Pilot Study of High-Dose Pemetrexed in Patients with Progressive Chordoma

PURPOSE

Chordomas are ultrarare tumors of the axial spine and skull-base without approved systemic therapy. Most chordomas have negative expression of thymidylate synthase (TS), suggesting a potential for responding to the antifolate agent pemetrexed, which inhibits TS and other enzymes involved in nucleotide biosynthesis. We evaluated the therapeutic activity and safety of high-dose pemetrexed in progressive chordoma.

PATIENTS AND METHODS

Adult patients with previously treated, progressive chordoma participated in an open-label, single-institution, single-arm, pilot clinical trial of intravenous pemetrexed 900 mg/m2 every 3 weeks and supportive medications of folic acid, vitamin B12, and dexamethasone. The primary endpoint was objective response rate according to RECIST v1.1. Secondary endpoints included adverse events, progression-free survival (PFS), tumor molecular profiles, and alterations in tissue and blood-based biomarkers.

RESULTS

Fifteen patients were enrolled and the median number of doses administered was 15 (range, 4-31). One patient discontinued treatment due to psychosocial issues after four cycles and one contracted COVID-19 after 13 cycles. Of the 14 response-evaluable patients, 2 (14%) achieved a partial response and 10 (71%) demonstrated stable disease. Median PFS was 10.5 months (95% confidence interval: 9 months-undetermined) and 6-month PFS was 67%. Adverse events were expected and relatively mild, with one grade 3 creatinine increased, and one each of grade 3 and 4 lymphopenia. No grade 5 adverse events, unexpected toxicities, or dose-limiting toxicities were observed. Several patients reported clinical improvement in disease-related symptoms.

CONCLUSIONS

High-dose pemetrexed appears tolerable and shows objective antitumor activity in patients with chordoma. Phase II studies of high-dose pemetrexed are warranted.

A phase I dose-escalation study of pulsatile afatinib in patients with recurrent or progressive brain cancer

Background

Afatinib (BIBW2992; Gilotrif®) is a selective and irreversible inhibitor of the epidermal growth factor receptor (ErbB; EGFR) family. It inhibits EGFR, HER2, and HER4 phosphorylation, resulting in tumor growth inhibition and regression. This phase I dose-escalation trial of pulsatile afatinib examined the safety, drug penetration into the central nervous system, preliminary antitumor activity, and recommended phase II dose in patients with progressive or recurrent brain cancers.

Methods

Afatinib was taken orally once every 4 days or once every 7 days depending on dose cohort, until disease progression or unacceptable toxicity.

Results

A total of 24 patients received the investigational agent and were evaluable for safety analyses, and 21 patients were evaluable for efficacy. Dosing was administered at 80 mg every 4 days, 120 mg every 4 days, 180 mg every 4 days, or 280 mg every 7 days. A recommended phase II dose of pulsatile afatinib was established at 280 mg every 7 days as there were no dose-limiting toxicities in any of the dosing cohorts and all toxicities were deemed manageable. The most common drug-related toxicities were diarrhea, rash, nausea, vomiting, fatigue, stomatitis, pruritus, and limb edema. Out of the 21 patients evaluable for efficacy, 2 patients (9.5%) exhibited partial response based on Response Assessment in Neuro-Oncology criteria and disease stabilization was seen in 3 patients (14.3%).

Conclusions

Afatinib taken orally was safe and well-tolerated up to 280 mg every 7 days in brain cancer patients.

Phase 2 study of AV-GBM-1 (a tumor-initiating cell targeted dendritic cell vaccine) in newly diagnosed Glioblastoma patients: safety and efficacy assessment

Background

Vaccine immunotherapy may improve survival in Glioblastoma (GBM). A multicenter phase II trial was designed to determine: (1) the success rate of manufacturing the Aivita GBM vaccine (AV-GBM-1), (2) Adverse Events (AE) associated with AV-GBM-1 administration, and (3) survival.

Methods

Fresh suspected glioblastoma tissue was collected during surgery, and patients with pathology-confirmed GBM enrolled before starting concurrent Radiation Therapy and Temozolomide (RT/TMZ) with Intent to Treat (ITT) after recovery from RT/TMZ. AV-GBM-1 was made by incubating autologous dendritic cells with a lysate of irradiated autologous Tumor-Initiating Cells (TICs). Eligible patients were adults (18 to 70 years old) with a Karnofsky Performance Score (KPS) of 70 or greater, a successful TIC culture, and sufficient monocytes collected. A cryopreserved AV-GBM-1 dose was thawed and admixed with 500 μg of Granulocyte-Macrophage Colony-Stimulating Factor (GM-CSF) before every subcutaneous (s.c.) administration.

Results

Success rates were 97% for both TIC production and monocyte collection. AV-GBM-1 was manufactured for 63/63 patients; 60 enrolled per ITT; 57 started AV-GBM-1. The most common AEs attributed to AV-GBM-1 were local injection site reactions (16%) and flu-like symptoms (10%). Treatment-emergent AEs included seizures (33%), headache (37%), and focal neurologic symptoms (28%). One patient discontinued AV-GBM-1 because of seizures. Median Progression-Free Survival (mPFS) and median Overall Survival (mOS) from ITT enrollment were 10.4 and 16.0 months, respectively. 2-year Overall Survival (OS) is 27%.

Conclusions

AV-GBM-1 was reliably manufactured. Treatment was well-tolerated, but there were numerous treatment-emergent central nervous system AEs. mPFS was longer than historical benchmarks, though no mOS improvement was noted.

Trial registration

NCT, NCT03400917, Registered 10 January 2018,

CTIM-33. PHASE II TRIAL OF VACCINE IMMUNOTHERAPY IN PRIMARY GLIOBLASTOMA: ADJUNCTIVE AUTOLOGOUS DENDRITIC CELLS PULSED WITH LYSATE FROM IRRADIATED SELF-RENEWING AUTOLOGOUS TUMOR CELLS (AV-GBM-1)

In primary glioblastoma (GBM), overall survival (OS) is poor despite standard aggressive therapy. Adjunctive AV-GBM-1 vaccine immunotherapy may improve OS. In this multi-institutional phase II trial, key eligibility criteria for intent-to-treat (ITT) enrollment were: (1) primary GBM, (2) age < 70 years when GBM was resected, (3) successful GBM cell culture, (4) successful monocyte collection by leukapheresis, (5) KPS > 70 post-surgery, and (6) plan to treat with concurrent RT/TMZ. Dendritic cells (DC) were differentiated from monocytes by culturing in IL-4 and granulocyte-macrophage colony stimulating factor (GM-CSF). AV-GBM-1 consisted of autologous DC incubated with autologous tumor antigens contained in the lysate of irradiated cultured GBM cells. After recovery from RT/TMZ, doses were admixed with 500 mcg GM-CSF; up to 8 doses were injected subcutaneously over 6 months. Patients were not excluded by apparent progression or pseudo-progression post RT/TMZ. OS and progression-free-survival (PFS) were calculated from ITT enrollment. The success rate was 97% for both GBM cell cultures and collection of monocytes; 60/60 vaccines were successfully manufactured. Median age was 59 years. 57 patients received 392 injections. After two weekly injections there were significant increases in plasma lipocalin-2 and angiopoietin-1, and decreases in thrombospondin-5, angiotensinogen, and beta-fibroblast growth factor. The most common adverse events attributed to AV-GBM-1 were local injection site reactions (16%) and flu-like symptoms (10%). With follow up from 15.2 to 32 months, median PFS and OS were 10.3 (8.5,11.6 95% CI) and 16.0 (13.0,21.3 95% CI) months respectively. OS was better in the 25 patients who had methylguanine-methyltransferase (MGMT) methylation and/or isocitrate dehydrogenase (IDH) mutation. Age was not independently correlated with survival. From date of first injection, OS was not increased in 14 patients who were treated with alternating electrical tumor-treating fields. CONCLUSION: feasibility, safety, and PFS were encouraging. A phase III trial is in development.

