NIH consensus development statement on management of hepatitis B.

OBJECTIVE: To provide health care providers, patients, and the general public with a responsible assessment of currently available data on the management of hepatitis B. PARTICIPANTS: A non-DHHS, nonadvocate 12-member panel representing the fields of hepatology and liver transplantation, gastroenterology, public health and epidemiology, infectious diseases, pathology, oncology, family practice, internal medicine, and a public representative. In addition, 22 experts from pertinent fields presented data to the panel and conference audience. EVIDENCE: Presentations by experts and a systematic review of the literature prepared by the Minnesota Evidence-based Practice Center, through the Agency for Healthcare Research and Quality. Scientific evidence was given precedence over anecdotal experience. CONFERENCE PROCESS: The panel drafted its statement based on scientific evidence presented in open forum and on published scientific literature. The draft statement was presented on the final day of the conference and circulated to the audience for comment. The panel released a revised statement later that day at http://consensus.nih.gov. This statement is an independent report of the panel and is not a policy statement of the NIH or the Federal Government. CONCLUSIONS: The most important predictors of cirrhosis or hepatocellular carcinoma in persons who have chronic HBV are persistently elevated HBV DNA and ALT levels in blood. Other risk factors include HBV genotype C infection, male sex, older age, family history of hepatocellular carcinoma, and co-infection with HCV or HIV. The major goals of anti-HBV therapy are to prevent the development of progressive disease, specifically cirrhosis and liver failure, as well as hepatocellular carcinoma development and subsequent death. To date, no RCTs of anti-HBV therapies have demonstrated a beneficial impact on overall mortality, liver-specific mortality, or development of hepatocellular carcinoma. Most published reports of hepatitis therapy use changes in short-term virologic, biochemical, and histologic parameters to infer likelihood of long-term benefit. Approved therapies are associated with improvements in intermediate biomarkers, including HBV DNA, HBeAg loss or seroconversion, decreases in ALT levels, and improvement in liver histology (Table). Although various monitoring practices have been recommended, no clear evidence exists for an optimal approach. The most important research needs include representative prospective cohort studies to define the natural history of the disease and large RCTs of monotherapy and combined therapies, including placebo-controlled trials, that measure the effects on clinical health outcomes. Table. Criteria Useful in Determining for Whom Therapy is Indicated: Patients for whom therapy is indicated: Patients who have acute liver failure, cirrhosis and clinical complications, cirrhosis or advanced fibrosis and HBV DNA in serum, or reactivation of chronic HBV after chemotherapy or immunosuppression; Infants born to women who are HBsAg-positive (immunoglobulin and vaccination). Patients for whom therapy may be indicated: Patients in the immune-active phase who do not have advanced fibrosis or cirrhosis. Patients for whom immediate therapy is not routinely indicated: Patients with chronic hepatitis B in the immune-tolerant phase (with high levels of serum HBV DNA but normal serum ALT levels or little activity on liver biopsy); Patients in the inactive carrier or low replicative phase (with low levels of or no detectable HBV DNA in serum and normal serum ALT levels); Patients who have latent HBV infection (HBV DNA without HBsAg). We recommend routine screening for hepatitis B of newly arrived immigrants to the United States from countries where the HBV prevalence rate is greater than 2%. Screening will facilitate the provision of medical and public health services for infected patients and their families and provide public health data on the burden of disease in immigrant populations. The screening test should not be used to prohibit immigration.

Oxaliplatin-induced neurotoxicity: acute hyperexcitability and chronic neuropathy.

Oxaliplatin, a platinum-based chemotherapeutic agent, is effective in the treatment of solid tumors, particularly colorectal cancer. During and immediately following oxaliplatin infusion, patients may experience cold-induced paresthesias, throat and jaw tightness, and occasionally focal weakness. We assessed nerve conduction studies and findings on needle electromyography of patients with metastatic colorectal cancer before and during treatment with oxaliplatin. Twenty-two patients had follow-up studies within 48 h following oxaliplatin infusions, and 14 patients had follow-up studies after 3-9 treatment cycles. Repetitive compound muscle action potentials and neuromyotonic discharges were observed in the first 24-48 h following oxaliplatin infusion, but resolved by 3 weeks. After 8-9 treatment cycles, sensory nerve action potential amplitudes declined, without conduction velocity changes or neuromyotonic discharges. The acute neurological symptoms reflect a state of peripheral nerve hyperexcitability that likely represents a transient oxaliplatin-induced channelopathy. Chronic treatment causes an axonal neuropathy similar to other platinum-based chemotherapeutic agents.

