Weekly infusional high-dose fluorouracil (HD-FU), HD-FU plus folinic acid (HD-FU/FA), or HD-FU/FA plus biweekly cisplatin in advanced gastric cancer: randomized phase II trial 40953 of the European Organisation for Research and Treatment of Cancer Gastrointestinal Group and the Arbeitsgemeinschaft Internistische Onkologie.

PURPOSE: This multicentric, randomized, two-stage phase II trial evaluated three simplified weekly infusional regimens of fluorouracil (FU) or FU plus folinic acid (FA) and cisplatin (Cis) with the aim to select a regimen for future phase III trials. PATIENTS AND METHODS: A total of 145 patients with advanced gastric cancer where randomly assigned to weekly FU 3,000 mg/m2/24 hours (HD-FU), FU 2,600 mg/m2/24 hours plus dl-FA 500 mg/m2 or l-FA 250 mg/m2 (HD-FU/FA), or FU 2000 mg/m2/24 hours plus FA plus biweekly Cis 50 mg/m2, each administered for 6 weeks with a 1-week rest. The primary end point was the response rate. RESULTS: Confirmed responses were observed in 6.1% (two of 33) of the eligible patients treated with HD-FU, in 25% (12 of 48, including one complete remission [CR]) with HD-FU/FA, and in 45.7% (21 of 46, including four CRs) with HD-FU/FA/Cis. The HD-FU arm was closed after stage 1 because the required minimum number of responses was not met. The median progression-free survival of all patients in the HD-FU, HD-FU/FA, and HD-FU/FA/Cis arm was 1.9, 4.0, and 6.1 months, respectively. The median overall survival was 7.1, 8.9, and 9.7 months, and the survival rate at 1 year was 24.3%, 30.3%, and 45.3%, respectively. Grade 4 toxicities were rare. The most relevant grade 3/4 toxicities were neutropenia in 1.9%, 5.4%, and 19.6%, and diarrhea in 2.7%, 1.9%, and 3.9% of the cycles in the HD-FU, HD-FU/FA, and HD-/FU/Cis arms, respectively. CONCLUSION: Weekly infusional FU/FA plus biweekly Cis is effective and safe in patients with gastric cancer.

Increased hepatic gluconeogenesis: the secret of Lance Armstrong's success.

Enormous amounts of lactic acid are produced during endurance sport by muscle cells. This metabolite is thought responsible for the muscle pain and the fatigue during sport. Its internal removal from the body by enzymatic conversion depends mainly on the capacity of the hepatic gluconeogenesis that converts lactic acid to glucose. The extraordinary sportive results of the racing cyclist Lance Armstrong did us realize that a high capacity of hepatic gluconeogenesis was the basis of his success, because it might have provided him with less pain complaints caused by lactic acid and with an extra source of energy from lactic acid. This enhanced gluconeogenesis can be due to his heavy training program. At the age of 12-13 years he daily swam 10,000m and cycled 32km. In later years as cyclist his training labour was also more than normal. A constitutional increased gluconeogenesis cannot be excluded, because as a boy of 12 years he became already fourth in 1500m free style swimming in a contest for swimmers from whole Texas. The last argument for an increased gluconeogenesis is that Armstrong in October 1996 suffered from an extensively disseminated testicular tumour. This large tumour load caused that in the tumour the oxidative (=aerobic) energy generation changed into a fermentative (=anaerobic) one. This resulted in a high increase of lactic acid that putted up the gluconeogenesis in the liver. We think that this stimulated, high level gluconeogenesis remained high in the following years, when Armstrong restarted cycling, that it provided him with extra energy from lactic acid and with fewer complaints due to the exercise, and that thus this was the basis of his success.

Prediction of chemotherapeutic response of colorectal liver metastases with dynamic gadolinium-DTPA-enhanced MRI and localized 19F MRS pharmacokinetic studies of 5-fluorouracil.

