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Biomedical subjects

A T van Oosterom

Publications and source records attributed to A T van Oosterom.

At least 19 recordsLinked to original sources
PubMed2005

Seven year update of an EORTC phase III trial of high-dose intensity M-VAC chemotherapy and G-CSF versus classic M-VAC in advanced urothelial tract tumours.

EORTC protocol 30924 is an international randomized trial reporting a 7.3 year update of a 2 weekly regimen of high-dose intensity chemotherapy with M-VAC plus granulocyte colony stimulating factor (HD-M-VAC) compared to classic M-VAC in advanced transitional cell carcinoma (TCC). Two hundred and sixty three untreated patients with bidimensionally measurable TCC were included. In an intention to treat analysis, there were 28 complete responses (CR) (21%) and 55 partial responses (PR) (41%), for an overall response rate (RR) of 64% on the HD-M-VAC arm. On M-VAC, there were 12 CR (9%) and 53 PR (41%), for an overall RR of 50% . The P-value for the difference in CR was 0.009; and for RR, was 0.06. After a median follow-up of 7.3 years, 24.6% are alive on the HD-M-VAC arm vs. 13.2% on the M-VAC arm. Median progression-free survival was better with HD-MVAC (9.5 months) vs. M-VAC (8.1 months). The mortality hazard ratio (HR) was 0.76. The 2-year survival rate for HD-M-VAC was 36.7% vs. 26.2% for M-VAC. At 5 years, the survival rate was 21.8% in the HD-M-VAC vs. 13.5%. Median survival was 15.1 months on HD-MVAC and 14.9 months on M-VAC. There was one death from toxicity in each arm; and more patients died to malignant disease in the M-VAC arm (76%) than in the HD-M-VAC arm (64.9%). With longer follow-up initial results have been confirmed, and shows that HD-M-VAC produces a borderline statistically significant relative reduction in the risk of progression and death compared to M-VAC.

Adult↗
PubMed2005

Intensive induction chemotherapy with C-BOP/BEP for intermediate- and poor-risk metastatic germ cell tumours (EORTC trial 30948).

New chemotherapy regimens are continuously explored in patients with high-risk malignant germ cell tumours (MGCTs). This multicentre phase II trial assessed the efficacy and toxicity of C-BOP/BEP chemotherapy in intermediate and poor prognosis MGCT (IGCCCG criteria). C-BOP/BEP treatment consisted of cycles of cisplatin, vincristine, bleomycin and carboplatin, followed by one cycle of vincristine and bleomycin and three cycles of BEP (bleomycon, etoposide, cisplatin). The trial was designed to demonstrate a 1-year progression-free survival rate of 80%, that is, to exclude a 1-year rate of 70% or less, with a one-sided significance level of 5%. Secondary end points included toxicity, overall survival and the postchemotherapy complete response rate. In total, 16 European hospitals entered 66 eligible patients (intermediate prognosis group: 37; poor prognosis group: 29). A total of 45 patients (68.2%, 95% confidence interval (95% CI): 56.9-79.4%) achieved a complete response (intermediate prognosis: 30; poor prognosis: 15). After a median observation time of 40.4 months (range: 13.7-66.3), the 1-year progression-free survival rate was 81.8% 95% CI: 72.5-91.1%). The 2-year overall survival was 84.5% (95% CI: 75.6-93.3%). In all, 51 patients experienced at least one episode of WHO grade 3/4 leucopenia, and at least one event of grade 3/4 thrombocytopenia occurred in 30 patients. There was no toxic death. With an 82% 1-year progression-free survival and a lower limit of the 95% CI above 70%, the efficacy of C-BOP/BEP is comparable to that of published alternative chemotherapy schedules in high-risk MGCT patients. The treatment's toxicity is manageable in a multicentre setting. In poor prognosis patients, C-BOP/BEP should be compared to standard chemotherapy of four cycles of BEP.

Adolescent↗
PubMed2005

Sensitive and specific quantification of the anticancer agent ZD1839 (Gefitinib) in plasma by on-column focusing capillary liquid chromatography-tandem mass spectrometry.

