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Biomedical subjects

J Verweij

Publications and source records attributed to J Verweij.

At least 91 records · Page 5Linked to original sources
PubMed2001

Active transepithelial transport of irinotecan (CPT-11) and its metabolites by human intestinal Caco-2 cells.

Irinotecan (CPT-11) is a camptothecin analog with low (about 10--20%) and variable oral bioavailability in animal models. Here, Caco-2 cells were used to evaluate the transepithelial transport of CPT-11 and its metabolites. Caco-2 cells demonstrated significant expression of P-glycoprotein (P-gp), multidrug resistance-associated protein and canalicular multispecific organic anion transporter. Both the lactone and carboxylate forms of CPT-11 and SN-38 were actively transported across the cell monolayers, mainly by the apical-localized P-gp pump. Cellular permeability of CPT-11 at a concentration of 17 microM converted from active to passive-diffusional transport between the 2 and 6 h exposure time points. Antiproliferative effects of CPT-11 were related to permeability of the lactone form, whereas for SN-38 efficacy was dependent on lactone accumulation. Exposure of CPT-11 with cyclosporin A significantly enhanced its efficacy, whereas this was not observed with verapamil and R101933. In contrast, SN-38 efficacy decreased in the presence of P-gp inhibitors due to active transport toward the basolateral side, thereby reducing drug accumulation. Hence, multiple-active transport systems could be demonstrated to be responsible for not only accumulation profiles but also cytotoxic efficacy of CPT-11 and SN-38 in the intestinal Caco-2 cells. It is suggested that CPT-11 might act in a time-dependent manner and that SN-38-mediated cytotoxicity relates to (dose-dependent) lactone kinetics. The results detailed in this report could contribute toward the development of a clinically useful oral formulation of CPT-11 with improved absorption characteristics and suggest that cyclosporin A is a suitable agent for further research of this concept.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed2001

Population pharmacokinetics and dynamics in phase II studies of the novel bioreductive alkylating cytotoxic indoloquinone EO9.

Population pharmacokinetic-dynamic analysis was prospectively integrated in the clinical phase II programme of EO9 to determine the population pharmacokinetic profile in a larger population of patients, to estimate individual patient pharmacokinetic parameters, and to investigate relationships between drug exposure and clinical outcome. A sparse sampling method was developed, which involved three sampling times, and was implemented during course 1. A Bayesian algorithm was used to estimate individual pharmacokinetic parameters, in particular total plasma clearance (CL) of EO9 and area under the curve (AUC). In total, samples were collected of 85 (65%) of the patients. Pharmacokinetic evaluation was successful in 61 (72%) of the sampled patients. CL of EO9 showed substantial variability (median 5.08 l/min; range 2.67-6.42) and was of the same magnitude as in the phase I study where full pharmacokinetic profiles were used. No significant relationships were noticed between exposure parameters and safety, but overall limited toxicity was observed. No tumor responses were documented. Prospective implementation of large-scale population pharmacokinetic-dynamic analysis is feasible and may generate important findings, in particular when tumor responses and relevant toxicity are observed.

Adult↗
PubMed2001

Adaptive intrapatient dose escalation of cisplatin in patients with advanced head and neck cancer.

The purpose of this study was to explore the feasibility and toxicity of intrapatient dose adjustment using predefined levels of exposure to cisplatin, with the ultimate goal to further improve the antitumor activity of the treatment. The primary parameter for adaptive dosing was the level of platinum DNA adducts in peripheral white blood cells (WBC) and the secondary parameter the area under the curve (AUC) of unbound platinum in plasma, which were determined during the applied courses. Target levels had been defined in a previously performed pharmacologic study. The concept of adaptive dosing was tested in 16 patients with locally advanced head and neck (H/N) cancer who would receive six weekly courses of cisplatin at a starting dose level of 80 mg/m(2), which was previously investigated in a phase II study. Forty-seven percent of patients received a dose increase varying from 10 to 40%. Only two patients had exposure levels significantly below the defined target levels for DNA adducts and AUC. The majority of patients reached the defined target levels by modest dose increases of 10-20% during course 2. Relevant but reversible ototoxicity (temporary grade 3 in two patients) and renal toxicity (temporary grade 2 in two other patients) were observed. The pattern and severity of the toxicity was comparable to that encountered in the previous phase II study in H/N cancer patients. We conclude that the strategy of intrapatient dose adjustment for cisplatin is practically feasible in a research setting even when a short turn around time of 1 week is the limit for reporting results. Although in some patients the dose increase that had to be applied to reach target levels was substantial (up to 40%), this approach in H/N cancer patients is not expected to improve the response rate significantly, because these significantly underdosed patients represented only a small percentage of the investigated population. The great majority of patients needed only limited (10-20%) dose increases which very likely will not improve the response rate to a clinically significant extent. The outlined concept is currently being explored in other tumor types and schedules of cisplatin.