Systemic chemotherapy is effective in only a subset of patients with metastasized colorectal cancer. Therefore, early selection of patients who are most likely to benefit from chemotherapy is desirable. Response to treatment may be determined by the delivery of the drug to the tumor, retention of the drug in the tumor and by the amount of intracellular uptake, metabolic activation and catabolism, as well as other factors. The first aim of this study was to investigate the predictive value of DCE-MRI with the contrast agent Gd-DTPA for tumor response to first-line chemotherapy in patients with liver metastases of colorectal cancer. The second aim was to investigate the predictive value of 5-fluorouracil (FU) uptake, retention and catabolism as measured by localized (19)F MRS for tumor response to FU therapy. Since FU uptake, retention and metabolism may depend on tumor vascularization, the relationship between (19)F MRS and the DCE-MRI parameters k(ep), K(trans) and v(e) was also examined (1). In this study, 37 patients were included. The kinetic parameters of DCE-MRI, k(ep), K(trans) and v(e), before start of treatment did not predict tumor response after 2 months, suggesting that the delivery of chemotherapy by tumor vasculature is not a major factor determining response in first-line treatment. No evident correlations between (19)F MRS parameters and tumor response were found. This suggests that in liver metastases that are not selected on the basis of their tumor diameter, FU uptake and catabolism are not limiting factors for response. The transfer constant K(trans), as measured by DCE-MRI before start of treatment, was negatively correlated with FU half-life in the liver metastases, which suggests that, in metastases with a larger tumor blood flow or permeability surface area product, FU is rapidly washed out from the tumor.

Cancer cachexia demonstrates the energetic impact of gluconeogenesis in human metabolism.

A review-based hypothesis is presented on the energy flow in cancer patients. This hypothesis centres on the hypoxic condition of tumours, the essential metabolic consequences, especially the gluconeogenesis, the adaptation of the body, and the pathogenesis of cancer cachexia. In growing tumours the O(2) concentration is critically low. Mammalian cells need O(2) for the efficient oxidative dissimilation of sugars and fatty acids, which gives 38 and 128 moles of ATP per mole glucose and palmitic acid, respectively. In the absence of sufficient O(2) they have to switch to anaerobic dissimilation, with only 2 moles of ATP and 2 moles of lactic acid from 1 mole of glucose. Since mammalian cells cannot ferment fatty acids, in vivo tumour cells completely depend on glucose fermentation. Therefore, growth of these tumour cells will require about 40 times more glucose than it should require in the presence of sufficient O(2). Since lactic acid lowers the intracellular pH, it decreases the activity of pyruvate dehydrogenase, stimulates fermentation, and thus amplifies its own fermentative production. Compensatory glucose is provided by hepatic gluconeogenesis from lactic acid. However, the liver must invest 3 times more energy to synthesize glucose than can be extracted by tumour cells in an anaerobic way. The liver extracts the required energy from amino acids and especially from fatty acids in an oxidative way. This may account for weight loss, even when food intake seems adequate. In the liver 6 moles of ATP are invested in the gluconeogenesis of one mole of glucose. The energy content of 4 out of these 6 moles of ATP is dissipated as heat. This may account for the elevated body temperature and sweating experience by cancer patients.

Gemcitabine plus CI-994 offers no advantage over gemcitabine alone in the treatment of patients with advanced pancreatic cancer: results of a phase II randomized, double-blind, placebo-controlled, multicenter study.

