Clinical and experimental pharmacokinetic interaction between 6-mercaptopurine and methotrexate

 Clinical and experimental pharmacokinetic interaction between 6-mercaptopurine (6-MP) and methotrexate (MTX) was investigated in patients as well as in rats and in HL-60 human leukemic cells. Ten children affected by acute lymphoblastic leukemia (ALL) in remission received daily doses of 6-MP given at 25 mg/m² and i.v. infusion of high-dose MTX at 2 or 5 g/m² once every other week. When 6-MP was given alone, the mean peak plasma concentration (C_max) and area under the curve (AUC) of 6-MP were 72.5 ng/ml and 225.3 h ng ml^-1. Concurrent treatment with MTX at 2 or 5 g/m² resulted in a mean increase of 108% and 121% in the C_max and of 69% and 93% in the AUC, respectively. In rats treated with an oral dose of 6-MP at 75 mg/m², MTX given i.p. at 5 g/m² produced mean increases of 110% and 230% in the C_max and AUC of 6-MP, respectively. In HL-60 human leukemic cells incubated with 6-MP at 250 ng/ml, the cumulative intracellular concentration of 6-thioguanine and 6-MP nucleotides was not significantly modified by treatment with 20 μg/ml of MTX. The present findings indicate that high-dose MTX enhances the bioavailability of 6-MP as evidenced by the observed increases in the plasma C_max and AUC of 6-MP in humans and animals. Received: 13 December 1994/Accepted: 12 July 1995     

A single-sample assay for the estimation of the area under the free carboplatin plasma concentration versus time curve

 The aim of this study was to develop and validate a simple and rapid method for the estimation of the area under the free carboplatin plasma concentration versus time curve (AUC). The relationship between the carboplatin AUC and the total plasma platinum (Pt) concentration 24 h after treatment was studied using data from 49 patients treated with 20–1600 mg/m² carboplatin as a 60–100 min infusion (median 60 min). The relationship was confirmed by the in vitro incubation of carboplatin in human plasma and prospectively validated in 13 ovarian cancer patients. Free carboplatin was separated by ultrafiltration (MW cut off 30,000), and free and total Pt measured by atomic absorption spectrophotometry. There was a linear relationship in vivo between the 24 h (median 24.4; range 16.3–27.3 h) total plasma Pt concentration (μM) and free carboplatin AUC (mg/ml.min): AUC=(24 h Pt+0.3)/0.82 (r ²=0.93, AUC median 5.8 (0.13–28)mg/ml.min, 24 h Pt median 4.4 (0.1–23) μM). A similar relationship was observed in vitro [AUC=(24 h Pt +0.1)/0.93 (r ²=0.98, AUC median 7.9 (2.0–17) mg/ml.min, 24 h Pt median 7.1 (1.8–15) μM)]. The relationship derived from the in vivo data gave an unbiased and reasonably accurate estimate of the measured carboplatin AUC in 13 patients (AUC=5.1–8.7 mg/ml.min, GFR=59–129 ml/min, infusion time 30–45 min, 24 h sampling time 22.9–24.5 h), giving a percentage mean error of −4.2% and root mean squared percentage error of 11.5%. These results show that the analysis of a single blood sample taken 24 h after carboplatin administration can be used to produce an unbiased and reasonably accurate measure of the free carboplatin AUC. Unlike published limited sampling strategies, this method is not complicated by the need to accurately control the duration of the carboplatin infusion or the time at which the sample is taken. Received: 13 January 1995/Accepted: 14 May 1995     

A Phase I and pharmacokinetics study of 2-chlorodeoxyadenosine in patients with solid tumors

 Preclinical studies of 2-chlorodeoxyadenosine (2-CdA) against solid tumors in the human tumor cloning assay and evidence that 2-CdA is active against slow-growing or resting tumor cells have stimulated interest in the clinical activity of this agent against solid tumors. This study sought to estimate the maximum tolerated dose, dose-limiting toxicity, and plasma and urine pharmacokinetics accompanying the intravenous administration of 2-CdA by 120-h continuous infusion in patients with solid tumors. Treated patients were also assessed for other toxicities of therapy and for antitumor response. A total of 23 patients received 35 courses of treatment given at doses of 3.5, 5.3, 6.5 and 8.1 mg/m² per day by continuous intravenous infusion for 5 days and repeated every 28 days. Blood and urine specimens were collected before, during, and after drug infusion. The dose-limiting toxicity at 8.1 mg/m² per day manifested as granulocytopenia in 2 of 5 patients (3 of 7 courses of treatment) and as thrombocytopenia in 3 of 5 patients (3 of 7 courses of treatment). At the dose levels of 6.5 and 8.1 mg/m² per day, recovery from thrombocytopenia was often delayed. Severe lymphocytopenia (<1,000/μl) was observed at all dose levels of 2-CdA. Dose-related anemia and leukopenia were observed and were infrequently severe. Nonhematological toxicities were confined to mild-to-moderate nausea, vomiting, fatigue, and anorexia. Fever of 37^°–40^°C was induced during drug infusion in 19 patients. No antitumor response was observed. Average plasma concentrations at steady-state (Cp_ss) ranged from 3 ng/ml at the initial dose level to 13 ng/ml at the dose level of 8.1 mg/m² per day. Both the Cp_ss and the area under the plasma concentration-time curve (AUC) were proportional to the dose. A relationship was observed between the percentage of change in absolute neutrophil count and the AUC. Renal excretion accounted for only 18% of the elimination of 2-CdA over the 5-day infusion period. The maximum tolerated dose for 2-CdA given by 5-day continuous infusion was 8.1 mg/m² per day in this study. The recommended dose on this schedule for phase II studies is 6.5 mg/m² per day. Granulocytopenia and thrombocytopenia were dose-limiting. No antitumor activity was observed during this study. On the basis of the plasma concentrations of 2-CdA observed, it is unlikely that this schedule of drug administration will permit achievement of the concentrations consistent with antitumor activity observed in preclinical studies. Received: 14 March 1994/Accepted: 22 July 1994     