A phase I and pharmacologic study of 9-aminocamptothecin administered as a 120-h infusion weekly to adult cancer patients.

PURPOSE: To define the toxicity profile and the recommended phase II doses of 9-aminocamptothecin (9-AC) administered as a weekly 120-h infusion. METHODS: 9-AC was administered over 120 h weekly to 55 adult cancer patients with solid tumors over doses ranging from 0.41 to 0.77 mg/m2 per day in a phase I and pharmacologic study. 9-AC formulated in dimethylacetamide/polyethylene glycol (DMA) was administered on a 3 of 4-week schedule, and the newer colloidal dispersion (CD) formulation was given on a 2 of 3-week schedule. RESULTS: Overall, 193 courses of therapy were administered over 122 dose levels. On the 3 of 4-week schedule, 9-AC DMA infused at > or = 0.6 mg/m2 per day for 120 h weekly produced dose-limiting neutropenia, thrombocytopenia, and diarrhea, or resulted in 1-2-week treatment delays. Shortening treatments to 2 of 3 weeks resulted in dose-limiting neutropenia and fatigue at infusion rates > 0.72 mg/m2 per day. The ratio of 9-AC lactone to total (carboxylate + lactone) drug plasma concentrations at steady-state was 0.15 +/- 0.07. Clinical toxicities and drug pharmacokinetics were not substantially different between the DMA and CD formulations. One objective response was observed in a patient with bladder cancer and minor responses were observed in patients with lung and colon cancers. Plasma area under the concentration versus time curve for 9-AC lactone modestly correlated with the degree of thrombocytopenia (r=0.51) using a sigmoid Emax pharmacodynamic model. CONCLUSION: The recommended phase II dose for the 9-AC DMA formulation is 0.48 mg/m2 per h over 120 h for 3 of 4 weeks and for the 9-AC CD formulation is 0.6 mg/m2 per day over 120 h for 2 of 3 weeks. Both regimens were well tolerated and feasible to administer.

Peripheral neuropathy associated with weekly oral 5-fluorouracil, leucovorin and eniluracil.

5-Fluorouracil (5-FU)-associated neurotoxicity is uncommon; symptoms may occur abruptly or more gradually during the course of chemotherapy. Peripheral neuropathy with 5-FU therapy has only rarely been reported. Two patients treated in a phase I trial of oral 5-FU, leucovorin and eniluracil, an inhibitor of dihydropyrimidine dehydrogenase (DPD), developed delayed onset symptoms of unsteady gait and reduced sensation in the legs. Magnetic resonance imaging scans of the brain and neurologic examination did not support a CNS basis for the condition. Electromyograms and nerve conduction studies revealed sensorimotor polyneuropathy. Other common etiologies of peripheral neuropathy were excluded. The neurological condition of these patients stabilized after 5-FU dose reduction and partial resolution gradually occurred when protocol therapy was stopped. Although CNS symptoms may rarely complicate 5-FU therapy, peripheral neuropathy is unexpected. Patients with DPD deficiency treated with conventional doses of 5-FU typically develop acute CNS toxicity shortly after therapy, accompanied by extremely high systemic exposure to 5-FU. Patients with normal 5-FU clearance may also experience CNS toxicity, particularly with high-dose schedules, and both parent drug and its catabolites may be contributory. Since DPD was profoundly inhibited during eniluracil therapy in these two patients, it is likely that 5-FU or its active metabolites were contributing factors to the peripheral neuropathy.