BACKGROUND: CI-994, an oral histone deacetylase inhibitor, has antineoplastic activity and synergism with gemcitabine preclinically. This randomized phase II trial explored whether CI-994 plus gemcitabine improves overall survival, objective response, duration of response, time to treatment failure and change in quality of life (QoL) or pain compared with gemcitabine alone. PATIENTS AND METHODS: A total of 174 patients received CG (CI-994 6 mg/m(2)/day days 1-21 plus gemcitabine 1000 mg/m(2) days 1, 8 and 15 each 28-day cycle) or PG (placebo plus gemcitabine 1000 mg/m(2) days 1, 8 and 15 of each 28-day cycle days 1-21). RESULTS: Median survival was 194 days (CG) versus 214 days (PG) (P = 0.908). The objective response rate with CG was 12% versus 14% with PG when investigator-assessed and 1% versus 6%, respectively, when assessed centrally. Time to treatment failure did not differ between the two arms (P = 0.304). QoL scores at 2 months were worse with CG than with PG. Pain response rates were similar between the two groups. There was an increased incidence of neutropenia and thrombocytopenia with CG. CONCLUSIONS: Adding CI-994 to gemcitabine in advanced pancreatic carcinoma does not improve overall survival, response rate or time to progression; CG produced decreased QoL and increased hematological toxicity and appears inferior to single-agent gemcitabine.

Weekly high-dose 5-fluorouracil and folinic acid in metastatic pancreatic carcinoma: a phase II study of the EORTC GastroIntestinal Tract Cancer Cooperative Group.

The aim of the study was to assess the response rate and toxicity of high-dose 24 h infusion of 5-fluorouracil (5FU) in metastatic adenocarcinoma of the pancreas. Patients with measurable disease, performance status 0-2, and no prior chemotherapy were registered to receive cycles of leucovorin (LV) 500 mg/m2 (or l-LV 250 mg/m2 over 1 h followed by 5FU 2.6 g/m2 over 24 h, weekly for 6 weeks, followed by a 2-week rest. The main endpoints were the response rate and toxicity. From 37 patients, 36 were the analysed for toxicity, and 33 were eligible and analysed for response. The median age was 59 years (range 28-74 years), and the median performance status was 1. Partial response was observed in three patients (9%) (95% Confidential Interval (CI): [2-24]%). Main grade 3/4 National Cancer Institute (NCI) common toxicity criteria toxicities (patients) were diarrhoea (n = 3), vomiting (n = 2) and hand-foot syndrome (n = 5). Median time to progression was 7 weeks (95% CI: [6.4-11.7] weeks) and median survival 19 weeks (95% CI: [12-35] weeks). In conclusion, high-dose 5FU and folinic acid is well tolerated, but has only modest activity in pancreatic cancer.

19F-magnetic resonance spectroscopy in patients with liver metastases of colorectal cancer treated with 5-fluorouracil.

The purpose of this study was to examine the uptake and metabolism of 5-fluorouracil (5-FU) in human liver metastases. Patients with liver metastases of colorectal cancer were treated with 5-FU (500/600 mg/m)+folinic acid with or without trimetrexate. The clinical application of F-magnetic resonance spectroscopy (MRS) of 5-FU in a random group of patients (n=17) was investigated. MR spectra of all patients showed 5-FU and catabolite resonances, and fluoronucleotides were also seen in seven patients. A correlation was found between maximum levels of 5-FU catabolites as measured by F-MRS and response in a group with larger metastases. However, such correlation was not observed in a group with smaller metastases, probably because of a significant contribution of normal liver tissue to the MR spectra.

Recombinant human erythropoietin attenuates weight loss in a murine cancer cachexia model.

