In vitro assessment of drug-drug interaction potential of boceprevir associated with drug metabolizing enzymes and transporters

The inhibitory effect of boceprevir (BOC), an inhibitor of hepatitis C virus nonstructural protein 3 protease was evaluated in vitro against a panel of drug-metabolizing enzymes and transporters. BOC, a known substrate for cytochrome P450 (P450) CYP3A and aldo-ketoreductases, was a reversible time-dependent inhibitor (k(inact) = 0.12 minute(-1), K(I) = 6.1 µM) of CYP3A4/5 but not an inhibitor of other major P450s, nor of UDP-glucuronosyltransferases 1A1 and 2B7. BOC showed weak to no inhibition of breast cancer resistance protein (BCRP), P-glycoprotein (Pgp), or multidrug resistance protein 2. It was a moderate inhibitor of organic anion transporting polypeptide (OATP) 1B1 and 1B3, with an IC(50) of 18 and 4.9 µM, respectively. In human hepatocytes, BOC inhibited CYP3A-mediated metabolism of midazolam, OATP1B-mediated hepatic uptake of pitavastatin, and both the uptake and metabolism of atorvastatin. The inhibitory potency of BOC was lower than known inhibitors of CYP3A (ketoconazole), OATP1B (rifampin), or both (telaprevir). BOC was a substrate for Pgp and BCRP but not for OATP1B1, OATP1B3, OATP2B1, organic cation transporter, or sodium/taurocholate cotransporting peptide. Overall, our data suggest that BOC has the potential to cause pharmacokinetic interactions via inhibition of CYP3A and CYP3A/OATP1B interplay, with the interaction magnitude lower than those observed with known potent inhibitors. Conversely, pharmacokinetic interactions of BOC, either as a perpetrator or victim, via other major P450s and transporters tested are less likely to be of clinical significance. The results from clinical drug-drug interaction studies conducted thus far are generally supportive of these conclusions.

A consolidated biovigilance system for blood, tissue and organs: one size does not fit all

Biovigilance systems to assess and analyze risks for disease transmission through the transfer of organs, tissue, cells and blood between people is part of administrative oversight and has impact upon clinical practice and policy. In 2009, a formal recommendation by the Public Health Service requested that Health and Human Services fund and support efforts to consolidate national biovigilance efforts. There are differences in the biovigilance issues involved in organ and tissue donation/transplantation. If disease avoidance is made the dominant principle guiding organ donor testing, an unintended consequence may be an increase in deaths on the waiting list. We propose that overall benefit for the organ transplant recipient, tempered by patient informed awareness of limited organ availability and assessment processes, should be the guiding principle of such a system.

Establishing an appropriate mode of comparison for measuring the performance of marbling score output from video image analysis beef carcass grading systems

A beef carcass instrument grading system that improves accuracy and consistency of marbling score (MS) evaluation would have the potential to advance value-based marketing efforts and reduce disparity in quality grading among USDA graders, shifts, and plants. The objectives of this study were to use output data from the Video Image Analysis-Computer Vision System (VIA-CVS, Research Management Systems Inc., Fort Collins, CO) to develop an appropriate method by which performance of video image analysis MS output could be evaluated for accuracy, precision, and repeatability for purposes of seeking official USDA approval for using an instrument in commerce to augment assessment of quality grade, and to use the developed standards to gain approval for VIA-CVS to assist USDA personnel in assigning official beef carcass MS. An initial MS output algorithm was developed (phase I) for the VIA-CVS before 2 separate preliminary instrument evaluation trials (phases II and III) were conducted. During phases II and III, a 3-member panel of USDA expert graders independently assigned MS to 1,068 and 1,242 stationary carcasses, respectively. Mean expert MS was calculated for each carcass. Additionally, a separate 3-member USDA expert panel developed a consensus MS for each carcass in phase III. In phase II, VIA-CVS stationary triple-placement and triple-trigger instrument repeatability values (n = 262 and 260, respectively), measured as the percentage of total variance explained by carcasses, were 99.9 and 99.8%, respectively. In phases II and III, 95% of carcasses were assigned expert MS for which differences between individual expert MS, and for which the consensus MS in phase III only, was < or = 96 MS units. Two differing approaches to simple regression analysis, as well as a separate method-comparability analysis that accommodates error in both dependent and independent variables, were used to assess accuracy and precision of instrument MS predictions vs. mean expert MS. Method-comparability analysis was more appropriate in assessing the bias and precision of instrument MS predictions. Ether-extractable fat percentages (n = 257; phase II) differed among MS (P < 0.05) but were not suitable to predict or validate assigned MS. The performance and reproducibility of expert MS assignment in future evaluations was considered, and an official USDA performance standard was established, to which an instrument must conform to be approved for official on-line MS assessment. The VIA-CVS subsequently was approved to assign MS to carcasses on-line after completion of a 2006 USDA instrument approval trial conducted according to methods developed during completion of this study.

Effect of visual marbling on sensory properties and quality traits of pork loin

Pork loins (N=53) were selected from a commercial packing plant to determine the influence of subjective marbling score on sensory attributes and eating quality properties. The pork loins were obtained from commercially raised hybrid barrows (average carcass weight=67.7 kg), originating from nine cooperating herds, and fed similar diets throughout the finishing period. Carcass quality measurements, trained sensory panel analyses, fatty acid composition, thiobarbituric acid-reactive substance (TBARS) index, and cholesterol content were assessed and analyzed on the individual pork loins. With an increase in marbling level, there was a corresponding decrease in drip loss (P=0.049) and observed increases in pH (P=0.001), sensory tenderness (P=0.001), and sensory juiciness scores (P=0.017). The most notable results demonstrated that protein concentrations were reduced as marbling levels amplified (P=0.012). The increase in marbling score was observed to be a significant source of variation in polyunsaturated fatty acid (PUFA) concentrations. Linoleic and arachidonic acids decreased in both raw and cooked samples as marbling score increased. The data demonstrated that visual marbling score does have an influence on sensory properties and pork quality.

Heterocycle-substituted proline dipeptides as potent VLA-4 antagonists

A variety of N-linked tertiary amines and heteroarylamines were examined at the 4-position of sulfonylated proline dipeptides in order to improve VLA-4 receptor off-rates and overcome the issue of CYP3A4 time-dependent inhibition of ester prodrugs. A tight-binding inhibitor 5j with a long off-rate provided sustained receptor occupancy despite poor oral pharmacokinetics.

Gefitinib treatment in hormone-resistant and hormone receptor-negative advanced breast cancer

BACKGROUND

Acquired and de novo endocrine resistance in breast cancer (BC) may be associated with overexpression of epidermal growth factor receptor (EGFR). Gefinitib is an orally active selective EGFR inhibitor which might benefit advanced breast cancer (ABC) patients either with acquired hormone resistance or with hormone receptor (HR)-negative tumors.

PATIENTS AND METHODS

A two-arm multicenter phase II trial of oral gefitinib 500 mg/day was planned in two groups of 45 patients with ABC for whom chemotherapy was not currently indicated. Group 1 had hormone-resistant BC defined as HR-positive BC with progression after treatment with tamoxifen and an aromatase inhibitor. Group 2 had HR-negative BC. Tumor response was assessed every 8 weeks. The primary end point was the clinical benefit rate (CBR).

RESULTS

Forty patients with hormone-resistant BC had a CBR of 0%. Two of 25 HR-negative BC patients showed stable disease (less than a 50% reduction and less than a 25% increase in the sum of the products of two perpendicular diameters of all measured lesions and the appearance of no new lesions) at 24 weeks resulting in a CBR of 7.7% (95% CI 0.9% to 25.1%). Enrollment ceased due to the low CBR. Toxicity resulted in treatment interruption (46%), dose reduction (20%) and withdrawal (11%) of patients.

CONCLUSION

At a dose of 500 mg/day, gefitinib monotherapy resulted in a low CBR and no tumor response was identified.

The effect of endocrine responsiveness on high-risk breast cancer treated with dose-intensive chemotherapy: results of International Breast Cancer Study Group Trial 15-95 after prolonged follow-up

BACKGROUND

The role of adjuvant dose-intensive chemotherapy and its efficacy according to baseline features has not yet been established.

