of 5-fluorouracil's activity. Overall, a median response rate of 26% was achieved by nine studies performed in 245 mainly pretreated patients with an acceptable degree of toxicity. Moreover, two additional studies explored the clinical activity of this combination as first-line chemotherapy for advanced disease with impressive results. Current efforts to further improve the therapeutic index of this combination will also be briefly discussed.

New vistas for leucovorin in cancer chemotherapy

With a resurgence of interest in leucovorin calcium (LV), many questions about its role in cancer chemotherapy are being asked again. How does it modulate 5-fluorouracil (5-FU) therapy? Can it potentiate the cytotoxicity of 5-FU more in malignant than in normal cells? Does it rescue tumor cells from high-dose methotrexate (MTX) more than it does normal cells? How should LV rescue be individualized to maximize the therapeutic index? When can LV be administered orally, and how can LV rescue be conducted at home? When is LV rescue necessary, and what toxicities occur when it is inadequate? Some answers to these questions are provided in this review.

Clinical experience with leucovorin and 5-fluorouracil

Two trials of leucovorin (LV) and 5-fluorouracil (5-FU) in patients with metastatic colorectal cancer were done, both using a 3-day loading dose and then weekly doses to minimize toxicity. The first trial used LV administered by intravenous infusion with a constant dose of 5-FU 400 mg/m2, and the second trail used oral LV with increasing doses of 5-FU. In the first trail, 45 eligible patients (20 with and 25 without previous therapy) were treated. Toxicity usually consisted of diarrhea or weakness and was controlled by delaying or decreasing the 5-FU dose. Subjective responses occurred in 75% of patients but did not correlate with antineoplastic effect. Objective responses were seen in 36% and stabilization of disease in 31% of patients; these correlated with prolonged survival. Median survival was 8 months for patients with previous treatment and 10 for those without. Twelve-month survival was 32% and 40%, respectively. There was no correlation between the development of toxicity and response or survival. The second trial was conducted recently in cooperation with Duke University to determine toxicity and efficacy of oral LV with intravenous 5-FU before a randomized trial of this combination versus placebo with intravenous 5-FU. Eighteen patients were treated, and serum levels of folates were obtained on ten. First toxicity occurred at 5-FU doses ranging from 375 to 850 mg/m2, and consisted of diarrhea in nine, lethargy in seven, nausea/vomiting in four, dermatitis in four, conjunctivitis in two, hypersalivation in two, stomatitis in one, and profound granulocytopenia in one. Response rate was 35%, and stabilization was 35% with median survival of 14 months. Twelve-month survival was 56%.

Clinical pharmacology of the stereoisomers of leucovorin during repeated oral dosing

As part of a clinical trial of cisplatin, 5-fluorouracil (5-FU), and leucovorin (LV) for treatment of patients with advanced head and neck cancer, patients received 100 mg of LV (d,l-5-formyltetrahydrofolate) orally every 4 hours for 5 days. On days 2 and 4 of treatment, plasma samples were obtained 2 hours after (peak) and 30 minutes before (trough) a dose of LV. Total LV and 5-methyltetrahydrofolate (THF) concentrations were measured with high-performance liquid chromatography (HPLC) analysis. LV stereoisomer concentrations were determined by chiral HPLC on a bovine serum albumin-bonded silica column. Thus far, plasma folate levels have been analyzed for ten cycles of treatment administered to 7 patients (40 samples). Administration of LV in divided oral doses approximates a plasma steady state with no significant differences noted between peak and trough concentrations. Mean (+/- SD) plasma concentrations for all samples were (mumol): LV, 3.2 +/- 1.3; l-LV, 0.28 +/- 0.21; d-LV, 2.9 +/- 1.2; and THF, 4.25 +/- 2.5. Plasma levels of d-LV and THF tended to be approximately 10% higher on day 4 than day 2, although mean differences were not significantly different due to substantial interpatient variability. Of note was that the sum of THF and l-LV exceeds that of d-LV which was consistent with selective absorption of the l-isomer of LV. Mean ratios of d-LV/l-LV and d-LV/l-LV and THF were 13.7 +/- 10 and 0.88 +/- 0.68, respectively. The authors conclude that oral administration of LV in divided dose (1) simulates a continuous intravenous infusion; (2) produces plasma levels of l-reduced folates in a range known to potentiate 5-FU cytotoxicity; and (3) results in low ratios of d/l-reduced folates that may be important in maximizing the effectiveness of 5-FU-LV chemotherapy.