A feasibility, pharmacokinetic and frequency-escalation trial of intraperitoneal chemotherapy in high risk gastrointestinal tract cancer.

AIMS: To assess the feasibility, pharmacokinetics and maximum tolerable frequency (MTF) of intraperitoneal (IP) 5-fluorouracil and leucovorin (FU/LV) added, as a regional boost, to intravenous chemotherapy after resection of gastrointestinal cancer. METHODS: Fifty-three patients were recruited following gastrointestinal cancer resection (43 colon; 10 stomach/small bowel) with serosal involvement. Peritoneal ports were implanted and IP fluid distribution evaluated ultrasonically. Twelve patients were studied for pharmacokinetics; 44 (41 evaluable) for MTF. Treatment was weekly intravenous bolus FU/LV for 6 months; to this was added IP FU/LV (400/20 mg/m(2) in 1500 ml 4% icodextrin) with increasing frequency from 4 weekly to 1 weekly in four successive cohorts. RESULTS: Peritoneal fluid distribution was excellent. Intraperitoneal FU exposure (AUC) after IP treatment was >1000-fold plasma AUC after IP treatment (regional pharmacokinetic advantage), and >100-fold plasma AUC after intravenous treatment (regional therapeutic advantage). IP therapy was well tolerated if given every 4, 3 or 2 weeks, but not weekly: 11/13, 7/8, 10/13 and 0/7 patients respectively completed treatment without IP modification in these cohorts. Problems with peritoneal access occurred in 20% of patients. CONCLUSION: Adding fortnightly IP FU/LV to a standard intravenous regimen is safe, tolerable and provides high peritoneal FU exposure. More reliable peritoneal access is needed to improve the feasibility of this otherwise promising therapeutic approach.

GAMEC--a new intensive protocol for untreated poor prognosis and relapsed or refractory germ cell tumours.

There is no consensus as to the management of untreated poor prognosis or relapsed/refractory germ cell tumours. We have studied an intensive cisplatin-based regimen that incorporates high-dose methotrexate (HD MTX) and actinomycin-D and etoposide every 14 days (GAMEC). Sixty-two patients were enrolled in a phase 2 study including 27 who were untreated (IGCCCG, poor prognosis) and 35 with progression despite conventional platinum based chemotherapy. The pharmacokinetics of the drugs were correlated with standard outcome measures. Twenty of the untreated patients were progression free following GAMEC and appropriate surgery, as were 18 individuals in the pretreated group. None of the established prognostic factors for therapy for pretreated patients could identify a poor-prognosis group. Five out of nine late relapses to prior chemotherapy were progression free following GAMEC and appropriate surgery. All patients had at least one episode of febrile neutropenia and there were five (8%) treatment-related deaths. PK values were not predictive of efficacy or toxicity, although the dose intensity in the pretreated group of patients, especially of HD MTX, was significantly correlated with progression-free survival (PFS). GAMEC is a novel intensive regimen for this group of patients producing encouraging responses, although with significant toxicity. For those in whom it fails, further therapy is still possible with durable responses being seen.

Clinical response to morphine in cancer patients and genetic variation in candidate genes.

Morphine is the analgesic of choice for moderate to severe cancer pain; however, 10-30% of patients do not tolerate morphine. This study evaluated genetic variation in the mu-opioid receptor, betaarrestin2, stat6 and uridine diphosphate-glucuronysltransferase 2B7 (UGT2B7) genes, in patients who responded to morphine vs those who were switched to alternative opioids. We prospectively recruited and genotyped 162 Caucasian patients (117 controls, 39 switchers). Switchers, were more likely to carry the common allele at 1182 G/A, 5864 G/A, 8622T/C and 11143 G/A in the betaarrestin2 gene (P = 0.021, 0.043, 0.013, 0.043, respectively). Switchers had increased carriage of the T allele (-1714 C/T) and a significant difference in the allelic frequency at 9065 C/T (chi(2) = 3.86, P = 0.049) in the stat6 gene. No differences were seen in genotype or allele frequencies of SNPs in the mu-opioid receptor gene or UGT2B7 gene. This study presents novel data suggesting that variation in genes involved in mu-opioid receptor signalling influence clinical response to morphine.