Clinicaltrials.gov NCT03400917.

Growth curve, blood parameters and carcass traits of grass-fed Angus steers

The increasing demand for natural products is currently transforming the meat industry, making grass-fed and finished beef a valuable option for improving profits. However, the transformation of conventional operations to grass-fed systems comprises many modifications, such as logistical, technological, and financial that could be very complex and expensive, involving economic risk. Therefore, in this study, we analyzed the growth curve, critical economic traits, and carcass quality and finished characteristics over several consecutive years in closely related grass-fed and finished Angus steers, to reduce the genetic effect on the results. We found that grass-fed steers require around 188 additional days to reach the market weight (approx. 470 kg) and had approximately 70% less average daily gain compared to the grain-fed and finished steers. Regression analysis demonstrated an interaction between feed and age (P < 0.01); thus, individual regressions were fitted for each regimen style, obtaining almost perfect linear curves for both treatments, which could be straightforwardly used in practical situations due to its simplicity. Six of eight carcass traits were different between grain-fed and grass-fed and finished steers. Hot-carcass weight, dressing, back fat, and quality grade were superior in grain-fed individuals, contrarily to yield grade and ribeye area/carcass ratio, which were better in grass-fed and finished steers (P < 0.05). Interestingly, the meat tenderness was certainly low and similar in both treatments (P = 0.25), indicating the feasibility of producing tender meat with animals under a grass-fed diet. Nevertheless, according to the quality grade analysis, grain-fed carcasses were greater ranked compared to grass-fed bodies (P < 0.01), regardless of their same tenderness. The results will provide valuable information for better understanding beef cattle in grass-feeding finishing systems, especially from weaning to harvest. Additionally, the study will expand the knowledge about the quality of meat obtained from animals that received grass exclusively, becoming relevant information for economic evaluation and management decisions for grass-based cattle operations.

Abstract CT182: Adjunctive treatment of primary glioblastoma with patient-specific dendritic cell vaccines pulsed with antigens from self-renewing autologous tumor cells: A phase II trial

Standard treatment of primary glioblastoma (GBM) is associated with poor survival. Adjunctive therapy with patient-specific vaccines may improve outcomes by inducing or enhancing each patient's anti-GBM immune response. A multi-institutional phase II clinical trial was designed with a primary objective of 75% survival 15 months after intent-to-treat enrollment. Key eligibility criteria were: (1) primary GBM diagnosis, (2) age &lt; 70 years at time of tumor resection, (3) successful cell culture of GBM cells in serum-free media, (4) successful monocyte collection by leukapheresis, and (5) KPS &gt; 70 after recovery from surgery. IL-4 and GM-CSF were used to generate dendritic cells (DC) from monocytes. DC were incubated with autologous tumor antigens (ATA) from the lysate of cultured GBM cells to produce each patient-specific DC-ATA vaccine. Each dose was admixed with GM-CSF at the time of subcutaneous injections at weeks 1, 2, 3, 8, 12, 16, 20 and 24. At the time of this analysis, cell line success rate is 61/63 (97%); monocyte collection success rate is 53/55 (96%), but 10 patients required a second apheresis. 50 of a planned 55 patients have enrolled after recovery from surgery, just prior to starting standard concurrent radiation therapy (RT) and temozolomide (TMZ), with intent-to-treat after recovery from RT/TMZ. The 50 patients include 36 men and 14 women; median age is 58 years with a range of 27 to 70. Average KPS is 82.8. MGMT methylation has been documented in 22% of patients and IDH mutation in 14%. 37 patients have started treatment and received 231 doses. 16 have completed all 8 doses, 7 received fewer than 8 doses, and 14 are currently undergoing treatment. No patient has discontinued treatment because of toxicity, but 20 patients have experienced 35 treatment-emergent serious adverse events including hospitalizations for falls and/or increased focal weakness (12 episodes), seizures (10 episodes), or severe headaches or visual changes (3 episodes). 6-month actual survival rate is 96% for the 28 patients at risk 6 months or longer from enrollment. Serologic analyses show that 12 of 16 patients (75%) had an increase in markers associated with Th1/NK, Th2/immunoglobulins, and Th2 hypersensitivity (eotaxins, IgE and IL17F) by week-3; 9 of 15 (60%) had a decrease in angiogenesis factors, growth factors, and tumor markers by week-8. On serial MRI scans, 7 of 13 patients (54%) have exhibited an increase in T2 (tumor) and flare (edema) for several weeks after starting DC-ATA, followed by a slow gradual decrease in both. This patient-specific DC-ATA immunotherapy approach is feasible, is associated with changes in serologic markers, and may be increasing intratumor inflammation that may be associated with on-target toxicity and efficacy. Longer follow up is needed before the survival objective can be assessed. [Clinicaltrials.gov NCT03400917]

Citation Format: Daniella A. Bota, Christopher M. Duma, Santosh Kesari, David E. Piccioni, Renato V. LaRocca, Robert T. O'Donnell, Robert D. Aiken, Jose A. Carrillo, Candace Hsieh, Chris J. Langford, Krystal Carta, Adrienne M. Wang, James A. Langford, Thomas H. Taylor, Gabriel I. Nistor, Robert O. Dillman. Adjunctive treatment of primary glioblastoma with patient-specific dendritic cell vaccines pulsed with antigens from self-renewing autologous tumor cells: A phase II trial [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr CT182.

Association of COMT Val158Met Polymorphism with Psychopathological Symptoms in Patients with Eating Disorders

BACKGROUND

Dopamine physiological functions make dopaminergic genes suitable candidates for association studies in eating disorders (ED). A Val158Met polymorphism in the catechol-O-methyltransferase (COMT) gene, which is involved in dopamine degradation, has been studied in relation to ED.

OBJECTIVE

We aimed to analyze the association between this polymorphism and general psychopathological symptoms that are often coupled to these disorders.

METHOD

A total of 303 ED patients, diagnosed according to DSM-5 criteria, completed the SCL-90R questionnaire and were genotyped for the Val158Met polymorphism.