A phase I trial of AUC-directed carboplatin with infusional doxorubicin and ifosfamide plus G-CSF in patients with advanced gynecologic malignancies

The effect of the addition of G-CSF to carboplatin, ifosfamide and doxorubicin (CIA) at the maximally tolerated dose (MTD) was studied in a phase I clinical trial. Nine patients with incurable solid tumors were treated: six endometrial and epithelial ovarian cancers, one colon cancer with pelvic masses and two unknown primary cancers. The carboplatin dose was calculated using the Calvert formula and administered in a standard 30-min intravenous infusion. The initial carboplatin dose was AUC 4.0 mg/ml per min. Fixed doses of ifosfamide (1.25 g/m² per day), mesna (1.0 g/m² per day, and doxorubicin (15 mg/m² per day) were combined and given as a 4-day continuous intravenous infusion in an attempt to decrease nonhematologic toxicity. The dose-limiting toxicity of CIA was myelosuppression, mainly neutropenia and thrombocytopenia. Nonhematologic toxicities were hemorrhagic cystitis, weakness, fatigue, and nausea and vomiting. The MTD for CIA was established at the first dose level of carboplatin (4.0 mg/ml per min). Following this, G-CSF was added to the regimen in an unsuccessful effort to escalate the carboplatin dose. Free and total carboplatin pharmacokinetics were determined using flameless atomic absorption spectroscopy. There was one complete response and one partial response among eight evaluable patients. Both responding patients had advanced ovarian cancer. We conclude that carboplatin dose intensification beyond an AUC of 4.0 mg/ml per min is not made feasible by the addition of G-CSF to infusional doxorubicin and ifosfamide in patients with advanced gynecologic cancer. Received: 22 December 1999 / Accepted: 28 April 2000     

Phase I/II dose escalation study of docetaxel and carboplatin combination supported with amifostine and GM-CSF in patients with incomplete response following docetaxel chemo-radiotherapy: additional chemotherapy enhances regression of residual cancer

Taxanes have been shown to interact with anti-apoptotic proteins. In the present study we investigated whether the addition of taxane in combination with DNA damaging drugs can further enhance tumor shrinkage in cases with incomplete response to radiotherapy. Since the dose of docetaxel in combination with carboplatin is not known, the above hypothesis was tested in the context of a dose escalation phase I study. Twenty-eight patients with locally advanced chest or pelvic tumors, showing residual disease on CT scans performed 40 d following docetaxel radio-chemotherapy, were recruited in a dose escalation protocol of docetaxel/carboplatin supported with amifostine and GM-CSF. The starting dose of docetaxel was 40 mg/m² every 2 weeks. Carboplatin dose was calculated using the Calvert formula and was escalated in cohorts of 4 patients (starting dose AUC2 every two weeks; AUC0.5 increments up to AUC3). Thereafter the docetaxel dose was increased to 50 and 60 mg/m², while carboplatin was escalated (by AUC0.5 increments) starting from AUC3 and AUC4 respectively. Amifostine (600 mg/m²) was administered i.v. before carboplatin and GM-CSF (480μg) was injected s.c. on days 5, 6 and 10, 11 of each cycle. Six cycles were given and response was assessed 2 weeks after the end of chemotherapy. None out of four patients treated in the 6th dose level cohort (50mg/m² of docetaxel and AUC4 of carboplatin every 2 weeks) showed any grade 2–4 hematologic toxicity. Mild non-hematologic toxicity such as neuropathy, leg edema, pleural effusion, pyrexia, alopecia grade 2 and hypersensitivity was observed in 4–12% of patients. Out of four patients treated in a 7th cohort (docetaxel 60mg/m² and carboplatin AUC4), one developed grade IV neutropenia and two developed grade 3 severe asthenia requiring treatment delay for 2 weeks. Out of 11 patients with PR following docetaxel radio-chemotherapy, 7 (63%) showed CR after docetaxel/carboplatin additional chemotherapy. Eight out of 17 patients with MR following docetaxel radio-chemotherapy showed PR (47%) and one showed CR (6%) after additional chemotherapy. High dose combined docetaxel (50 mg/m²) and carboplatin (AUC4) chemotherapy can be safely administered on a two-weekly basis if supported with amifostine and GM-CSF. Such an additional therapy may be important in patients with incomplete response after chemo-RT. Broad spectrum cytoprotection with amifostine and GM-CSF may also contribute to the reduction of incidence of neurosensory reactions and asthenia in patients treated with taxanes.     