Measurement of the novel antitumor agent 17-(allylamino)-17-demethoxygeldanamycin in human plasma by high-performance liquid chromatography.

A sensitive HPLC assay has been developed to determine the concentration of 17-(allylamino)-17-demethoxygeldanamycin (AAG) in human plasma over the concentration range of 12.5 to 2,500 nM (7.33 to 1,465 ng/mL). After the addition of 1,000 nM geldanamycin as the internal standard, 1 mL samples of human plasma were subjected to solid-phase extraction, via Bond-Elut C18 cartridges, followed by analysis using an isocratic reversed-phase HPLC assay with UV detection. A Phenomenex Kingsorb, 3 micron, C18, 150x4.60 mm column and a Phenomenex Security Guard pre-column, C18 (ODS, Octadecyl), were used to achieve separation. AAG and GM were monitored at 334 and 308 nm, respectively, on a Hewlett-Packard 1050 Diode-Array Detector. The mobile phase, run at a flow-rate of 1 mL/min, was composed of 50% (v/v) 25 mM sodium phosphate (pH 3.00) with 10 mM triethylamine and 50% acetonitrile. HPLC effectively resolved AAG with retention times of 14.60 +/- 0.54 min and the internal standard geldanamycin at 10.72+/-0.38 min (n = 15). This assay was able to measure plasma concentrations of AAG, the lower limit of quantitation being 12.5 nM, at a starting dose of 10 mg/m2 infused intravenously over 1 h in a Phase I clinical trial in adult patients with solid tumors.

Human plasma carboxylesterase and butyrylcholinesterase enzyme activity: correlations with SN-38 pharmacokinetics during a prolonged infusion of irinotecan.

PURPOSE: To characterize the relationships between human plasma irinotecan carboxylesterase-converting enzyme activity, caboxylesterase-mediated hydrolysis of p-nitrophenyl acetate (pNPA), and the butyrylcholinesterase-mediated hydrolysis of butyrylthiocholine in human plasma and to test the ability of these in vitro tests to predict the variability in SN-38 pharmacokinetics in adult patients during a prolonged infusion of irinotecan. METHODS: Individual plasma-converting enzyme activity was measured in 20 adult cancer patients participating in a pharmacokinetic and phase I clinical trial of a prolonged 96-h intravenous infusion of irinotecan. The pNPA and butyrylthiocholine hydrolysis in patient plasma was also assayed. RESULTS: The irinotecan carboxylesterase-converting enzyme in human plasma had a Vmax of 89.9 +/- 22.7 pmol/h per ml plasma and a Km of 207 +/- 56 microM (mean +/- SD, n = 3). The mean value of the specific activity of this enzyme in 20 adult cancer patients was 10.08 +/- 2.96 pmol/h per ml plasma ranging from 5.43 to 15.39 pmol/h per ml. The area-under-the-concentration-versus time curve (AUC) ratio of SN-38 to irinotecan (AUCSN-38/AUCCPT-11) was used to assess the relative SN-38 exposure to the active metabolite in individual patients. Pharmacokinetic variations in the relative exposure to SN-38 did not correlate with the measured carboxylesterase-converting enzyme activity nor with plasma butyrylcholinesterase activity in our patient population. However, it did correlate with the measured pNPA hydrolysis activity in patient plasma (r2 = 0.350, P = 0.0124, n = 18). CONCLUSIONS: Determination of patient plasma pNPA hydrolysis activity may have utility in predicting SN-38 pharmacokinetics during prolonged infusions of irinotecan.

Thymidine kinase, thymidylate synthase, and dihydropyrimidine dehydrogenase profiles of cell lines of the National Cancer Institute's Anticancer Drug Screen.