RESULTS

There were significant differences in the global indices of the SCL-90R inventory between the three ED groups (Anorexia Nervosa (AN), Bulimia Nervosa (BN) and binge-eating disorder; ANOVA-p < 0.05). Females with BN showed the highest scores (worse symptomatology) of all participants. In this group, a gene-dose effect was observed on the psychometric evaluation of the patients, as Val/Val carriers displayed the highest scores for all the SCL-90R scales, followed by Val/Met and then Met/Met carriers. Significant differences between genotypes were observed in the Obsessive- Compulsive (p = 0.018), Paranoid Ideation (p = 0.0005) and Psychoticism (p = 0.039) scales, as well as in the PSDI (p = 0.014) general index.

CONCLUSION

The results taken together suggest that COMT genetic variability may contribute to general psychopathological symptoms in patients with BN.

A population dynamics model of cell-cell adhesion incorporating population pressure and density saturation

We discuss several continuum cell-cell adhesion models based on the underlying microscopic assumptions. We propose an improvement on these models leading to sharp fronts and intermingling invasion fronts between different cell type populations. The model is based on basic principles of localized repulsion and nonlocal attraction due to adhesion forces at the microscopic level. The new model is able to capture both qualitatively and quantitatively experiments by Katsunuma et al. (2016). We also review some of the applications of these models in other areas of tissue growth in developmental biology. We finally explore the resulting qualitative behavior due to cell-cell repulsion.

Phase II study of ERC1671 plus bevacizumab versus bevacizumab plus placebo in recurrent glioblastoma: interim results and correlations with CD4+ T-lymphocyte counts

Aim:

ERC1671 is an allogeneic/autologous therapeutic glioblastoma (GBM) vaccine – composed of whole, inactivated tumor cells mixed with tumor cell lysates derived from the patient and three GBM donors.

Methods:

In this double-blinded, randomized, Phase II study bevacizumab-naive patients with recurrent GBM were randomized to receive either ERC1671 in combination with granulocyte-macrophage colony-stimulating factor (GM-CSF) (Leukine^® or sargramostim) and cyclophosphamide plus bevacizumab, or placebo plus bevacizumab.

Interim results:

Median overall survival (OS) of patients treated with ERC1671 plus bevacizumab was 12 months. In the placebo plus bevacizumab group, median OS was 7.5 months. The maximal CD4⁺ T-lymphocyte count correlated with OS in the ERC1671 but not in the placebo group.

Conclusion:

The addition of ERC1671/GM-CSF/cyclophosphamide to bevacizumab resulted in a clinically meaningful survival benefit with minimal additional toxicity.

Intracranial meningioma with carcinoma tumor-to-tumor metastasis: two case reports

Meningiomas have been implicated as the most common primary intracranial tumor to contain tumor-to-tumor metastasis. In the following two case reports, we describe cases of adenocarcinoma and breast carcinoma that metastasized into an intracranial meningioma. The first patient was a 64-year-old man presenting to the emergency department with seizures and loss of consciousness. After a left frontal mass resection, pathology reported a heterogeneous mass consisting of a meningioma and a metastatic adenocarcinoma component. The second patient was a 63-year-old woman presenting with significant vision problems and unstable gait. After a right frontal mass resection, pathology reported a heterogeneous mass consisting of a meningioma and a metastatic breast carcinoma component. Possible explanations for the development of the tumor-to-tumor metastasis are described.

Case of glioblastoma patient treated with tumor treating fields therapy at recurrence degenerating to sarcoma

Optune^® treatment is a US FDA-approved treatment for glioblastoma (GBM) that employs alternating electric fields. Tumor treating field (TTF) therapy can exert its effects on GBM via cell cycle mitosis disruption and cytokinesis. We describe a patient with recurrent GBM who had disease progression following standard surgical treatment and concomitant chemoradiotherapy, and was found to have sarcomatous transformation after initiation of TTF therapy with bevacizumab. Upon tumor progression, repeat surgical resection revealed transformation into a GFAP-negative, reticulin-positive sarcoma with rhabdomyoid features. The possibility of a causal connection between TTF therapy and sarcomatous transformation needs to be further evaluated. No such case of apparent sarcoma formation in the CNS following chemoradiotherapy and/or TTF treatment for GBM has been reported.

Use of ERC-1671 Vaccine in a Patient with Recurrent Glioblastoma Multiforme after Progression during Bevacizumab Therapy: First Published Report

Glioblastoma multiforme is a highy aggressive tumor that recurs despite resection, focal beam radiation, and temozolamide chemotherapy. ERC-1671 is an experimental treatment strategy that uses the patient's own immune system to attack the tumor cells. The authors report preliminary data on the first human administration of ERC-1671 vaccination under a single-patient, compassionate-use protocol. The patient survived for ten months after the vaccine administration without any other adjuvant therapy and died of complications related to his previous chemotherapies.

Morphology, cell viability, karyotype, expression of surface markers and plasticity of three human primary cell line cultures before and after the cryostorage in LN2 and GN2

Primary cell line cultures from human skin biopsies, adipose tissue and tumor tissue are valuable samples for research and therapy. In this regard, their derivation, culture, storage, transport and thawing are important steps to be studied. Towards this end, we wanted to establish the derivation, and identify the culture characteristics and the loss of viability of three human primary cell line cultures (human adult dermal fibroblasts (hADFs), human adult mesenchymal stem cells (hMSCs), and primary culture of tumor cells from lung adenocarcinoma (PCTCLA)). Compared to fresh hADFs, hMSCs and PCTCLA, thawed cells stored in a cryogenic Dewar tanks with liquid nitrogen (LN2), displayed 98.20% ± 0.99, 95.40% ± 1.41 and 93.31% ± 3.83 of cell viability, respectively. Thawed cells stored in a Dry Vapor Shipper container with gas phase (GN2), for 20 days, in addition displayed 4.61% ± 2.78, 3.70% ± 4.09 and 9.13% ± 3.51 of average loss of cells viability, respectively, showing strong correlation between the loss of viability in hADFs and the number of post-freezing days in the Dry Vapor Shipper. No significant changes in morphological characteristics or in the expression of surface markers (being hADFs, hMSCs and PCTCLA characterized by positive markers CD73+; CD90+; CD105+; and negative markers CD14-; CD20-; CD34-; and CD45-; n=2) were found. Chromosome abnormalities in the karyotype were not found. In addition, under the right conditions hMSCs were differentiated into adipogenic, osteogenic and chondrogenic lineages in vitro. In this paper, we have shown the characteristics of three human primary cell line cultures when they are stored in LN2 and GN2.

