Irinotecan (CPT-11) high-dose escalation using intensive high-dose loperamide to control diarrhea.

BACKGROUND: Diarrhea is a serious side effect that may prevent the administration of high doses of the antitumor drug Irinotecan (CPT-11). PURPOSE: Intensive, high-dose loperamide was used in an attempt to control or downstage CPT-11-induced diarrhea and thus permit the use of higher dose intensities of CPT-11. METHODS: Twenty-three patients with various cancers were treated with doses of CPT-11 ranging from 400 to 600 mg/m2, administered as a 30-minute intravenous infusion every 3 weeks. Starting 8 hours or more after the administration of CPT-11, any episode of diarrhea was treated with 2 mg of loperamide taken every 2 hours. Patients stopped taking loperamide only after a 12-hour diarrhea-free period. If diarrhea was not controlled after 3 consecutive days of nonstop loperamide intake, or if the patient was dehydrated, loperamide was stopped and the patient was hospitalized for intravenous fluids. If blood or mucus were found in the stools at any time during diarrhea, loperamide was stopped and the patient was hospitalized. RESULTS: Seventeen of 23 patients had diarrhea while on CPT-11 treatment. Eighty-two CPT-11 cycles were administered to these 17 patients, and diarrhea occurred in 49 of these cycles, at a median time-to-onset of 6 days after CPT-11 administration. The loperamide protocol was followed in 46 of the 49 episodes of diarrhea, with 21 capsules of loperamide the median number being taken (range, 5-72). Only one patient was hospitalized for failure to respond to loperamide, and no major toxicity was associated with loperamide use. Fourteen of the 17 patients who experienced diarrhea were rechallenged with CPT-11 three or more times, and seven patients six or more times. CONCLUSIONS: High-dose loperamide controlled diarrhea in patients receiving CPT-11 and allowed administration of higher doses of CPT-11. IMPLICATIONS: The effectiveness of CPT-11 might be increased by higher dose intensities, which can be made tolerable by control of diarrhea with loperamide.

Plasma and cerebrospinal fluid pharmacokinetics of 5-Aza-2'-deoxycytidine in rabbits and dogs.

5-Aza-2'-deoxycytidine (5-aza-dCyd) is an effective antileukemic agent. In view of the importance for an antileukemic agent to cross effectively the blood-brain-barrier, we studied the plasma and cerebrospinal fluid (CSF) pharmacokinetics of this drug in rabbits and dogs. The 5-aza-dCyd concentrations in biological fluids were determined by bioassay and high-performance liquid chromatography. 5-Aza-dCyd was administered either as an i.v. bolus or as a continuous i.v. infusion following a loading dose. Blood and CSF samples were collected at various time intervals. After an i.v. bolus, the plasma disappearance of 5-aza-dCyd was biphasic with half-lives of 5 and 43 min in rabbits and of 5 and 75 min in dogs. The apparent volume of distribution at steady state was in the order of 800 ml/kg for both species. The total plasma clearance of the drug was 15 ml/min/kg in rabbits and 9 ml/min/kg in dogs. After a 180 min i.v. infusion, 5-aza-dCyd slow disappearance half-lives were of 39 min in rabbits and of 144 min in dogs. The 5-aza-dCyd concentrations attained in the CSF were 27 and 58% of the plateau plasma concentration in rabbits and dogs, respectively. The drug disparition from the CSF followed closely the plasma profile after an i.v. infusion with a somewhat longer half-life. These results showed that 5-aza-dCyd can cross the blood-CSF barrier effectively, producing cytotoxic concentrations in the CSF when given by i.v. infusion.

Granulocytic differentiation of human NB4 promyelocytic leukemia cells induced by all-trans retinoic acid metabolites.

The metabolism of all-trans retinoic acid (ATRA) has been reported to be partly responsible for the in vivo resistance to ATRA seen in the treatment of human acute promyelocytic leukemia (APL). However, ATRA metabolism appears to be involved in the growth inhibition of several cancer cell lines in vitro. The purpose of this study was to evaluate the in vitro activity of the principal metabolites of ATRA [4-hydroxy-retinoic acid (4-OH-RA), 18-hydroxy-retinoic acid (18-OH-RA), 4-oxo-retinoic acid (4-oxo-RA), and 5,6-epoxy-retinoic acid (5,6-epoxy-RA)] in NB4, a human promyelocytic leukemia cell line that exhibits the APL diagnostic t(15;17) chromosomal translocation and expresses the PML-RAR alpha fusion protein. We established that the four ATRA metabolites were indeed formed by the NB4 cells in vitro. NB4 cell growth was inhibited (69-78% at 120 h) and cell cycle progression in the G1 phase (82-85% at 120 h) was blocked by ATRA and all of the metabolites at 1 microM concentration. ATRA and its metabolites could induce NB4 cells differentiation with similar activity, as evaluated by cell morphology, by the nitroblue tetrazolium reduction test (82-88% at 120 h) or by the expression of the maturation specific cell surface marker CD11c. In addition, nuclear body reorganization to macropunctated structures, as well as the degradation of PML-RAR alpha, was found to be similar for ATRA and all of its metabolites. Comparison of the relative potency of the retinoids using the nitroblue tetrazolium reduction test showed effective concentrations required to differentiate 50% of cells in 72 h as follows: ATRA, 15.8 +/- 1.7 nM; 4-oxo-RA, 38.3 +/- 1.3 nM; 18-OH-RA, 55.5 +/- 1.8 nM; 4-OH-RA, 79.8 +/- 1.8 nM; and 5,6-epoxy-RA, 99.5 +/- 1.5 nM. The ATRA metabolites were found to exert their differentiation effects via the RAR alpha nuclear receptors, because the RAR alpha-specific antagonist BMS614 blocked metabolite-induced CD11c expression in NB4 cells. These data demonstrate that the principal ATRA Phase 1 metabolites can elicit leukemia cell growth inhibition and differentiation in vitro through the RAR alpha signaling pathway, and they suggest that these metabolites may play a role in ATRA antileukemic activity in vivo.