BACKGROUND: Within hypoxic tumor regions anaerobic dissimilation of glucose is the sole source of energy generation. It yields only 5% of the ATP that is normally gained by means of oxidative glucose catabolism. The increased need for glucose may aggravate cancer cachexia. We investigated the impact of recombinant human erythropoietin (RhEPO) and increased inspiratory oxygen concentrations on weight loss in tumor-bearing mice. METHODS: Fragments of the murine C26-B adenocarcinoma were implanted in 60 BALB/c-mice. The mice were divided into four groups and assigned to: (A) no treatment; (B) RhEPO- administration (25 IU daily from day 1-11, three times per week from day 12); (C) RhEPO and 25% oxygen; and (D) RhEPO and 35% oxygen. Three control groups of four healthy mice each received the same treatment as groups A, B, and D, respectively. Hematocrit and hemoglobin levels, tumor volume, and body weight were monitored. At day 17 the experiment was terminated and the serum lactate concentration was measured. The tumors were excised and weighed and, for each mouse, the percentage weight loss was calculated. The impact of tumor weight and the treatments on lactate concentration and weight loss was evaluated. RESULTS: Significant positive correlations were found between tumor weight and lactate concentration and between tumor weight and percentage weight loss. In the mice with the largest tumors, RhEPO displayed a significant weight loss-reducing effect, and a significant negative correlation was found between hemoglobin concentration and weight loss. An oxygen-rich environment did not appear to influence weight loss. CONCLUSION: Anaerobic glycolysis in a growing C26-B tumor is related to weight loss. RhEPO administration results in a reduction of the percentage weight loss; this effect is probably mediated by an increased hemoglobin concentration.

Cancer cachexia: what is known about its etiology and what should be the current treatment approach?

Cancer cachexia, defined as involuntary weight loss and tissue wasting due to cancer, negatively influences physical condition, quality of life and prognosis. Well known causes, such as ileus or hypercalcemia, do not suffice to explain the entire phenomenon. Metabolic changes induced by the tumor and/or host are supposed to play a deciding role. In the present review current insights into the etiology and treatment are discussed.

An analysis of chemotherapy dose and dose-intensity in small-cell lung cancer: lessons to be drawn.

BACKGROUND: The survival in untreated small-cell lung cancer (SCLC) is <3 months. Prognosis has improved with chemotherapy, but remains poor. One of the issues concerning current chemotherapy is whether there is any benefit of increasing chemotherapy dose or dose intensity (DI). DESIGN: In the present review, 20 randomised studies, published in the period 1980-2001, in which dose or DI of chemotherapy in SCLC were the only variables tested, are analysed. The studies were categorised as follows: (i) number of cycles (treatment duration); (ii) dose per cycle; (iii) interval between cycles (dose densification); and (iv) a combination of these variables. RESULTS: (i) With treatment duration reduced to three to six cycles, median survival time (MST) was 2 months shorter, most evident in patients showing a (complete) response to initial chemotherapy. (ii) An improved survival was observed in two out of five high-dose studies. (iii) Survival was increased by 0.6 to 6.2 months in all four densification studies. (iv) Survival was not improved in studies that used dose-escalation and/or -densification in combination with a reduced number of cycles. The sample sizes were too small to be conclusive in most of the individual trials. The median of the MSTs in the 20 trials taken together was 9.8 months for the standard arms and 11.5 months for the intensified arms (i.e. more cycles, higher dose per cycle and/or shorter intervals). After omitting the two trials with reduced number of cycles in the so-called 'high-dose' arm, the median of MSTs was 8.7 and 11.5 months, respectively. There was only a slight improvement (1%) in 2-year survival for all trials taken together. However, when only taking high-dose and dose-densified chemotherapy trials into account, the difference in median 2-year survival became 19% (12% versus 31%). CONCLUSIONS: The above classification facilitates our understanding about doses of chemotherapy and it makes us appreciate the relevance of the individual determinants. It appears that the number of cycles, dose level, dose density, cumulative dose and DI are all important factors for improving survival. Intensification of chemotherapy still deserves further research in SCLC.

Vinorelbine and cisplatin in metastatic squamous cell carcinoma of the oesophagus: response, toxicity, quality of life and survival.