Genome-wide mapping of DNase I hypersensitive sites and association analysis with gene expression in MSB1 cells

DNase I hypersensitive sites (DHSs) mark diverse classes of cis-regulatory regions, such as promoters and enhancers. MSB-1 derived from chicken Marek's disease (MD) lymphomas is an MDV-transformed CD4+ T-cell line for MD study. Previously, DNase I HS sites were studied mainly in human cell types for mammalian. To capture the regulatory elements specific to MSB1 cells and explore the molecular mechanisms of T-cell transformation caused by MDV in MD, we generated high-quality of DHSs map and gene expression profile for functional analysis in MSB1 cell line. The total of 21,724 significant peaks of DHSs was identified from around 40 million short reads. DHSs distribution varied between chromosomes and they preferred to enrich in the gene-rich chromosomes. More interesting, DHSs enrichments appeared to be scarce on regions abundant in CpG islands. Besides, we integrated DHSs into the gene expression data and found that DHSs tended to enrich on high expressed genes throughout whole gene regions while DHSs did not show significant changes for low and silent expressed genes. Furthermore, the correlation of DHSs with lincRNAs expression was also calculated and it implied that enhancer-associated lincRNAs probably originated from enhancer-like regions of DHSs. Together, our results indicated that DNase I HS sites highly correlate with active genes expression in MSB1 cells, suggesting DHSs can be considered as markers to identify the cis-regulatory elements associated with chicken Marek's disease.

Efficacy and safety of bevacizumab and etoposide combination in patients with recurrent malignant gliomas who have failed bevacizumab

Despite recent advances in the treatment of malignant gliomas (World Health Organization grade III and grade IV tumors- Glioblastoma Multiforme, Anaplastic Astrocytoma and Anaplastic Oligodendroglioma), the overall prognosis remains poor. Tumor recurrence in malignant glioma is inevitable, and associated with reduced overall survival (OS). Bevacizumab is approved for use in progressive GBM as a second line treatment, and is associated with improvements in progression free survival (PFS). However, all GBM patients eventually recur on bevacizumab therapy, with a very short OS after bevacizumab failure. No FDA-approved therapy is available for this clinical setting. Etoposide crosses the blood-brain barrier and has activity in recurrent malignant gliomas. The use of bevacizumab with etoposide in recurrent malignant gliomas in the setting of bevacizumab resistance is evaluated in this review. Bevacizumab and etoposide combined therapy is associated with radiographic response and effectiveness in selected patients.

Combined analysis of O6-methylguanine-DNA methyltransferase protein expression and promoter methylation provides optimized prognostication of glioblastoma outcome

BACKGROUND

Promoter methylation of the DNA repair gene, O-6-methylguanine-DNA methyltransferase (MGMT), is associated with improved treatment outcome for newly diagnosed glioblastoma (GBM) treated with standard chemoradiation. To determine the prognostic significance of MGMT protein expression as assessed by immunohistochemistry (IHC) and its relationship with methylation, we analyzed MGMT expression and promoter methylation with survival in a retrospective patient cohort.

METHODS

We identified 418 patients with newly diagnosed GBM at University of California Los Angeles Kaiser Permanente Los Angeles, nearly all of whom received chemoradiation, and determined MGMT expression by IHC, and MGMT promoter methylation by methylation-specific PCR (MSP) and bisulfite sequencing (BiSEQ) of 24 neighboring CpG sites.

RESULTS

With use of the median percentage of cells staining by IHC as the threshold, patients with <30% staining had progression-free survival (PFS) of 10.9 months and overall survival (OS) of 20.5 months, compared with PFS of 7.8 months (P < .0001) and OS of 16.7 months (P < .0001) among patients with ≥30% staining. Inter- and intrareader correlation of IHC staining was high. Promoter methylation status by MSP was correlated with IHC staining. However, low IHC staining was frequently observed in the absence of promoter methylation. Increased methylation density determined by BiSEQ correlated with both decreased IHC staining and increased survival, providing a practical semiquantitative alternative to MSP. On the basis of multivariate analysis validated by bootstrap analysis, patients with tandem promoter methylation and low expression demonstrated improved OS and PFS, compared with the other combinations.

CONCLUSIONS

Optimal assessment of MGMT status as a prognostic biomarker for patients with newly diagnosed GBM treated with chemoradiation requires determination of both promoter methylation and IHC protein expression.

Targeting Werner syndrome protein sensitizes U-2 OS osteosarcoma cells to selenium-induced DNA damage response and necrotic death

Mutations in the Werner syndrome protein (WRN), a caretaker of the genome, result in Werner syndrome, which is characterized by premature aging phenotypes and cancer predisposition. Methylseleninic acid (MSeA) can activate DNA damage responses and is a superior compound to suppress tumorigenesis in mouse models of cancer. To test the hypothesis that targeting WRN can potentiate selenium toxicity in cancer cells, isogenic WRN small hairpin RNA (shRNA) and control shRNA U-2 OS osteosarcoma cells were treated with MSeA for 2d, followed by recovery for up to 7d. WRN deficiency sensitized U-2 OS cells to MSeA-induced necrotic death. Co-treatment with the ataxia-telangiectasia mutated (ATM) kinase inhibitor KU55933 desensitized the control shRNA cells, but not WRN shRNA cells, to MSeA treatment. WRN did not affect MSeA-induced ATM phosphorylation on Ser-1981 or H2A.X phosphorylation on Ser-139, but promoted recovery from the MSeA-induced DNA damage. Taken together, WRN protects U-2 OS osteosarcoma cells against MSeA-induced cytotoxicity, suggesting that oxidative DNA repair pathway is a promising target for improving the efficacy of selenium on tumor suppression.

Relationship between tumor enhancement, edema, IDH1 mutational status, MGMT promoter methylation, and survival in glioblastoma

BACKGROUND AND PURPOSE

Both IDH1 mutation and MGMT promoter methylation are associated with longer survival. We investigated the ability of imaging correlates to serve as noninvasive biomarkers for these molecularly defined GBM subtypes.

MATERIALS AND METHODS

MR imaging from 202 patients with GBM was retrospectively assessed for nonenhancing tumor and edema among other imaging features. IDH1 mutational and MGMT promoter methylation status were determined by DNA sequencing and methylation-specific PCR, respectively. Overall survival was determined by using a multivariate Cox model and the Kaplan-Meier method with a log rank test. A logistic regression model followed by ROC analysis was used to classify the IDH1 mutation and methylation status by using imaging features.

RESULTS

MGMT promoter methylation and IDH1 mutation were associated with longer median survival. Edema levels stratified survival for methylated but not unmethylated tumors. Median survival for methylated tumors with little/no edema was 2476 days (95% CI, 795), compared with 586 days (95% CI, 507-654) for unmethylated tumors or tumors with edema. All IDH1 mutant tumors were nCET positive, and most (11/14, 79%) were located in the frontal lobe. Imaging features including larger tumor size and nCET could be used to determine IDH1 mutational status with 97.5% accuracy, but poorly predicted MGMT promoter methylation.

CONCLUSIONS

Imaging features are potentially predictive of IDH1 mutational status but were poorly correlated with MGMT promoter methylation. Edema stratifies survival in MGMT promoter methylated but not in unmethylated tumors; patients with methylated tumors with little or no edema have particularly long survival.

Evidence for sequenced molecular evolution of IDH1 mutant glioblastoma from a distinct cell of origin

PURPOSE

Mutation in isocitrate dehydrogenase 1 (IDH1) at R132 (IDH1(R132MUT)) is frequent in low-grade diffuse gliomas and, within glioblastoma (GBM), has been proposed as a marker for GBMs that arise by transformation from lower-grade gliomas, regardless of clinical history. To determine how GBMs arising with IDH1(R132MUT) differ from other GBMs, we undertook a comprehensive comparison of patients presenting clinically with primary GBM as a function of IDH1(R132) mutation status.