Phase I trial of intravesical Suramin in recurrent superficial transitional cell bladder carcinoma.

Suramin is an antitrypanosomal agent with antineoplastic activity, but with serious systemic side effects. We administered Suramin intravesically to determine a concentration with low toxicity but with evidence of a pharmacodynamic effect, to recommend a dose level for phase II trials. This was an open-labelled, non-randomized dose-escalation phase I study. In all, 12 patients with a history of recurrent superficial bladder cancer were grouped into four dose levels (10-150 mg ml(-1) in 60 ml saline). Six catheter instillations at weekly intervals were used. Cystoscopy and biopsy were performed before and 3 months after the start of treatment. Suramin was assayed using high-performance liquid chromatography, vascular endothelial growth factor (VEGF) using ELISA (enzyme-linked immunosorbent assay), and urinary protein profile using surface-enhanced laser desorption ionisation mass spectroscopy (SELDI). Minimal systemic absorption of Suramin was found at the highest dose of 150 mg ml(-1). Urinary VEGF was affected by Suramin at doses above 50 mg ml(-1), corresponding to the estimated threshold of saturation of Suramin binding to urine albumin. SELDI showed a specific disappearance of urinary protein peaks during treatment. Intravesical Suramin shows lack of toxicity and low systemic absorption. The results of this phase I trial support expanded clinical trials of efficacy at a dose of 100 mg ml(-1) intravesically.

Histone acetylation-mediated regulation of genes in leukaemic cells.

Histone deacetylase (HDAC) and histone acetyltransferase (HAT) functions are associated with various cancers, and the inhibition of HDAC has been found to arrest disease progression. Here, we have investigated the gene expression profiles of leukaemic cells in response to the HDAC inhibitor trichostatin A (TSA) using oligonucleotide microarrays. Nucleosomal histone acetylation was monitored in parallel and the expression profiles of selected genes were confirmed by quantitative polymerase chain reaction (PCR). A large number of genes (9% of the genome) were found to be similarly regulated in CCRF-CEM and HL-60 cells in response to TSA, and genes showing primary and secondary responses could be distinguished by temporal analysis of gene expression. A small fraction of genes were highly sensitive to histone hyper-acetylation, including XRCC1, HOXB6, CDK10, MYC, MYB, NMI and CBFA2T3 and many were trans-acting factors relevant to cancer. The most rapidly repressed gene was MKRN3, an imprinted gene involved in the Prader-Willi syndrome.

A 'modified de Gramont' regimen of fluorouracil, alone and with oxaliplatin, for advanced colorectal cancer.

The standard de Gramont (dG) regimen of fortnightly leucovorin, bolus fluorouracil and 22-h infusion of fluorouracil, d1+2, and the same regimen plus oxaliplatin, are effective but also cumbersome. We therefore present simplified 'Modified de Gramont' (MdG) regimens. Forty-six advanced gastrointestinal cancer patients entered a dose-exploring study of MdG, including an expanded cohort of colorectal cancer patients at optimum dose. Treatment (fortnightly) comprised: 2-h i.v.i. leucovorin (350 mg d,l-LV or 175 mg l-LV, not adjusted for patient surface area); bolus fluorouracil (400 mg m(-2)), then ambulatory 46-h fluorouracil infusion (2000-3600 mg m(-2), cohort escalation). Subsequently, 62 colorectal patients (25 unpretreated; 37 fluorouracil-resistant) received MdG plus oxaliplatin (OxMdG) 85 mg m(-2). Fluorouracil pharmacokinetics during MdG were compared with dG. The optimum fluorouracil doses for MdG alone were determined as 400 mg m(-2) bolus + 2800 mg m(-2) 46-h infusion. A lower dose of 400 mg m(-2) bolus + 2400 mg m(-2) infusion which, like dG produces minimal toxicity, was chosen for the OxMdG combination. Fluorouracil exposure (AUC(0-48 h)) at this lower dose is equivalent to dG. With OxMdG, grade 3-4 toxicity was rare (neutropenia 2.8% cycles; vomiting or diarrhoea <1% cycles), but despite this there were two infection-associated deaths. Oxaliplatin was omitted for cumulative neurotoxicity in 17 out of 62 patients. Objective responses in colorectal cancer patients were: 1st-line MdG (22 assessable): PR=36%, NC=32%, PD=32%. 1st-line OxMdG (24 assessable): CR/PR=72%; NC=20%; PD=8%; 2nd line OxMdG (34 assessable): PR=12%; NC=38%; PD=50%. MdG and OxMdG are convenient and well-tolerated. OxMdG was particularly active as 1st-line treatment of advanced colorectal cancer. Both regimens are being further evaluated in the current UK MRC phase III trial.