Sequence effect of docetaxel and carboplatin on toxicity, tumor response and pharmacokinetics in non-small-cell lung cancer patients: a phase I study of two sequences

Purpose To investigate sequence effects on toxicity, tumor response and pharmacokinetics of docetaxel and carboplatin, together with a determination of the maximum-tolerated dose (MTD) and recommended dose for each schedule.Patients and methods A total of 46 chemotherapy-naive patients with advanced non-small-cell lung cancer were randomized to receive docetaxel before (schedule A) or after (schedule B) carboplatin. The dose levels studied were [docetaxel (mg/m²)/carboplatin (mg×min/ml)] 50/5, 60/5, 60/6, 60/7, and 70/6. Treatment cycles were repeated every 3 or 4 weeks unless disease progression or undue toxicity occurred.Results Of the 46 patients, 44 were assessable for toxicity and received a total of 84 cycles. The major dose-limiting toxicity was neutropenia. When the docetaxel dose was 60 mg/m², the carboplatin MTD was deemed to be AUC 7 in both schedules. When the docetaxel dose was escalated to 70 mg/m², the carboplatin MTD was reached in schedule A, and the dose-limiting toxicity was not observed in schedule B. Tumor response was observed in 4 of 22 patients (18%) with schedule A and 8 of 19 (42%) with schedule B. Clearances of both drugs were not affected by sequence: 111.2±26.8 ml/min and 107.8±29.0 ml/min for carboplatin (P=0.69), and 26.7±8.3 l/h and 22.8±7.0 l/h for docetaxel (P=0.19) in schedules A and B, respectively.Conclusions Carboplatin AUC 6 followed by docetaxel 70 mg/m² was a favorable regimen for phase II study because of likely lower toxicity and a potentially higher response rate than the reverse sequence schedule. The mechanism of the sequence effects on toxicity and tumor response could not be explained by the pharmacokinetic interactions.Supported by grants from the Ministry of Health, Labor and Welfare, and the Ministry of Education, Culture, Sports, Science and Technology of Japan.     

Cerebrospinal fluid pharmacokinetics of carboplatin in children with brain tumors

Summary The pharmacokinetics of carboplatin in cerebrospinal fluid (CSF) and plasma was studied in five children with brain tumors (four medulloblastomas and one ependimoblastoma) who underwent preirradiation treatment with carboplatin. Carboplatin pharmacokinetics was studied following the administration of 600 mg/m² as a 1-h infusion. Four children were treated a few weeks after surgery, whereas one child with an unresectable tumor was treated prior to surgery. All patients had a ventricular-peritoneal CSF shunt connected to a subcutaneous reservoir. Total platinum and free carboplatin were measured. The mean AUC values for free carboplatin in CSF and plasma were 2.29±1.20 and 8.18±1.27 mg ml^–1 min, respectively. The mean ratio of CSF AUC to plasma AUC was 0.28 (range, 0.17–0.46). Both plasma peak levels and AUC values showed limited interpatient variability. On the other hand, carboplatin levels in CSF showed substantial interpatient variability, with a>5-fold difference in peak levels and a 3-fold difference in AUC values being recorded. The interpatient difference in CSF pharmacokinetics may have been related at least in part to the different anatomical alterations induced by the surgical procedures or by the presence of a large tumor mass. In the four evaluable patients exhibiting macroscopic residual tumor, we observed one complete remission (CR) and two partial remissions (PR) following two cycles that consisted of two doses of 600 mg/m² carboplatin given on 2 consecutive days (total dose, 1200 mg/m²) and were separated by a l-month interval. These results may give some indication as to the optimal dose and schedule for carboplatin administration in the treatment of primitive neuroectodermic tumors (PNET).This work was partially supported by the AIRC     