The development of an on-column focusing gradient capillary LC method coupled to tandem mass spectrometry (quadrupole-linear ion trap) for the quantitative determination of the anticancer agent ZD1839 (Gefitinib, Iressa) in blood plasma is described. Plasma samples (0.2 ml) were extracted with methyl tert-butyl ether. The analytes of interest, ZD1839 and the internal standard [(2)H8]ZD1839 (ZD1839-d8) were eluted on a 50 mm x 1 mm, 5 microm particle size, capillary ODS Hypersil column using an aqueous ammonium acetate gradient at 40 microl/min. Mass spectrometric detection was performed by a Q-Trap tandem mass spectrometer with electrospray positive ionisation, and monitored in the multiple reaction monitoring transitions 447 >128 and 455 >136, respectively. The limit of quantification of ZD18395 was 0.1 ng/ml. The method proved to be robust, allowing quantification of ZD1839 with sufficient precision, accuracy and sensitivity.

Antineoplastic Agents↗
PubMed2005

Phase I and pharmacokinetic study of oral irinotecan given once daily for 5 days every 3 weeks in combination with capecitabine in patients with solid tumors.

PURPOSE: To assess the maximum tolerated dose, dose-limiting toxicity, pharmacokinetics, and preliminary antitumor activity of oral irinotecan given in combination with capecitabine to patients with advanced, refractory solid tumors. PATIENTS AND METHODS: Patients were treated from day 1 with irinotecan capsules given once daily for 5 consecutive days (50 to 60 mg/m2/d) concomitantly with capecitabine given twice daily for 14 consecutive days (800 to 1,000 mg/m2); cycles were repeated every 21 days. RESULTS: Twenty-eight patients were enrolled and received 155 cycles of therapy (median, five cycles; range, one to 18 cycles). With irinotecan 60 mg/m2/d and capecitabine 2 x 800 mg/m2/d, grade 3 delayed diarrhea in combination with grade 2 nausea (despite maximal antiemetic support) and grade 3 anorexia and colitis, were the first-cycle dose-limiting toxicities in two of six patients, respectively. At the recommended doses (irinotecan 50 mg/m2/d; capecitabine 2 x 1,000 mg/m2/d), side effects were mostly mild to moderate and uniformly reversible. Pharmacokinetic analysis showed that there was no interaction between oral irinotecan and capecitabine, and that body-surface area was not significantly contributing to the observed pharmacokinetic variability. Confirmed partial responses were observed in two patients with gallbladder carcinoma and in one patient with melanoma. Disease stabilization was noted in 16 patients. CONCLUSION: The recommended phase II doses for oral irinotecan and capecitabine are 50 mg/m2/d for 5 consecutive days, and 2 x 1,000 mg/m2/d for 14 consecutive days repeated every 3 weeks, respectively.

Administration, Oral↗
PubMed2004

Differential protein expression profile in gastrointestinal stromal tumors.

Gastrointestinal stromal tumors (GISTs) arise from the interstitial cells of Cajal through gain of function mutations of the oncogene KIT. Imatinib offers the first effective treatment for patients with GISTs, but the therapeutic outcome strongly depends on the type of KIT mutation. We used ProteinChip technology to investigate whether GISTs with different KIT mutations express different proteins. In total, 154 proteins were significantly differentially expressed in GISTs with exon 9 KIT mutation compared to GISTs with exon 11 KIT mutation.

Exons↗
PubMed2004

A phase I study with MAG-camptothecin intravenously administered weekly for 3 weeks in a 4-week cycle in adult patients with solid tumours.

In MAG-camptothecin (MAG-CPT), the topoisomerase inhibitor camptothecin is linked to a water-soluble polymer. Preclinical experiments showed enhanced antitumour efficacy and limited toxicity compared to camptothecin alone. Prior phase I trials guided the regimen used in this study. The objectives were to determine the maximum tolerated dose, dose-limiting toxicities, safety profile, and pharmacokinetics of weekly MAG-CPT. Patients with solid tumours received MAG-CPT intravenously administered weekly for 3 weeks in 4-week cycles. At the starting dose level (80 mg x m(-2) week(-1)), no dose-limiting toxicities occurred during the first cycle (n=3). Subsequently, three patients were enrolled at the second dose level (120 mg x m(-2) week(-1)). Two of three patients at the 80 mg x m(-2) week(-1) cohort developed haemorrhagic cystitis (grade 1/3 dysuria and grade 2/3 haematuria) during the second and third cycles. Next, the 80 mg x m(-2) week(-1) cohort was enlarged to a total of six patients. One other patient at this dose level experienced grade 1 haematuria. At 120 mg x m(-2) week(-1), grade 1 bladder toxicity occurred in two of three patients. Dose escalation was stopped at 120 mg x m(-2) week(-1). Cumulative bladder toxicity was dose-limiting toxicity at 80 mg x m(-2) week(-1). Pharmacokinetics revealed highly variable urinary camptothecin excretion, associated with bladder toxicity. Due to cumulative bladder toxicity, weekly MAG-CPT is not a suitable regimen for treatment of patients with solid tumours.