Exposure to low concentrations of etoposide reduces the apoptotic capability of leukaemic cell lines.

The use of topoisomerase inhibitors has been associated with the development of secondary malignancies, suggesting that these agents can induce DNA damage that may be persistent. We have investigated the effect of short exposures (>3 days) to low etoposide concentrations (LC-etoposide, 0.01-0.04 microM) on the ability of leukaemic cells to initiate apoptosis. Results showed that although LC-etoposide had no effect on cell growth characteristics, the pre-culture of cells with LC-etoposide conferred resistance to subsequent exposure to cytotoxic concentrations of etoposide (0.3 microM etoposide in HL60 on day 3: %V: 95.2 +/- 1.6% vs 60.3 +/- 12.1% in control cells with no pre-culture, and %A: 5.1 +/- 0.2 vs 19.0 +/- 0.7%; P < 0.001). This effect was still observed 4 weeks after the initial drug exposure. Associated with these observations was a three-fold increase in genetic instability and a reduction in induced bax protein levels. The anti-cytotoxic effect was also shown to be specific to topoisomerase II (topo II) inhibitors, as the pre-culture of cells with a low doxorubicin concentration also induced resistance, while low cisplatin concentrations did not. The persistence of these alterations in cellular processes following an initial exposure to topo II inhibitors suggests a DNA-based mechanism, and highlights the existence of drug/target interactions even at very low drug concentrations.

The in vitro activity of the tyrosine kinase inhibitor STI571 in BCR-ABL positive chronic myeloid leukaemia cells: synergistic interactions with anti-leukaemic agents.

Chronic myeloid leukaemia is typically characterised by the presence of dysregulated BCR-ABL tyrosine kinase activity, which is central to the oncogenic feature of being resistant to a wide range of cytotoxic agents. We have investigated whether the inhibition of this tyrosine kinase by the novel compound STI571 (formerly CGP57148B) would render K562, KU812 cell lines and chronic myeloid leukaemia-progenitor cells sensitive to induction of cell kill. Proliferation assays showed STI571 to be an effective cytotoxic agent in chronic myeloid leukaemia-derived cell lines (IC(50) on day 5 of 4.6 microg ml(-1) and 3.4 microg ml(-1) for K562 and KU812 respectively) and in leukaemic blast cells (per cent viability on day 3 at 4 microg ml(-1): 55.5+/-8.7 vs 96.4+/-3.7%). STI571 also appeared to specifically target bcr-abl expressing cells, as results from colony forming assays using the surviving cell fraction from STI571-treated peripheral CD34(+) chronic myeloid leukaemia blast cells, indicated a reduction in the expansion of colonies of myeloid lineage, but no effect on normal colony formation. Our data also showed synergy between STI571 and other anti-leukaemic agents; as an example, there were significant increases in per cent cell kill in cell lines cultured with both STI571 and etoposide compared to the two alone (per cent cell kill on day 3: 73.7+/-11.3 vs 44.5+/-8.7 and 17.8+/-7.0% in cultures with STI571 and etoposide alone respectively; P<0.001). This study confirms the central oncogenic role of BCR-ABL in the pathogenesis of chronic myeloid leukaemia, and highlights the role of targeting this tyrosine kinase as a useful tool in the clinical management of the disease.