BACKGROUND: Vinorelbine and cisplatin are active against squamous cell oesophageal carcinoma. The purpose of this phase II study was to evaluate the efficacy and safety of vinorelbine plus cisplatin in previously untreated patients with metastatic squamous cell oesophageal carcinoma and to estimate the progression-free survival, overall survival and quality of life (QoL) of the patient population. PATIENTS AND METHODS: Seventy-one eligible patients were entered into a study of vinorelbine 25 mg/m2 on days 1 and 8 plus cisplatin 80 mg/m2 on day 1, every 3 weeks. Degree of dysphagia relief was monitored and QoL was measured using the EORTC QLQ-C30. RESULTS: All eligible patients were assessed for response and 24 achieved a confirmed partial response (33.8%; 95% confidence interval 23-46); the median duration of response was 6.8 months, progression-free survival was 3.6 months and median survival of the whole group was 6.8 months. Toxicity was mainly related to neutropenia (grade 3/4 in 41% of patients). At cycle 2, 43% of the patients reported at least a moderate improvement in global health status/QoL and 25% experienced a large improvement. CONCLUSIONS: Vinorelbine plus cisplatin represents a well-tolerated active palliative regimen for patients with advanced squamous cell carcinoma of the oesophagus. This combination may offer a better therapeutic index than cisplatin-5-fluorouracil.

Results of a randomised phase II study of cisplatin plus 5-fluorouracil versus cisplatin plus 5-fluorouracil with alpha-interferon in metastatic pancreatic cancer: an EORTC gastrointestinal tract cancer group trial.

A randomised phase II study of 5-fluorouracil (5-FU) plus cisplatin (CDDP) with or without alpha-interferon 2b was performed in patients with pancreatic cancer with measurable metastatic disease outside the pancreas. The treatment in arm A consisted of cisplatin (100 mg/m(2)) on day 1, followed by a continuous infusion of 5-FU 1000 mg/m(2) for 4 days and in arm B the same treatment was given plus alpha-interferon 2b in a dose of 3 million Units/day subcutaneously (s.c.) from day 1 for 5 days. 36 patients were entered in the trial, 18 in each arm. In arm B only 15 patients were eligible. No responses were observed in the 5-FU/CDDP arm and only 2 partial responses were achieved in the interferon-arm, lasting 27 and 32 weeks, respectively. Both treatment arms showed considerable toxicity. It has to be concluded that both treatment regimens have little activity and cannot be recommended.

Phase II study of a combination of cyclophosphamide, adriamycin and cisplatin in advanced fallopian tube carcinoma. An EORTC gynecological cancer group study. European Organization for Research and Treatment of Cancer.

OBJECTIVE: To investigate the clinical activity and toxicity of a combination chemotherapy consisting of cyclophosphamide (C), adriamycin (A) and cisplatin (P) for patients with primary adenocarcinoma of the Fallopian tube having FIGO stage III-IV disease. METHODS: The CAP-regimen consisted of cyclophosphamide 600 mg/m2, adriamycin 45 mg/m2, and cisplatin 50 mg/m2 administered intravenously on day one every 28 days. RESULTS: Twenty-four eligible patients with histologically-confirmed Fallopian tube adenocarcinoma were entered in the trial. Fourteen patients had FIGO stage III, and ten had stage IV disease. The median number of CAP cycles was six. Ten patients had a complete and six had a partial response (response rate: 67%, 95% confidence limits: 45-84%). WHO grade III-IV side-effects included haematological toxicity, nausea/vomiting and alopecia. Furthermore, mild signs of cisplatin-related peripheral neurotoxicity were observed. At a median follow-up of 40 months, nine patients were alive and 15 had died due to malignant disease. The median time to progression was 13 months for all patients. The median overall survival was 24 months and the 1-, 3- and 5-year survival and their 95% confidence limits were 73% (54-92%), 25% (4-46%) and 19% (0-38%), respectively. CONCLUSION: The present data confirm the therapeutic activity of the CAP-regimen in primary Fallopian tube adenocarcinoma. The response rate is moderate and the toxicity profile is acceptable.

Phase I and pharmacokinetic study of the orally administered farnesyl transferase inhibitor R115777 in patients with advanced solid tumors.

