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Clinical Trials |
Department of Medical Oncology, Rotterdam Cancer Institute (Daniel den Hoed Kliniek) and University Hospital Rotterdam, 3075 EA Rotterdam, the Netherlands [M. J. A. d. J., J. V., A. S. T. P., M. E. L. v. d. B., G. S., M. M. d. B-D., P. d. B., E. B., A. S.], and Rhône-Poulenc Rorer, 92165 Antony Cedex, France [L. V.]
| ABSTRACT |
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0.20). In addition, CPT-11 had no influence on the clearance of nonprotein-bound CDDP (40.8 ± 16.7 versus 50.3 ± 18.6 liter/h/m2; P = 0.08) and the platinum DNA-adduct formation in peripheral leukocytes in either sequence (1.94 ± 2.20 versus 2.42 ± 1.62 pg Pt/µg DNA; P = 0.41). These data indicate that the toxicity of the combination CPT-11 and CDDP is schedule independent and that there is no mutual pharmacokinetic interaction. | INTRODUCTION |
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In general, the design of effective combination chemotherapy regimens requires adequate attention to possible drug interactions at the pharmacokinetic and/or pharmacodynamic level. Until now, the importance of drug sequencing for the combination of topoisomerase I inhibitors and platinum-derivatives has clinically only been investigated for the combination of topotecan and CDDP (5 , 6) . When CDDP was administered before a 5-day schedule of topotecan, significantly more and severe hematological toxicity was encountered than with the alternate sequence. Pharmacokinetic studies suggested that the differences in toxicity were due, in part, to a slower topotecan clearance when CDDP preceded topotecan (5) .
In all Phase I studies on the combination of CPT-11 and CDDP, CPT-11 administration preceded that of CDDP (1 , 7, 8, 9, 10, 11, 12, 13) , and pharmacokinetic data were only scarcely obtained (8) . Against this background, we initiated a study in which patients were treated in a randomized cross-over design to determine whether the sequence of CPT-11 and CDDP administration has any influence on the observed toxicity or is related to any pharmacokinetic interaction between the drugs.
| MATERIALS AND METHODS |
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2.0 x 109/liter) and platelet count (
100 x 109/liter)], renal [serum creatinine concentration (
135 µmol/liter) or creatinine clearance (
60 ml/min)], and hepatic function [total serum bilirubin (
1.25 x UNL) and serum aspartate aminotransferase and alanine aminotransferase (
3.0 x UNL); in case of liver metastasis: total serum bilirubin (
1.5 x UNL) and serum aspartate aminotransferase and alanine aminotransferase (
5.0 x UNL)]. All patients gave written informed consent before study entry.
Treatment Plan and Drug Administration.
Patients were randomized to one of two treatment groups. In group A, patients received CPT-11 as a 90-min i.v. infusion at a dose of 200 mg/m2 on day 1, immediately followed by the infusion of CDDP at a dose of 80 mg/m2 as a 3-h i.v. infusion diluted in 250 ml of sodium chloride 3% (w/v) on day 1. Doses were selected based on experience obtained in a preceding Phase I study.3
In the second course, the sequence of administration of CPT-11 and CDDP was reversed, administering CDDP before CPT-11 at the same doses. In case a patient encountered neutropenic fever or grade 3 or 4 nonhematological toxicity (except nausea and vomiting), the dose of CPT-11 was reduced to 175 mg/m2 and CDDP was reduced to 60 mg/m2 in the second course. Group B patients received the two treatment cycles in reverse order.
In all patients, premedication consisted of ondansetron (8 mg i.v.) combined with dexamethasone (10 mg i.v.) administered 30 min before the start of the chemotherapy. The administration of chemotherapy was followed by infusion of 2000 ml of dextrose/saline applied over 8 h and another 1000 ml of the same solution infused over the following 8 h to avoid CDDP-induced renal damage.
Pharmacokinetic Sampling and Analysis.