The importance of drug scheduling and recovery phases in determining drug activity. Improving etoposide efficacy in BCR-ABL-positive CML cells.

K562 leukaemic cells are known to be less sensitive to etoposide than other cell lines, despite having similar topo II mRNA levels and cleavable complex formation. We have investigated the effect of etoposide schedule on cell cycle distribution, apoptosis and p21(waf1) and cdk1(p34) status in two bcr-abl-positive chronic myeloid leukaemia (CML) cell lines (K562 and KU812) and two small cell lung cancer (SCLC) cell lines (H69 and GLC4). During a continuous 5-day exposure, the SCLC cell lines showed a time and concentration-dependent loss of cell viability, with an initial block in the G2/M phase of the cell cycle followed by apoptosis. In contrast, the two CML cell lines showed no significant apoptosis or loss of viability after a similar block in G2/M. However, when K562 or KU812 cells were placed in drug-free medium following a 3-day drug exposure there was marked, concentration-dependent apoptosis (% apoptosis after release at 1 microM etoposide in K562, 10% at 24 h, 30% at 48 h). Our data also show that p21(waf1) does not increase after etoposide treatment in either H69 or GLC4 (both with mutated-p53). Although K562 and KU812 cells are null-p53, the arrest in G2/M during drug exposure was associated with increased p21(waf1) and a decrease in cdk1 (both P<0.001 compared with controls). Upon release of these cells from drug-medium, p21(waf1) gradually returned to control levels, which was associated with an easing of the block at G2/M and an induction of apoptosis. This study highlights the importance of cell cycle regulatory proteins in drug sensitivity and resistance, and suggests that in cells such as K562 and KU812, a pulsed schedule may be more active than a single prolonged exposure.

Limited phase I study of morphine-3-glucuronide.

The toxicity of morphine-3-glucuronide (M3G) has been investigated in an open, uncontrolled, single-blinded, single dose study over a limited range of doses. Three cohorts each of three healthy volunteers received 7.5, 15, and 30 mg/70 kg intravenous (IV) M3G. Blood sampling was undertaken for the following 24 h. Subjective toxicity was recorded on visual analogue scales and plasma M3G concentrations measured by a specific HPLC assay. Virtually no effects and no change in cardiovascular or respiratory parameters were seen. The pharmacokinetics fitted a two-compartment model. The mean elimination half-life (+/- S.D.) of M3G was 1.66 (+/- 0.47) h. Mean AUC standardized to a dose of 1 mg/70 kg was 228 (+/- 62) etamolL(-1) x h. Mean M3G clearance was 169 (+/- 48) mLmin(-1) and the mean volume of distribution was 23.1 (+/- 4.8) liters. At the doses investigated there were no clear neuroexcitatory effects, no opioid effects, and the pharmacokinetics were very similar to those of morphine-6-glucuronide (M6G).

The pharmacokinetics of morphine and morphine glucuronide metabolites after subcutaneous bolus injection and subcutaneous infusion of morphine.