R115777 is a novel selective inhibitor of farnesyl transferase, an enzyme that is involved in the proliferation of the malignant cell type. This study was designed to determine the toxicity, maximal tolerated dose and pharmacokinetics of R115777 when given orally b.i.d. for 28 days followed by 1-2 weeks of rest. Patients with advanced solid tumors for whom no standard therapy was available could enter the study. The starting dose of R115777 was 200 mg/dose and inter- as well as intra-patient dose escalations were performed with increments of 100 mg/dose. Nine patients entered the study and received in total 23 treatment cycles. A dose of 300 mg b.i.d. proved feasible with grade 4 neutropenia occurring in one of six patients who completed the first treatment cycle. Other toxicities were infrequent. Pharmacokinetic analysis demonstrated that peak plasma concentrations of 881+/-393 ng/ml were reached within 1-5 h. No accumulation of R115777 was observed over a 28-day period. The study was terminated based on these results together with the observation from a related phase I study in which higher doses of R115777 were associated with the frequent occurrence of grade 3-4 myelosuppression. We conclude that the recommended dose of R115777 given for 28 days followed by 1-2 weeks of rest is 300 mg b.i.d. Myelosuppression is the dose-limiting toxicity.

Glutathione S-transferases and iododeoxyuridine labelling index during chemotherapy of gastric cancer.

BACKGROUND: Resistance to chemotherapeutic agents is a major problem in the treatment of patients with gastric cancer. Many factors may play a role in the resistance to cytotoxic drugs. The purpose of this study was to investigate the significance of glutathione (GSH), glutathione S-transferases (GSTs) and cell proliferation as parameters for response and resistance to chemotherapy in patients with gastric cancer. METHODS: In endoscopic biopsies of normal and malignant gastric tissue from 15 patients with gastric cancer treated by chemotherapy, the GSH content, GST activity and levels of GST Alpha, Mu and Pi isoenzymes were determined before the start of chemotherapy and after 2 and 6 cycles. Furthermore, cell proliferation was determined in these biopsies after in vivo Iododeoxyuridine (IdU) labelling. RESULTS: None of the above mentioned parameters were predictive for response to chemotherapy. After 2 courses of chemotherapy there was an increase of median GSH content (367%) in three patients with partial response (PR), whereas there was a decrease (43%) in five patients with progressive disease (PD) (p < 0.05). Median GST activity increased (257%) in patients with PR and declined (31%) in patients with PD (p < 0.05). GST Pi showed a median increase of 326% in responding patients and a 59% decrease in progressive patients (p < 0.05). There were no significant changes in GST Alpha and Mu. In seven patients with stable disease (SD) there were no significant changes in GSH/GST parameters. CONCLUSION: GSH/GST parameters and IdU labelling index determined before the start of chemotherapy were not predictive for response to that chemotherapy. However, the differences of GSH and GST parameters between responding and progressive patients suggests a role for the GSH/GST system in the susceptibility of gastric tumor cells to chemotherapy.

Effect of carbogen breathing on the pharmacodynamics of 5-fluorouracil in a murine colon carcinoma.

To determine whether carbogen breathing has an effect on 5-fluorouracil (5-FU) uptake, retention and metabolism in C38 murine colon tumours grown in C57Bl/6 mice, we used in vivo 19F nuclear magnetic resonance (NMR) spectroscopy. Eleven tumour-bearing mice were treated with 150 mg/kg of 5-FU given intraperitoneally (i.p.). Five mice received carbogen gas (95% O(2) and 5% CO(2)) for 9.5 min, starting 1 min before 5-FU administration. We found increased levels of 5-FU and its anabolites and catabolites by sequential ¿19F NMR spectroscopy in the group treated with 5-FU in combination with carbogen compared with the group treated with 5-FU alone. The maximum of normalised values of 5-FU and its metabolites, reached after carbogen breathing, was almost 2-fold higher than after treatment with 5-FU alone. Despite these increased concentrations no significant effect of carbogen on growth inhibition of the tumour by 5-FU was observed, which may be related to the size as well as the well vascularised and perfused conditions of the tumours studied.