PATIENTS AND METHODS

In all, 618 treatment-naive primary GBMs and 235 lower-grade diffuse gliomas were sequenced for IDH1(R132) and analyzed for demographic, radiographic, anatomic, histologic, genomic, epigenetic, and transcriptional characteristics.

RESULTS

Investigation revealed a constellation of features that distinguishes IDH1(R132MUT) GBMs from other GBMs (including frontal location and lesser extent of contrast enhancement and necrosis), relates them to lower-grade IDH1(R132MUT) gliomas, and supports the concept that IDH1(R132MUT) gliomas arise from a neural precursor population that is spatially and temporally restricted in the brain. The observed patterns of DNA sequence, methylation, and copy number alterations support a model of ordered molecular evolution of IDH1(R132MUT) GBM in which the appearance of mutant IDH1 protein is an initial event, followed by production of p53 mutant protein, and finally by copy number alterations of PTEN and EGFR.

CONCLUSION

Although histologically similar, GBMs arising with and without IDH1(R132MUT) appear to represent distinct disease entities that arise from separate cell types of origin as the result of largely nonoverlapping sets of molecular events. Optimal clinical management should account for the distinction between these GBM disease subtypes.

Consequences of long-term inbreeding accumulation on preweaning traits in a closed nucleus Angus herd

The effect of individual and dam (maternal) inbreeding was quantified for preweaning traits in an Angus nucleus herd that has been closed to outside breeding for 70 yr. The effectiveness of 5 models (linear, quadratic, exponential, Michaelis-Menten, and Rumford-Newton) was evaluated for describing the effect of inbreeding on growth traits, hock length (HL), and scrotal circumference (SC). Pedigree information and production records were retrieved for 10,938 animals and analyzed in an animal model that included the fixed effects of year of birth, age of the dam, sex, and age at weaning (for traits measured at weaning). Average individual and maternal inbreeding in the herd were 0.068 and 0.066, respectively, for all animals; in the last calf crop these values were 0.120 for the calves and 0.121 for their dams. Inbreeding depression was observed for BW at birth (WB), weaning weight (WW), BW adjusted to 205 d of age (W205), ADG, HL, and SC. The effect of maternal inbreeding was smaller than for individual inbreeding for WB, WW, W205, and ADG. Nonlinear prediction was done more effectively by the exponential and Michaelis-Menten models. Quadratic polynomials were an inadequate descriptor of inbreeding effects. Genetic gain from selection at an intensity equivalent to 0.25 can be nullified by an inbreeding accumulation of 0.187 (WB), 0.056 (WW), 0.068 (W205), 0.065 (ADG), or 0.092 (SC). Inbreeding accumulation of 0.018 is required to nullify genetic gain for HL; this particular prediction is valid for non-inbred cows due to an observed interaction between individual and maternal inbreeding. At current inbreeding accumulation levels in this herd, 7 generations of inbreeding accumulation will be necessary to nullify the genetic progress from 1 generation of selection in growth traits.

Effect of common NAT2 variant alleles in the acetylation of the major clonazepam metabolite, 7-aminoclonazepam

We investigated the role of NAT2 on clonazepam acetylation, using transiently expressed human NAT2 alleles. The NAT25*B and the NAT2*6A variant alleles cause a 20 and 22-fold reduction in the Vmax, respectively. We conclude that NAT2 is responsible for 7-aminoclonazepam acetylation and that NAT2 gene polymorphisms impair such metabolic pathway.

Isolation and characterization of two families of satellite DNA with repetitive units of 135 bp and 2.5 kb in the ant Monomorium subopacum (Hymenoptera, Formicidae)

Analyzing the satellite DNA in the ant species Monomorium subopacum we found two unrelated families of satellite DNA. Because these satellite DNA families were isolated using the two enzymes HaeIII and EcoRI we called the two families HaeIII and EcoRI family, respectively. The HaeIII family proved to be organized in a 135-bp basic unit repeat, the EcoRI family in a 2.5-kb basic unit repeat. The latter represents perhaps the longest satellite DNA isolated up to now in insects. The HaeIII family apparently comprises about 10% of the total genomic DNA whereas the EcoRI family represents only about 1-2%. A comparative analysis of the two satellite DNA sequences showed no homology between the two families although both sequences possessed long A and T stretches. Eight of the 34 chromosomes showed hybridization with the HaeIII family and hybridization signals are visible in six chromosomes with the EcoRI family. Analysis of the electrophoretic mobility of satellite DNA on non-denaturing polyacrylamide showed that the HaeIII family is only slightly curved. However, the unit of the EcoRI satellite DNA family has curvature, especially the first 1000 bp of the monomeric repeat, in which this DNA is AT rich and has numerous A and T stretches. There are also internal inverted subrepeats in each family. The sequences of satellite DNA families found in Monomorium subopacum are different from the sequences of other satellite DNAs cloned in insects, including other species of ants.

Satellite DNA in the elm leaf beetle, Xanthogaleruca luteola (Coleoptera, Chrysomelidae): characterization, interpopulation analysis, and chromosome location

In this paper the satellite DNA (stDNA) of the phytophagous beetle Xanthogaleruca luteola is analyzed. It is organized in a tandem repeat of 149-bp-long monomers, has an AT content of 59%, and presents inverted internal repeats. Restriction analysis of the total DNA with methylation-sensitive enzymes suggests that this repetitive DNA is not methylated. Analysis of the electrophoretic mobility of stDNA on non-denaturing polyacrylamide gels showed that this stDNA is not curved. In situ hybridization with a biotinylated probe of the stDNA revealed a pericentromeric localization of these sequences in the majority of the meiotic bivalents. We have studied the stDNA of X. luteola from two populations with very distinct geographical origins. The sequence and phylogenetic analysis of monomers from these two populations showed that the repetitive element is conserved within the species. Putative gene conversion tracts are identified when the different monomers of the same population are compared. These results could indicate the existence of processes of homogenization that would extend these mutations to all the satellite repeats.

Conservation of (TTAGG)(n) telomeric sequences among ants (Hymenoptera, Formicidae)

To determine the telomere sequence in Tapinoma nigerrimum, we carried out in situ hybridization using TTAGGG and TTAGG repeat polymerase chain reaction (PCR)-generated probes. No hybridization signals were found when TTAGGG was used as a probe. However, strong signals were observed at the end of the chromosomes with the TTAGG probe. Southern blot analysis carried out on genomic DNA using TTAGG as a probe showed a strong hybridization signal even under highly stringent conditions. Similar results were obtained in Southern blot analysis carried out on genomic DNA of 19 species of ants belonging to three different subfamilies. In accordance with all the results shown in this article, the TTAGG repeat seems to be the major component of the telomere sequence in the majority of ant species.

A new repetitive DNA sequence family in the olive (Olea europaea L.)