PURPOSE: To determine the expression of three targets of 5-fluorouracil (5-FU) and 5-fluoro-2'-deoxyuridine (FdUrd) in human tumor cell lines and to compare these with the 50% growth inhibition concentrations (GI(50)) from the National Cancer Institute database. EXPERIMENTAL DESIGN: Thymidine kinase (TK) activity was assessed by conversion of [(3)H]thymidine to [(3)H]TMP. Thymidylate synthase (TS) protein expression was determined by Western analysis. TS and dihydropyrimidine dehydrogenase (DPD) mRNA expression were measured by quantitative reverse transcription-PCR. RESULTS: The median (range) for the targets were as follows: 5-FU GI(50), 20.8 microM (0.8-536); FdUrd GI(50), 0.75 microM (0.25-237); TK, 0.93 nmol/min/mg (0.16-5.7); in arbitrary units: TS protein, 0.41 (0.05-2.95); TS mRNA, 1.05 (0.12-6.41); and DPD mRNA, 1.09 (0.00-24.4). A moderately strong correlation was noted between 5-FU and FdUrd GI(50)s (r = 0.60), whereas a weak-moderate correlation was seen between TS mRNA and protein expression (r = 0.45). Neither TS expression nor TK activity correlated with 5-FU or FdUrd GI(50)s, whereas lines with lower DPD expression tended to be more sensitive to 5-FU. Cell lines with faster doubling times and wild-type p53 were significantly more sensitive to 5-FU and FDURD: CONCLUSIONS: The lack of correlation may in part be attributable to the influence of downstream factors such as p53, the observation that the more sensitive cell lines with faster doubling times also had higher TS levels, and the standard procedure of the screen that uses a relatively short (48-h) drug exposure.

Pharmacokinetics and pharmacodynamic effects of 5-fluorouracil given as a one-hour intravenous infusion.

PURPOSE: Clinical toxicity associated with 5-fluorouracil (5-FU) is related to the area under the plasma concentration-time curve (AUC). Recently, short-term infusions of 5-FU given over 30 or 60 min have been substituted for conventional "bolus" 5-FU given over 3-5 min in randomized clinical trials, but there are only limited pharmacokinetic data for these altered infusion durations. We therefore wished to determine the pharmacokinetics and toxicity associated with 5-FU given as a 1-h intravenous (i.v.) infusion. METHODS: A group of 22 adults with advanced gastrointestinal tract cancers and no prior systemic chemotherapy for advanced disease received interferon alpha-2a (5 MU/m2 s.c., days 1-7), leucovorin (500 mg/m2 i.v. over 30 min, days 2-6) and 5-FU (370 mg/m2 i.v. over 1 h, days 2-6). The doses of 5-FU and interferon-alpha were adjusted according to individual tolerance. The pharmacokinetics and clinical toxicity were retrospectively compared with patients receiving the same regimen under the same treatment guidelines except that 5-FU was given over 5 min. RESULTS: The regimen was well tolerated, and 41% of the patients tolerated 5-FU dose escalations to 425-560 mg/m2 per day. Grade 3 or worse diarrhea and fatigue ultimately occurred in 14% of the patients each. Granulocytopenia, mucositis, and diarrhea appeared to be appreciably milder in the present trial compared with our prior phase II experience in colorectal cancer. The peak 5-FU plasma levels and AUC with 370 mg/m2 5-FU given over 1 h were 7.3-fold and 2.4-fold lower than previously measured in 31 patients who received 5-FU over 5 min. CONCLUSION: Increasing the length of 5-FU infusion to 1 h seemed to substantially reduce the clinical toxicity with this modulated 5-FU regimen, likely due to markedly lower peak 5-FU plasma levels and AUC. Changes in the duration of a short infusion of 5-FU clearly affects the clinical toxicity, but raises the concern of a potentially adverse impact on its antitumor activity. These results suggest the importance of including precise guidelines concerning the time over which 5-FU is given in clinical trials. Having a specified duration of 5-FU infusion is also important if 5-FU dose escalation is considered.

Biochemical modulation of 5-FU in systemic treatment of advanced colorectal cancer.