Correlation between iododeoxyuridine and MIB-1 labelling index in gastric carcinoma and adjacent normal gastric tissue.

BACKGROUND: In vivo labelling with synthetic thymidine analogues, such as Iododeoxyuridine (IdU) and Bromodeoxyuridine (BrdU), has frequently been used to estimate tumour proliferation. However, this method requires intravenous administration of IdU or BrdU, thymidine analogues that are potential mutagens. Recently, the monoclonal antibody MIB-1 has been developed, recognizing the Ki-67 nuclear antigen, which is associated with cell cycle proliferation and is found throughout the cell cycle (G1, S, G2 and M phases), but not in resting (G0) cells. We studied the correlation between the MIB-1 labelling index (LI) and the IdU labelling index in normal and malignant gastric tissue. PATIENTS AND METHODS: Twenty patients with gastric cancer received an intravenous injection of IdU (200 mg/m2) before surgery. Specimens were obtained from gastric carcinoma and adjacent normal gastric tissue. The samples were fixed in formalin and immunohistochemical analyses of IdU LI and MIB-1 LI were performed. The LI was defined as the percentage of labelled nuclei of 5000 nuclei counted. RESULTS: The IdU LI ranged from 3.3% to 18.2% in gastric carcinoma and from 0.5% to 5.6% in adjacent normal gastric mucosa, whereas the MIB-1 LI ranged from 4.2% to 46.0% in gastric cancer and from 1.3% to 25.1% in adjacent normal gastric mucosa. Comparison of IdU LI with MIB-1 LI, using the Spearman rank correlation coefficient test showed a significant correlation between IdU LI and MIB-1 LI in normal gastric tissue (r = 0.63, p < 0.05). However, in gastric carcinoma no significant correlation was found between either proliferation marker (r = 0.07, N.S.). CONCLUSION: MIB-1 accurately reflects the in vivo IdU LI in normal gastric tissue, whilst in gastric carcinoma the MIB-1 LI does not seem to be a substitute for the in vivo IdU LI.

Phase I and pharmacologic study of oral (PEG-1000) 9-aminocamptothecin in adult patients with solid tumors.

PURPOSE: 9-Amino-20(S)-camptothecin (9-AC) is a specific inhibitor of topoisomerase-I. Recently, a bioavailability of approximately 48% for the oral PEG-1000 formulation was reported. We conducted a phase I and pharmacokinetic study of the oral PEG-1000 formulation of 9-AC to define the maximum-tolerated dose, toxicity profiles, pharmacokinetic-dynamic relationships, and preliminary antitumor activity in patients with solid tumors. PATIENTS AND METHODS: Patients were treated with oral (PEG-1000) 9-AC given once a day for 7 or 14 days at doses ranging from 0.25 to 1.1 mg/m(2)/d; cycles were repeated every 21 days. For pharmacokinetic analysis, plasma sampling was performed on days 1 and 6 or 8 of the first course using a validated high-performance liquid chromatographic assay. RESULTS: Thirty patients were entered onto the study; three patients were not assessable for toxicity and response. Twenty-seven patients received a total of 89 courses. The dose-limiting toxicities (DLTs) were myelosuppression and diarrhea at a dose of 1.1 mg/m(2)/d for 14 days. Pharmacokinetics showed a substantial interpatient variation of the area under the plasma concentration-time curve (AUC) of 9-AC. The intrapatient variability was extremely small. A significant correlation was observed between the percentage decrease in WBC count and the AUC of 9-AC lactone (r(2) = 0.86). One partial response was noted in a patient with metastatic colorectal cancer. CONCLUSION: DLTs in this phase I study of oral 9-AC daily for 14 days every 21 days were myelosuppression and diarrhea. The recommended dose for phase II studies is 0.84 mg/m(2)/d. In view of the substantial interpatient variability in AUC and the availability of a limited sampling model, a pharmacokinetic guided phase II study should be considered.