Phase I study and pharmacokinetics of weekly high-dose 13-cis-retinoic acid.

In an attempt to increase the peak plasma levels of 13-cis-retinoic acid (13-cis-RA) and its efficacy in vivo, a Phase I study and pharmacokinetics of weekly high-dose, oral 13-cis-RA was conducted in 23 cancer patients who were refractory to conventional treatments. At 200 mg/sq m, the mean peak plasma level of 13-cis-RA was 1.5 +/- 0.1 (SE) micrograms/ml; at 400 mg/sq m, the mean peak plasma level increased to 3.8 +/- 0.7 micrograms/ml. Further increases of the 13-cis-RA dose up to 1800 mg/sq m did not lead to proportional increases in either the mean peak plasma levels or area under the curve, indicating a saturable absorption phenomenon. The terminal half-life was highly variable (range, 2.8 to 101.3 h) and was not related to the dose given. A secondary peak plasma concentration was seen in five patients, suggesting enterohepatic circulation. The toxicities such as headache, cheilitis, dry skin, and dry eyes were frequent on the weekly schedule but were not dose-limiting. One patient had an elevation of the triglycerides of 2 to 5 times the upper limit of normal; five patients had an elevation of 1.1 to 2 times normal. No objective responses were observed to treatment with 13-cis-RA. Of 20 patients receiving an adequate trial of the drug, 18 showed progression of their cancer, and two had stable disease.

Flavone acetic acid (NSC 347512)-induced DNA damage in Glasgow osteogenic sarcoma in vivo.

Flavone acetic acid (FAA) is a new antitumor agent with broad activity against transplantable solid tumors of mice but with only scant or no activity against leukemias and lymphomas. The technique of alkaline elution was used to study DNA lesions in s.c. implanted Glasgow osteogenic sarcoma in C57BL/6 x DBA/2 F1 mice treated i.v. with FAA. At efficacious dosages (235 and 200 mg/kg), FAA produced extensive single strand breakage. Formation of single strand breaks was dependent on time of assay after exposure to FAA with only minimal damage occurring prior to 5 h posttreatment. Apparently Glasgow osteogenic sarcoma had no capacity to repair single strand breaks for at least 45 h after drug administration. Thus, FAA differs in its mechanism from other scission agents (e.g., VP-16). Neither interstrand cross-links nor DNA-protein cross-links were detected. DNA single strand breaks did not occur in the bone marrow cells or in the unresponsive P388 leukemia cells at dosages causing extensive DNA damage in solid tumor cells.

Acodazole hydrochloride: phase I trial, pharmacokinetics, and evaluation of cardiotoxicity in dogs.

Acodazole (NSC 305884) was examined in a Phase I trial evaluating a 1-h infusion repeated every 21 days in 37 patients with advanced carcinomas. Cardiac toxicity was dose-limiting at 1370 mg/m2, manifested as multiple premature ventricular contractions, QTc interval prolongation, and decreasing heart rate. Other toxicities included mild to moderate nausea and vomiting and local reaction near the i.v. injection site requiring the use of central venous catheters. Antineoplastic activity was not observed. Acodazole levels assayed by high-performance liquid chromatography disclosed a peak plasma level of 19 +/- 4 (SEM) micrograms/ml for 1370 mg/m2. Acodazole plasma levels decreased in a triphasic manner over a 100-fold range. The volume of distribution at steady state was 238 +/- 18 liter/m2 suggesting extensive tissue binding. The total body clearance was 13.6 +/- 0.9 liter/h/m2; the percentage of urinary excretion was 29 +/- 2% for 48 h. To evaluate cardiac toxicity, acodazole was administered to five dogs at 2262 mg/m2 (1-h infusion) which provided plasma concentrations similar to those achieved at 1370 mg/m2 in humans. Consistent findings in dogs were drug-related prolongation of QTc intervals, and reduction in heart rate, left ventricular dP/dt, and mean blood pressures. Clinical development of acodazole requires studies to further elucidate and alleviate this cardiac toxicity.

Main drug- and carcinogen-metabolizing enzyme systems in human non-small cell lung cancer and peritumoral tissues.