Carboplatin pharmacokinetics in young children with brain tumors

 Purpose: The pharmacokinetic parameters and maximal tolerated systemic exposure were determined for carboplatin in young children given in combination with cyclophosphamide and etoposide. Patients and methods: Carboplatin was administered as part of a multiagent chemotherapy regimen to 21 pediatric patients less than 5 years of age with newly diagnosed, malignant central nervous system tumors. Patients received cyclophosphamide, 1.2 g/m², on day 1 and carboplatin on day 2 followed by etoposide, 100 mg/m², each day. Carboplatin doses were calculated to achieve a targeted area under the serum concentration versus time curve (TAUC) of 5, 6.5 or 8 mg/ml . min based on each patient’s measured glomerular filtration rate (GFR). Carboplatin pharmacokinetic parameters were determined after course 1 and then after every third course of therapy. Results: The median carboplatin clearance and GFR after course 1 were 118 and 98 ml/min per m², respectively. Targeted doses based on measured GFR reliably achieved the TAUC for carboplatin. The median (range) carboplatin clearance for four children less than 1 year of age was 76 (66–84) ml/min per m², significantly lower (P=0.05) than the value of 131 (80–158) ml/min per m² for children from 1 to 4 years of age. The mean carboplatin clearance declined by 23% in 12 patients studied from course 1 to course 4 of therapy. The decrease was greater than 20% (range 20–53%) in 7 of the 12 patients studied. Conclusion: Carboplatin clearance for children aged between 1 and 4 years at diagnosis is approximately 45% higher than previously reported for pediatric patients, but declines after four courses of therapy. For children less than 1 year of age, carboplatin clearance per square meter is approximately 40% lower than patients 1 to 4 years of age. There are corresponding differences in GFR that provide a plausible explanation for the age and therapy-related changes in carboplatin clearance. Toxicity was acceptable for patients treated at a TAUC of 6.5 mg/ml . min for carboplatin given with etoposide and cyclophosphamide. The average carboplatin dose required for this AUC was 767 mg/m². Received: 13 July 1995/Accepted: 18 December 1995     

Pharmacokinetics of the hypoxic cell cytotoxic agent tirapazamine and its major bioreductive metabolites in mice and humans: retrospective analysis of a pharmacokinetically guided dose-escalation strategy in a phase I trial

 Tirapazamine (3-amino-1,2,4-benzotriazine-1,4-di-N-oxide; SR 259075) is a selective hypoxic cell cytotoxic agent that is bioreductively activated in tumours to a reactive-drug free radical. Preclinically the agent has been shown to possess additive and synergistic anti-tumour activity in combination with radiotherapy and chemotherapy regimens. In the present study the pharmacokinetics and metabolism of tirapazamine were investigated in mice and patients as part of pre-clinical and phase I investigations. The objectives of this work were twofold; firstly, to evaluate retrospectively the utility of a pharmacokinetically guided dose-escalation (PGDE) strategy for tirapazamine, and secondly, to investigate if pharmacologically relevant plasma concentrations could be achieved at tolerable doses. Pharmacokinetic studies for PGDE were conducted in mice at four dose levels ranging from one-tenth of the LD₁₀ to the LD₅₀. The AUC at the LD₁₀ (2932 μg ml^-1min) was used to determine a target AUC value of 1173 μg ml^-1min (equivalent to 40% of the mouse LD₁₀ AUC) for clinical studies. A phase I study to investigate the tolerance of a single i.v. infusion of tirapazamine (once every 3 weeks) was initiated with close pharmacokinetic monitoring. The starting dose (36 mg/m²) was based on toxicity data obtained in the mouse, rat and dog. Doses were escalated by increases in the volume and duration of infusion. A retrospective analysis of the pharmacokinetic and toxicity data was then made to determine the utility of a PGDE approach. The drug exhibited a steep dose-lethality relationship in mice (LD₁₀ 294 mg/m², LD₅₀ 303 mg/m²). The major gross toxicities were body-weight loss (15–20%), pilo-erection and hypoactivity at all dose levels. Sporadic ptosis and conjunctivitis were observed at doses of >300 mg/m². The plasma elimination of tirapazamine fitted a monoexponential open model, with rapid elimination from the plasma (t _1/2=36±0.65 min) occuring at the LD₁₀ dose of 294 mg/m². A 10.3-fold increase in dose resulted in a 25.0-fold increase in AUC. Clinically, doses were escalated over the range of 36–450 mg/m². Ototoxicity (tinnitus and reversible hearing loss) was dose-limiting at 450 mg/m² and the MTD was 390 mg/m² for this schedule. Pharmacokinetic analyses in patients revealed that the elimination of tirapazamine in patients was generally bi-phasic, with low inter-patient variability being found in clearance. A 12.5-fold increase in dose resulted in a 19.0-fold increase in AUC. There was good quantitative agreement in metabolite formation between mice and humans with respect to the two- and four-electron bioreductive metabolites. AUC values recorded for tirapazamine at the MTD of 390 mg/m² (range 1035–1611 μg ml^-1min) were similar to the target AUC in mice. Importantly, these levels are consistent with the levels required for radiation-dose enhancement and effective combination with cisplatin in mice. Given (a) the similarities in plasma pharmacokinetics and metabolism observed at the target AUC/MTD in mice, rats, dogs and humans, (b) the similar degree of plasma protein binding seen between species and (c) the relatively low inter-patient variability noted in drug clearance, a successful PGDE approach should have been feasible. The results also indicate that potentially therapeutic levels of tirapazamine are achievable in patients at tolerable doses. Received: 27 May 1996 / Accepted: 30 September 1996     

A pilot study of docetaxel-carboplatin versus paclitaxel-carboplatin in Japanese patients with epithelial ovarian cancer