Two families of repeated DNA sequences were cloned from Olea europaea ssp sativa cv. "Picual". The first repetitive DNA is organized in a tandem repeat of monomers of 178 bp. Sequencing of several clones showed that it is relatively A-T rich (54.49%) and possesses short direct and inverted subrepeats as well as some palindromic sequences. Comparison between the monomers revealed heterogeneity of the sequence primary structure. This repetitive DNA is present in several cultivars of olive cultivates. Comparison of sequences with other repetitive DNAs described in Olea europaea has been carried out. No significant similarity was found. All the obtained results suggest that this repetitive DNA described here is a new family of repetitive DNA. The second repetitive DNA is organized in a tandem repeat of monomers of 78 bp. This second family of repetitive DNA showed significant similarity with other repetitive DNAs previously described in Olea europaea. Their existence in new cultivars of olive is shown.

Steady states of a boltzmann equation for driven granular media

We study a three-dimensional model for driven granular media in which particles interact inelastically while they follow Brownian dynamics in between collisions. A steady Boltzmann-type kinetic equation associated with a pseudo-Maxwellian model is analyzed. Homogeneous steady states are found by a small inelasticity expansion. These states are given by a Maxwellian distribution corrected by the second Sonine polynomial up to third order in the expansion. The resulting correction is a quartic polynomial in velocity space. This result agrees qualitatively with the molecular dynamics simulation in C. Bizon, M. D. Shattuck, J. B. Swift, and H. L. Swinney, Phys. Rev. E 60, 4340 (1999).

Clinically significant pharmacokinetic interactions between dietary caffeine and medications

Caffeine from dietary sources (mainly coffee, tea and soft drinks) is the most frequently and widely consumed CNS stimulant in the world today. Because of its enormous popularity, the consumption of caffeine is generally thought to be safe and long term caffeine intake may be disregarded as a medical problem. However, it is clear that this compound has many of the features usually associated with a drug of abuse. Furthermore, physicians should be aware of the possible contribution of dietary caffeine to the presenting signs and symptoms of patients. The toxic effects of caffeine are extensions of their pharmacological effects. The most serious caffeine-related CNS effects include seizures and delirium. Other symptoms affecting the cardiovascular system range from moderate increases in heart rate to more severe cardiac arrhythmia. Although tolerance develops to many of the pharmacological effects of caffeine, tolerance may be overwhelmed by the nonlinear accumulation of caffeine when its metabolism becomes saturated. This might occur with high levels of consumption or as the result of a pharmacokinetic interaction between caffeine and over-the-counter or prescription medications. The polycyclic aromatic hydrocarbon-inducible cytochrome P450 (CYP) 1A2 participates in the metabolism of caffeine as well as of a number of clinically important drugs. A number of drugs, including certain selective serotonin reuptake inhibitors (particularly fluvoxamine), antiarrhythmics (mexiletine), antipsychotics (clozapine), psoralens, idrocilamide and phenylpropanolamine, bronchodilators (furafylline and theophylline) and quinolones (enoxacin), have been reported to be potent inhibitors of this isoenzyme. This has important clinical implications, since drugs that are metabolised by, or bind to, the same CYP enzyme have a high potential for pharmacokinetic interactions due to inhibition of drug metabolism. Thus, pharmacokinetic interactions at the CYP1A2 enzyme level may cause toxic effects during concomitant administration of caffeine and certain drugs used for cardiovascular, CNS (an excessive dietary intake of caffeine has also been observed in psychiatric patients), gastrointestinal, infectious, respiratory and skin disorders. Unless a lack of interaction has already been demonstrated for the potentially interacting drug, dietary caffeine intake should be considered when planning, or assessing response to, drug therapy. Some of the reported interactions of caffeine, irrespective of clinical relevance, might inadvertently cause athletes to exceed the urinary caffeine concentration limit set by sports authorities at 12 mg/L. Finally, caffeine is a useful and reliable probe drug for the assessment of CYP1A2 activity, which is of considerable interest for metabolic studies in human populations.

Evaluation of caffeine as an in vivo probe for CYP1A2 using measurements in plasma, saliva, and urine

Twenty-five healthy volunteers were given 100 mg caffeine orally and several estimates of cytochrome P450 1A2 (CYP1A2) activity were evaluated. The validation was performed by correlation of different parameters in plasma, saliva, and urine to two measures of caffeine clearance, CL(oral) and CL(137X-->17X) that served as standards of reference. Two subjects were excluded because of noncompliance with a caffeine-free diet. In the remaining 23 subjects, both plasma and saliva total clearances of caffeine were highly correlated with each other (r(s) = 0.97, p < 0.0001). The ratio 17X/137X restricted to one sampling point taken 4 hours after dose, showed a high correlation (r(s)) with CL(oral) and CL(137X-->17X) in plasma (0.84/0.83) and saliva (0.82/0.77) (p < 0.0001 for all the correlation values) where 17X is 1,7-dimethylxanthine (paraxanthine) and 137X is 1,3,7-trimethylxanthine (caffeine). Additionally, the ratio (AFMU + 1U + 1X + 17U + 17X)/137X in a 0-24 hours urine sampling showed the highest correlation with CL(137X-->17X) (r(s) = 0.85, p < 0.001) where AFMU is 5-acetylamino-6-formylamino-3-methyluracil, 1U is 1-methyluracil, 1X is 1-methylxanthine, and 17U is 1,7-dimethyluric acid. The major estimates of CYP1A2 activity were significantly less in nonsmoking females, and this probably was related to the use of oral contraceptives in this subpopulation. In summary, among caffeine-based approaches for CYP1A2, the authors recommend either plasma or saliva 17X/137X ratio and the urinary (AFMU + 1U + 1X + 17U + 17X)/137X ratio during a sampling interval of at least 8 hours, starting at time zero since caffeine intake. These indices are simple, reliable, and relatively inexpensive estimates of CYP1A2 activity to be used in the study of human populations.

Modulation of midazolam 1-hydroxylation activity in vitro by neurotransmitters and precursors

OBJECTIVE

The aim of this study was to find whether endogenous substances could modulate CYP3A activity. There is evidence that CYP3A, a major phase-I xenobiotic metabolizing enzyme, is present in human brain but, at the present time, endogenous substrates for such an enzyme remain to be identified. A possible linkage between the CYP2D6 enzyme and serotonergic transmission has been recently reported by our group. In the same manner, structurally related enzymes such as CYP3A could also be related to endogenous compounds.

METHODS

CYP3A activity was measured using the enzyme-specific substrate midazolam in human liver microsomes. Several neurotransmitters, precursors, and their metabolites, corresponding to three different metabolic routes, were assayed as putative modulators of CYP3A enzyme activity. These comprised serotonergic, catecolaminergic, and GABAergic transmitters and precursors. The inhibitory capacity of ketoconazole, a competitive inhibitor of CYP3A, was also analyzed for comparison.