To better understand the importance of drug-metabolizing enzymes in carcinogenesis and anticancer drug sensitivity of human non-small cell lung cancer, we studied the main drug-metabolizing enzyme systems in both lung tumors and their corresponding nontumoral lung tissues in 12 patients. The following enzymes were assayed by Western blot analysis: cytochromes P-450 (1A1/A2, 2B1/B2, 2C8-10, 2E1, 3A4); epoxide hydrolase; and glutathione S-transferase isoenzymes (GST-alpha, -mu, and -pi). The activity of the following enzymes or cofactor were determined by spectrophotometric or fluorometric assays: glutathione S-transferase (GST); total glutathione; UDP-glucuronosyltransferase; beta-glucuronidase; sulfotransferase; and sulfatase. Results showed the presence of cytochrome P-450 1A1/1A2 in both tumoral and nontumoral tissues. P-450 1A1/1A2 levels were 3-fold lower in tumors compared to corresponding nontumoral tissues (P < 0.05). None of the other probed cytochromes P-450 were detected in either tumoral or nontumoral lung tissues. For the glutathione system, no significant difference between tumoral and nontumoral tissues was observed (GST activity, glutathione content, GST-alpha, -mu, and -pi). A positive linear correlation was observed between GST activity and GST-alpha or GST-pi. No significant difference was observed for the glucuronide and the sulfate pathways and their corresponding hydrolytic enzymes. Epoxide hydrolase was significantly decreased in tumors compared to nontumoral lung tissues (P < 0.05). In conclusion, these results showed differences between non-small cell lung tumors and nontumoral tissues for cytochrome P-450 1A1/1A2 and epoxide hydrolase. These differences between tumors and peritumoral tissues with regard to these drug-metabolizing enzymes could reflect differences occurring after malignant transformation and may play a role in drug sensitivity to anticancer drugs.

Comparison of mouse and human colon tumors with regard to phase I and phase II drug-metabolizing enzyme systems.

Since human colorectal tumors are insensitive to most chemotherapeutic agents, there is a need for the discovery of new drugs that would show activity against this disease. In an attempt to better appreciate the relevance of a widely used mouse colon tumor (colon adenocarcinoma Co38) as a screening model for human colorectal tumors, we compared the main phase I and phase II drug-metabolizing enzyme systems in both tumoral and nontumoral colon tissues. The following enzymes were assayed by Western blot: cytochromes P-450 (1A1/A2, 2B1/B2, 2C, 2E1, and 3A), epoxide hydrolase, and glutathione-S-transferases (GST-alpha, -mu, and -pi). The activities of the following enzymes or cofactors were determined by spectrophotometric or fluorometric assays: total cytochrome P-450, 1-chloro-2,4-dinitrobenzene-GST, selenium-independent glutathione peroxidase, 3,4-dichloronitrobenzene-GST, ethacrynic acid-GST, total glutathione, epoxide hydrolase, UDP-glucuronosyltransferase, beta-glucuronidase, sulfotransferase, and sulfatase. Results obtained by Western blot showed that mouse colon adenocarcinoma Co38 did not express any of the probed cytochromes P-450, whereas human colorectal tumors expressed only low levels of cytochrome P-450 3A. GST-alpha and GST-pi were detected in all tumoral and nontumoral tissues of both species. The neutral GST-mu was expressed in all murine tissues investigated and was found to be polymorphic in human tissues. For human peritumoral and tumoral colorectal tissues there was no significant difference between GST isoenzyme levels, whereas mouse colon adenocarcinoma Co38 had a lower expression of GST-mu and GST-pi, compared to normal mouse colon. Enzymatic activities for glutathione peroxidase, 3,4-dichloronitrobenzene-GST, and ethacrynic acid-GST confirmed the Western blot results for GST-alpha, GST-mu, and GST-pi, respectively. Total GSH levels were similar between murine and human tumors but were 3-fold higher in human tumors than in peritumoral tissues, whereas they were 7-fold lower in mouse colon tumor Co38, compared to normal mouse colon. Epoxide hydrolase was not expressed in either mouse colon adenocarcinoma Co38 or normal mouse colon tissues, whereas it was expressed in human colon peritumoral and tumoral tissues at similar levels. No significant difference was observed between human tumors and peritumoral tissues for UDP-glucuronosyltransferase, beta-glucuronidase, sulfotransferase, and sulfatase. For murine colon tissues, the conjugation pathways (UDP-glucuronosyltransferase and sulfotransferase) were lower in colon adenocarcinoma Co38, whereas the converse was observed for the corresponding hydrolytic enzymes (beta-glucuronidase and sulfatase).(ABSTRACT TRUNCATED AT 400 WORDS)

Flavone acetic acid (NSC 347512)-induced modulation of murine tumor physiology monitored by in vivo nuclear magnetic resonance spectroscopy.

Flavone acetic acid (FAA), a new drug with broad activity against transplanted solid tumors of mice, induces nonrepairable DNA single strand breaks that correlate with therapeutic efficacy. To test the hypothesis that the inability of the cells to repair single strand breaks is associated with a disruption of tumor energy metabolism, in vivo 31P nuclear magnetic resonance (NMR) spectra were acquired from s.c. implanted Glasgow osteogenic sarcomas in C57BL/6 x DBA/2 F1 mice both before and after treatment with FAA i.v. at 100, 150, or 200 mg/kg and from a control (no treatment) group (n = 4 in each group). While FAA produced a dose-dependent decrease in both the nucleoside triphosphates level and pH, only treatment with an efficacious dose of 200 mg/kg resulted in both a reduction in pH and a complete loss of nucleoside triphosphates from the NMR spectrum at 4 h with no recovery until 48 h and little recovery out to 72 h. The ATP concentration determined by high pressure liquid chromatography in a parallel set of experiments was 5.59 +/- 1.16 (SE) mumol/g (wet weight) in control tumors (n = 9) and 0.24 +/- 0.12 mumol/g (wet weight) at 4 h after 200 mg/kg FAA (n = 7). To examine the possibility that the loss of ATP and decreased pH are associated with a reduction in tumor blood flow, we used 2H NMR to monitor the washout of D2O injected directly into the tumor both before and 4 h after treatment with 200 mg/kg FAA. The pretreatment tumor blood flow of 12.4 +/- 1.7 ml/min/100 g was reduced to 1.9 +/- 0.5 ml/min/100 g at 4 h after treatment (n = 3). The FAA-induced reduction of both tumor blood flow and ATP may play an important role in its mechanism of action and should be considered in the combination of FAA with other drugs or therapeutic modalities. In addition, because 31P NMR can be used clinically, it should provide a nonambiguous early indicator of activity for clinical trials of FAA.