Background It has been reported that a docetaxel-carboplatin combination as first-line chemotherapy for ovarian cancer showed a level of progression-free survival similar to that of paclitaxel-carboplatin while reducing neurotoxicity and improving quality of life. We investigated the recommended doses of docetaxel-carboplatin in Japanese patients with ovarian cancer and conducted a comparative study of docetaxel-carboplatin versus paclitaxel-carboplatin. Methods Thirty-nine patients with ovarian cancer were enrolled in this study and 38 patients were evaluated. We conducted a dose-escalation study using a docetaxel dose of 70 mg/m² and carboplatin AUC 5 and 6. In the comparative study, patients received either docetaxel 70 mg/m² and carboplatin AUC 5 or paclitaxel 175 mg/m² and carboplatin AUC 5. Progression-free survival, survival rate at 2 years, response rate, toxicity, and quality of life were investigated. Results In the dose-finding study, we determined the recommended doses as docetaxel 70 mg/m² and carboplatin AUC 5. In the comparative study, the two arms showed similar progression-free survival. Grade 4 neutropenia occurred more frequently in the docetaxel-carboplatin group (84.6%) than in the paclitaxel-carboplatin group (43.8%), while sensory neurotoxicity was less frequent in the docetaxel-carboplatin group (53.8%) than in the paclitaxel-carboplatin (68.8%) group. There were significant differences in the quality-of-life data in favor of docetaxel-carboplatin. Conclusion We determined the recommended doses of docetaxel-carboplatin for Japanese patients with ovarian cancer to be docetaxel 70 mg/m² and carboplatin AUC 5. In the comparative study, we suggest that the docetaxel-carboplatin combination is effective and well tolerated as first-line chemotherapy for Japanese patients with ovarian cancer.     

Phase I/II trial of docetaxel and carboplatin in previously untreated patients with advanced non-small-cell lung cancer

Background. This trial was conducted to determine the maximum tolerated dose (MTD) and principal toxicities of combinations of docetaxel and carboplatin administered every 3 weeks to patients with advanced non-small-cell lung cancer (NSCLC) previously untreated with chemotherapy, and to find suitable doses for phase II studies in Japanese subjects. Methods. Japanese patients with advanced NSCLC and performance status 0 to 2 according to the World Health Organization classification, but previously untreated with chemotherapy received docetaxel followed by carboplatin, each infused over a 1-h period. The carboplatin dose was based on the target area under the curve (AUC), using Calvert's formula. Dose levels studied were: docetaxel (mg/m²)/carboplatin AUC (mg/ml·min), 50/4, 60/4, and 60/5, repeated every 3 weeks. Granulocyte-colony stimulating factor (G-CSF) support was first used when dose-limiting toxicities (DLTs) were encountered. Results. Of 14 patients entered, 12 were assessable for toxicity and response. The MTD schedule was: docetaxel, 60 mg/m², with carboplatin, AUC 5 mg/ml·min (DLTs in 3 of 3 patients). The recommended dosage was: docetaxel, 60 mg/m², with carboplatin, AUC 4 mg/ml·min (DLTs in 2 of 6 patients). The main toxic effect was neutropenia, and any nonhematologic toxic effects were mild. No thrombocytopenia occurred. Six of the 12 patients (50%) showed responses; 4 of the 6 at the recommended doses. Conclusion. Docetaxel 60 mg/m², given over a 1-h period, followed by carboplatin, AUC 4 mg/ml·min, given over a 1-h period, is recommended for phase II studies in Japan. This combined chemotherapy has mild toxicity, except for neutropenia, and is useful and easy to administer. We therefore believe that phase II and phase III studies of this therapy would be well justified. Received: October 4, 1999 / Accepted: June 28, 2000     

Stereoselective pharmacokinetics of ifosfamide and its 2- and 3-N-dechloroethylated metabolites in female cancer patients

 The pharmacokinetics of the R and S enantiomers of ifosfamide (IFF) and of its 2- and 3-N-dechloroethylated metabolites (2-DCE-IFF and 3-DCE-IFF) were investigated in 14 cancer patients treated with a 3-h infusion of (R,S)-IFF (3 g/m²) with mesna uroprotection. An enantioselective gas chromatographic-mass spectrometric (GC-MS) assay was used to determine the concentrations in plasma and urine. The AUCs of (R)-IFF were significantly larger than those of (S)-IFF (2480±200 vs 1960±150 μM . h). The terminal half-lives (7.57±0.99 h) and mean residence times (11.17±1.10 h) of (R)-IFF were significantly longer than those of (S)-IFF, 6.03±0.82 h and 9.37±0.88 h, respectively. The mean volume of distribution at steady state of (R)-IFF (25.68±0.80 l/m²) was slightly smaller than that of (S)-IFF (27.35±0.89 l/m²). While the renal clearances of (R)-IFF and (S)-IFF were similar, the nonrenal clearance was significantly lower for (R)-IFF (30.20±2.70 vs 41.40±3.55 ml/m² per min) as was total clearance (41.52±2.90 vs 52.37±3.75 ml/m² per min). The AUC values for all of the DCE metabolites from (S)-IFF were significantly greater than those from (R)-IFF with 47% of the measured AUC accounted for by DCE from (S)-IFF compared to only 20% for (R)-IFF. Therefore, the enantioselective difference in IFF elimination can be partially explained by differences in N-dechloroethylation. Received: 13 December 1994/Accepted: 14 May 1995     