RESULTS

The kinetic analysis of the midazolam 1-hydroxylase activity measured in microsomes from five human liver samples indicated Km values (mean +/- SD) of 5.8 +/- 4.9 microM, and Vmax values of 1.7 +/- 1.4 nmol min(-1) per mg microsomal protein in all the samples used in the study. Of the 14 substances analyzed, adrenaline, serotonin, and 5-hydroxytriptofol were full inhibitors of CYP3A enzyme activity (Ki values of 42.3, 26.4, and 43 microM, respectively). The remaining substances were weak inhibitors or had no inhibitory effect.

CONCLUSION

Brain CYP3A activity could be modulated by some neurotransmitters and precursors.

Pharmacokinetic interaction of fluvoxamine and thioridazine in schizophrenic patients

This study investigated to what extent fluvoxamine affects the pharmacokinetics of thioridazine (THD) in schizophrenic patients under steady-state conditions. Concentrations of THD, mesoridazine, and sulforidazine were measured in plasma samples obtained from 10 male inpatients, aged 36 to 78 years, at three different time points: A, during habitual monotherapy with THD at 88 +/-54 mg/day; B, after addition of a low dosage of fluvoxamine (25 mg twice a day) for 1 week; and C, 2 weeks after fluvoxamine discontinuation. After the addition of fluvoxamine, THD concentrations relative to time point A significantly increased approximately threefold from 0.40 to 1.21 micromol/L (225%) (p < 0.002), mesoridazine concentrations increased from 0.65 to 2.0 micromol/L (219%) (p < 0.004), and sulforidazine levels increased from 0.21 to 0.56 micromol/L (258%) (p < 0.004). The THD-mesoridazine and THD-sulforidazine ratios remained unchanged during the study. Mean plasma THD, mesoridazine, and sulforidazine levels decreased at time point C, but despite fluvoxamine discontinuation for 2 weeks, three patients continued to exhibit elevated concentrations of THD and its metabolites. In conclusion, fluvoxamine markedly interferes with the metabolism of THD, probably at the CYP2C19 and/or CYP1A2 enzyme level. Therefore, clinicians should be aware of the potential for a clinical drug interaction between both compounds, and careful monitoring of THD levels is valuable to prevent the accumulation of the drug and resulting toxicity.

[Safety of meningococcal A and C vaccine. Data from the Spanish drug surveillance system. Meningococcal Vaccine Research Group of the Spanish System of Drug Surveillance]

OBJECTIVE

Data on meningococcal vaccines safety are scanty. In 1997 several vaccination campaign took place in Spain. Thus, this situation was used to improve our knowledge about the safety profile of this vaccine.

METHODS

An inquiry was carried out to the Regional Centers of the Spanish Pharmacovigilance System to know the number of vaccinated people and the type and number of suspected cases of adverse reactions.

RESULTS

There were 133 identified cases of suspected adverse reactions associated with meningococcal A and C vaccine until June 1st, 1998. Most of them affected the skin (25,3%) or nervous system (similar proportion). Those of allergic reactions accounted for 35,2%. Two cases were considered as severe, although they were resolved without secuelae.

CONCLUSIONS

Serious risks were not detected. The Spanish Pharmacosurveillance System as an epidemiological surveillance resource has been useful to know the safety problems associated with antimeningococcal vaccine in the community.

Comparative in vitro and in vivo inhibition of cytochrome P450 CYP1A2, CYP2D6, and CYP3A by H2-receptor antagonists

The isozymes CYP1A2, CYP2D6, and CYP3A4/5 are involved in the majority of all cytochrome P450-mediated drug biotransformations. In this study we investigated the inhibition profiles of CYP1A2 (substrate: caffeine) CYP2D6 (substrate: dextromethorphan), and CYP3A4/5 (substrate: dextrorphan) by cimetidine, ranitidine, and the novel H2-receptor antagonist ebrotidine in human liver microsomes. The inhibitory effect of the drugs on the enzymes activities were as follows: CYP1A2: cimetidine >> ranitidine = ebrotidine; CYP2D6: cimetidine >>> ranitidine = ebrotidine; CYP3A4/5: ebrotidine > cimetidine >>> ranitidine. The inhibition of CYP3A4/5 enzyme activity by ebrotidine was competitive. To test whether the inhibitory effect of ebrotidine in CYP3A activity was also found in vivo, we analyzed the biodisposition of midazolam in 8 healthy volunteers. Midazolam biodisposition was significantly reduced when administered together with cimetidine (P < .05), whereas no significant inhibition was observed with ebrotidine or ranitidine compared with placebo. Psychomotor performance analysis revealed no significant effect of the observed reduction on midazolam biodisposition. We concluded that patients who are receiving treatment with drugs metabolized through CYP3A may experience enhanced drug effects as a result of pharmacokinetic interaction when treated concomitantly with cimetidine. In contrast, the effect of ranitidine or ebrotidine on CYP3A activity in vivo seems to have little clinical significance.

Metabolism of ropivacaine in humans is mediated by CYP1A2 and to a minor extent by CYP3A4: an interaction study with fluvoxamine and ketoconazole as in vivo inhibitors

BACKGROUND

Potential drug-drug interactions can be identified in vitro by exploring the importance of specific cytochrome P450 (CYP) isozymes for drug metabolism. The metabolism of the local anesthetic ropivacaine to 3-hydroxyropivacaine and (S)-2',6'-pipecoloxylidide was shown in vitro to be dependent on CYP1A2 and 3A4, respectively. In this in vivo model study we quantitated the role of these 2 isozymes for the metabolism of ropivacaine.

METHODS

In a randomized, 3-way crossover study, 12 healthy subjects received a single dose of 40 mg ropivacaine intravenously alone or combined either with 25 mg fluvoxamine as a CYP1A2 inhibitor or with 100 mg ketoconazole as a CYP3A4 inhibitor twice daily for 2 days. Venous plasma and urine samples were collected over 10 hours and 24 hours, respectively. The samples were analyzed for ropivacaine base, 3-hydroxyropivacaine, and (S)-2',6'-pipecoloxylidide.

RESULTS

Coadministration with fluvoxamine decreased the mean total plasma clearance of ropivacaine from 354 to 112 mL/min (68%), whereas ketoconazole decreased plasma clearance to 302 mL/min (15%). The relative changes in unbound plasma clearance were similar to the changes in total plasma clearance. The ropivacaine half-life (t1/2) of 1.9 hours was almost doubled during fluvoxamine administration and the plasma concentration at the end of infusion increased slightly, whereas the corresponding parameters after ketoconazole administration remained unchanged. Coadministration with ketoconazole almost abolished the (S)-2',6'-pipecoloxylidide concentrations in plasma, whereas fluvoxamine administration increased the (S)-2',6'-pipecoloxylidide levels. The fraction of dose excreted as 3-hydroxyropivacaine in urine decreased during fluvoxamine administration from 39% to 13%.

CONCLUSIONS

CYP1A2 is the most important isozyme for the metabolism of ropivacaine. Drug-drug interactions with strong inhibitors of this isozyme could be of clinical relevance during repeated administration. A potent inhibitor of CYP3A4 causes a minor decrease in clearance, which should be of no clinical relevance.