Adult↗
PubMed2001

Matrix metalloproteinase inhibitors: current developments and future perspectives.

Malignant tumors are characterized by invasive growth and metastasis. To facilitate this invasive behavior, the enzymatic breakdown of the extracellular matrix (ECM) is a prerequisite. Many human tumors are characterized by locally increased concentrations of matrix metalloproteinases (MMPs), enzymes that are able to degrade this ECM. A vast number of matrix metalloproteinase inhibitors (MMPIs) have been developed in recent years and after extensive preclinical testing, the results of the first clinical studies with several of these compounds have recently been presented. In this review we will describe some of the basic concepts of the degradation of the ECM, with special emphasis on the role of MMPs in the progression of cancer. Furthermore we will review the results of preclinical and clinical studies with MMPIs and discuss their future perspective.

Clinical Trials as Topic↗
PubMed2001

Capecitabine in breast cancer: current status.

Anthracyclines, together with taxanes, are at present the most active agents in metastatic breast cancer, while single-agent, bolus 5-fluorouracil (5-FU) is not very active in this setting. In view of encouraging results and tolerable toxicity of continuous infusion of 5-FU in gastrointestinal cancer, innovative oral 5-FU agents such as capecitabine have been developed. Capecitabine is a prodrug that is converted into the active compound 5-FU preferentially at the tumor site. An intermittent dosing schedule of capecitabine twice daily at a dose of 2510 mg/m2/day on days 1-14 in a 3-week cycle appeared to be feasible and resulted in a high dose intensity. A large phase II study investigating capecitabine in 135 advanced breast cancer patients, pretreated with anthracyclines and taxanes, observed three complete and 24 partial responses (response rate, 20%), with a mean duration of 8.0 months. Preliminary results of a study comparing capecitabine with paclitaxel in 42 breast cancer patients failing anthracyclines indicate that the efficacy of capecitabine is comparable to that of paclitaxel, with response rates of 36% and 21%, respectively. Another study reported a response rate of 25% for capecitabine as first-line therapy for advanced breast cancer in women aged > or = 55 years, which tended to be better than combination chemotherapy with cyclophosphamide/methotrexate/5-FU. In all studies, capecitabine side effects were mainly mild, and treatment-related grade 3/4 toxicity consisted of diarrhea (8%-11%), nausea (4%-11%), hand-foot syndrome (10%-18%), neutropenia (3%-20%), and bilirubin elevation (6%). Capecitabine is clearly an active agent for the treatment of breast cancer. It is currently registered in various countries for use in third-line treatment of metastatic disease. Its further role will have to be defined from data of randomized phase III studies.

Antimetabolites, Antineoplastic↗
PubMed2001

Modulation of irinotecan-induced diarrhea by cotreatment with neomycin in cancer patients.

This study was designed to evaluate irinotecan (CPT-11) disposition and pharmacodynamics in the presence and absence of the broad-spectrum antibiotic neomycin. Seven evaluable cancer patients experiencing diarrhea graded > or =2 after receiving CPT-11 alone (350 mg/m(2) i.v. once every 3 weeks) received the same dose combined with oral neomycin at 1000 mg three times per day (days -2 to 5) in the second course. Neomycin had no effect on the systemic exposure of CPT-11 and its major metabolites (P > or = 0.22). However, it changed fecal beta-glucuronidase activity from 7.03 +/- 1.76 microg/h/mg (phenolphthalein assay) to undetectable levels and decreased fecal concentrations of the pharmacologically active metabolite SN-38. Although neomycin had no significant effect on hematological toxicity (P > 0.05), diarrhea ameliorated in six of seven patients (P = 0.033). Our findings indicate that bacterial beta-glucuronidase plays a crucial role in CPT-11-induced diarrhea without affecting enterocycling and systemic SN-38 levels.