Phase I study of paclitaxel,carboplatin and UFT in chemo-naive patients with advanced non-small cell lung cancer (NSCLC)

Objective We conducted a phase I study of paclitaxel (PTX), carboplatin (CBDCA), and UFT in chemo-naive patients with advanced non-small cell lung cancer (NSCLC). Method Twenty-one chemo-naive patients with advanced NSCLC were enrolled. The study was conducted as a phase I dose-escalation study of various doses of systemic PTX followed by CBDCA on day 1 and oral UFT (400 mg/m²) on days 1–5 and 8–12, with the cycle repeated at 21-day intervals. At least three patients were enrolled in each step. Results The main toxicities were neutropenia and paresthesia, but were tolerable and reversible in all cases. Overall response rate was 57% (12 out of 21). The MTD was not reached at the highest dose level after the first cycle. Given previous recommends of PTX at 225 mg/m² and CBDCA AUC 6 for two-drug therapy, the recommended dose for the phase II study under our regimen was set at PTX 225 mg/m² on day 1, CBDCA AUC 6 on day 1, and UFT 400 mg/m² on days 1–5 and 8–12. Conclusion The combination of PTX, CBDCA, and UFT showed promising activity and acceptable toxicity in these chemo-naive patients, supporting the development of this combination as a feasible chemotherapeutic option for advanced NSCLC.     

Phase II study of the combination of carboplatin and 5-fluorouracil in metastatic nasopharyngeal carcinoma

 A carboplatin and 5-fluorouracil (CF) chemotherapy protocol was designed to evaluate tumor response and toxicity in patients with metastatic nasopharyngeal carcinoma (NPC). Patients with metastatic NPC were treated with a maximum of eight courses of CF. Carboplatin was given at 300 mg/m² by intravenous bolus on day 1 and 5-fluorouracil at 1 g/m² per day by continuous infusion on days 1 – 3; cycles were repeated once every 3 weeks. A total of 42 patients were evaluable for response and toxicity. They received a median of 6 courses (range 2 – 8) of chemotherapy. The overall response rate was 38% (16/42), comprising 7 complete responses (CR, 17%) and 9 partial responses (PR, 21%). The median survival was 12.1 months (range 6 – 54.2 months). The treatment was well tolerated. Toxicity was mainly bone marrow suppression. There were four episodes of neutropenic fever, but no renal toxicity or treatment-related death was documented. The combination of carboplatin given at a fixed dose of 300 mg/m² for 1 day and 5-fluorouracil given at 1 g/m² per day for 3 days produced an objective response rate of 38% and tolerable side effects. Received: 21 October 1995 / Recepted: 1 March 1996     

Pharmacokinetic studies of 13-cis-retinoic acid in pediatric patients with neuroblastoma following bone marrow transplantation

 A phase I clinical trial of 13-cis-retinoic acid (cis-RA) was undertaken to determine the maximally tolerated dose (MTD) and pharmacokinetics (PK) of cis-RA following bone marrow transplantation (BMT) in children with high-risk neuroblastoma. Mean peak serum levels of cis-RA in 31 pediatric patients ranged from 4.9 to 8.9 μM following doses of 100–200 mg/m² per day, divided into two doses every 12 h administered orally. The PK of cis-RA obeyed a single-compartment model following first-order absorption in the majority of patients. A linear increase in the mean peak serum levels and area under the time-concentration curve (AUC) with increasing dose was observed. The average half-lives of absorption and elimination were 1.0 and 5.8 h, respectively. At the MTD of 160 mg/m² per day, the mean cis-RA peak serum concentration was 7.2±5.3 μM. AUC values were not altered significantly during a 2-week course of treatment or over a long period of multiple courses. Levels of trans-retinoic acid, a metabolite of cis-RA, remained low but were similar on days 1 and 14, whereas the 4-oxo-13-cis-RA metabolite had increased in 64% of patients by day 14. Peak serum cis-RA concentrations correlated with clinical toxicity as grade 3 to 4 toxicity was seen in 44% of patient-courses (8/18) with peak serum levels ≥10 μM, but only 13% (12/96) with peak serum levels <10 μM. These results show that cis-RA given at 160 mg/m² to children achieved serum concentrations known to be effective against neuroblastoma in vitro, and the PK for cis-RA differs from that reported for trans-retinoic acid in children. Received: 6 February/Accepted: 29 January 1996     

Pharmacokinetics of carboplatin administered with lobradimil to pediatric patients with brain tumors