Phase I and pharmacokinetic study of the camptothecin derivative irinotecan, administered on a weekly schedule in cancer patients.

Irinotecan (CPT-11) is a novel water-soluble, semisynthetic derivative of camptothecin, with inhibitory effects on mammalian DNA topoisomerase I, high cytotoxic activity in vitro and anticancer activity in animal models. Fifty-nine patients, with cancer refractory to conventional therapy, were entered in this phase I study, using a weekly schedule administration. A total of 304 weekly doses were administered at dose levels ranging from 50 to 145 mg/m2 (30-90 min i.v. infusion). Leukoneutropenia and diarrhea were the dose-limiting toxicities and appeared to be dose related, reversible and noncumulative. However, interpatient variability of toxic effects was substantial. Prolongation of the infusion time from 30 min to 90 min appeared to decrease the diarrhea. Other toxicities included moderate emesis, asthenia, alopecia, abdominal pain, and anemia. CPT-11 plasma disposition was bi- or triphasic with a terminal half-life of 9.3 h. CPT-11 area under the plasma concentration versus time curves increased linearly with dose (r = 0.47, P < 0.01). The active metabolite area under the plasma concentration versus time curve correlated significantly with that of CPT-11, but not with that of CPT-11 dose. Both CPT-11 and 7-ethyl-10-hydroxycamptothecin areas under the plasma concentration versus time curve correlated significantly with leukoneutropenia and diarrhea. One partial and 4 minor responses were observed at dose levels of 130 and 145 mg/m2. Using this weekly schedule, recommended doses for phase II studies are 100 mg/m2 in high risk patients and 115 mg/m2 in others.

Main drug-metabolizing enzyme systems in human breast tumors and peritumoral tissues.

In an attempt to better understand breast tumors sensitivity or resistance to anticancer drugs, the main drug-metabolizing enzyme systems were evaluated in both breast tumors and their corresponding peritumoral tissues in 12 patients. The following enzymes were assayed by Western blot: cytochromes P-450 (1A1/A2, 2B1/B2, 2C8-10, 2E1, 3A4); glutathione S-transferases (GST-alpha, -mu, and -pi); and epoxide hydrolase. The activity of the following enzymes or cofactor were determined by spectrophotometric or fluorometric assays: GST; total glutathione; UDP-glucuronosyltransferase; beta-glucuronidase; sulfotransferase; and sulfatase. Results showed the absence of all probed cytochromes P-450 in both tumoral and peritumoral tissues. GST activity was significantly (P < 0.05) higher in tumors (mean +/- SD, 399 +/- 362 nmol/min/mg) than in corresponding peritumoral tissues (86 +/- 67). The GST isoenzymes GST-mu and GST-pi (determined by immunoblotting) were also higher in tumors than in corresponding peritumoral tissues (3- and 5-fold, respectively). Both GST-mu and GST-pi levels were significantly correlated with GST activity. GST-alpha was not detected in either tumoral or peritumoral tissues. Glutathione levels in tumors (22 +/- 23 nmol/mg protein) were not statistically different from peritumoral tissues (11 +/- 12). Epoxide hydrolase was expressed at similar levels in tumors and peritumoral tissues. The glucuronide-forming enzyme UDP-glucuronosyltransferase was 5-fold lower in tumors (0.1 +/- 0.2 nmol/h/mg) than in peritumoral tissues (0.5 +/- 1), whereas the opposite was observed for the hydrolytic enzyme beta-glucuronidase, which was 6-fold higher in tumors (736 +/- 1392 nmol/h/mg) compared to peritumoral tissues (125 +/- 75). No difference was noted between tumoral and peritumoral tissues for sulfotransferase (1 +/- 2 nmol/h/mg), but the corresponding hydrolytic enzyme (sulfatase) was 2-fold higher in tumoral tissues (14 +/- 15 nmol/h/mg) than in peritumoral tissues (6 +/- 2). In conclusion, several differences were observed between human breast tumors and peritumoral tissues for many conjugating enzymes (GST-mu, GST-pi, and UDP-glucuronosyltransferase) and hydrolytic enzymes (sulfatase and beta-glucuronidase). These noteworthy differences between tumoral and peritumoral tissues with regard to their main drug-metabolizing enzymes could play a role in the relative drug sensitivity or insensitivity of human breast cancer tissues to chemotherapeutic agents and could be potential targets for chemotherapeutic interventions.

Pharmacokinetic and pharmacodynamic advantages of pirarubicin over adriamycin after intraarterial hepatic administration in the rabbit VX2 tumor model.