PATIENTS AND METHODS

Three hundred and forty-four patients were randomized to receive seven courses of standard-dose chemotherapy (SD-CT) or three cycles of dose-intensive epirubicin and cyclophosphamide (epirubicin 200 mg/m(2) plus cyclophosphamide 4 mg/m(2) with filgrastim and progenitor cell support). All patients were assigned tamoxifen at the completion of chemotherapy. The primary end point was disease-free survival (DFS). This paper updates the results and explores patterns of recurrence according to predicting baseline features.

RESULTS

At 8.3-years median follow-up, patients assigned DI-EC had a significantly better DFS compared with those assigned SD-CT [8-year DFS percent 47% and 37%, respectively, hazard ratio (HR) 0.76; 95% confidence interval 0.58-1.00; P = 0.05]. Only patients with estrogen receptor (ER)-positive disease benefited from the DI-EC (HR 0.61; 95% confidence interval 0.39, 0.95; P = 0.03).

CONCLUSIONS

After prolonged follow-up, DI-EC significantly improved DFS, but the effect was observed only in patients with ER-positive disease, leading to the hypothesis that efficacy of DI-EC may relate to its endocrine effects. Further studies designed to confirm the importance of endocrine responsiveness in patients treated with dose-intensive chemotherapy are encouraged.

In vitroandin vivoevaluation of albumin-encapsulated primaquine diphosphate prepared by nebulization into heated oil

Nebulization of an aqueous mixture of primaquine diphosphate and albumin into heated vegetable oil produces spherical particles with an average size of 6 microm. The microparticles are relatively stabile in buffers of pH 7.2 and 4.5 and completely degrade when exposed to proteolytic enzymes such as trypsin. Pharmacokinetic evaluation of the albumin-encapsulated primaquine diphosphate shows significantly higher levels in mouse liver tissue relative to free drug 2-48 h post-IP administration. Higher AUC (2.8x), lower steady-state volume of distribution (10x) and slower half-life (2.5x) relative to an equivalent dose of free primaquine diphosphate suggest liver targeting and sustained release of the drug from the microparticles.

An automated electrophysiology serum shift assay for K(V) channels

The presence of serum in biological samples often negatively impacts the quality of in vitro assays. However, assays tolerant of serum are useful for assessing the in vivo availability of a small molecule for its target. Electrophysiology assays of ion channels are notoriously sensitive to serum because of their reliance on the interaction of the plasma membrane with a recording electrode. Here we investigate the tolerance of an automated electrophysiology assay for a voltage-gated potassium (K(V)) channel to serum and purified plasma proteins. The delayed rectifier channel, K(V)2.1, stably expressed in Chinese hamster ovary cells produces large, stable currents on the IonWorks Quattro platform (MDS Analytical Technologies, Sunnyvale, CA), making it an ideal test case. K(V)2.1 currents recorded on this platform are highly resistant to serum, allowing recordings in as high as 33% serum. Using a set of compounds related to the K(V) channel blocker, 4-phenyl-4-[3-(2-methoxyphenyl)-3-oxo-2-azaprop-1-yl]cyclohexanone, we show that shifts in compound potency with whole serum or isolated serum proteins can be reliably measured with this assay. Importantly, this assay is also relatively insensitive to plasma, allowing the creation of a bioassay for inhibitors of K(V)2.1 channel activity. Here we show that such a bioassay can quantify the levels of the gating modifier, guangxitoxin-1E, in plasma samples from mice dosed with the peptide. This study demonstrates the utility of using an automated electrophysiology platform for measuring serum shifts and for bioassays of ion channel modulators.

Quality of life and quality-adjusted survival (Q-TWiST) in patients receiving dose-intensive or standard dose chemotherapy for high-risk primary breast cancer

Quality of life (QL) is an important consideration when comparing adjuvant therapies for early breast cancer, especially if they differ substantially in toxicity. We evaluated QL and Q-TWiST among patients randomised to adjuvant dose-intensive epirubicin and cyclophosphamide administered with filgrastim and progenitor cell support (DI-EC) or standard-dose anthracycline-based chemotherapy (SD-CT). We estimated the duration of chemotherapy toxicity (TOX), time without disease symptoms and toxicity (TWiST), and time following relapse (REL). Patients scored QL indicators. Mean durations for the three transition times were weighted with patient reported utilities to obtain mean Q-TWiST. Patients receiving DI-EC reported worse QL during TOX, especially treatment burden (month 3: P<0.01), but a faster recovery 3 months following chemotherapy than patients receiving SD-CT, for example, less coping effort (P<0.01). Average Q-TWiST was 1.8 months longer for patients receiving DI-EC (95% CI, -2.5 to 6.1). Q-TWiST favoured DI-EC for most values of utilities attached to TOX and REL. Despite greater initial toxicity, quality-adjusted survival was similar or better with dose-intensive treatment as compared to standard treatment. Thus, QL considerations should not be prohibitive if future intensive therapies show superior efficacy.

Antimalarial drug resistance and the importance of drug quality monitoring

The availability of counterfeit and poor quality drugs contribute to resistance and erroneous efficacy study results as well as directly affecting the health of individuals. This report describes the importance of drug quality monitoring as part of a comprehensive disease surveillance program.

Cyclohexenyl- and dehydropiperidinyl-alkynyl pyridines as potent metabotropic glutamate subtype 5 (mGlu5) receptor antagonists

Structure-activity relationship studies leading to the discovery of novel mGlu5 receptor antagonists are described. These compounds show high in vitro potency, have good in vivo receptor occupancy, and a reasonable intravenous pharmacokinetic profile.

In vitro metabolic studies on the selective metabotropic glutamate receptor sub-type 5 (mGluR5) antagonist 3-[(2-methyl-1,3-thiazol-4-yl) ethynyl]-pyridine (MTEP)

Metabotropic glutamate receptors (mGluR) are G-protein-coupled receptors that play a major role in modulatory pathways in the CNS and have been suggested to have pharmacological implications in pain, psychiatric disorders and other neurological states. 3-[(2-Methyl-1,3-thiazol-4-yl) ethynyl]-pyridine (MTEP) is a specific and selective antagonist for the mGluR sub-type 5. Previous studies using rat liver microsomes showed that the major oxidative metabolites of MTEP are a hydroxymethyl metabolite (M1), two oxides (M2 and M4), a thiazole-ring opened metabolite (M3) and CO(2) (M5). In the present study, we examined the metabolism of MTEP in liver microsomes and expressed rat and human CYP isoforms. In rat liver microsomes, metabolic stability studies accurately predicted the in vivo clearance for MTEP. Incubation of MTEP with expressed rat and human CYP isoforms showed that CYP1A and CYP2C isoforms are primarily responsible for the metabolism of this compound. The results suggest that species differences in MTEP metabolism is possible and could contribute to specie-differences in biological effects of the compound.

Fake antimalarials in Southeast Asia are a major impediment to malaria control: multinational cross-sectional survey on the prevalence of fake antimalarials

OBJECTIVE

To assess the prevalence of counterfeit antimalarial drugs in Southeast (SE) Asia.

DESIGN

Cross-sectional survey.

SETTING

Pharmacies and shops selling antimalarial drugs in Myanmar (Burma), Lao PDR, Vietnam, Cambodia and Thailand.

MAIN OUTCOME MEASURES

Proportion of artemisinin derivatives or mefloquine containing drugs of substandard quality.

RESULTS

Of the 188 tablet packs purchased which were labelled as 'artesunate' 53% did not contain any artesunate. All counterfeit artesunate tablets were labelled as manufactured by 'Guilin Pharma', and refinements of the fake blisterpacks made them often hard to distinguish from their genuine counterparts. No other artemisinin derivatives were found to be counterfeited. Of the 44 mefloquine samples, 9% contained <10% of the expected amount of active ingredient.

CONCLUSIONS

An alarmingly high proportion of antimalarial drugs bought in pharmacies and shops in mainland SE Asia are counterfeit, and the problem has increased significantly compared with our previous survey in 1999-2000. This is a serious threat to public health in the region.