Randomized studies have tested a variety of strategies to improve the activity of 5-fluorouracil (5-FU) in colorectal cancer patients. Results from 14 randomized trials comparing 5-FU administered via intravenous (i.v.) bolus either as a single agent or modulated by leucovorin indicate a significantly higher response rate with 5-FU/leucovorin (25% vs 13% of assessable patients). Sequential methotrexate followed by i.v. bolus 5-FU is associated with a higher response rate. Continuous infusion schedules also produce superior response rates compared to bolus 5-FU alone. Published meta-analyses indicate a small, but statistically significant, survival advantage for methotrexate/5-FU and infusional 5-FU, but not for leucovorin-modulated 5-FU. Although the incidence of hand-foot syndrome is higher with protracted infusional 5-FU, the incidence of other toxicities including myelosuppression, diarrhea, and mucositis is low. Oral administration of 5-FU may simulate infusional schedules while avoiding catheter-related complications.

N-(phosphonacetyl)-L-aspartate and calcium leucovorin modulation of fluorouracil administered by constant rate and circadian pattern of infusion over 72 hours in metastatic gastrointestinal adenocarcinoma.

BACKGROUND: We have reported that N-(phosphonacetyl)-L-aspartic acid (PALA) 1266 mg/m2 can safely be given 24 hours prior to the start of a 72-hour infusion of fluorouracil (FUra) and leucovorin (LV) at doses of 2000 and 500 mg/m2/day. Since inhibition of aspartate carbamoyltransferase (ACTase) activity was evident 4 hours post PALA, we wished to evaluate PALA given 1 hour prior to FUra. Further, we studied the toxicity and pharmacokinetics with FUra given by either fixed- or variable-rate infusion. PATIENTS AND METHODS: Twenty-seven patients with gastrointestinal tract adenocarcinomas were treated with PALA 1266 mg/m2/15 min followed by a 72-hour infusion of FUra and LV (1750 & 500 mg/m2/day) given by fixed- or variable-rate (peak at 4:00 A.M.). RESULTS: Clinical toxicity was similar in two consecutive cycles in 17 patients receiving fixed- and variable-rate infusion at the same FUra dose. Overall, grade 3 stomatitis and hand-foot syndrome occurred in 12% and 4% patients receiving fixed- and in 16% and 10.5% of patients receiving variable-rate infusions. Six of 24 evaluable patients (25%) had a partial response. The profile of FUra plasma levels (Cp) over a 24-hour period during fixed- and variable-rate infusions were strikingly different, but the average Cp and area under the concentration-time curves were comparable. ACTase activity was significantly decreased at 4 and 24 hours after PALA (12% and 18% of baseline; P < 0.001), but enzyme activity had recovered to 40% by 72 hours. CONCLUSIONS: This regimen was active and well tolerated with similar toxicities with FUra given by either fixed- or variable rate infusion. PALA 1266 mg/m2 significantly inhibited ACTase activity for at least 24 hours.

Phase I and pharmacokinetic trial of weekly oral fluorouracil given with eniluracil and low-dose leucovorin to patients with solid tumors.

PURPOSE: Fluorouracil (5-FU) given as a weekly, high-dose 24-hour infusion is active and tolerable. We evaluated an oral regimen of eniluracil (which inactivates dihydropyrimidine dehydrogenase [DPD]), 5-FU, and leucovorin to simulate this schedule. PATIENTS AND METHODS: Patients received a single 24-hour infusion of 5-FU (2,300 mg/m(2) on day 2) with leucovorin (15 mg orally [PO] bid on days 1 through 3) to provide reference pharmacokinetic data. Two weeks later, patients began treatment with eniluracil (20 mg) and leucovorin (15 mg) (PO bid on days 1 through 3) and 5-FU (10 to 15 mg/m(2) PO bid on day 2). RESULTS: Dose-limiting toxicity (diarrhea, neutropenia, and fatigue) was seen with 5-FU 15 mg/m(2) PO bid on day 2 given weekly for either 6 of 8 weeks or 3 of 4 weeks, whereas five of seven patients tolerated 5-FU 10 mg/m(2) PO bid given weekly for 3 of 4 weeks. Eniluracil led to a 35-fold reduction in 5-FU clearance. Fluoro-beta-alanine, a 5-FU catabolite, was not detected in plasma during oral 5-FU-eniluracil therapy. DPD activity was markedly suppressed in all patients during eniluracil therapy; the inactivation persisted after the last eniluracil dose; percentages of baseline values were 1.8% on day 5, 4.5% on day 12, and 23.6% on day 19. CONCLUSION: The recommended oral dosage of 5-FU (10 mg/m(2) PO bid) given with eniluracil and leucovorin is approximately 115-fold lower than the reference dosage for 24-hour infusional 5-FU. This difference is greater than expected given the reduction in 5-FU clearance. DPD inactivation persisted for several weeks after completion of eniluracil therapy.