Intraarterial chemotherapy with Adriamycin (ADM) has shown limited advantages over i.v. administration, with no reduction in systemic toxicities and modest decrease in peripheral plasma levels. In an effort to improve the selectivity of i.a. anthracycline chemotherapy, we compared pirarubicin (4'-O-tetrahydropyranyladriamycin, THP) and ADM in the surgically implanted VX2 rabbit tumor model. Both drugs were administered at the same dose (0.5 mg/kg) either by the intraarterial hepatic route (i.a.h.) or by the i.v. route. Anthracycline plasma and tissue levels were determined by high-performance liquid chromatography with fluorescence detection. ADM peak plasma concentration and area under the curve were not significantly reduced after i.a.h. administration compared to the i.v. route; however, ADM tumor concentration was 1.9-fold higher following i.a.h. administration compared to the i.v. infusion. After THP administration by the i.a.h. route, systemic exposure (area under the curve) was markedly reduced (8-fold) compared to the same dose administered i.v. These findings correlated well with the very low concentration of the drug in heart tissue following i.a.h. infusion. After i.a.h. administration, tumor THP concentrations were 10.5 times higher compared to the i.v. route. The pharmacokinetic advantage of i.a.h. administration of THP also led to a better antitumoral effect, as shown by a significantly lower tumor growth rate [3 +/- 2% (SD)] in the i.a.h.-treated animals compared to the i.v.-treated groups (58 +/- 9%). Administration of ADM by the i.a.h. route was also inferior to i.a.h. THP. Taken together, our results suggest a clear-cut advantage of THP over ADM for i.a.h. locoregional chemotherapy, because of higher local tumor concentrations, greater antitumoral effect, and lower systemic exposure following the i.a.h. administration of THP. This anthracycline analogue could also be of therapeutic advantage in tumors partially resistant to anthracyclines that would become vulnerable to the high local concentrations achieved with i.a.h. administration. Based on these encouraging results, clinical trials using THP administered by the i.a.h. route were initiated.

Phase I and pharmacologic studies of the camptothecin analog irinotecan administered every 3 weeks in cancer patients.

PURPOSE: A phase I study was undertaken to determine the maximum-tolerated dose (MTD), principal toxicities, and pharmacokinetics of the novel topoisomerase I inhibitor irinotecan (CPT-11). PATIENTS AND METHODS: Sixty-four patients meeting standard phase I eligibility criteria were included (24 women, 40 men; median age, 51 years; primary sites: colon, head and neck, lung, pleura; 60 of 64 had been previously treated). Pharmacokinetics was determined by high-performance liquid chromatography (HPLC). RESULTS: One hundred ninety CPT-11 courses were administered as a 30-minute intravenous (IV) infusion every 3 weeks (100 to 750 mg/m2). Grade 3 to 4 nonhematologic toxicities included diarrhea (16%; three hospitalizations), nausea and vomiting (9%), asthenia (14%), alopecia (53%), elevation of hepatic transaminases (8%), and one case of skin toxicity. An acute cholinergic syndrome was observed during CPT-11 administration. Diarrhea appeared dose-limiting at 350 mg/m2, but this was circumvented by using a high-dose loperamide protocol that allowed dose escalation. Dose-dependent, reversible, noncumulative granulocytopenia was the dose-limiting toxicity (nadir, days 6 to 9; median recovery time, 5 days). Grade 3 to 4 anemia was observed in 9% of patients. One patient died during the study, 8 days after CPT-11 treatment. Two complete responses (cervix, 450 mg/m2; head and neck, 750 mg/m2) and six partial responses in fluorouracil (5-FU)-refractory colon cancer were observed (260 to 600 mg/m2). Pharmacokinetics of CPT-11 and active metabolite SN-38 were performed in 60 patients (94 courses). CPT-11 plasma disposition was bi- or triphasic, with a mean terminal half-life of 14.2 +/- 0.9 hours (mean +/- SEM). The mean volume of distribution (Vdss) was 157 +/- 8 L/m2, and total-body clearance was 15 +/- 1 L/m2/h. The CPT-11 area under the plasma concentration versus time curves (AUC) and SN-38 AUC increased linearly with dose. SN-38 plasma decay had an apparent half-life of 13.8 +/- 1.4 hours. Both CPT-11 and SN-38 AUCs correlated with nadir leukopenia and granulocytopenia, with grade 2 diarrhea, and with nausea and vomiting. CONCLUSION: The MTD of CPT-11 administered as a 30-minute IV infusion every 3 weeks is 600 mg/m2, with granulocytopenia being dose-limiting. At 350 mg/m2, diarrhea appeared dose-limiting, but high-dose loperamide reduced this toxicity and allowed dose escalation. For safety reasons, the recommended dose is presently 350 mg/m2 every 3 weeks; more experience must be gained to establish the feasibility of a higher dose in large multicentric phase II studies. However, when careful monitoring of gastrointestinal toxicities is possible, a higher dose of 500 mg/m2 could be recommended in good-risk patients. The activity of this agent in 5-FU-refractory colorectal carcinoma makes it unique and mandates expedited phase II testing.

Phase I/II trial of continuous infusion vinorelbine for advanced breast cancer.