Synthesis, characterization, and first successful monkey imaging studies of metabotropic glutamate receptor subtype 5 (mGluR5) PET radiotracers

Three metabotropic glutamate receptor subtype 5 (mGluR5) PET tracers have been labeled with either carbon-11 or fluorine-18 and their in vitro and in vivo behavior in rhesus monkey has been characterized. Each of these tracers share the common features of high affinity for mGluR5 (0.08-0.23 nM vs. rat mGluR5) and moderate lipophilicity (log P 2.8-3.4). Compound 1b was synthesized using a Suzuki or Stille coupling reaction with [11C]MeI. Compounds 2b and 3b were synthesized by a SNAr reaction using a 3-chlorobenzonitrile precursor. Autoradiographic studies in rhesus monkey brain slices using 2b and 3b showed specific binding in cortex, caudate, putamen, amygdala, hippocampus, most thalamic nuclei, and lower binding in the cerebellum. PET imaging studies in monkey showed that all three tracers readily enter the brain and provide an mGluR5-specific signal in all gray matter regions, including the cerebellum. The specific signal observed in the cerebellum was confirmed by the autoradiographic studies and saturation binding experiments that showed tracer binding in the cerebellum of rhesus monkeys. In vitro metabolism studies using the unlabeled compounds showed that 1a, 2a, and 3a are metabolized slower by human liver microsomes than by monkey liver microsomes. In vivo metabolism studies showed 3b to be long-lived in rhesus plasma with only one other more polar metabolite observed.

Five years managing metastatic non-small cell lung cancer: experience at a teaching hospital

BACKGROUND

The management of patients with metastatic non-small cell lung cancer (NSCLC) is complex. Some studies have demonstrated that the care of patients with NSCLC may be suboptimal.

AIM

To review the management of patients with metastatic NSCLC treated at a single teaching hospital over a 5-year period.

METHOD

All patients with metastatic NSCLC treated at a single teaching hospital over a 5-year period (1998-2002) were identified. Data were collected by a retrospective record review.

RESULTS

Of 343 patients with metastatic NSCLC, 157 patients were deemed eligible for this review. Thirty-one patients (19%) were admitted to the Medical Oncology Unit at initial presentation. Twenty-four patients (15%) were not referred to either the Medical Oncology Unit or the Palliative Care Unit. Forty-four patients (28%) received chemotherapy, six of whom (14%) were enrolled onto a clinical trial. Six separate chemotherapy regimens were used. The median survival was 5 months and the 1-year survival rate was 19.8%.

CONCLUSIONS

The present audit demonstrates some shortfalls in the optimal clinical care of patients with metastatic NSCLC at a large teaching hospital. The main selection criteria of consideration for chemotherapy are age, performance status and presence of symptoms. A subset of patients was not referred to either the Medical Oncology Unit or the Palliative Care Unit and consistency in the choice of chemotherapy was lacking. Survival data and the rate of patients entered onto clinical trials are acceptable; however, further improvements can be made by the institution of multidisciplinary clinics and the education of referring clinicians.

Inhibition of human hepatic CYP isoforms by mGluR5 antagonists

Characterization of new chemical entities for their potential to produce drug-drug interactions is an important aspect of early drug discovery screening. In the present study, the potential for three metabotropic glutamate receptor antagonists to interact with recombinant human CYPs was investigated. 2-Methyl-6-(phenylethenyl) pyridine (SIB-1893), 2-methyl-6-(phenylethynyl) pyridine (MPEP) and 3-[2-methyl-1,3-thiazol-4-yl) ethynyl]-pyridine (MTEP) were moderate competitive inhibitors of recombinant human CYP1A2 (Ki, 0.5-1 microM). SIB-1893, but not MPEP or MTEP, was also a moderate competitive inhibitor of CYP1B1. MPEP and MTEP were weak inhibitors of CYP2C19. None of the three compounds tested were significant inhibitors (IC(50) values >50 microM) of CYP3A4, 2C9, 2D6, 2A6, 2B6 or 2E1. The results suggest that MTEP is a selective inhibitor of CYP1A2 and may prove to be a useful tool in studying drug-drug interactions involving this enzyme.

A randomized double-blind multicenter phase III study of fixed-dose single-administration pegfilgrastim versus daily filgrastim in patients receiving myelosuppressive chemotherapy

BACKGROUND

We evaluated the efficacy of a single fixed 6 mg dose of pegfilgrastim (a pegylated version of filgrastim) per cycle of chemotherapy, compared with daily administration of filgrastim, in the provision of neutrophil support.

PATIENTS AND METHODS

Patients (n = 157) were randomized to receive either a single 6 mg subcutaneous (s.c.) injection of pegfilgrastim or daily 5 mg/kg s.c. injections of filgrastim, after doxorubicin and docetaxel chemotherapy (60 mg/m(2) and 75 mg/m(2), respectively). Duration of grade 4 neutropenia, depth of neutrophil nadir, incidence of febrile neutropenia, time to neutrophil recovery and safety information were recorded.

RESULTS

A single 6 mg injection of pegfilgrastim was as effective as daily injections of filgrastim for all efficacy measures for all cycles. The mean duration of grade 4 neutropenia in cycle 1 was 1.8 and 1.6 days for the pegfilgrastim and filgrastim groups, respectively. Results for all efficacy end points in cycles 2-4 were consistent with the results from cycle 1. A trend towards a lower incidence of febrile neutropenia was noted across all cycles with pegfilgrastim compared with filgrastim (13% versus 20%, respectively). A single fixed dose of pegfilgrastim was as safe and well tolerated as standard daily filgrastim.

CONCLUSIONS

A single fixed dose of pegfilgrastim administered once per cycle of chemotherapy was comparable to multiple daily injections of filgrastim in safely providing neutrophil support during myelosuppressive chemotherapy. Pegfilgrastim may have utility in other clinical settings of neutropenia.

Treatment with the novel anti-angiogenic agent PI-88 is associated with immune-mediated thrombocytopenia

BACKGROUND

The novel molecule PI-88 is a highly sulfonated oligosaccharide which inhibits heparanase activity and competes with heparan sulfate binding of growth factors such as FGF and VEGF. Preclinical data demonstrates that PI-88 inhibits angiogenesis and has anti-metastatic effects. The aim of this phase I study was to determine the recommended dose and toxicity profile of PI-88.

PATIENTS AND METHODS

PI-88 was given intravenously in increasing duration of administration (0.57 mg/kg for 2 h, 0.57 mg/kg/day for 1 day, 4, 7 and 14 consecutive days) and then increasing dose for 14 consecutive days (1.14 mg/kg/day and 2.28 mg/kg/day) in patients with advanced malignancies until dose-limiting toxicity (DLT) was observed. Fourteen assessable patients with advanced malignancies received PI-88 intravenously.

RESULTS

DLT was thrombocytopenia. The thrombocytopenia appeared to be immunologically mediated with the development of anti-heparin platelet factor 4 complex antibodies. There were no other significant toxicities. At the final dose and schedule (2.28 mg/kg/day for 14 days), there was limited evidence of biological activity as measured by the surrogate marker activated partial thromboplastin time (APTT), although two patients had stabilisation of disease.

CONCLUSIONS

In conclusion, PI-88 at a dose of 2.28 mg/kg/day for 14 days resulted in dose-limiting thrombocytopenia which appeared to be immune related. Limited evidence of biological activity was noted. Alternate scheduling and routes of administration are now being explored.

Expression of UGT2B7, a UDP-glucuronosyltransferase implicated in the metabolism of 4-hydroxyestrone and all-trans retinoic acid, in normal human breast parenchyma and in invasive and in situ breast cancers

Glucuronidation, mediated by UDP-glucuronosyltransferases (UGTs), affects the actions and disposition of diverse endo- and xenobiotics. In the case of catecholestrogens (CEs), glucuronidation is likely to block their oxidation to quinone estrogens that are the putative mediators of CEs' actions as initiators of cancers. The goal of this study was to determine whether UGT2B7, the isoenzyme with a high affinity for 4-hydroxyestrone, is expressed in human breast parenchyma. Glucuronidation of 4-hydroxyestrone has relevance to breast carcinogenesis because quinone metabolites of 4-hydroxylated CEs can form potentially mutagenic depurinating DNA adducts, and because in breast tissue estrone is likely to be the predominant estrogen available for 4-hydroxylation. Using reverse transcriptase-polymerase chain reaction, immunocytochemistry, immunoblot analyses, and assays of glucuronidation of 4-hydroxyestrone, we show that UGT2B7 is expressed in human mammary epithelium, and that its expression is dramatically reduced in invasive breast cancers. In many in situ carcinomas, however, 4-hydroxyestrone immunostaining was not only preserved but even more intense than in normal mammary epithelium. The finding of reduced UGT2B7 protein and glucuronidation of 4-hydroxyestrone in invasive cancers suggests a tumor-suppressor function for the enzyme. Recent identification of all-trans retinoic acid as a substrate of UGT2B7 suggests that this function includes the generation of retinoyl-beta-glucuronide, a potent mediator of actions of retinoids important for maintaining epithelia in a differentiated state. Current knowledge does not provide any ready explanation for the apparent increase in UGT2B7 expression in carcinomas in situ. However, this finding, together with reduced immunostaining at loci showing breach of the basement membrane (microinvasion), suggests involvement of UGT2B7-catalyzed reaction(s) in protection against invasion of surrounding tissue by cancer cells.