5-Fluorouracil: forty-plus and still ticking. A review of its preclinical and clinical development.

5-Fluorouracil (5-FU) and 5-fluoro-2'-deoxyuridine (FdUrd) are pyrimidine analogs that have been part of the therapeutic armamentarium for a variety of solid tumors for over forty years. 5-FU has customarily required intravenous administration due to poor and erratic oral bioavailability, while FdUrd has generally been employed for regional administration to the liver or the peritoneal cavity. A great deal of knowledge has been gained concerning the cellular pharmacology and mechanism of action of 5-FU since it was first synthesized in the late 1950's. A more thorough understanding of the factors influencing the metabolic activation of 5-FU and its cellular effects has generated considerable interest in combining it with both modulatory agents such as leucovorin and methotrexate that enhance its metabolism or cytotoxic effects. In addition, 5-FU has also been employed to enhance the therapeutic activity of other antineoplastic agents or modalities such as cisplatin and ionizing radiation with which it can synergize. Appreciation of the clinical pharmacology of 5-FU and FdUrd have led to a variety of schedules that are clinically useful. The preclinical and clinical pharmacology of 5-FU is reviewed to provide a basis for exploring the novel approaches to permit oral administration of 5-FU or its prodrugs that will be described in other articles in this issue.

Identification and proposed mechanism of action of thymidine kinase inhibition associated with cellular exposure to camptothecin analogs.

PURPOSE: To investigate the effects of several camptothecin analogs including 9-aminocamptothecin (9-AC), SN38, topotecan, and irinotecan (CPT-11) on the enzymes involved in the pyrimidine salvage pathway including thymidylate synthase (TS). A COMPARE analysis using the NCI 60 cell line drug-screening panel suggested that there were similarities in the mechanisms of action of camptothecin analogs and TS inhibitors. METHODS: TS enzymatic activity was measured by both an in situ tritium release assay using both the H630 colon cancer cell line and the CEM human leukemia cell line, and by a radiolabelled in vitro assay using partially purified human TS as the enzyme source. Thymidine kinase (TK) activity was measure by a radiolabelled in vitro assay using H630 colon cancer cell lysates as the enzyme source. RESULTS: In vitro studies indicated that none of the analogs directly inhibited TS enzymatic activity; however, utilization of a coupled TS/TK in situ assay with radiolabelled deoxyuridine as the precursor revealed marked inhibition by the camptothecin analogs. 9-AC, SN38, and topotecan yielded IC50 values of 1.3, 1.6, and 1.1 microM respectively. In contrast, there was no inhibition detected when deoxycytidine was used as the radiolabelled nucleoside precursor, suggesting that the drug effect was through inhibition of TK, rather than inhibition of TS. In vitro studies using cell lysates from H630 human colon cancer cells to measure TK activity showed no decrease in TK activity after 9-AC treatment. In addition, no changes were detected in the dATP and dTTP nucleotide pools. Permeabilizing the cell membranes with saponin did not abolish the inhibitory effect of the camptothecins indicating that altered cell transport was not responsible for the decreased activity in the in situ assay in intact cells. CONCLUSION: These studies suggest that there is inhibition of TK in intact cells associated with topoisomerase I inhibition by camptothecin analogs, and the inhibition of TK is the result of an indirect effect not related to feedback inhibition by changes in dTTP pools.

Measurement of plasma uracil using gas chromatography-mass spectrometry in normal individuals and in patients receiving inhibitors of dihydropyrimidine dehydrogenase.