AIMS: To investigate the pharmacokinetics of morphine, morphine-6-glucuronide (M6G) and morphine-3-glucuronide (M3G) in healthy volunteers after the administration of morphine by subcutaneous bolus injection (s.c.b.) and subcutaneous infusion (s.c. i.) over 4 h, and to compare the results with the intravenous bolus (i.v.) administration of morphine. METHODS: Six healthy volunteers each received 5 mg morphine sulphate by i.v., s.c.b. and short s.c.i. over 4 h, on three separate occasions, in random order, each separated by at least 1 week. Plasma samples were assayed for morphine, M6G and M3G. RESULTS: After i.v. morphine, the concentrations of morphine, M6G and M3G and their pharmacokinetic parameters were similar to those we have observed previously, in other healthy volunteers (when standardized to nmol l- 1, for a 10 mg dose to a 70 kg subject). After s.c.b. morphine, similar results were obtained except that the median tmax values for morphine and M3G were significantly longer than after i.v. morphine (P< 0.001 and P< 0.05, respectively), with a trend to a longer tmax for M6G (P = 0. 09). The appearance half-lives after s.c.b. morphine for M6G and M3G were also significantly longer than after i.v. morphine (P = 0.03 and P< 0.05, respectively). Comparison of log-transformed AUC values indicated that i.v. and s.c.b. administration of morphine were bioequivalent with respect to morphine, M6G and M3G. In comparison with i.v. morphine, morphine by s.c.i. was associated with significantly longer median tmax values for morphine (P< 0.001), M6G (P< 0.001) and M3G (P< 0.05), and the mean standardized Cmax values significantly lower than after both i.v. and s.c.b. morphine (morphine P< 0.001, M6G P< 0.001 and M3G P< 0.01 for each comparison). Comparison of log-transformed AUC values after i.v. and s.c.i. morphine indicated that the two routes were not bioequivalent for morphine (log-transformed AUC ratio 0.78, 90% CI 0.66-0.93), M6G (0.72, 90% CI 0.63-0.82), or M3G (0.65, 90% CI 0.54-0.78). A small stability study indicated no evidence of adsorptive losses from morphine infused over 4 h using the infusion devices from the study. CONCLUSIONS: Although bioequivalence was demonstrated between the s. c.b. and i.v. routes of morphine administration, the bioavailabilities of morphine, M6G and M3G after s.c.i. were significantly lower than after i.v. administration. However, despite this, the study demonstrates that the subcutaneous route is an effective method for the parenteral administration of morphine.

Randomized placebo-controlled trial of the activity of the morphine glucuronides.

BACKGROUND: Morphine-6-glucuronide (M6G) is an active metabolite of morphine with potent analgesic activity. Morphine-3-glucuronide (M3G), the most prevalent metabolite, has minimal affinity for opioid receptors. It has been suggested from animal model data and by examination of metabolite ratios in humans that M3G may functionally antagonize the respiratory depressant and analgesic actions of morphine and M6G. METHODS: We performed a double-blind placebo-controlled trial with 10 healthy volunteers. The trial had 6 arms: (1) placebo, (2) 10 mg/70 kg of morphine, (3) 3.3 mg/70 kg of M6G, (4) 30.6 mg/70 kg of M3G, (5) 30.6 mg/70 kg of M3G with 10 mg/70 kg of morphine, and (6) 30.6 mg/70 kg of M3G with 3.3 mg/70 kg of M6G; all were give by slow intravenous bolus. Analgesia was assessed with the use of the submaximal ischemic pain model. The effects were quantified on numerical and visual analogue scales. Respiratory parameters and response to steady state 5% carbon dioxide challenge were assessed with spirometry, mass spectroscopy, and earlobe blood gas analysis. RESULTS: Morphine and M6G produced significant pain relief compared with placebo (morphine, P < .0001; M6G, P = .033). Pain relief after M6G was less than after morphine (P = .009) and M3G was no better than placebo (P = .26). Pain relief with morphine and M6G were not significantly altered by M3G (P = .59 and P = .28, respectively). Significant and similar dysphoria and sedation occurred with both morphine (P < .002) and M6G (P < .016) but were absent with both M3G and placebo. Respiratory parameters suggested that M6G produced less respiratory depression than morphine. Both morphine and M6G caused a significant reduction in respiratory drive compared with placebo (morphine, P = .002; M6G, P = .013); this effect was not reversed by M3G (P = .35 and P = .83, respectively). CONCLUSIONS: M3G appears to be devoid of significant activity; in these circumstances and at these doses, it does not antagonize either the analgesic or respiratory depressant effects of M6G or morphine.