Estrogen replacement therapy: a perspective on cognitive impact

Studies suggest that use of estrogen replacement therapy (ERT) after menopause may be beneficial toward preservation of cognitive functioning. However, potentially confounding variables such as alcohol consumption are typically not systematically considered. The purpose of this study was to determine whether ERT users and nonusers differ with regard to memory and concentration ability when potential confounds are eliminated. Alcohol consumption was included as an independent variable so that ERT by alcohol interactions could be examined. One-hundred-sixty-two postmenopausal women participated in the study and were classified as moderate drinkers or teetotalers. Logical Memory (Wechsler Memory Scale-Revised), Digit Span (Wechsler Adult Intelligence Scale-Revised) and the Cognitive Symptom Checklist-Memory subscale were administered. No main effects of ERT were found. However, ERT by alcohol interactions among some Digit Span Forward variables were observed. We conclude that confounding variables such as alcohol consumption, may be at least partly responsible for observed differences in cognition commonly attributed to ERT.

Authentication of artemether, artesunate and dihydroartemisinin antimalarial tablets using a simple colorimetric method

The recent and widespread appearance of counterfeit antimalarial tablets in South-east Asia prompted the search for simple field assays to identify genuine drugs. In a recently described colorimetric assay for artesunate, Fast red TR salt reacted with an alkali-decomposition product of artesunate to produce a distinct yellow colour. However, that assay is specific for artesunate and it cannot be used to test for artemether. Because of potential concerns over artemether tablet counterfeiting, the colorimetric assay was modified to detect artemether, dihydroartemisinin and artesunate tablets. Other common antimalarials (artemisinin, chloroquine diphosphate, mefloquine HCl, sulphadoxine and pyrimethamine), as well as aspirin and acetaminophen, were negative in the assay, indicating its specificity for artemether, dihydroartemisinin and artesunate. The colorimetric method can be used to obtain a rapid visual assessment of tablet authenticity. The method can also be used to quantify the drug content of tablets, when used in conjunction with a spectrophotometer.

Efficacy of mefloquine and sulfadoxine-pyrimethamine for the treatment of uncomplicated Plasmodium falciparum infection in Machinga District, Malawi, 1998

In response to the spread of chloroquine-resistant Plasmodium falciparum, Malaŵi changed its first-line antimalarial drug in 1993 from chloroquine to sulfadoxine-pyrimethamine (SP). Surveillance data has suggested that resistance to SP may be increasing. We compared the efficacy of SP with a potential successor, mefloquine (MQ). By use of a modified World Health Organization in vivo protocol, children infected with P. falciparum were randomized to receive SP (sulfadoxine 25 mg/kg) or MQ (15 mg/kg). We observed combined RII and RIII parasitologic failures of 20.0 and 22.0% in the SP and MQ arms, respectively. Among those in the MQ arm, the relative hazard of failing with a Day 2 drug level < 500 ng/mL was 10.6 times higher than those with levels > or = 500 ng/mL. Given the decreased efficacy of the first-line antimalarial drug and the high failure rates of MQ at this lower dosage, Malaŵi should consider assessing the efficacy and feasibility of alternative drugs to treat uncomplicated falciparum malaria.

Phase II clinical trial of preoperative combined chemoradiation for T3 and T4 resectable rectal cancer: preliminary results

PURPOSE

Although preoperative chemoradiation for high-risk rectal cancer may improve survival and local recurrence rate, its adverse effects are not well defined. This prospective study evaluated the use of preoperative chemoradiation for T3 and T4 resectable rectal cancer, with special emphasis on treatment morbidity, pathologic remission rate, quality of life, and anorectal function.

METHODS

Forty-two patients (30 men, 12 women) were enrolled in the study. Median distance of the distal tumor margin from the anal verge was 6.5 cm. Preoperative staging was based on digital rectal examination, endorectal ultrasound, and computed tomography. None of the patients had distant metastases. All patients had 45 Gy (1.8 Gy/day in 25 fractions) over five weeks, plus 5-fluorouracil (350 mg/m(2)/day) and leucovorin (20 mg/m(2)/day) bolus on days 1 to 5 and 29 to 33. Quality of life was assessed with the European Organization for Research and Treatment of Cancer 30-item quality-of-life questionnaire (QLQ-C30) and its colorectal cancer-specific module (QLQ-CR38) questionnaires. Objective anorectal function was assessed by anorectal manometry and pudendal nerve terminal motor latency. Surgery was performed 46 (range, 24-63) days after completion of adjuvant therapy.

RESULTS

Nineteen patients (45 percent) had Grade 3 or 4 chemoradiation-induced toxic reactions. Four patients developed intercurrent distant metastases or intraperitoneal carcinomatosis at completion of chemoradiation. Thirty-eight patients underwent surgical resection: abdominoperineal resection, anterior resection, and Hartmann's procedure were performed in 55 percent, 39 percent (11 of 15 patients had a diverting stoma), and 5 percent, respectively. Major surgical complications occurred in 7 patients (18 percent) and included anastomotic leak (n = 1), pelvic abscess (n = 1), small-bowel obstruction (n = 3), and wound breakdown (n = 2). Final pathology was Stage 0 (no residual disease), I, II, and III in 6 (16 percent), 7 (18 percent), 9 (24 percent), and 16 (42 percent) patients, respectively. There was a deterioration, after chemoradiation and surgery, in the quality of life on all subscales assessed, with physical, role, and social function being most severely affected. The symptoms most adversely affected were micturition, defecation, and gastrointestinal problems. Body image and sexual enjoyment deteriorated in both men and women. Chemoradiation alone led to prolonged pudendal nerve terminal motor latency in 57 percent of 7 patients assessed.

CONCLUSION

Preliminary results have identified defined costs with preoperative chemoradiation, which included treatment-induced toxicity, a high stoma rate, and adverse effects on quality of life and anorectal function.

Analysis of Opioid Binding to UDP-Glucuronosyltransferase 2B7 Fusion Proteins Using Nuclear Magnetic Resonance Spectroscopy

The UDP-glucuronosyltransferase UGT2B7 is an important human UGT isoform that catalyzes the conjugation of many endogenous and exogenous compounds, among them opioids, resulting in the formation of D-glucuronides. The binding site of the aglycone is located in the N-terminal half of the protein. In this study, we demonstrate that the opioid binding site in UGT2B7 is within the first 119 amino-terminal amino acids. Two maltose binding protein fusion proteins, 2B7F1 and 2B7F2, incorporating the first 157 or 119 amino acids, respectively, of UGT2B7 were expressed in Escherichia coli and purified by affinity chromatography. NMR spectroscopy using one-dimensional spectra, the inversion recovery method, and the transferred nuclear Overhauser effect spectroscopy was used to study the binding properties of opioids to the fusion proteins. Morphine was found to bind at a single site within the first 119 amino acids and to undergo a conformational change upon binding, as demonstrated by transferred nuclear Overhauser effect spectroscopy. Dissociation constants were obtained for morphine, naloxone, buprenorphine, and zidovudine, and the results were confirmed by equilibrium dialysis determinations. Two possible opioid binding sites, based on the nearest neighbors from opioid binding to the micro-receptor and to cytochrome 2D6, are proposed.