A sensitive gas chromatographic-mass spectrometric method is described for reliably measuring endogenous uracil in 100 microl of human plasma. Validation of this assay over a wide concentration range, 0.025 microM to 250 microM (0.0028 microg/ml to 28 microg/ml), allowed for the determination of plasma uracil in patients treated with agents such as eniluracil, an inhibitor of the pyrimidine catabolic enzyme, dihydropyrimidine dehydrogenase. Calibration standards were prepared in human plasma using the stable isotope, [15N2]uracil, to avoid interference from endogenous uracil and 10 microM 5-chlorouracil was added as the internal standard.

Phase I and pharmacologic study of irinotecan administered as a 96-hour infusion weekly to adult cancer patients.

PURPOSE: We conducted a phase I and pharmacologic study of a weekly 96-hour infusion of irinotecan to determine the maximum-tolerated dose, define the toxicity profile, and characterize the clinical pharmacology of irinotecan and its metabolites. PATIENTS AND METHODS: In 26 adult patients with solid tumors, the duration and dose rate of infusion were escalated in new patients until toxicity was observed. RESULTS: In 11 patients who were treated with irinotecan at 12.5 mg/m(2)/d for 4 days weekly for 2 of 3 weeks, dose-limiting grade 3 diarrhea occurred in three patients and grade 3 thrombocytopenia occurred in two patients. The recommended phase II dose is 10 mg/m(2)/d for 4 days given weekly for 2 of 3 weeks. At this dose, the steady-state plasma concentration (Css) of total SN-38 (the active metabolite of irinotecan) was 6.42 +/- 1.10 nmol/L, and the Css of total irinotecan was 28.60 +/- 17.78 nmol/L. No patient experienced grade 3 or 4 neutropenia during any cycle. All other toxicities were mild to moderate. The systemic exposure to SN-38 relative to irinotecan was greater than anticipated, with a molar ratio of the area under the concentration curve (AUC) of SN-38 to irinotecan of 0.24 +/- 0.08. One objective response lasting 12 months in duration was observed in a patient with metastatic colon cancer. CONCLUSION: The recommended phase II dose of irinotecan of 10 mg/m(2)/d for 4 days weekly for 2 of 3 weeks was extremely well tolerated. Further efficacy testing of this pharmacologic strategy of administering intermittent low doses of irinotecan is warranted.

A Phase I study of raltitrexed, an antifolate thymidylate synthase inhibitor, in adult patients with advanced solid tumors.

The purpose of this study was to perform a Phase I trial of raltitrexed, a selective inhibitor of thymidylate synthase, and to determine the pharmacokinetic and toxicity profiles as a function of raltitrexed dose. Fifty patients with advanced solid tumors and good performance status were treated with raltitrexed as a 15-min i.v. infusion every 3 weeks, at doses escalating from 0.6 to 4.5 mg/m2. Asthenia, neutropenia, and hepatic toxicity were the most common dose-limiting toxicities in this largely pretreated patient population, but they occurred during the initial cycle in only one of nine patients treated with 4.0 mg/m2 and in two of nine patients treated with 4.5 mg/m2. Only 2 of 13 patients treated with 3.5 mg/m2 ultimately experienced unacceptable toxicity after three and seven cycles, compared with 42 and 56% of patients receiving 4.0 and 4.5 mg/m2 after medians of three and two cycles, respectively. The maximum raltitrexed plasma concentration and the area under the plasma concentration-time curve increased in proportion to dose. Raltitrexed clearance was independent of dose and was associated with the estimated creatinine clearance. Asthenia, neutropenia, and hepatic transaminitis were dose-related and tended to occur more frequently when patients received three or more cycles of therapy. A 3-week treatment interval was feasible in the majority of patients at all doses. Although 4.0 mg/m2 appeared to be a safe starting dose in this pretreated patient population, about half who received two or more courses ultimately experienced dose-limiting toxicity. A dose of 3.5 mg/m2 was well tolerated in most patients.

A pilot study of interferon alpha-2a, fluorouracil, and leucovorin given with granulocyte-macrophage colony stimulating factor in advanced gastrointestinal adenocarcinoma.