Adult↗
PubMed2004

Combretastatin A-4 phosphate enhances CPT-11 activity independently of the administration sequence.

We evaluated the effect of different intervals and sequences of the vascular targeting agent combretastatin A-4 disodium phosphate (CA4DP) and CPT-11 administration on tumour growth delay and intratumoral uptake of CPT-11 using a syngeneic rhabdomyosarcoma tumour model. Irrespective of the administration sequence, the combination of CA4DP and CPT-11 significantly increases tumour growth delay in comparison with both drugs alone (P<0.001). Intratumoral CPT-11 concentration generally decreased (up to 5-fold) in the combination groups, while SN-38, the active metabolite of CPT-11, increased up to 9-fold. However, the increased amount of intratumoral SN-38 trapping after CA4DP injection did not correlate with the observed tumour growth delay. In conclusion, CA4DP significantly enhances the antitumour effect of CPT-11, which is not greatly influenced by the administration sequence, and which lacks a correlation with the intratumoral trapping of CPT-11 or SN-38. Mechanisms other than trapping are likely to be involved in the chemosensitising capacity of CA4DP.

Animals↗
PubMed2004

Use of c-KIT/PDGFRA mutational analysis to predict the clinical response to imatinib in patients with advanced gastrointestinal stromal tumours entered on phase I and II studies of the EORTC Soft Tissue and Bone Sarcoma Group.

Previous studies have shown that activating mutations of c-KIT/PDGFRA, potential therapeutic targets for imatinib mesylate, are implicated in the pathophysiology of gastrointestinal stromal tumours (GISTs). In this study, GISTs from 37 patients enrolled in an European Organisation for Research and Treatment of Cancer (EORTC) phase I/II clinical study of imatinib were examined for mutations of c-KIT/PDGFRA in order to explore whether the mutational status of the tumour predicts the clinical response to therapy. Mutations were screened by denaturing high-pressure liquid chromatography (DHPLC) and characterised by bi-directional DNA sequencing. Activating mutations of c-KIT or PDGFRA were found in 29 (78%) and 2 (6%) GISTs, respectively. Most c-KIT mutations involved exon 11 (n=24; 83%), all but one being an in-frame deletion; no isolated point mutations were found. The other c-KIT mutations included exon 9 AY 502-503 duplication (n=4; 14%) and exon 13 Lys-->Glu(642) missense mutation (n=1; 3%). Two tumours with no detectable c-KIT mutations demonstrated PDGFRA Asp-->Glu(842) amino acid substitutions. Patients with GISTs harbouring exon 11 mutations were more likely to achieve a partial response (PR) on imatinib therapy (83%) than all of the others (23%). The overall survival and progression-free survival rates for the entire group at 106 weeks were 78.3% and 46.9%, respectively. Based on a Kaplan-Meier analysis, patients with GISTs harbouring c-KIT mutations had longer median survival times and were less likely to progress than the other patients. These findings indicate that the mutational status of the c-KIT/PDGFRA oncoproteins could be useful to predict the clinical response of patients imatinib therapy.

Adult↗
PubMed2004

Phase II study on 9-nitrocamptothecin (RFS 2000) in patients with advanced or metastatic urothelial tract tumors.

OBJECTIVE: To investigate the antitumor activity and the safety of RFS2000, an oral topoisomerase I inhibitor, in patients with advanced or metastatic urothelial tract tumors refractory to one prior chemotherapy regimen. PATIENTS AND METHODS: Eligible patients were to have failed first line treatment for advanced or metastatic disease. Patients received RFS2000 as one daily oral intake at the dose of 1.5 mg/m(2)/day according to a "5 days on/2 days" off schedule continuously. One cycle was arbitrarily defined as a 3 week period. Sufficient oral fluid intake to prevent cystitis previously described in phase I trials with RFS2000 was recommended. Gehan design was used for sample size determination. Anti-tumor activity was evaluated according to the RECIST criteria and toxicity according to CTC version 2. RESULTS: Twenty patients received a total of 57 cycles (range 1-8). Grade 3-4 toxicity was observed in 10 patients requiring dose or schedule modifications. Hematological grade 3-4 toxicity was observed in 16% of the cycles. Only one patient experienced a partial response. CONCLUSIONS: RFS2000 could be administered orally as a "5 days on/2 days off" schedule continuously with a median dose intensity of 90.6% with an acceptable toxicity profile. However, RFS2000 did not exert significant activity in patients with advanced/metastatic urothelial tract tumors failing prior chemotherapy. The results of this study do not suggest further investigation of RFS2000 at the present dose and schedule for the treatment of urothelial tract tumors in this refractory population.