Epirubicin glucuronidation is catalyzed by human UDP-glucuronosyltransferase 2B7

Epirubicin is one of the most active agents for breast cancer. The formation of epirubicin glucuronide by liver UDP-glucuronosyltransferase (UGT) is its main inactivating pathway. This study aimed to investigate epirubicin glucuronidation in human liver microsomes, to identify the specific UGT isoform for this reaction, and to correlate epirubicin glucuronidation with other UGT substrates. Microsomes from human livers were used. UGTs specifically expressed in cellular systems, as well as two UGT2B7 variants, were screened for epirubicin glucuronidation. Epirubicin, morphine, and SN-38 glucuronides were measured by high-pressure liquid chromatography. The mean +/- S.D. formation rate of epirubicin glucuronide in human liver microsomes (n = 47) was 138 +/- 37 pmol/min/mg (coefficient of variation, 24%). This phenotype was normally distributed. We screened commercially available UGT1A1, UGT1A3, UGT1A4, UGT1A6, UGT1A9, UGT2B7, and UGT2B15 for epirubicin glucuronidation. Only UGT2B7 converted epirubicin to its glucuronide. No differences in epirubicin glucuronidation were found in HK293 cells expressing the two UGT2B7 variants at position 268. Catalytic efficiency (V(max)/K(m)) of epirubicin glucuronidation was 1.4 microl/min/mg, a value higher than that observed for morphine, a substrate of UGT2B7. Formation of epirubicin glucuronide was significantly related to that of morphine-3-glucuronide (r = 0.76, p < 0.001) and morphine-6-glucuronide (r = 0.73, p < 0.001). No correlation was found with SN-38, a substrate of UGT1A1 (r = 0.04). UGT2B7 is the major human UGT catalyzing epirubicin glucuronidation, and UGT2B7 is the candidate gene for this phenotype. The reported tyrosine to histidine polymorphism in UGT2B7 does not alter the formation rate of epirubicin glucuronide, and undiscovered genetic polymorphisms in UGT2B7 might change the metabolic fate of this important anticancer agent.

Phase I and pharmacokinetic study of photodynamic therapy for high-grade gliomas using a novel boronated porphyrin

PURPOSE

To determine the recommended dose, toxicity profile, and pharmacokinetics of a novel boronated porphyrin (BOPP) for photodynamic therapy (PDT) of intracranial tumors.

PATIENTS AND METHODS

BOPP was administered alone in increasing doses (0.25, 0.5, 1.0, 2.0, 4.0, or 8.0 mg/kg) preoperatively in patients with intracranial tumors undergoing postresection PDT until dose-limiting toxicity (DLT) was observed.

RESULTS

Twenty-nine assessable patients with intracranial tumors received BOPP intravenously 24 hours before surgery. The recommended dose was 4 mg/kg. Dose escalation was limited by thrombocytopenia. The most common nonhematologic toxicity was skin photosensitivity. Pharmacokinetic parameters showed increased area under the plasma concentration-time curve and maximum concentration with increased dose. Tumor BOPP concentrations also increased with increased dose.

CONCLUSION

BOPP at a dose of 4 mg/kg was well tolerated. DLT was thrombocytopenia, and photosensitivity was the only other toxicity of note. The efficacy of PDT using BOPP requires further exploration.

A colorimetric field method to assess the authenticity of drugs sold as the antimalarial artesunate

Artesunate is the most widely used of the artemisinin derivatives. These drugs are being used increasingly throughout the tropical world, and are an essential component of the treatment of multi-drug resistant malaria. The recent and widespread appearance of counterfeit artesunate tablets in several countries in Southeast Asia poses a serious threat to health in this region. We have developed a simple, inexpensive colorimetric test to determine artesunate authenticity in tablets. The test is based on a reaction between an alkali decomposition product of artesunate and a diazonium salt, fast red TR (FRTR). The appearance of a yellow color indicates the presence of artesunate. The specificity of the test is dependent on the pH of the reaction. Among other antimalarials tested, (i.e. artemisinin, artemether, chloroquine, quinine, primaquine, sulfadoxine, and pyrimethamine) only artesunate produced a positive color reaction at pH 4. The assay requires only 1% of the total weight of a standard tablet containing 50 mg of artesunate and can be completed within 10 min. The method was tested on six genuine artesunate tablets and six counterfeit artesunate tablets obtained in Southeast Asia. The average amount of artesunate in the genuine tablets was determined to be 50.8 +/- 2.9 mg while the counterfeit tablets were found to contain no artesunate.

Malaria in Brazilian military personnel deployed to Angola

BACKGROUND

Malaria represents one of the most important infectious disease threats to deployed military forces; most personnel from developed countries are nonimmune personnel and are at high risk of infection and clinical malaria. This is especially true for forces deployed to highly-endemic areas in Africa and Southeast Asia where drug-resistant malaria is common.

METHODS

We conducted an outbreak investigation of malaria cases in Angola where a total of 439 nonimmune Brazilian troops were deployed for a 6-month period in 1995-1996. A post-travel medical evaluation was also performed on 338 (77%) of the 439 soldiers upon return to Brazil. Questionnaire, medical record, thick/thin smear, and serum anti-Plasmodium falciparum antibody titer (by IFA) data were obtained. Peak serum mefloquine (M) and methylmefloquine (MM) metabolite levels were measured in a subsample of 66 soldiers (42 cases, 24 nonmalaria controls) who were taking weekly mefloquine prophylaxis (250 mg).

RESULTS

Seventy-eight cases of malaria occurred among the 439 personnel initially interviewed in Angola (attack rate = 18%). Four soldiers were hospitalized, and 3 subsequently died of cerebral malaria. Upon return to Brazil, 63 (19%) of 338 soldiers evaluated were documented to have had clinical symptoms and a diagnosis of malaria while in Angola. In addition, 37 (11%) asymptomatically infected individuals were detected upon return (< 1% parasitemia). Elevated, post-travel anti-P. falciparum IFA titers (> or = 1:64) were seen in 101 (35%) of 292 soldiers tested, and was associated with a prior history of malaria in-country (OR = 3.67, 95% CI 1.98-6.82, p <.001). Noncompliance with weekly mefloquine prophylaxis (250 mg) was associated with a malaria diagnosis in Angola (OR = 3.75, 95% CI 0.97-17.41, p =.03) but not with recent P. falciparum infection (by IFA titer). Mean peak levels (and ratios) of serum M and MM were also found to be lower in those who gave a history of malaria while in Angola.

CONCLUSIONS

Malaria was a significant cause of morbidity among Brazilian Army military personnel deployed to Angola. Mefloquine prophylaxis appeared to protect soldiers from clinical, but not subclinical, P. falciparum infections. Mefloquine noncompliance and an erratic chemoprophylaxis prevention policy contributed to this large outbreak in nonimmune personnel. This report highlights the pressing need for development of newer, more efficacious and practical, prophylactic drug regimens that will reduce the malaria threat to military forces and travelers.

UDP-glucuronosyltransferases

Glucuronidation represents a major pathway which enhances the elimination of many lipophilic xenobiotics and endobiotics to more water-soluble compounds. The UDP-glucuronosyltransferase (UGT) family catalyzes the glucuronidation of the glycosyl group of a nucleotide sugar to an acceptor compound (aglycone) at a nucleophilic functional group of oxygen (eg, hydroxyl or carboxylic acid groups), nitrogen (eg, amines), sulfur (eg, thiols), and carbon, with the formation of a beta-D-glucuronide product. At this time, over 35 different UGT gene products have been described from several different species. UGTs have been divided into two distinct subfamilies based on sequence identities, UGT1 and UGT2. The UGT1 gene subfamily consists of a number of UGTs that result from alternate splicing of multiple first exons and share common exons 2-5. The substrate specificities of the various isoforms have been examined in cultured cell experiments, and include bilirubin, amines, and planar and bulky phenol. The UGT2 gene family is different in that the UGT2 mRNAs are transcribed from individual genes. The UGT2 subfamily consists of numerous enzymes which catalyze the glucuronidation of a diverse chemical base including steroids, bile acids, and opioids. Until recently, the liver has been the major focus for studying the metabolism of xenobiotics and endobiotics. Several groups have identified extrahepatic tissues that express UGT isoforms including the kidney, gastrointestinal tract and brain. This review discusses the two UGT gene families, substrate specificities, and the recent discoveries of UGTs in extrahepatic tissues.

Enhancement of platelet recovery after myelosuppressive chemotherapy by recombinant human megakaryocyte growth and development factor in patients with advanced cancer

PURPOSE

To explore the influence of dose and schedule on the ability of pegylated recombinant human megakaryocyte growth and development factor (PEG-rHuMGDF) to abrogate thrombocytopenia after multiple cycles of chemotherapy and to mobilize peripheral-blood progenitor cells (PBPC).