Blood samples for pharmacokinetic analysis were obtained during the first and second treatment cycle (total blood volume, 283 ml). Blood was drawn from a vein in the arm opposite to that used for drug infusion and collected in 10-ml heparinized tubes. For analysis of CPT-11 kinetics, samples were obtained at the following time points: before infusion; 0.5, 1, and 1.5 h during infusion; and 0.17, 0.33, 0.5, 1, 1.5, 2, 4, 5, 8.5, 11, 24, 32, 48, and 56 h after infusion. Samples for measurement of CDDP concentrations were obtained immediately before infusion; 1, 2, and 3 h during infusion; and 0.5, 1, 2, 3, 4, and 24 h after infusion.
Plasma samples were assayed for total drug forms of CPT-11 and metabolites and the lactone forms of CPT-11 and SN-38, according to validated reversed-phase high performance liquid chromatography methods reported previously (14 , 15) . Nonprotein-bound and total CDDP concentrations in plasma and platinum DNA-adduct levels in leukocytes were determined by flameless atomic absorption spectrometry (16) .
Individual plasma concentrations of CPT-11 and its metabolites were fitted to a three-compartment model using Siphar v4.0 (SIMED, Creteil, France), as described (17) . Metabolic ratios for the various CPT-11 metabolites were calculated as defined by Rivory et al. (18) and included the relative extent of conversion of CPT-11 to SN-38 (i.e., AUCSN-38/AUCCPT-11), the relative extent of glucuronidation of SN-38 (i.e., AUCSN-38G/AUCSN-38), and the relative extent of metabolism (i.e., AUCAPC or NPC/AUCCPT-11). Kinetic profiles of CDDP were obtained similarly using a one- or two-compartment model with extended least-squares regression analysis, as reported earlier (16) . The platinum DNA-adduct levels in leukocytes were expressed as pg platinum/µg DNA (pg Pt/µg DNA).
Statistical Considerations.
Pharmacokinetic parameters for all compounds are reported as mean values ± SD. Differences in pharmacodynamic and pharmacokinetic parameters between sequences were evaluated statistically using a paired Students t test and the 95% confidence limits for the mean difference using Number Cruncher Statistical System version 5.X (Dr. Jerry Hintze, Kaysville, UT) and STATGRAPHICS Plus version 2.0 (Manugistics Inc., Rockville, MA). The power to discern potentially clinically relevant differences in the test parameters >30% (
) was determined at
= 0.05 and previous pharmacological data (17)
.4
Probability values (two-sided) of <0.05 were regarded as statistically significant.
| RESULTS |
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CPT-11, and one patient (first course only) in the sequence CPT-11
CDDP, which required dose reductions for the second course in three cases (CDDP
CPT-11, n = 2; CPT-11
CDDP, n = 1). Hence, only eight patients received the planned dose in the sequence CPT-11
CDDP, compared to nine patients in the reversed sequence. Paired analysis of hematological pharmacodynamic parameters indicated, however, that drug-sequencing had no significant influence on the observed myelotoxicity (Table 1)
= 0.93). The severity and incidence of nonhematological toxicities, including nausea [grade 2 or 3, n = 4 (CPT-11
CDDP) versus n = 4 (CDDP
CPT-11)], vomiting (grade 3 or 4, n = 1 versus n = 2), and diarrhea (grade 3 or 4, n = 0 versus n = 1), were also sequence independent.
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= 0.99). The AUC ratios of CPT-11 lactone to total drug were 0.37 ± 0.07 and 0.35 ± 0.14, whereas for SN-38 these were 0.67 ± 0.15 and 0.62 ± 0.27, in the sequences CPT-11
CDDP and CDDP
CPT-11, respectively (Table 3)
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CDDP pharmacokinetics could best be described with a two-compartment model (Fig. 1B)
, as described (16)
. The total body clearance and the Vss of unbound CDDP were the same in both sequences (
= 0.64), indicating no influence of the drug sequence on the protein binding of CDDP (Table 4)
. The platinum-DNA adduct levels in leukocytes peaked consistently at 1 h after the end of infusion, and showed wide interpatient variability (Table 4)
. Administration of CPT-11 before CDDP resulted in a mean value of 1.94 ± 2.20 pg Pt/µg DNA that was comparable with 2.42 ± 1.62 pg Pt/µg DNA observed in the reverse sequence (P = 0.41).