We reported previously that the addition of recombinant Escherichia coli human granulocyte-macrophage colony stimulating factor (GM-CSF) to a 5-fluorouracil (5-FU) and leucovorin (LV) regimen seemed to ameliorate diarrhea and permit increased 5-FU dose intensity (J. L. Grem et al., J. Clin. Oncol., 12: 560-568, 1994). We then tested the effect of GM-CSF given with a more toxic regimen of 5-FU/LV/IFN-alpha (IFN alpha-2a). Thirty-one patients with a good performance status and no prior chemotherapy for systemic disease received IFN alpha(-2a (5 MU/m2 s.c., days 1-7), 5-FU (370 mg/m2 i.v., days 2-6), LV (500 mg/m2 i.v., days 2-6), and GM-CSF (Saccharomyces cerevisiae 250 microg/m2 s.c., days 7-18) every 3 weeks. Toxicities and 5-FU dose intensity were compared with that observed in our prior Phase II trial with 5-FU/LV/IFN alpha-2a (J. L. Grem et al., J. Clin. Oncol., 11: 1737-1745, 1993). In comparison with the prior Phase II study, the WBC and granulocyte nadirs in the present trial were significantly higher. When trends in toxicity grades for all cycles were compared, stratifying for 5-FU dose, the incidence and severity of mucositis, skin rash, WBC toxicity, and granulocyte toxicity were significantly lower in the present trial, whereas nausea/vomiting and fatigue were significantly worse. The delivered 5-FU dose intensity for all cycles of therapy appeared to be significantly higher in the present trial. Six of 28 evaluable patients had a partial response (21.4%), and 13 (46%) had stable disease for > or =12 weeks. Despite treatment-related toxicity, patient quality of life did not worsen during the study. No correlation was observed between thymidylate synthase content in primary tumor specimens and response, time to treatment failure, or survival. The addition of GM-CSF appeared to decrease the severity of leukopenia, granulocytopenia, mucositis, and skin rash when compared with our prior experience with this regimen of 5-FU/LV/IFN alpha-2a, at the cost of greater nausea/vomiting and fatigue. The potential impact of increased 5-FU dose intensity on clinical response, however, remains to be determined.

Sequence-dependent antagonism between fluorouracil and paclitaxel in human breast cancer cells.

The effects of 24-hr exposures to 5-fluorouracil (FUra) and paclitaxel in various sequences were studied in MCF-7 breast cancer cells to determine an optimal schedule for possible clinical use. In clonogenic assays, pre-exposure to FUra followed by paclitaxel resulted in marked antagonism, while sequential paclitaxel followed by FUra was optimal. Concurrent or pre-exposure to paclitaxel did not affect [3H]FUra metabolism, [3H]FUra-RNA incorporation, or the extent of FUra-mediated thymidylate synthase inhibition. Paclitaxel led to G2/M phase accumulation that persisted for up to 24 hr after drug exposure, while a 24-hr FUra exposure produced S-phase accumulation. FUra pre-exposure diminished paclitaxel-associated G2/M phase block, whereas subsequent exposure to FUra after paclitaxel did not. FUra exposure resulted in transient induction of p53 and p21, which returned to basal levels 24 hr after drug removal. p53 and p21 protein content also increased markedly during paclitaxel exposure, accompanied by phosphorylation of Bcl-2. Double-stranded DNA fragmentation (approximately 50 kb) was seen at 48 hr when cells were exposed to paclitaxel for an initial 24-hr period. Paclitaxel-associated DNA fragmentation was not prevented by concurrent or subsequent exposure to FUra. Thus, paclitaxel-mediated G2/M phase arrest appeared to be a crucial step in induction of DNA fragmentation. Since an initial 24-hr paclitaxel exposure did not interfere with subsequent FUra metabolism or thymidylate synthase inhibition, and delayed exposure to FUra did not impede either paclitaxel-mediated induction of mitotic blockade or DNA fragmentation, the sequence of paclitaxel followed by FUra is recommended for clinical trials.