PURPOSE: A phase I/II trial of vinorelbine (VRL) administered by continuous infusion (CIV) was conducted in advanced breast carcinoma (ABC) patients to determine the maximum-tolerated dose (MTD) and to evaluate the toxicity pattern and antitumor activity of this alternative administration schedule to the currently recommended weekly short intravenous (IV) administration. PATIENTS AND METHODS: Between February 1990 and July 1991, 64 consecutive, eligible patients with ABC were treated; 33 had received one or two previous palliative chemotherapy combinations and 31 had not received chemotherapy for metastatic disease. VRL was administered, after an initial IV bolus of 8 mg/m2 on day 1, by a 4-day CIV at five different 24-hour dose levels (DLs) to be repeated every 21 or 28 days: DL1, 5.5 mg/m2; DL2, 7 mg/m2; DL3, 8 mg/m2, DL4, 9 mg/m2; and DL5, 10 mg/m2. RESULTS: The limiting noncumulative toxicity was neutropenia, with the MTD established at 8 mg/m2 bolus plus 10 mg/m2/d for 4 days (total dose per cycle, 48 mg/m2). At DL3 and DL4, we observed mucositis (14% of patients; five percent of cycles > grade 2), alopecia, and asthenia. By contrast, neurotoxicity was minor. The toxicity was otherwise predictable and manageable. Pharmacokinetic data obtained at DL1 and DL3 showed a mean VRL plasma concentration of 967 +/- 331 ng/mL after the initial 8 mg/m2 IV bolus dose, which declined rapidly thereafter to reach mean steady-state levels of 12 ng/mL (n = 5) for the 30-mg/m2 dose and 8 ng/mL (n = 2) for the 40-mg/m2 dose. These levels were maintained over the 96-hour CIV. The mean residence time (MRT) was 29 +/- 7 hours (terminal half-life [t1/2], 23 hours), the total-body clearance (CL) was 24 +/- 11 L/hr/m2, and the volume of distribution at steady-state (Vss) was high at 1,832 +/- 359 L/m2. Two patients achieved a complete response (CR) and 21 a partial response (PR), for an objective response rate of 36% (95% confidence interval [Cl], 23 to 49). The median duration of response was 6 months. The median survival duration was 24 months (range, 3 to 37). A relationship between given dose-intensity and objective response rate was found, with an overall response (OR) rate of 13.3% (two of 15) for 8 to 10 mg/m2/wk, 35.4% (11 of 31) for 10 to 12 mg/m2/wk, and 55.5% (10 of 18) for 12 to 14.5 mg/m2/wk. CONCLUSION: This trial, while confirming VRL activity in ABC, shows the feasability of a CIV administration schedule. A decrease of the administrated total dose per 3- to 4-week cycle to less than the weekly schedule with the same therapeutic activity suggests a better therapeutic index. The data are also suggestive of a dose-response relationship and a dose-intensity/activity correlation.

Etoposide bioavailability after oral administration of the prodrug etoposide phosphate in cancer patients during a phase I study.

PURPOSE: The purpose of this study was to determine the bioavailability (F) of etoposide (E;VP-16) after oral administration of the water-soluble prodrug etoposide phosphate (EP;BMY-40481) during a phase I trial in cancer patients. PATIENTS AND METHODS: Twenty-nine patients received oral EP (capsules, 50 to 150 mg/m2/d of E equivalent) for 5 days in week 1 (course 1), followed every 3 weeks thereafter by a daily intravenous (i.v.) infusion for 5 days of E (80 mg/m2, 1-hour i.v. infusion; course 2); in three patients, the i.v. E course was given before oral EP. Plasma and urine E pharmacokinetics (high-performance liquid chromatography [HPLC]) were performed on the first day of oral EP administration and on the first day of i.v. E. RESULTS: Twenty-six of 29 patients completed two courses or more, whereas three patients received only one course due to toxicity. Myelosuppression was dose-dependent and dose-limiting, with grade 4 leukoneutropenia in four of 15 patients at 125 mg/m2 and in five of seven patients at 150 mg/m2. One patient died of meningeal hemorrhage related to grade 4 thrombocytopenia. Other toxicities were infrequent and/or manageable. No objective response was observed. The maximum-tolerated dose (MTD) is therefore 150 mg/m2, and the recommended oral dose of EP for phase II trials in this poor-risk patient population is 125 mg/m2. Twenty-six patients had pharmacokinetic data for both oral EP and i.v. E, whereas three had pharmacokinetic data on the i.v. E course only. After oral administration of EP, the pharmacokinetics of E were as follows: mean absorption rate constant (Ka), 1.7 +/- 1.7 h-1 (mean +/- SD); lag time, 0.3 +/- 0.2 hours; time of maximum concentration (t(max)), 1.6 +/- 0.8 hours; and mean half-lives (t1/2), 1.6 +/- 0.2 (first) and 10.3 +/- 5.8 hours (terminal); the increase in the area under the plasma concentration-versus-time curve (AUC) of E was proportional to the EP dose. After the 1-hour i.v. infusion of E, maximum concentration (C(max)) was 15 +/- 3 micrograms/mL; mean AUC, 88.0 +/- 22.0 micrograms.h/mL; mean total-body clearance (CL), 0.97 +/- 0.24 L/h/m2 (16.2 mL/min/m2); and mean t1/2, 0.9 +/- 0.6 (first) and 8.1 +/- 4.1 hours (terminal). The 24-hour urinary excretion of E after i.v. E was significantly higher (33%) compared with that of oral EP (17%) (P < .001). Significant correlation was observed between the neutropenia at nadir and the AUC of E after oral EP administration (r = .58, P < .01, sigmoid maximum effect [E(max)] model). The mean F of E after oral administration of EP in 26 patients was 68.0 +/- 17.9% (coefficient of variation [CV], 26.3%; F range, 35.5% to 111.8%). In this study, tumor type, as well as EP dose, did not significantly influence the F in E. There was no difference in F of E, whether oral EP was administered before or after i.v. E. Compared with literature data on oral E, the percent F in E after oral prodrug EP administration was 19% higher at either low ( < or = 100 mg/m2) or high ( > 100 mg/m2) doses. CONCLUSION: Similarly to E, the main toxicity of the prodrug EP is dose-dependent leukoneutropenia, which is dose-limiting at the oral MTD of 150 mg/m2/d for 5 days. The recommended oral dose of EP is 125 mg/m2/d for 5 days every 3 weeks in poor-risk patients. Compared with literature data, oral EP has a 19% higher F value compared with oral E either at low or high doses. This higher F in E from oral prodrug EP appears to be a pharmacologic advantage that could be of potential pharmacodynamic importance for this drug.