Adolescent↗
PubMed2001

Phase I and pharmacological study of the oral matrix metalloproteinase inhibitor, MMI270 (CGS27023A), in patients with advanced solid cancer.

This Phase I study of MMI270, an p.o. administered matrix metalloproteinase inhibitor, assessed toxicity, pharmacokinetics, and tumor response data and investigated markers of biological activity to recommend a dose for Phase II studies. MMI270 was administered continuously at seven dose levels (50 mg once daily to 600 mg three times/day). Patients were evaluated for toxicity and tumor response, and blood and urine samples were taken for pharmacokinetics, bone resorption markers, direct targets of the inhibitor [matrix metalloproteinase-2 (MMP-2), MMP-8, and MMP-9], indirect targets [tissue inhibitor of metalloproteinase-1 (TIMP-1), TIMP-2, basic fibroblast growth factor, vascular endothelial growth factor, vascular cell adhesion molecule-1, soluble urokinase plasminogen activator receptor, and cathepsins B and H] and for a tumor necrosis factor-alpha cytokine release assay. Ninety-two patients were entered. There was no myelotoxicity. Eighteen patients developed a widespread maculopapular rash, which increased in frequency and severity at doses > or = 300 mg bid. Thirty nine patients developed musculoskeletal side effects, which were related to duration of treatment, not to dose level. Pharmacokinetics were linear, and MMI270 was rapidly absorbed and eliminated with minimal accumulation on chronic dosing. Sustained plasma concentrations in excess of 4 x mean IC(50) for the target enzymes were observed at dose levels > or = 150 mg bid. There were no tumor regressions; however, 19 patients had stable disease for > or = 90 days. There was a dose-response increase of MMP-2 and TIMP-1 with MMI270. Transient effects on the bone resorption markers were detected. MMI270 was generally well tolerated, with adequate plasma levels for target enzyme inhibition. The two main toxicities were rash, resulting in a maximum tolerated dose of 300 mg bid and musculoskeletal side effects. Biological marker data indicate drug effects. The rise in TIMP-1 suggests that a reflex rise in inhibitors could modify the effects of MMI270. The recommended Phase II dose is 300 mg bid.

Administration, Oral↗
PubMed2001

Clinical pharmacokinetics and metabolism of irinotecan (CPT-11).

CPT-11 belongs to the class of topoisomerase I inhibitors, and it acts as a prodrug of SN-38, which is approximately 100-1000-fold more cytotoxic than the parent drug. CPT-11 has shown a broad spectrum of antitumor activity in preclinical models as well as clinically, with responses observed in various disease types including colorectal, lung, cervical, and ovarian cancer. The pharmacokinetics and metabolism of CPT-11 are extremely complex and have been the subject of intensive investigation in recent years. Both CPT-11 and SN-38 are known in an active lactone form and an inactive carboxylate form, between which an equilibrium exists that depends on the pH and the presence of binding proteins. CPT-11 is subject to extensive metabolic conversion by various enzyme systems, including esterases to form SN-38, UGT1A1 mediating glucuronidation of SN-38, as well as CYP3A4, which forms several pharmacologically inactive oxidation products. Elimination routes of CPT-11 also depend on the presence of drug-transporting proteins, notably P-glycoprotein and canalicular multispecific organic anion transporter, present on the bile canalicular membrane. The various processes mediating drug elimination, either through metabolic breakdown or excretion, likely impact substantially on interindividual variability in drug handling. Strategies to individualize CPT-11 administration schedules based on patient differences in enzyme or protein expression or by coadministration of specific agents modulating side effects are under way and may ultimately lead to more selective chemotherapeutic use of this agent.

Antineoplastic Agents, Phytogenic↗
PubMed2001

Sarcomas.

Explore the source record for details and available documents.

Antineoplastic Agents↗
PubMed2000

New guidelines to evaluate the response to treatment in solid tumors. European Organization for Research and Treatment of Cancer, National Cancer Institute of the United States, National Cancer Institute of Canada.