Purpose To determine the pharmacokinetics of adaptively dosed carboplatin when administered in combination with the bradykinin agonist, lobradimil (RMP-7, Cereport), to pediatric patients with brain tumors.Methods Carboplatin pharmacokinetic studies were performed on 21 of 25 children with primary brain tumors who received carboplatin and lobradimil on two consecutive days every 28 days in a phase I dose-escalation trial of lobradimil. Carboplatin was adaptively dosed, based on the radioisotopic glomerular filtration rate (GFR) to achieve a target plasma area under the concentration vs time curve (AUC) of 3.5 mgmin/ml per dose ×2 (2.5 mgmin/ml per dose ×2 in patients with prior craniospinal radiation or myeloablative chemotherapy). The adaptive dosing formula was: carboplatin dose (mg/m²)=target AUC (mgmin/ml) × [0.93 × GFR (ml/min/m²)+15]. Carboplatin was infused over 60 min (n=15) or 15 min (n=6). The 10-min lobradimil infusion (100–600 ng/kg ideal body weight) began 5 min before the end of the carboplatin infusion. Frequent blood samples were drawn over 24 h after the first dose of carboplatin/lobradimil. Ultrafilterable platinum was measured by atomic absorption spectroscopy, and the AUC of ultrafilterable platinum was derived using the linear trapezoidal rule and extrapolated to infinity.Results The median GFR was 65 ml/min/m² (range 38–95 ml/min/m²) and the median carboplatin doses for the 2.5 and 3.5 mg min/ml target AUCs were 154 and 276 mg/m²/day (124–235 and 179–360 mg/m²/day), respectively. The measured carboplatin AUC exceeded the target AUC in all 21 patients by a median of 35% (range 0.2–131%). The median carboplatin AUCs at the 2.5 and 3.5 mgmin/ml target AUCs were 3.4 and 4.8 mgmin/ml (2.51–5.8 and 3.9–7.7 mgmin/ml), respectively. Carboplatin clearance was lower than values previously reported in children and correlated poorly with GFR (r²=0.14).Conclusions Adaptive dosing of carboplatin based on GFR overestimated the dose required to achieve the target carboplatin AUC in pediatric patients with brain tumors treated with concurrent lobradimil. The degree to which the measured carboplatin AUC exceeded the target AUC appeared to be greater at higher doses of lobradimil, suggesting that the failure of the adaptive dosing method was related to an unexpected pharmacokinetic drug interaction.     

A phase I trial of carboplatin and etoposide for elderly (≥75 year-old) patients with small-cell lung cancer

Purpose: The combination of carboplatin and etoposide is currently considered the most appropriate regimen for treating elderly patients with small-cell lung cancer (SCLC). Previous reports on elderly patients, 70 years or older, found that the recommended dose was close to that of younger patients. Then, we conducted a phase I study of carboplatin and etoposide in elderly patients, 75 years or older, with SCLC. This study aimed to determine the maximum tolerated dose (MTD) and dose-limiting toxicity (DLT). Methods: Twenty-six patients fulfilling the eligibility criteria, chemotherapy-naive, performance status (PS) of 0–2, age ≥75, and adequate organ functions were enrolled. Patients’ characteristics were: male/female=21/5; PS 0/1/2=9/11/6; median age (range)=78 (75–82); and limited/extensive stage=16/10. The patients intravenously received carboplatin with a target AUC of 4 or 5 mg min/ml (Chatelut formula) on day 1 and etoposide at 80–120 mg/m² on days 1, 2 and 3. Therapy was repeated four times in every 4 weeks. Results: The MTD of carboplatin/etoposide was AUC=5/80, 4/110, and 4/120. The DLTs were thrombocytopenia, neutropenia, leukopenia, and febrile neutropenia. Overall, grade 4 thrombocytopenia, neutropenia (≥4 days), leukopenia (≥4 days), and febrile neutropenia occurred in 27, 20, 7, and 13% of cases at MTD levels, respectively, and 0% at other levels. Twenty of 26 patients showed objective responses (2CR, 18PR; RR=77%). Conclusion: A dose of carboplatin of AUC=4 and etoposide of 100 mg/m² was recommended in this regimen.The authors indicated no potential conflicts of interest.     

Clinical pharmacokinetics of carboplatin in children

The present study was undertaken to evaluate in children the plasma pharmacokinetics of free carboplatin given at different doses and schedules and to evaluate the inter- and intrapatient variability and the possible influence of schedule on drug exposure. A total of 35 children (age range, 1–17 years) with malignant tumors were studied. All patients had normal renal function (creatinine clearance corrected for surface body area, above 70 ml min^–1 m^–2; range, 71–151 ml min^–1 m^–2) and none had renal involvement by malignancy. Carboplatin was given at the following doses and schedules: 175, 400, 500, and 600 mg/m² given as a 1-h infusion; 1,200 mg/m² divided into equal doses and infused over 1 h on 2 consecutive days; and 875 and 1,200 mg/m² given as a 5-day continuous infusion. A total of 57 courses were studied. Carboplatin levels in plasma ultrafiltrate (UF) samples were measured both by high-performance liquid chromatography and by atomic absorption spectrophotometry. Following a 1-h infusion, carboplatin free plasma levels decayed biphasically; the disappearance half-lives, total body clearance, and apparent volume of distribution were similar for different doses. In children with normal renal function as defined by creatinemia and blood urea nitrogen (BUN) and creatinine clearance, we found at each dose studied a limited interpatient variability of the peak plasma concentration (C_max) and the area under the concentration-time curve (AUC) and a linear correlation between the dose and both C_max (r=0.95) and AUC (r=0.97). The mean value ± SD for the dose-normalized AUC was 13±2 min m² l^–1 (n=57). The administration schedule does not seem to influence drug exposure, since prolonged i.v. infusion or bolus administration of 1,200 mg/m² achieved a similar AUC (13.78±2.90 and 15.05±1.44 mg ml^–1 min, respectively). In the nine children studied during subsequent courses a limited interpatient variability was observed and no correlation (r=0.035) was found between AUC and subsequent courses by a multivariate analysis of dose, AUC, and course number. The pharmacokinetic parameters were similar to those previously reported in adults; however, a weak correlation (r=0.52,P=0.03) between carboplatin total body clearance and creatinine clearance varying within the normal range was observed. A dosing formula appears unnecessary in children with normal renal function since a generally well-predictable free carboplatin AUC is achieved following a given dose.Supported by the Associazione Italiana per la Ricerca sul Cancro (A.I.R.C.)     