PATIENTS AND METHODS

In this open-label study, 68 patients with advanced cancer were randomized to receive PEG-rHuMGDF subcutaneously at different doses and durations before administration of carboplatin 600 mg/m(2), cyclophosphamide 1,200 mg/m(2), and filgrastim 5 microgram/kg/d. PEG-rHuMGDF was not given after the first cycle of chemotherapy but was given after the second and subsequent cycles. Chemotherapy was given every 28 days for up to six cycles.

RESULTS

In patients who received the same dose of chemotherapy for at least two cycles, the platelet nadir was significantly higher (47.5 x 10(9)/L v 35.5 x 10(9)/L; P =.003) and duration of grade 3 or 4 thrombocytopenia significantly shorter (0 v 3 days; P =.004) when PEG-rHuMGDF was administered after chemotherapy. There was no evidence of an effect of PEG-rHuMGDF when it was given before chemotherapy. Platelet recovery after the first cycle of chemotherapy was no different for different PEG-rHuMGDF regimens, and there was no difference between patients treated with PEG-rHuMGDF and historical controls treated with identical chemotherapy. There was a modest dose-related increase in progenitor cell levels after administration of PEG-rHuMGDF alone. Peak levels of PBPC occurred later in cycle 2 than in cycle 1 but were not different in magnitude.

CONCLUSION

PEG-rHuMGDF abrogated severe thrombocytopenia after dose-intensive chemotherapy. However, it had only a modest effect on progenitor cell levels and did not enhance progenitor cell mobilization after chemotherapy and filgrastim.

Comparative N-glucuronidation kinetics of ketotifen and amitriptyline by expressed human UDP-glucuronosyltransferases and liver microsomes

Like other basic amphiphilic drugs, the (S)-enantiomer of the antiallergic drug ketotifen exhibited biphasic kinetics when it was converted to two isomeric quaternary ammonium-linked glucuronides in human liver microsomes. For (R)-ketotifen this applied when incubations were carried out in the absence of a detergent. Two UDP-glucuronosyltransferases (UGTs) present in human liver, UGT1A4 and UGT1A3, were previously shown to catalyze tertiary amine N-glucuronidation when expressed in HK293 cells. Therefore, the conjugation kinetics of (R)- and (S)-ketotifen were investigated with the two expressed proteins. When homogenates of HK293 cells expressing UGT1A4 were incubated without detergent, N-glucuronidation kinetics were monophasic with K(M) values of 59 +/- 5 microM for (R)- and 86 +/- 26 microM for (S)-ketotifen. In experiments with membranes containing expressed UGT1A3, somewhat higher K(M) values were obtained. These values correspond to the high rather than to the low K(M) components of ketotifen glucuronidation in liver microsomes, the latter exhibiting K(M) values around 2 and 1 microM, respectively, with (R)- and (S)-ketotifen. With amitriptyline as the substrate, N-glucuronidation kinetics in the absence of detergent were biphasic in human liver microsomes and monophasic with a high K(M) value in cell homogenates containing UGT1A4. The results suggest that UGT1A4 and UGT1A3 catalyze high-K(M) N-glucuronidation of tertiary amine drugs, whereas the low-K(M) reaction requires either an alternative enzyme or a special conformation of UGT1A4 or UGT1A3 that can be attained in liver microsomes, but not in HK293 cell membranes.

Prescription drugs, alternative designs, and the Restatement (Third): preliminary reflections

This Article is based upon a presentation given at Seton Hall University School of Law's Seventh Annual Health Law Symposium on February 12, 1999.

3'-azido-3'-deoxythimidine (AZT) is glucuronidated by human UDP-glucuronosyltransferase 2B7 (UGT2B7)

3'-Azido-3'-deoxythymidine (AZT) is frequently prescribed to patients infected with the human immunodeficiency virus. After absorption, AZT is rapidly metabolized into 3'-azido-3'-deoxy-5'-glucuronylthymidine by UDP-glucuronosyltransferase (UGT) enzymes. Using labeled [(14)C]UDP-glucuronic acid and microsomal preparations from human kidney 293 cells stably expressing the different human UGT2B isoenzymes, it was demonstrated that AZT glucuronidation is catalyzed specifically by human UGT2B7. The identity of the metabolite formed was confirmed as AZT-G by liquid chromatography coupled with mass spectrometry. UGT2B7 is encoded by a polymorphic gene and kinetic analysis of AZT glucuronidation by the two allelic variants UGT2B7(H(268)) and UGT2B7(Y(268)), yielded apparent K(m) values of 91.0 and 80.1 microM, respectively. Normalization to protein levels yielded glucuronidation efficiency ratios (V(max)/K(m)) of 21.3 and 11.0 microl. min(-1). mg protein(-1) for UGT2B7(H(268)) and UGT2B7(Y(268)), respectively. It remains possible that other UGT enzymes are also involved in AZT conjugation; however, the glucuronidation of AZT by UGT2B7, which is a UGT2B protein expressed in the liver, is consistent with previous findings and supports the physiological relevance of this enzyme in AZT conjugation.

A phase I and pharmacokinetic study of subcutaneously-administered recombinant human interleukin-4 (rhuIL-4) in patients with advanced cancer

PURPOSE

To investigate the pharmacokinetics and tolerability of recombinant human interleukin-4 (rhuIL-4), administered by daily subcutaneous injection, in patients with advanced cancer.

PATIENTS AND METHODS

Fourteen patients with advanced cancer treated with rhuIL-4 at escalating dose levels of 0.25, 1.0 and 5.0 microg/kg/day, on days 1, 8-17, and 28-57. The primary endpoints of the study were toxicity of rhuIL-4 and the determination of the pharmacokinetics of rhuIL-4 when given by subcutaneous injection. Secondary endpoints included effects on blood counts, hematopoietic cell precursors, and various immunologic parameters.

RESULTS

rhuIL-4 was well tolerated at all three dose levels. Detectable serum levels of IL-4 were found in patients at the 1.0 and 5.0 microg/kg/day dose levels. Peak serum IL-4 levels were achieved about 2 h after injection and IL-4 was still detectable 8 h after injection. No grade 4 toxicities were observed and grade 3 toxicities were confined to fever, headache and raised hepatic alkaline phosphatase. No consistent hematological or immunologic effects were observed. Although therapeutic efficacy was not an endpoint, one complete response (Hodgkin's disease) was observed. One patient with chronic lymphocytic leukemia progressed on therapy.

CONCLUSION

rhuIL-4 up to 5.0 microg/kg/day is well tolerated when given by subcutaneous injection. Biologically relevant serum IL-4 levels can be achieved and sustained for at least 8 h after a single injection.

KRN8602 (MX2-hydrochloride): an active new agent for the treatment of recurrent high-grade glioma

PURPOSE

To assess the efficacy and toxicity of KRN8602 when administered as an intravenous bolus to patients with recurrent high-grade malignant glioma.

PATIENTS AND METHODS

Patients with recurrent or persistent anaplastic astrocytoma or glioblastoma multiforme who had not received recent chemotherapy or radiotherapy and were of good performance status (Eastern Cooperative Oncology Group score < or = 2) were treated with an intravenous bolus of 40 mg/m(2) KRN8602 every 28 days. Tumor responses were assessed radiologically and clinically after every second cycle of therapy. Treatment was continued until documented progression or a total of six cycles.

RESULTS

A median of three cycles (range, one to six cycles) of KRN8602 was administered to 55 patients, 49 of whom received at least two cycles and were, therefore, assessable for response. The overall response rate (disease stabilization or better) was 43% (95% confidence interval, 29% to 58%). There were three complete responses, one partial response, seven minor responses, and 10 patients with stable disease. The median time to progression was 2 months (range, 1.5 to 37 months) and overall survival was 11 months (range, 1.5 to 40 months). Neutropenia was the most common toxicity, although it was generally of brief duration, and there were only seven episodes of febrile neutropenia in 176 cycles delivered. Nonhematologic toxicity was mostly gastrointestinal (nausea and vomiting, diarrhea) and events were grade 2 or lower except for a single episode of grade 3 vomiting.

CONCLUSION

KRN8602 is an active new agent with minimal toxicity in the treatment of relapsed or refractory high-grade glioma. Further studies with KRN8602 in combination with other cytotoxics and in adjuvant treatment of gliomas are warranted.