Anticancer cytotoxic agents go through a process by which their antitumor activity-on the basis of the amount of tumor shrinkage they could generate-has been investigated. In the late 1970s, the International Union Against Cancer and the World Health Organization introduced specific criteria for the codification of tumor response evaluation. In 1994, several organizations involved in clinical research combined forces to tackle the review of these criteria on the basis of the experience and knowledge acquired since then. After several years of intensive discussions, a new set of guidelines is ready that will supersede the former criteria. In parallel to this initiative, one of the participating groups developed a model by which response rates could be derived from unidimensional measurement of tumor lesions instead of the usual bidimensional approach. This new concept has been largely validated by the Response Evaluation Criteria in Solid Tumors Group and integrated into the present guidelines. This special article also provides some philosophic background to clarify the various purposes of response evaluation. It proposes a model by which a combined assessment of all existing lesions, characterized by target lesions (to be measured) and nontarget lesions, is used to extrapolate an overall response to treatment. Methods of assessing tumor lesions are better codified, briefly within the guidelines and in more detail in Appendix I. All other aspects of response evaluation have been discussed, reviewed, and amended whenever appropriate.

Antineoplastic Agents↗
PubMed2000

Liposomal lurtotecan (NX211): determination of total drug levels in human plasma and urine by reversed-phase high-performance liquid chromatography.

Lurtotecan (GI147211; LRT) is a semisynthetic and water-soluble analogue of the topoisomerase I inhibitor camptothecin. To determine whether the therapeutic efficacy of LRT in patients could be improved, the drug was encapsulated in liposomes (NX211; Gilead Sciences). In order to allow accurate description of the pharmacokinetic behavior of NX211 in cancer patients, we have developed sensitive RP-HPLC assays with fluorescence detection (lambdaex=378 nm; lambdaem=420 nm) for the determination of total LRT levels in human plasma and urine. Sample pretreatment involved deproteinization with 10% (w/v) aqueous perchloric acid-acetonitrile (2:1, v/v), and chromatographic separations were achieved on an Inertsil-ODS 80A analytical column. The lower limit of quantitation (LLQ) was established at 1.00 ng/ml in plasma (200-microl sample) and at 100 ng/ml in urine (200 microl of 40-fold diluted sample). The within-run and between-run precisions were <7.5%. LRT concentrations in urine of <100 ng/ml were determined by a modified procedure comprising a single solvent extraction with n-butanol-diethyl ether (3:4, v/v). In this assay, the fluorescence signal of LRT was increased 14-fold prior to detection by post-column exposure to UV light (254 nm) in a photochemical reaction unit. The LLQ of this assay was 0.500 ng/ml (150-microl sample) and the within-run and between-run precisions were <10%.

Acetonitriles↗
PubMed2000

Phase I trial with weekly EO9, a novel bioreductive alkylating indoloquinone, by the EORTC Early Clinical Study Group (ECSG).

PURPOSE: EO9 is a new synthetic bioreductive alkylating indoloquinone, with preferential activity against solid tumors and higher antitumor activity under anaerobic conditions compared with aerobic conditions. In preclinical models EO9 demonstrated no major organ toxicity. The aim of the present phase I study was to determine the toxicities and the maximal tolerated dose (MTD) of EO9 administered as a 5-min i.v. infusion weekly to patients with solid cancers. METHODS: Twenty-eight patients entered the study. The dose was escalated from 2.7 mg/m2 according to a Fibonacci-like schedule. RESULTS AND CONCLUSION: The dose-limiting toxicity was proteinuria. No other major toxicities were detected and in particular there was no significant increase in serum creatinine. This was in contrast to findings in a previous phase I trial using EO9 in a 3-weekly schedule, where a number of patients experienced severely decreased kidney function. The MTD in the present study was 15.0 mg/m2 weekly and the recommended dose for phase II studies was 12.0 mg/m2 weekly. Compared with 3-weekly EO9, the dose intensity could be increased from 22 mg/m2 to 36 mg/m2 with the weekly administration. Phase II studies have been performed by the EORTC Early Clinical Study Group in advanced breast, gastric, colorectal, pancreatic, and non-small-cell lung cancer.

Adult↗
PubMed2000

Carzelesin phase II study in advanced breast, ovarian, colorectal, gastric, head and neck cancer, non-Hodgkin's lymphoma and malignant melanoma: a study of the EORTC early clinical studies group (ECSG).