A phase I study of the safety and pharmacokinetics of the histone deacetylase inhibitor belinostat administered in combination with carboplatin and/or paclitaxel in patients with solid tumours

Background:

This phase I study assessed the maximum tolerated dose, dose-limiting toxicity (DLT) and pharmacokinetics of belinostat with carboplatin and paclitaxel and the anti-tumour activity of the combination in solid tumours.

Methods:

Cohorts of three to six patients were treated with escalating doses of belinostat administered intravenously once daily, days 1–5 q21 days; on day 3, carboplatin (area under the curve (AUC) 5) and/or paclitaxel (175 mg m⁻²) were administered 2–3 h after the end of the belinostat infusion.

Results:

In all 23 patients received 600–1000 mg m⁻² per day of belinostat with carboplatin and/or paclitaxel. No DLT was observed. The maximal administered dose of belinostat was 1000 mg m⁻² per day for days 1–5, with paclitaxel (175 mg m⁻²) and carboplatin AUC 5 administered on day 3. Grade III/IV adverse events were (n; %): leucopenia (5; 22%), neutropenia (7; 30%), thrombocytopenia (3; 13%) anaemia (1; 4%), peripheral sensory neuropathy (2; 9%), fatigue (1; 4%), vomiting (1; 4%) and myalgia (1; 4%). The pharmacokinetics of belinostat, paclitaxel and carboplatin were unaltered by the concurrent administration. There were two partial responses (one rectal cancer and one pancreatic cancer). A third patient (mixed mullerian tumour of ovarian origin) showed a complete CA-125 response. In addition, six patients showed a stable disease lasting ⩾6 months.

Conclusion:

The combination was well tolerated, with no evidence of pharmacokinetic interaction. Further evaluation of anti-tumour activity is warranted.     

Phase 1 and pharmacokinetic study of concurrent carboplatin and irinotecan in subjects aged 1 to 21 years with refractory solid tumors

BACKGROUND:

Preclinical testing suggests the combination of carboplatin and irinotecan has at least additive antitumor activity. The primary objectives of the current study were to determine the maximum tolerated doses (MTDs) and recommended phase 2 doses of carboplatin administered with irinotecan to pediatric patients with refractory solid tumors.

METHODS:

This was a multicenter, open‐label, single‐arm dose escalation study in which subjects with refractory solid tumors received 21‐day treatment cycles of intravenous carboplatin on Day 1 followed by intravenous irinotecan administered daily for 10 days within 2 consecutive weeks. The plasma pharmacokinetics of ultrafiltrable platinum, irinotecan, and 2 irinotecan metabolites were determined during Cycle 1. The interpatient plan for dose escalation at study initiation was to increase irinotecan first followed by increases in carboplatin.

RESULTS:

Twenty‐eight patients with a median age of 8.5 years (range, 1‐21 years) were enrolled with a variety of solid tumors. Two of 6 subjects at the first dose level (carboplatin target area under the curve [AUC], 4.0 mg/mL*min; irinotecan, 18 mg/m²/dose) experienced dose‐limiting gastrointestinal toxicities requiring a dose de‐escalation scheme (carboplatin AUC, 4.0 mg/mL*min; irinotecan, 15 mg/m²/dose). Three of 6 subjects at the second dose level experienced dose‐limiting gastrointestinal complications and bone marrow suppression. A further dose de‐escalation to carboplatin AUC of 4.0 mg/mL*min and irinotecan of 12 mg/m²/dose resulted in dose‐limiting bone marrow suppression in 1 of 13 patients treated at that dose, and therefore was determined to be the MTD. One complete response (in a patient with medulloblastoma) and 3 partial responses (in patients with neuroblastoma, medulloblastoma, and lymphoendothelial carcinoma, respectively) were observed.

CONCLUSIONS:

The recommended phase 2 dose in heavily pretreated pediatric patients is carboplatin (AUC, 4 mg/mL*min on Day 1) and irinotecan (12 mg/m²/ day × 10 days) given every 21 days. Cancer 2009. © 2008 American Cancer Society.