Schedule-dependent cytotoxicity of SN-38 in p53 wild-type and mutant colon adenocarcinoma cell lines.

In this study the effects of SN-38 on colon adenocarcinoma cell lines expressing wild-type p53 (LS174T) or mutant non-functional p53 (HT29) have been investigated. On exposure to SN-38, HT29 cells rapidly progressed through G1 and S and arrested in G2/M. Release and concomitant increase in apoptosis after 48 h was concentration- and time-dependent (P < 0.001), being more rapid at higher concentrations, but reaching plateau at 10 ng ml(-1) with prolonged exposure. LS174T cells showed only a small increase in apoptosis, and only at high concentrations (50-100 ng ml(-1)). The main effect of SN-38 in LS174T cells was prolonged cell cycle arrest, which was independent of concentration. Arrest occurred in all phases of the cell cycle, with the distribution depending on concentration (P < 0.001) and not duration (P > 0.05). With increasing concentration, LS174T cells arrested in G2/M, S and G1. Cell cycle arrest was coincident with increased p53 expression in each phase of the cell cycle. Expression in G1 increased with time and concentration (P < 0.001, P = 0.01 respectively)whereas in S and G2/M p53 expression increased only with time (P< 0.001). Dose-dependent p53-associated G1 arrest, in the absence of DNA synthesis indicates an additional cytotoxic mechanism for SN-38, which requires higher concentrations than the S phase mechanism, and detection of which seems to involve p53. For incubations with the same ED (exposure x duration), apoptosis in HT29 cells was significantly higher for prolonged exposure to lower concentrations, whereas in LS174T cells there was a trend towards increased apoptosis with shorter exposures to higher concentrations, indicating a schedule effect of SN-38. Although expression of wild-type p53 leads to a more rapid induction of apoptosis, SN-38 cytotoxicity was generally greater in cells with mutant p53, as wild-type cells escaped apoptosis by p53 associated prolonged cell cycle arrest. Thus, pulsed schedules with higher doses may be more effective in cells expressing wild-type p53, whereas continued exposure with protracted schedules may be more active in cells expressing mutant p53.

RNA synthesis block by 5, 6-dichloro-1-beta-D-ribofuranosylbenzimidazole (DRB) triggers p53-dependent apoptosis in human colon carcinoma cells.

Most modern chemo- and radiotherapy treatments of human cancers use the DNA damage pathway, which induces a p53 response leading to either G1 arrest or apoptosis. However, such treatments can induce mutations and translocations leading to secondary malignancies or recurrent disease, which often have a poor prognosis because of resistance to therapy. Here we report that 5, 6-dichloro-1-beta-D-ribofuranosylbenzimidazole (DRB), an inhibitor of CDK7 TFIIH-associated kinase, CKI and CKII kinases, blocking RNA polymerase II in the early elongation stage, triggers p53-dependent apoptosis in human colon adenocarcinoma cells in a transcription independent manner. The fact that DRB kills tumour-derived cells without employment of DNA damage gives rise to the possibility of the development of a new alternative chemotherapeutic treatment of tumours expressing wild type p53, with a decreased risk of therapy-related, secondary malignancies.

Effects of haemopoietic growth factors in combination with etoposide on sister chromatid exchange frequencies in peripheral blood mononuclear cells.