PURPOSE: In a phase II trial, the activity of carzelesin, a cyclopropylpyrroloindole prodrug analog, was assessed. PATIENTS AND METHODS: Carzelesin was used as second- or third-line chemotherapy in patients with breast, ovarian, head and neck cancer and non-Hodgkin's lymphoma, and as first-line chemotherapy in patients with colorectal and gastric cancer and melanoma. The drug was given as a bolus infusion at a 4-weekly dose of 150 microg/m2. A total of 140 patients were entered and a total of 285 courses were administered. RESULTS: In general, the compound was well tolerated. Myelotoxicity was the most common toxicity. Grade 3 and 4 leukopenia was observed in 18.6% of the courses, neutropenia in 20.3%, thrombocytopenia in 16.2% and anemia in 8.7%. Double nadirs were seen in a total of 41 courses for neutrophils, in 40 for leukocytes and in 3 for platelets. Non-hematological toxicity was very mild. Only one partial response in a patient with melanoma was seen. CONCLUSIONS: At this dose and schedule carzelesin did not yield activity in the types of tumors studied.

Adult↗
PubMed2000

Achievements and future of chemotherapy.

Although surgery and radiotherapy result in a cure in 40% of all cancer patients, the remaining 60% of the patients die as a result of metastatic disease. For those patients cancer has to be considered as a systemic disease and cure from cancer will likely come from some type of systemic treatment. This article gives a brief overview of the achievements in the development of chemotherapy over the last 50 years and the new potential targets for further drug development.

Antineoplastic Agents↗
PubMed2000

Effect of high-dose ifosfamide in advanced soft tissue sarcomas. A multicentre phase II study of the EORTC Soft Tissue and Bone Sarcoma Group.

In this phase II study the effect of high-dose ifosfamide (HDI) given as a 3-day continuous infusion at a dose of 12 g/m2 repeated every 4 weeks with adequate mesna protection and hydration was evaluated in patients with advanced soft tissue sarcomas. A total of 124 patients entered the trial of which 10 were ineligible. HDI was given both as first-line and second-line chemotherapy. Median age was 46 years (19-66 years). Median World Health Organization (WHO) performance status was 1 (0-1). Fifty two per cent of the patients were males. The predominant histology was leiomyosarcoma (33%). A maximum of six cycles was given. At the time of analysis 55 patients have died. The partial response (PR) rate was 16%. The median time to progression was 15 weeks. 8 of the 18 responding patients (44%) had synovial sarcomas, whereas only 5% of the patients having leiomyosarcomas responded. The grade 3 + 4 haematological toxicity encountered was neutrophils in 78% and platelets in 12%. The major grade 3 + 4 non-haematological toxicities encountered were febrile neutropenia in 39%, infection in 20%, and acute renal failure in 4%. In conclusion, it is possible to administer HDI on a multicentre basis, but the toxicity is substantial. HDI given as a continuous infusion at this dose cannot be recommended as the standard treatment of advanced soft tissue sarcomas, even in selected patients.

Adult↗
PubMed2000

Clinical studies in the development of new anticancer agents exhibiting growth inhibition in models: facing the challenge of a proper study design.

Various new specifically targeted anticancer agents such as matrixmetalloproteinase inhibitors, angiogenesis inhibitors, farnesyl transferase inhibitors, and tyrosine kinase inhibitors have been developed in recent years. These agents exert antitumor activity through specific target inhibition, and preclinical studies showed dose-dependent tumor growth inhibition and only sporadic tumor regressions. Toxicity of these new agents was often strikingly mild or did not occur at all. Clinical studies are now being performed. Because these new agents might have a different toxicity profile and exert their antitumor activity in a way that is completely different from that of cytotoxic agents, the design of clinical studies will have to be adapted in several ways, and new endpoints for phase I, II, and III studies must be defined.

Animals↗
PubMed2000

Development of multidrug-resistance convertors: sense or nonsense?

This review describes the clinical relevance of the two drug transporters P-glycoprotein (Pgp) and multidrug resistance-associated protein (MRP) and the in vitro phenomenon which is referred to as multidrug resistance (MDR). The attempts to try to block these resistance mechanisms are summarized with specific attention for the intentionally designed "second generation" MDR-convertors. Potential explanations of the limited clinical success rate are given and recommendations for the design of future studies provided.

ATP Binding Cassette Transporter, Subfamily B, Mem↗