Administration, Oral↗
PubMed2004

Combination therapy with gefitinib, an epidermal growth factor receptor tyrosine kinase inhibitor, gemcitabine and cisplatin in patients with advanced solid tumors.

BACKGROUND: The aim of this study was to investigate the tolerability, pharmacokinetic interaction and antitumor activity of gefitinib ("Iressa", ZD1839), an orally active, selective epidermal growth factor receptor tyrosine kinase inhibitor, combined with gemcitabine and cisplatin in chemotherapy-naïve patients with advanced solid tumors. PATIENTS AND METHODS: This was an open-label feasibility trial evaluating two doses of gefitinib (250 and 500 mg/day) in combination with gemcitabine and cisplatin. Gefitinib was administered daily from day 2 onwards. Gemcitabine 1250 mg/m(2) was given on days 1 and 8 and cisplatin 80 mg/m(2) on day 1 for up to six 3-week cycles. Patients could then continue to receive gefitinib monotherapy. RESULTS: Eighteen patients were entered, nine at each gefitinib dose level. Two patients developed dose-limiting toxicity: one grade 3 convulsion (250 mg/day dose group) and one grade 3 rash (500 mg/day dose group). The most frequently occurring adverse events in the combination phase were vomiting (17 patients), asthenia (16), nausea (14), diarrhea (14) and skin rash (13). The most common grade 3/4 adverse events were vomiting (seven patients), asthenia (six), thrombocytopenia (six), diarrhea (five) and anorexia (five). Pharmacokinetic analyses showed no apparent pharmacokinetic interaction between gefitinib and cisplatin or gemcitabine, with the exception of a possible small increase in the geometric mean exposure to gemcitabine seen on day 8 of therapy when given alone with the higher dose of gefitinib. Of 17 evaluable patients, nine had confirmed partial responses, seven had stable disease and one had progressive disease. CONCLUSIONS: Combination therapy of gefitinib with cisplatin and gemcitabine had a manageable and predictable safety profile, no major effect on exposure to any of the three drugs and antitumor activity.

Adult↗
PubMed2003

Effect of antivascular endothelial growth factor treatment on the intratumoral uptake of CPT-11.

Promising preclinical activity with agents blocking the function of vascular endothelial growth factor (VEGF) has been observed in various cancer types, especially with combination therapy. However, these drugs decrease microvessel density, and it is not known whether this reduced vessel density (VD) results in decreased delivery of concomitantly administered classical anticancer drugs. We designed an in vivo study to investigate the relation between VEGF-blocking therapy, tumoral blood vessels, and intratumoral uptake of anticancer drugs. Nude NMRI mice bearing colon adenocarcinoma (HT29) were treated with the anti-VEGFmAb A4.6.1 or placebo. After 1 week, CPT-11 was administered 1 h prior to killing the animals. In A4.6.1 treated tumours, there was a significant decrease in VD, more pronounced with potentially functional large vessels than endothelial cords. Interestingly, a trend to increased intratumoral CPT-11 concentration was observed (P=0.09). In parallel, we measured an increase in tumour perfusion, as estimated by high-performance liquid chromatography determination of intratumoural Hoechst 33342 concentration. In the growth delay study, CPT-11 was at least equally effective with or without pretreatment with A4.6.1. These data suggest that tumour vascular function and tumour uptake of anticancer drugs improve with VEGF-blocking therapy, and indicate the relevance for further investigations.

Adenocarcinoma↗
PubMed2003

Advanced soft-tissue sarcoma: a disease that is potentially curable for a subset of patients treated with chemotherapy.