Prior to work on the influence of dosing and scheduling of the drug etoposide in bone marrow cells, the DNA-damaging effects of three haemopoietic growth factors, either alone or in combination with etoposide, were investigated. Sister chromatid exchange (SCE) frequencies in phytohaemagglutinin-stimulated mononuclear cells of six normal volunteers were used as an indicator of DNA damage. The effects of three growth factors on SCEs were investigated at concentrations ranging between 0 and 100 ng/ml and those of etoposide alone, at concentrations varying between 0 and 2 microM. The effect of combinations of growth factor (GF) and etoposide were assessed at a 40-ng/ml concentration of each cytokine and at 0.4 microM etoposide. Results showed not only a dose-dependent rise in SCE frequency in cells treated with etoposide but also a cytokine effect. Stem-cell factor did not cause a significant change in SCE numbers. However, cytokines with activity at the progenitor cell level induced small but significant increases in SCE numbers at concentrations of 50 and 100 ng/ml (P < 0.001). Results of combination studies indicated a significant 60% increase in SCE numbers in cells treated with GF and etoposide as compared with etoposide alone (P < 0.00001). This finding suggests a sensitivity of peripheral blood mononuclear cells to SCE induction by GFs given either as single agents or in combination with etoposide.

A pharmacokinetic study of sublingual aerosolized morphine in healthy volunteers.

A pharmacokinetic study was undertaken to compare the pharmacokinetics of morphine after an intravenous dose with the pharmacokinetics after a sublingual dose administered from an aerosol. Plasma levels of morphine, morphine-3-glucuronide and morphine-6-glucuronide were measured in five normal volunteers after morphine administration by the intravenous route and from a novel sublingual pressurized aerosol formulation. The mean (+/- s.d.) bioavailability of the sublingual aerosol morphine was 19.7 +/- 6.7%. The morphine-3-glucuronide/morphine and the morphine-6-glucuronide/morphine ratios were 5.1 +/- 1.6 and 1.2 +/- 0.4, respectively, for the intravenous route and 28.3 +/- 11.3 and 5.2 +/- 1.4, respectively, for the sublingual route. The combined total areas under the plots of systemic concentration against time (AUC) for the metabolites after the two routes was not significantly different. When compared with published data for oral administration the results demonstrate that the sublingual aerosol morphine might provide an alternative to conventional methods of morphine delivery, and has similar pharmacokinetics to a sublingual morphine tablet. It has no particular pharmacokinetic advantages over oral morphine, except a potential for a faster onset of analgesia. Bioavailability, maximum plasma concentration, Cpmax, and the time at which the maximum plasma concentration is reached, Tmax, are equivalent to those for orally administered morphine.

Therapeutic monitoring of continuous infusion etoposide in small-cell lung cancer.

PURPOSE: To investigate the feasibility of therapeutic monitoring of etoposide at different plasma concentrations of the drug, and the resulting pharmacodynamic effects of such an approach. PATIENTS AND METHODS: Forty-nine previously untreated small-cell lung cancer (SCLC) patients received single-agent etoposide every 3 weeks by continuous infusion over 5 days. Plasma etoposide concentrations were monitored 18 and 66 hours into the infusion to permit dose modification. The first cohort of 15 patients began treatment with etoposide 2 micrograms/mL, with dose escalation to 3 micrograms/mL for cycles 3 and 4 and 4 micrograms/mL for cycles 5 and 6, toxicity permitting. The second cohort of 34 patients commenced at 3 micrograms/mL, with dose escalation to 4 and 5 micrograms/mL on cycles 3 and 5, respectively. RESULTS: Mean plasma etoposide concentration during the first treatment cycle was 93.4% +/- 26.6% of the target level at 18 hours (57% of patients within +/- 20% of the target) and 98.9% +/- 14.5% of the target level at 66 hours (82% of patients within +/- 20%). Hematologic toxicity was more pronounced in those treated with 3 micrograms/mL versus 2 micrograms/mL (median nadir neutrophil count, 1.3 v 2.6 x 10(9)/L, P = .032). Tumor responses, typically documented by the third cycle, were similar in each cohort (71% in patients commenced at 2 micrograms/mL and 70% at 3 micrograms/mL). Treatment cohort was not independently predictive of survival. CONCLUSION: Therapeutic monitoring of infusional etoposide is feasible and dramatically reduces interpatient pharmacokinetic variability. Although this was a small nonrandomized trial, the observation of different hematologic toxicity at the two starting concentrations but similar antitumor activity further suggests that these effects may be associated with different plasma etoposide concentrations.