Tumour necrosis factor-alpha plasma levels after flavone acetic acid administration in man and mouse.

Flavone acetic acid (FAA) is a synthetic flavonoid with a remarkable spectrum of anticancer activities in mouse tumours, but with no anticancer activity in humans. The mechanism of action of this drug is complex and involves a tumour vasculature action similar to the effects of tumour necrosis factor (TNF). To assess directly the role of TNF in FAA mechanism of action, this cytokine was assayed in both mouse and human plasma after intravenous administration of the drug. In mouse, a species particularly sensitive to FAA antitumour action, FAA plasma concentrations reached 268 micrograms/ml at 0.5 h and remained high (165 micrograms/ml) at 6 h following the intravenous administration of an anticancer efficacious dose (540 mg/m2). After FAA administration in mouse, TNF activity (L929 mouse cell bioassay) increased to 300 pg/ml TNF-alpha-equivalent at 2 h, reached a maximum concentration of 600 pg/ml at 4 h, and declined thereafter to 220 pg/ml at 6 h. TNF activity in mouse plasma was completely abrogated in the presence of mouse TNF-alpha antibodies. FAA added directly to blank mouse plasma did not show TNF activity. In patients receiving the drug as a 6-h intravenous infusion at doses ranging from 3.6 to 8.1 g/m2, FAA plasma levels ranged from 58 to 449 micrograms/ml at the end of infusion. Human TNF-alpha levels assayed with an immunoradiometric assay were either not detectable or very low (< 25 pg/ml) before FAA administration. At completion of the FAA infusion, TNF-alpha remained near background levels in 20 of the 21 courses. A slight increase in plasma TNF-alpha was observed in 1 patient at the 8.1 g/m2 dose level of FAA, from 13 pg/ml before intravenous infusion, to 70 pg/ml at completion of intravenous infusion. Taken together, these data demonstrate a marked interspecies difference with regard to TNF-alpha secretion after FAA treatment, as this cytokine is produced in mice, whereas it is not significantly secreted in pretreated patients. Although the low TNF-alpha levels achieved in mice probably do not explain all of FAA antitumour activity in that species, the observed interspecies difference in TNF-alpha secretion after FAA administration could partly explain the marked difference in FAA antitumour activity observed between mice and humans.

Phase I and pharmacokinetic study of brequinar (DUP 785; NSC 368390) in cancer patients.

Brequinar (DUP 785, NSC 368390) is a 4-quinoline carboxylic acid derivative with broad spectrum antitumour activity in experimental models that acts as an antimetabolite by specific inhibition of de novo pyrimidine synthesis. We performed a phase I study of brequinar administered as a 10 min intravenous (i.v.) infusion for 5 consecutive days, every 4 weeks. 67 evaluable patients were entered in this study and a total of 130 courses were administered at doses ranging from 2 to 350 mg/m2. The dose-limiting toxicity was myelosuppression with predominant thrombocytopenia. Myelosuppression was dose-related and non-cumulative, with considerable interpatient variability depending on haematological risk factors. The maximum tolerated dose of brequinar was 210 mg/m2/day in poor risk patients whereas patients with good risk haematological profile tolerated higher doses (up to 350 mg/m2/day). Other non-limiting toxicities included nausea and vomiting, mucositis and skin reactions. Brequinar plasma pharmacokinetic profiles were biphasic with alpha half-life ranging from 0.1 to 0.7 h, and beta half-life ranging from 1.5 to 8.2 h. Increase in brequinar area under the plasma concentration versus time curves (AUC) was nonlinear. Day 5 brequinar pharmacokinetics obtained in 21 patients indicated a significant increase in AUC (47%) and half-life beta (133%) compared to day 1 pharmacokinetics in the same patient. Brequinar plasma AUC and the per cent change in platelet count at nadir were correlated (P < 0.001). Although no objective response was observed in this study, one minor response was noted in cervical lymph nodes of a Hodgkin's disease patient.

Phase I and pharmacological study of intra-arterial hepatic administration of pirarubicin in patients with advanced hepatic metastases.