Adult patients with metastatic or locally advanced irresectable soft-tissue sarcoma (ASTS) are generally considered as incurable. Whether some of these patients achieve long-term survival after first-line treatment with chemotherapy is not known. Patients with ASTS still alive 5 years after initial treatment with a doxorubicin-containing regimen, i.e. long-term survivors, were analysed among the 2187 patients included in first-line chemotherapy protocols between 1976 and 1990 in seven trials of the European Organization for Research and Treatment of Cancer Soft Tissue and Bone Sarcoma Group (EORTC STBSG) group. 1888 patients were followed for at least 5 years. The initial clinical characteristics and the outcome of the long-term survivors were investigated. 66 of the 1888 patients were alive at 5 years and the projected 5-year survival was 8% in this series. Age or histological subtypes were similar in the long-term survivors compared with the other patients. The percentages of females (69%), of grade 1 tumours (35%), of patients with an initial performance status (PS) of 0 (63%) were significantly higher in the long-term survivors while liver metastasis (6% versus 21%) were significantly less frequent. Long-term survivors were observed in all subgroups of patients. 31, 31, 31 and 6% of the long-term survivors were in complete response (CR), partial response (PR), stable disease (SD), and progressive disease (PD), respectively, after the first-line regimen. A CR to a doxorubicin-containing regimen was the major parameter correlated to 5-year survival. In multivariate analysis using a logistic model, independent parameters correlated to 5-year survival were PS, female gender, grade I tumours, and the achievement of a CR after first-line treatment, which was retained as the most powerful predictor for 5-year survival. 10 of the 66 patients died after 5 years in this series, including 8 patients in PD or SD after first-line treatment versus 2 patients in PR or CR (P=0.01). 8% of patients with ASTS are alive 5 years after first-line chemotherapy with a doxorubicin-containing regimen. Long-term survivors are observed in all prognostic subgroups of patients, in particular those achieving a CR to first-line chemotherapy.

Adult↗
PubMed2003

Phase I and pharmacokinetic study of continuous twice weekly intravenous administration of Cilengitide (EMD 121974), a novel inhibitor of the integrins alphavbeta3 and alphavbeta5 in patients with advanced solid tumours.

A single-agent dose escalating phase I and pharmacokinetic study with Cilengitide, an inhibitor of the integrins alphavbeta3 and alphavbeta5, was performed to determine its safety and toxicity. Cilengitide was administered as a one-hour infusion twice weekly without interruption to patients with histologically- or cytologically-confirmed metastatic solid tumours. Plasma pharmacokinetics were determined at days 1 and 15. 37 patients were enrolled into the study. Dose levels studied were 30, 60, 120, 180, 240, 400, 600, 850, 1200, and 1600 mg/m(2)/infusion. There was no dose-limiting toxicity (DLT). Pharmacokinetics were dose-independent and time-invariant. Apparent terminal half-life ranged from 3 to 5 h. At 120 mg/m(2)/infusion, peak plasma concentrations were attained that optimally inhibited tumour growth in preclinical models. Cilengitide can be safely administered using a continuous twice-weekly infusion regimen. As DLT was not reached, future trials should explore Cilengitide at different doses.

Adult↗
PubMed2002

Hyphenated techniques in anticancer drug monitoring. I. Capillary gas chromatography-mass spectrometry.

Most anticancer agents are relatively unstable substances and are subjected to intensive metabolism in vivo and radiation during sample pretreatment. Hyphenated techniques including a separation technique and, most frequently, mass spectrometry are therefore chosen to obtain insight into the in vivo behavior of anticancer agents. Once established, simpler assays can be derived from those based on hyphenation, which are less expensive. Capillary gas chromatography (cGC)-mass spectrometry (MS) is amongst the most frequently applied hyphenated analytical technologies in anticancer drug monitoring. Here a selection has been made of: (i) cGC-MS applied to the analysis of agents frequently used in clinical oncology (e.g. tamoxifen, oxazaphosphorines); (ii) cGC-MS applied to the development of new agents (Swainsonine and Brefeldin); (iii) cGC-MS applied to the analysis of agents for which comparisons with other frequently applied hyphenation technologies are possible (see Part I of this series). cGC-MS played a key role in the elucidation of the in vivo behavior of the oxazaphosphorine cyclophosphamide, historically the most frequently applied anticancer agent. cGC-MS appeared to be of special interest in the analysis of cyclophosphoramide and congeners in human erythrocytes by coupling of the hyphenated technique with a measurement of sediment technique. This resulted in the quantitative and qualitative analysis of oxaphosphorine-related mustard gas moieties in human erthrocytes for the first time.

Antineoplastic Agents↗
PubMed2002

Gemcitabine in advanced adult soft-tissue sarcomas. A phase II study of the EORTC Soft Tissue and Bone Sarcoma Group.