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| DISCUSSION |
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The total body clearance and Vss of unbound CDDP, as well as the plasma AUC of total CDDP, indicated no significant influence of CPT-11 (or its metabolites) on the protein binding and plasma disposition of CDDP. The values of the maximal platinum DNA-adduct formation in peripheral leukocytes and the area under the DNA-adduct versus time curve were consistent with single-agent data (16) and were independent of the drug sequence. In preclinical studies, however, topoisomerase I inhibitors delayed the repair of platinum-induced DNA interstrand cross-links without modifying their formation (1) . Although there is no formal proof that this preclinical observation also applies to the clinical situation, it is possible that the small patient population studied, in combination with the extreme variability in platinum DNA-adduct values, would not allow any alteration to be observed even if it were present.
In our study, CDDP was immediately administered at the end of the CPT-11 infusion, or vice versa in the alternate sequence. The lack of sequence dependence in the kinetic profiles of both drugs in this schedule does not necessarily indicate that any reciprocal pharmacokinetic interference will be absent when the administration interval is increased. In this respect, it is noteworthy that CDDP can modulate specific CYP450 mRNA levels and may alter hepatic drug metabolism in vivo (20) , a mechanism that has recently been proposed to account for drug interactions between CDDP and paclitaxel (21) or CDDP and etoposide (22) . In view of the major role of CYP450 isozymes in CPT-11 metabolism and disposition (17) , drug interactions with CDDP cannot be excluded a priori in case of alternative schedules of administration.
In conclusion, no sequence-dependent side effects between CPT-11 and CDDP could be demonstrated in this study, nor an indication of a mutual pharmacokinetic interaction. On the basis of these findings and the conflicting data on the mechanism of drug interaction between topoisomerase I inhibitors and platinum derivatives in preclinical models, no clear preference in administration sequence can yet be formulated.
| FOOTNOTES |
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1 To whom requests for reprints should be addressed, Department of Medical Oncology, Rotterdam Cancer Institute (Daniel den Hoed Kliniek) and University Hospital Rotterdam, Groene Hilledijk 301, 3008 AE Rotterdam, the Netherlands. Phone: 31-10-4391733; Fax: 31-10-4391003; E-mail: jonge{at}onch.azr.nl ![]()
2 The abbreviations used are: CPT-11, irinotecan (7-ethyl-10-[4-(1-piperidino)-1-piperidino]-carbonyloxycamptothecine; CDDP, cisplatin; Vss, volume of distribution at steady state; AUC, area under the plasma concentration-time curve; SN-38, 7-ethyl-10-hydroxycamptothecine; SN-38G, SN-38 glucuronide; APC, 7-ethyl-10-[4-N-(5-aminopentanoic acid)-1-piperidino]carbonyloxycamptothecine; NPC, 7-ethyl-10-[4-N-(1-piperidino)-1-amino]carbonyloxycamptothecine; UNL, upper normal limit; CYP450, cytochrome P-450. ![]()
3 M. J. A. de Jonge, A. Sparreboom, A. S. T. Planting, M. E. L. van der Burg, M. M. de Boer-Dennert, J. ter Steeg, C. Jacques, and J. Verweij. Phase I study of 3-weekly irinotecan combined with cisplatin in patients with advanced solid tumors. J. Clin. Oncol., in press, 1999. ![]()
4 M. J. A. de Jonge, J. Verweij, P. de Bruijn, E. Brouwer, R. H. J. Mathijssen, R. J. van Alphen, L. Vernillet, C. Jacques, and A. Sparreboom. Pharmacokinetic, metabolic and pharmacodynamic profiles in a dose escalating study of irinotecan and cisplatin. J. Clin. Oncol., in press, 1999. ![]()
Received 2/26/99; revised 5/11/99; accepted 5/14/99.
| REFERENCES |
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