Phase I and subsequent phase II study of filgrastim (r-met-HuG-CSF) and dose intensified cyclophosphamide plus epirubicin in patients with non-Hodgkin's lymphoma and advanced solid tumors

BACKGROUND

To define a maximum tolerated dose (MTD) for the combination of epirubicin and cyclophosphamide with filgrastim (r-met-HuG-CSF) in patients with advanced solid tumors and non-Hodgkin's lymphoma (NHL).

PATIENTS AND METHODS

Thirty-five patients with advanced solid tumors were enrolled in stages I and II. Twenty-one patients were treated in stage I in sequential cohorts of at least three patients at increasing dosage levels of cyclophosphamide and epirubicin, for up to six cycles every 21 days. At the completion of stage I, a MTD for epirubicin was established. Fourteen patients were treated in stage II, in cohorts of three or more. The epirubicin dose remained constant at the MTD dosage from stage I. Cyclophosphamide was further dose-escalated to establish its MTD. Twenty-one patients with previously untreated non-Hodgkin's lymphoma were treated in stage III with the MTD established in the prior stages.

RESULTS

The MTD in stage I was epirubicin 150 mg/m2 and cyclophosphamide 1500 mg/m2 with cumulative neutropenia as the dose-limiting toxicity (DLT). Cumulative thrombocytopenia prevented further dose-escalation of cyclophosphamide in stage II. The stage III regimen consisted of six, 21-day cycles of epirubicin 150 mg/m2, cyclophosphamide 1500 mg/m2, vincristine 2 mg, and prednisolone 100 mg for five days with filgrastim support. Nineteen of twenty-one patients (90%) completed six cycles of treatment, eight (38%) without dose reduction. Common toxicity criteria (CTC) grade 4 neutropenia (neutrophil nadir < 0.5 x 10(9)/l) was documented in 85 of 118 cycles (72%). Neutropenic fever was documented in 17 of 21 patients (81%) on at least one occasion. Severe thrombocytopenia (< 25 x 10(9)/l) was seen in fourteen of 118 cycles (12%) and increased with cycle number. There was no significant non-hematological toxicity.

CONCLUSION

Significant dose-escalation of epirubicin and cyclophosphamide was possible with filgrastim support. The MTD achieved was approximately double that of standard-dose therapy. This study forms the basis of an ongoing randomized study evaluating dose-intensification in intermediate grade NHL.

Differential glucuronidation of bile acids, androgens and estrogens by human UGT1A3 and 2B7

In this work, UDP-glucuronosyltransferases (UGTs), UGT1A3, 2B7(H268) and 2B7(Y268), stably expressed in human embryonic kidney cells (HK293) were used to assess glucuronidation activities with a variety of steroid hormone and bile acid substrates. The rate of synthesis of carboxyl- and hydroxyl-linked glucuronides was determined under optimal reaction conditions. Expressed UGT1A3 catalyzed bile acid glucuronidation at high rates exclusively at the carboxyl moiety for all compounds tested. In contrast, UGT1A4 catalyzed bile acid glucuronidation at very low rates exclusively at the 3alpha-hydroxyl function. Both UGT2B7 allelic variants glucuronidated the bile acid substrates at both carboxyl and hydroxyl moieties, however, the 3alpha-hydroxyl position was preferentially conjugated compared to the carboxyl function. Similarly, androsterone, a 3alpha-hydroxylated androgenic steroid, was glucuronidated at very high rates by expressed UGT2B7. Of the estrogenic compounds tested, UGT2B7 catalyzed the glucuronidation of estriol at rates comparable to those determined for androsterone. Other structural discrimination was found with UGT2B7 which had activity toward estriol and estradiol exclusively at the 17beta-OH position, yielding the cholestatic steroid D-ring glucuronides.

Improved validated assay for the determination of mefloquine and its carboxy metabolite in plasma, serum and whole blood using solid-phase extraction and high-performance liquid chromatography

An improved high-performance liquid chromatography method using a low silanol activity octadecylsilica column and a solid-phase extraction technique is validated for the simultaneous analysis of mefloquine and its carboxy metabolite in whole blood, plasma and serum. An octadecylsilica column with high silanol activity is compared to a column of low activity in terms of pH dependent variability of chromatographic retention times for mefloquine and its carboxy metabolite. The low silanol activity column showed a relatively large mobile phase pH range where retention times for both components are consistent. The solid-phase extraction procedure consists of a simple protein precipitation step followed by sample concentration and extraction using a C18 membrane disk. The inter- and intra-assay variability for a therapeutic concentration of mefloquine (1000 ng/ml) is less than 2% in whole blood, plasma and serum while carboxymefloquine (1000 ng/ml) is 2.3% or less. At concentrations as low as 100 ng/ml the inter-assay variability is 6.2% or less for both analytes. This method shows a robust analytical procedure for the simultaneous analysis of mefloquine and its carboxy metabolite where precise measurements are useful in pharmacokinetic studies and in estimating drug compliance.

Morbidities of adjuvant chemotherapy and radiotherapy for resectable rectal cancer: an overview

PURPOSE

Although adjuvant chemoradiotherapy may improve outcomes after surgery for high-risk rectal cancer, its toxicities are not well documented. This is a review of complications associated with adjuvant therapy in randomized, controlled trials.

METHODS

A MEDLINE and literature search was performed for randomized, controlled trials of adjuvant therapy for rectal cancer. Modalities of adjuvant therapy evaluated included preoperative radiotherapy, preoperative chemoradiotherapy, postoperative radiotherapy, and postoperative chemoradiotherapy. All documented complications were analyzed, including any effect on pelvic floor function and quality of life.

RESULTS

Short-term (acute) complications of preoperative radiotherapy include lethargy, nausea, diarrhea, and skin erythema or desquamation. These acute effects develop to some degree in most patients during treatment but are usually self-limiting. With preoperative radiotherapy the incidence of perineal wound infection increases from 10 to 20 percent. The acute toxicities after postoperative radiotherapy for rectal cancer occur in 4 to 48 percent of cases, and serious toxicities, requiring hospitalization or surgical intervention, occur in 3 to 10 percent of cases. Postoperative radiotherapy is associated with more complications than preoperative radiotherapy. The main problems with postoperative radiotherapy are small-bowel obstruction (5-10 percent), delay in starting radiotherapy caused by delayed wound healing (6 percent) and postoperative fatigue (14 percent), and toxicities precluding completion of adjuvant therapy (49-97 percent). The morbidity and mortality of both preoperative and postoperative radiotherapy are higher in elderly patients and when two-portal rather than three-portal or four-portal radiation technique is used. Meticulous radiation technique is important, and multiple fields of irradiation are mandatory. After combined adjuvant chemotherapy and radiotherapy acute hematologic and gastrointestinal toxic effects are frequent (5-50 percent). Delayed radiation toxicities include radiation enteritis (4 percent), small-bowel obstruction (5 percent), and rectal stricture (5 percent). Pelvic floor function and quality of life have not been well evaluated in randomized, controlled trials.

CONCLUSION

Adjuvant therapy for rectal cancer has considerable adverse effects. Adverse effects on bowel and sphincter function and quality of life have not been defined.

Cardiac effects of high-dose epirubicin and cyclophosphamide in women with poor prognosis breast cancer

PURPOSE

To prospectively evaluate the long term cardiac effects of high-dose epirubicin and cyclophosphamide given to women with early stage, poor prognosis breast cancer.

PATIENTS AND METHODS

Women with stage 2 breast cancer and 10+ nodes or 4+ nodes and estrogen receptor negative tumor, or stage 3 breast cancer received three cycles of epirubicin 200 mg/m2 and cyclophosphamide 4 gm/m2 with peripheral blood progenitor cell and filgrastim support. Treatment was given every 28 days (n = 79) or 21 days (n = 20). Fifty patients received radiotherapy to the chest wall or breast, 25 of to the left side. Patients were assessed clinically regularly during chemotherapy and at least three times yearly after completion of treatment. Cardiac left ventricular ejection fraction (LVEF) was assessed by radionuclide scan before therapy, after each cycle of chemotherapy, three months and six months after completion of chemotherapy, and yearly thereafter until relapse.