Intra-arterial hepatic (i.a.h.) administration of the doxorubicin analogue pirarubicin was evaluated in a phase I trial, based on preclinical studies that showed an advantage of pirarubicin over doxorubicin after locoregional hepatic administration. Pirarubicin was given to 9 patients with metastatic liver disease with intrapatient dose escalation. Of the 58 cycles evaluable for tolerance, no hepatobiliary or vascular toxicity was observed. The dose-limiting toxicity was granulocytopenia: the maximum administered doses ranged from 50 to 120 mg/m2, suggesting variable rates of pirarubicin hepatic extraction between patients. Pharmacokinetic data obtained in 7 patients, in which a direct comparison of intravenous (i.v.) and i.a.h. administration was possible, indicated a median i.v./i.a.h. ratio of 7.4 for the maximal plasma concentration, and a median ratio of 4 for the area under the plasma concentrations versus time curves, suggesting a high pirarubicin hepatic extraction. An unexpectedly high response rate was observed: two complete (colorectal carcinoma) and two partial responses. These data demonstrate that i.a.h. pirarubicin not only produced high locoregional concentrations and reduced systemic exposure, but can also achieve responses in metastatic liver disease of colorectal origin.

Clinical pharmacokinetics of irinotecan.

This article reviews the clinical pharmacokinetics of a water-soluble analogue of camptothecin, irinotecan [CPT-11 or 7-ethyl-10-[4-(1-piperidino)-1-piperidino]-carbonyloxy-camptoth eci n]. Irinotecan, and its more potent metabolite SN-38 (7- ethyl-10-hydroxy-camptothecin), interfere with mammalian DNA topoisomerase I and cancer cell death appears to result from DNA strand breaks caused by the formation of cleavable complexes. The main clinical adverse effects of irinotecan therapy are neutropenia and diarrhoea. Irinotecan has shown activity in leukaemia, lymphoma and the following cancer sites: colorectum, lung, ovary, cervix, pancreas, stomach and breast. Following the intravenous administration of irinotecan at 100 to 350 mg/m2, mean maximum irinotecan plasma concentrations are within the 1 to 10 mg/L range. Plasma concentrations can be described using a 2- or 3-compartment model with a mean terminal half-life ranging from 5 to 27 hours. The volume of distribution at steady-state (Vss) ranges from 136 to 255 L/m2, and the total body clearance is 8 to 21 L/h/m2. Irinotecan is 65% bound to plasma proteins. The areas under the plasma concentration-time curve (AUC) of both irinotecan and SN-38 increase proportionally to the administered dose, although interpatient variability is important. SN-38 levels achieved in humans are about 100-fold lower than corresponding irinotecan concentrations, but these concentrations are potentially important as SN-38 is 100- to 1000-fold more cytotoxic than the parent compound. SN-38 is 95% bound to plasma proteins. Maximum concentrations of SN-38 are reached about 1 hour after the beginning of a short intravenous infusion. SN-38 plasma decay follows closely that of the parent compound with an apparent terminal half-life ranging from 6 to 30 hours. In human plasma at equilibrium, the irinotecan lactone form accounts for 25 to 30% of the total and SN-38 lactone for 50 to 64%. Irinotecan is extensively metabolised in the liver. The bipiperidinocarbonylxy group of irinotecan is first removed by hydrolysis to yield the corresponding carboxylic acid and SN-38 by carboxyesterase. SN-38 can be converted into SN-38 glucuronide by hepatic UDP-glucuronyltransferase. Another recently identified metabolite is 7-ethyl-10-[4-N-(5-aminopentanoic acid)-1-piperidino]-carbonyloxy-camptothecin (APC). This metabolite is a weak inhibitor of KB cell growth and a poor inducer of topoisomerase I DNA-cleavable complexes (100-fold less potent than SN-38). Numerous other unidentified metabolites have been detected in bile and urine. The mean 24-hour irinotecan urinary excretion represents 17 to 25% of the administered dose. Recovery of SN-38 and its glucuronide in urine is low and represents 1 to 3% of the irinotecan dose. Cumulative biliary excretion is 25% for irinotecan, 2% for SN-38 glucuronide and about 1% for SN-38. The pharmacokinetics of irinotecan and SN-38 are not influenced by prior exposure to the parent drug. The AUC of irinotecan and SN-38 correlate significantly with leuco-neutropenia and sometimes with the intensity of diarrhoea. Certain hepatic function parameters have been correlated negatively with irinotecan total body clearance. It was noted that most tumour responses were observed at the highest doses administered in phase I trials, which indicates a dose-response relationship with this drug. In the future, these pharmacokinetic-pharmacodynamic relationships will undoubtedly prove useful in minimising the toxicity and maximise the likelihood of tumour response in patients.

In vivo induction of cytochrome P450 CYP3A expression in rat leukocytes using various inducers.

Although the induction of cytochromes P450 3A (CYP3A) is relatively well characterized in liver, its inducibility in an easily available tissue such as the peripheral leukocytes is not known. The purpose of this study was, therefore, to determine if CYP3A is inducible in vivo in peripheral leukocytes. Microsomes from rat leukocytes and liver were examined for CYP3A protein expression using Western blotting with a rabbit polyclonal antibody against rat CYP3A. Although CYP3A was not detected in control leukocytes, in vivo treatment with known CYP3A inducers (dexamethasone, clotrimazole, phenobarbital, pregnenolone-16 alpha-carbonitrile) resulted in CYP3A leukocyte levels of 0.2-0.8 pmol/mg protein. This leukocyte induction was approximately 1000-fold lower than in induced liver. Interestingly, there was an apparent linear relationship between leukocyte and liver CYP3A contents (r2 = 0.748, n = 29). These results not only demonstrate for the first time that CYP3A is inducible in rat leukocytes after in vivo treatment with various CYP3A inducers, but also suggest that peripheral leukocytes could be used to assess induction in vivo.