Predicting etoposide toxicity: relationship to organ function and protein binding.

PURPOSE: To investigate the effect of organ function on total and free etoposide pharmacokinetics and hematologic toxicity. PATIENTS AND METHODS: Seventy-two patients who received single-agent intravenous (i.v.) etoposide over 5 or 8 days (total dose, 500 mg/m2) were studied. Pharmacokinetic parameters were derived after analysis of total plasma etoposide by high-performance liquid chromatography (HPLC) with ultraviolet (UV) detection, and etoposide protein binding by ultrafiltration of an etoposide-spiked, pretreatment serum sample, followed by HPLC analysis. Free etoposide area under the concentration-time curve (AUC) was derived from the total AUC and protein binding. RESULTS: Patients with renal impairment (serum creatinine level > 130 mumol/L) had a lower plasma etoposide clearance (13.6 v 18.5 mL/min/m2; P = .016), resulting in an increased total-drug and free-drug AUC (total etoposide AUC 615 v 452 micrograms/mL.hr; P = .016; free etoposide AUC 26.0 v 17.6 micrograms/mL.hr; P = .026) and increased hematologic toxicity (nadir neutrophil count 0.3 v 1.9 x 10(9)/L; P = .005). Patients with albumin levels less than 35 g/L had no change in total etoposide kinetics but had an increase in unbound etoposide (5.2% v 4.1%; P = .01), resulting in an increase in free etoposide AUC (27.5 v 16.5 micrograms/mL.hr; P = .003) and more profound toxicity (nadir neutrophil count 0.6 v 1.9 x 10(9)/L; P = .004). In patients with normal albumin and creatinine, increased toxicity in those older than 65 years was associated with a reduced drug clearance, and in those with increased liver enzymes by a trend toward an increase in free etoposide AUC. CONCLUSION: Increased hematologic toxicity after etoposide in patients with abnormal organ function is mediated by an increase in free etoposide AUC. A reduction in dose is clearly indicated in such patients.

Respiratory depression following morphine and morphine-6-glucuronide in normal subjects.

1. Morphine 6-glucuronide (M6G) is a metabolite of morphine with analgesic activity. A double-blind, randomised comparison of the effects of morphine and M6G on respiratory function was carried out in 10 normal subjects after i.v. morphine (10 mg 70 kg-1) or M6G (1, 3.3 and 5 mg 70 kg-1). Analgesic potency was also assessed using an ischaemic pain test and other toxic effects were monitored. 2. Following morphine there was a significant increase in arterial PCO2, as measured by blood gases 45 min post dose (0.54 +/- 0.24 (s.d.) kPa, P < 0.001), and in transcutaneous PCO2 from 15 min post dose until the end of the study period (4 h), whereas blood gas and transcutaneous PCO2 were unchanged after M6G at 1.0, 3.3 and 5.0 mg 70 kg-1. This increased PCO2 following morphine was associated with an increase in expired CO2 concentration (FECO2) (0.20 +/- 0.14% expired air at 15 min post dose, P = 0.002), compared with small but significant reductions in FECO2 following morphine 6-glucuronide (-0.15 +/- 0.17% at 1 mg 70 kg-1 P = 0.030, -0.14 +/- 0.15% at 3.3 mg 70 kg-1 P = 0.017, -0.18 +/- 0.11% at 5 mg 70 kg-1 P = 0.024). Maximum transcutaneous PCO2 was significantly increased after morphine (0.63 +/- 0.28 kPa P = 0.009), but was not changed after M6G at 1 mg (0.10 +/- 0.34 kPa P = 0.11) 3.3 mg (0.06 +/- 0.37 kPa P = 0.34) or 5 mg (0.26 +/- 0.07 kPa P = 0.10).(ABSTRACT TRUNCATED AT 250 WORDS)