RESULTS

Ninety-nine women were treated, and 92 completed all three cycles of chemotherapy. The median age was 43 years (range 24 to 60 years). All patients were included in this analysis. The median relapse-free survival was 39 months (11 to 68 months). There was a significant fall in LVEF during chemotherapy. In general, there was no further deterioration in cardiac function from the third month after cessation of treatment, however there was substantial variation between individuals. 35 patients had at least one LVEF measure less than normal (< 50%), but the LVEF returned to normal in 20 of these with further follow-up. Cardiac dysfunction was not increased in women who received radiotherapy and was not different between cohorts given chemotherapy every three or every four weeks. One patient died of acute myocardial necrosis following the third cycle of chemotherapy. Two patients developed clinical evidence of cardiac failure, and another had radiological signs but was asymptomatic. One woman died of progressive cardiac failure, one recovered clinically but also developed recurrent breast cancer, while the third recovered after commencement of medical therapy.

CONCLUSIONS

During follow-up after high-dose epirubicin and cyclophosphamide as delivered in this study, the LVEF fell to below normal in approximately one third of patients. However, in over half of these patients the LVEF subsequently recovered to the normal range, and the incidence of clinically evident chronic cardiac failure was low. Further follow-up is required to assess the long-term safety. A randomized comparison with standard-dose anthracycline-based chemotherapy is needed to determine whether this regimen is associated with an increased risk of clinical cardiac toxicity.

Multicycle high-dose chemotherapy and filgrastim-mobilized peripheral-blood progenitor cells in women with high-risk stage II or III breast cancer: five-year follow-up

PURPOSE

To determine the safety and efficacy of multiple cycles of dose-intensive, nonablative chemotherapy in women with poor-prognosis breast cancer.

PATIENTS AND METHODS

Women with stage II breast cancer and 10 or more involved nodes or four or more involved nodes and estrogen receptor-negative tumors and women with stage III disease received three cycles of epirubicin 200 mg/m2 and cyclophosphamide 4 g/m2, with progenitor cell and filgrastim support every 28 days (n = 79) or 21 days (n = 20). Patients were reviewed at least twice yearly thereafter. Twenty-six patients had bone marrow and apheresis collections assessed for the presence of micrometastatic tumor cells.

RESULTS

Ninety-nine women (median age, 43 years; range, 24 to 60 years) were treated. Ninety-two completed all three cycles of chemotherapy. The major toxicity was severe, reversible myelosuppression that was more prolonged with successive cycles, and this did not differ between patients given treatment every 28 days and those treated every 21 days. Febrile neutropenia occurred in 176 (61%) of 287 cycles. Severe mucositis (grade 3 or 4) occurred in 23% of cycles but tended to be short-lived and was reversible. The cardiac ejection fraction fell by a median of 4% during treatment, and three patients developed evidence of cardiac failure after chemotherapy. Two patients (2%) died of acute toxicity. Three of 26 patients had evidence of circulating micrometastatic tumor cells. The actuarial distant disease-free and overall survival rates at 60-month follow-up were 64% (95% confidence interval [CI], 53% to 75%) and 67% (95% CI, 56% to 78%), respectively.

CONCLUSION

Multiple cycles of dose-intensive, nonablative chemotherapy is a feasible and safe approach. Disease control and survival are similar to those in other studies of myeloablative chemotherapy in poor-prognosis breast cancer. The regimen is being evaluated in a randomized trial of the International Breast Cancer Study Group.

Glucuronidation of catechol estrogens by expressed human UDP-glucuronosyltransferases (UGTs) 1A1, 1A3, and 2B7

Catechol estrogens are major estrogen metabolites in mammals and are the most potent naturally occurring inhibitors of catecholamine metabolism. These estrogen compounds have been implicated in carcinogenic activity and the 4/2-hydroxyestradiol concentration has been shown to be elevated in neoplastic human mammary tissue compared to normal human breast tissue. Three human liver UDP-glucuronosyltransferases, UGT2B7, UGT1A1, and UGT1A3, have been shown to catalyze the glucuronidation of catechol estrogens and lead to their enhanced elimination via urine or bile. The present study was designed to study the kinetic interaction of expressed human UGT2B7(Y) or (H), UGT1A1, and UGT1A3 toward 2- and 4-hydroxycatechol estrogens. cDNAs encoding UGT2B7(Y) or (H), UGT1A1, and UGT1A3 were expressed in HK293 cells, and cell homogenates or membrane preparations were used to determine their glucuronidation ability. UGT2B7(Y) reacted with higher efficiency toward 4-hydroxyestrogenic catechols, whereas UGT1A1 and UGT1A3 showed higher activities toward 2-hydroxyestrogens. UGT2B7(H) catalyzed estrogen catechol glucuronidation with efficiencies similar to UGT2B7(Y). Flunitrazepam (FNZ), a competitive inhibitor of morphine glucuronidation in hepatic microsomes, competitively inhibited catechol estrogen glucuronidation catalyzed by UGT2B7(Y), UGT1A1, and UGT1A3. Buprenorphine, an opioid substrate that reacts at high efficiency with each of these UGTs, was also studied. FNZ competitively inhibited buprenorphine glucuronidation with UGT1A1 and UGT2B7 but had no inhibitory activity toward UGT1A3. This suggests that buprenorphine and 2-hydroxycatechol estrogens react with separate active sites of UGT1A3. A catecholamine, norepinephrine, did not inhibit UGT2B7(Y)-, UGT1A1-, and UGT1A3-catalyzed glucuronidation of catechol estrogens. These results also suggest that drug-endobiotic interactions are possible in humans and may have implication in carcinogenesis.

Glucuronidation of amine substrates by purified and expressed UDP-glucuronosyltransferase proteins

Conjugation of many primary, secondary, and tertiary amine-containing xenobiotics with glucuronic acid can result in the formation of N-glucuronide metabolites. For carcinogenic arylamines and their N-hydroxylated metabolites, N-glucuronidation can result in the formation of either inactive metabolites or labile conjugates, which can be transported to their target tissue (urinary bladder) where they may be converted to reactive metabolites. Drugs with primary amine (e.g. dapsone) or secondary amine moieties (e.g. sulfadimethoxine and clozapine) can also be metabolized to N-glucuronides. The metabolism of a number of tertiary amine-containing pharmacological agents to quaternary ammonium-linked glucuronides represents a unique and important metabolic pathway for these compounds that is highly species-dependent. This review summarizes our present knowledge of the uridine diphosphate (UDP)-glucuronosyltransferase enzymes involved in catalyzing N-glucuronide formation. Of the more than 30 UDP-glucuronosyltransferases that have been purified or cloned and expressed, many catalyze N-glucuronide formation for primary and secondary amine substrates. In contrast, only human UDP-glucuronosyltransferases 1A3 and 1A4 have been shown to catalyze quaternary ammonium-linked glucuronide formation for aliphatic tertiary amines. The structure of the UGT1 gene complex is highly conserved across species, and it appears that a mutation in the first exon encoding UDP-glucuronosyltransferase 1A4, resulting in a pseudo-gene, may explain the inability of some species to form quaternary ammonium-linked glucuronides.

Phase I and pharmacokinetic study of KRN8602 alone and with filgrastim in patients with advanced cancer

PURPOSE

To determine the recommended dose, toxicity profile, and pharmacokinetics of KRN8602 (MX2-hydrochloride), a novel morpholino anthracycline with potent cytotoxicity against anthracycline-sensitive and resistant experimental tumors in vitro and in vivo.

PATIENTS AND METHODS

KRN8602 was administered alone in increasing doses to patients with advanced cancer or high-grade gliomas until dose-limiting toxicity (DLT) was observed in three or more of five patients treated in a dose level. Because neutropenia was dose limiting, further escalation was investigated with filgrastim support.

RESULTS

Fifty-six assessable patients completed at least one cycle of chemotherapy. The recommended dose of KRN8602 alone was 40 mg/m2. Dose escalation was limited by neutropenia. The recommended dose of KRN8602 with filgrastim was 70 mg/m2, and limiting toxicities were neutropenia, diarrhea, and vomiting. The most commonly experienced nonhematologic toxicity was nausea and vomiting. Alopecia and mucositis were infrequent and mild. Pharmacokinetic parameters showed substantial variation, although the area under the plasma concentration-time curve (AUC) and maximum concentration both increased with dose. There was no relationship between pharmacokinetic parameters and toxicity.

CONCLUSION

KRN8602 at doses of 40 mg/m2 when administered alone and 70 mg/m2 when administered with filgrastim appeared to be manageable. The major DLTs were neutropenia and, at higher doses, diarrhea and vomiting. The efficacy of this drug is currently being tested in phase II studies.