Gemcitabine (2'-deoxy-2'-difluorocytidine monohydrochloride) at a dose of 1250 mg/m(2) was given as a 30-min intravenous (i.v.) infusion on days 1 and 8 in a 3-weekly schedule to 32 patients with advanced soft-tissue sarcoma (STS) failing first-line chemotherapy. One patient was ineligible due to a delay between the previous chemotherapy and the start of treatment. Of the eligible patients, median age was 53 years (range 23-73 years). The predominant histological subtype was leiomyosarcoma in 12 patients (38%). The median number of cycles was three (range 1-8 cycles) with a median total dose of gemcitabine of 6.25 g/m(2) (range 1.25-19.97 g/m(2)). The relative dose intensity of gemcitabine was 96% (range 50-103%). Treatment was tolerated very well with non-complicated haematological toxicity as the most frequently observed side-effect. Only one partial tumour response was documented, giving a response rate of 3.23% (95% Confidence Interval (CI): 0.08-16.2%). The median overall survival was 268 days (95% CI: 129-377) and the median time to progression was 45 days (95% CI: 41-79). These results indicate that gemcitabine given at this dose and schedule is not active as second-line therapy in advanced STS.

Adult↗
PubMed2002

Results of randomised studies of the EORTC Soft Tissue and Bone Sarcoma Group (STBSG) with two different ifosfamide regimens in first- and second-line chemotherapy in advanced soft tissue sarcoma patients.

The aim of this phase II study was to evaluate the efficacy and toxicity of two regimens of ifosfamide in metastatic soft tissue sarcoma patients given as first- and second-line chemotherapy. Two different schedules of ifosfamide were investigated in a randomised manner: Ifosfamide was given either at a dose of 5 g/m(2) over 24 h (5 g/m(2)/1 day), every 3 weeks or at a dose of 3 g/m(2) per day, administered over 4 h on three consecutive days (3 g/m(2)/3 days), every 3 weeks. Both schedules were given as first-line or second-line chemotherapy. A total of 182 patients was entered, 103 in first- and 79 in second-line, of whom 8 patients were ineligible, 5 in the first- and 3 in the second-line study. Most patients had a leiomyosarcoma, 46 of the 98 in the first-line and 34 of the 76 in the second-line. The two study arms were well balanced in both the first- and second-lines with respect to sex, age and performance status. In first-line treatment, 5 g/m(2)/1 day yielded five partial responses (PR) (Response Rate (RR) 10%), versus 12 PR (RR 25%) for the 3 g/m(2)/3 days. As second-line treatment, the 24-h infusion yielded: one CR and one PR (RR 6%) and the 3-day schedule one CR and two PR (RR 8%). Survival did not differ between the two regimens. The major World Health Organization (WHO) grade 3 and 4 toxicities encountered were: leucopenia in 19% of all courses in the first-line and 32% in the second-line with the 5 g/m(2)/1 day, while for the 3 g/m(2)/3 days schedule the rates were 57 and 63% respectively. Grade 3 or 4 infections were seen in 4% of patients treated with 5 g/m(2)/1 day first-line and 10% of patients given 3 g/m(2)/3 days, both as first- and second-lines. No such infections were seen in patients receiving 5 g/m(2)/1 day as second line treatment. In advanced soft-tissue sarcomas in the first-line, ifosfamide 3 g/m(2), given over 4 h on three consecutive days, is an active regimen with acceptable toxicity while the 5 g/m(2) over 24 hours schedule resulted in a disappointing response rate.

Adult↗
PubMed2002

Population pharmacokinetic and dynamic analysis of the topoisomerase I inhibitor lurtotecan in phase II studies.

Population pharmacokinetic-dynamic analysis was prospectively integrated in a broad phase II program of lurtotecan (GI147211), a novel camptothecin derived topoisomerase I inhibitor, to determine the population pharmacokinetic profile in a larger population, to estimate individual pharmacokinetic parameters and to investigate relationships with clinical outcome. A sparse sampling method was applied during course one, which involved two sampling time-points. A Bayesian algorithm was used to estimate individual pharmacokinetic parameters, in particular total plasma clearance (CL) and volume of distribution. In total, samples were collected of 109 (63%) of 173 patients. Pharmacokinetic-dynamic evaluation could be carried out successfully in 85 (78%) of the sampled patients. CL of lurtotecan showed substantial variability (mean 87 +/- 28 L/h) and was of the same magnitude as in the phase I studies where full pharmacokinetic curves were used. Residual variability in the population estimate of CL was 9.9%. No significant relationships were observed between exposure parameters and toxicity nor likelihood of tumor response, however the latter relationship may well have been obscured by the heterogeneity of the studied population. Prospective implementation of large scale population pharmacokinetic-dynamic analysis is feasible and important to establish whether interpatient variability in drug exposure is a major determinant of toxicity or activity.

Adult↗