Effects of caffeine withdrawal from the diet on the metabolism of clozapine in schizophrenic patients

Both clozapine (CLZ) and caffeine are CYP1A2 substrates. This study raises the hypothesis of whether caffeine withdrawal from the diet alters the metabolism and/or clinical status of patients receiving CLZ. Seven schizophrenic patients (six men and one woman) receiving monotherapy with CLZ at 271+/-102 mg/day (3.73+/-1.4 mg/kg) participated in the study. CLZ, norclozapine (NOR), and clozapine-N-oxide (NOX) were assayed in plasma by high-performance liquid chromatography at three different time points: A, with concomitant intake of caffeine from the diet; B, after caffeine withdrawal for 5 days; and C, after 2 weeks of rechallenge to habitual caffeine intake. The CYP1A2 activity was determined by means of a urinary caffeine test. After a caffeine-free diet for 5 days, CLZ concentrations relative to time point A decreased from 486 to 306 ng/mL (-47%) (p < 0.02), NOX levels decreased from 66 to 49 ng/mL (-31%) (p < 0.03), and the NOR/CLZ ratio significantly increased from 0.47 to 1.04 (185%) (p < 0.02). All parameters returned to initial figures at time point C. The NOR/CLZ ratio was significantly correlated to the CYP1A2 index (rs = 0.96, p < 0.0005). In conclusion, changes in the habitual caffeine intake alter the metabolism of CLZ in schizophrenic patients. Thus, patient intake of caffeine should be medically supervised, and the monitoring of CLZ and metabolite levels may be warranted. Furthermore, in those patients who receive therapy with CLZ, the NOR/CLZ ratio may provide an additional and valuable estimate of CYP1A2 activity.

Analysis of midazolam and metabolites in plasma by high-performance liquid chromatography: probe of CYP3A

Hydroxylation of midazolam (MDZ) is mediated almost exclusively by CYP3A isoforms. The authors describe a high-performance liquid chromatography assay involving MDZ, 1'-hydroxymidazolam, and 4-hydroxymidazolam in plasma. The compounds were eluted on an Ultrasphere ODS, 3-microm particle size, 7.5 cm x 4.6 mm reversed-phase column and monitored by ultraviolet absorbance at 254 nm. The composition of the mobile phase was 35.2% acetonitrile:4.8% methanol:60% buffer acetate (vol/vol/vol), 0.1 M, pH 4.7; the flow rate was 1 ml/minute. Calibration curves were linear (coefficients of correlation > 0.99) within the range of concentrations established (20 to 640 nM). Within- and between-day coefficients of variation were consistently better than 8%. The overall recovery was >90% and the lowest detectable concentration was 8 nM. This approach provides a simple, rapid, and sensitive assessment of MDZ and metabolites in plasma, with a very good accuracy and precision, which enables it as an in vivo marker of CYP3A activity in humans.

Disposition of fluvoxamine in humans is determined by the polymorphic CYP2D6 and also by the CYP1A2 activity

BACKGROUND

Fluvoxamine is a selective serotonin reuptake inhibitor used widely in the treatment of depression and other psychiatric diseases, but little is known about the specific isozymes involved in its metabolism. This study investigated the relationship between fluvoxamine disposition and the polymorphic CYP2D6 and the polycyclic aromatic hydrocarbon (as contained in cigarette smoke) inducible CYP1A2.

METHODS

Fluvoxamine (50 mg orally) was given to 10 extensive metabolizers and four poor metabolizers of debrisoquin, and concentrations were assessed in plasma by high performance liquid chromatography. Five of the extensive metabolizers and one of the poor metabolizers were smokers of more than 10 cigarettes per day. The CYP1A2 activity was determined by means of a urinary caffeine test.

RESULTS

Compared with nonsmoking extensive metabolizers, nonsmoking poor metabolizers had a statistically significant (p = 0.02, Mann-Whitney U test) about twofold higher maximum plasma concentration, longer half-life, and fivefold lower oral clearance of fluvoxamine. The oral clearance of fluvoxamine correlated to the CYP1A2 index in the 14 subjects (rs = 0.58; p < 0.05; Spearman rank correlation).

CONCLUSION

The disposition of fluvoxamine in humans is associated with the polymorphic CYP2D6 activity, but CYP1A2 also seems to be involved.

CYP1A2 activity, gender and smoking, as variables influencing the toxicity of caffeine

We have investigated several factors that might be related to the occurrence of toxic effects during the performance of a urinary test with caffeine (300 mg p.o.), in 120 healthy volunteers. A total of 218 toxic effects were self-reported by eighty-two (68%) subjects. Females and nonsmokers were at the highest risk (chi-square test, P = 0.01). Furthermore, two nonsmoking females experienced a symptomatology with delirium, restlessness, muscle tremor, vomiting and wakefulness. Among females and nonsmokers, those subjects who experienced toxic effects had lower caffeine N3-demethylation index (CYP1A2 activity) compared with unaffected females (1.87 +/- 0.51 vs 1.47 +/- 0.27, P < 0.0005) and nonsmokers (1.69 +/- 0.23 vs 1.49 +/- 0.31, P < 0.02). Caffeine N1- and N7-demethylations indices were also lower among females (P < 0.0005) and nonsmokers (P < 0.02) who reported toxic symptoms. We conclude that CYP1A2 activity, gender and smoking are variables to be considered as influencing the toxicity of caffeine.

Aminopyrine metabolism in man: the acetylation of aminoantipyrine cosegregates with acetylation of caffeine

Aminopyrine and caffeine metabolism was evaluated in vivo in 21 healthy volunteers in order to elucidate whether the acetylation capacity of the two substances correlates. The ratio of the aminopyrine metabolites 4-acetylaminoantipyrine (AAA)/4-aminoantipyrine (AA) was compared with the ratios of caffeine metabolites AAMU/1-X and AAMU/(AAMU + 1-X + 1-U). All the subjects phenotyped as slow acetylators with caffeine displayed AAA/AA ratios lower than 3.4, whereas the extensive acetylators had ratios higher than 3.8. Therefore, the acetylator phenotype determined with caffeine cosegregated with the capacity to acetylate the aminopyrine metabolite AA. The N-demethylation of aminopyrine and caffeine correlated strongly in the subjects studied (p < 0.001). A highly significant correlation (r = 0.92; p < 0.001) was also observed between caffeine N(1)- and N(7)-demethylation activities. In addition, most N-demethylation steps of both drugs significantly correlated, suggesting partial contributions by identical or closely related enzymes in their metabolism.

Clozapine disposition covaries with CYP1A2 activity determined by a caffeine test

In a previous study we showed that the disposition of clozapine after a single oral dose is unrelated to either debrisoquine or S-mephenytoin hydroxylation polymorphism. The same 14 healthy subjects studied in that investigation were given 150 mg of caffeine. The reciprocal of plasma clozapine AUC (0,24), was correlated with an index of the N3-demethylation of caffeine (rs = 0.84; P = 0.0024), used as a measure of cytochrome P4501A2 (CYP1A2) activity. N1- and N7-demethylation indices of caffeine also reflect CYP1A2 activity and were also correlated with clozapine clearance (rs = 0.89 and 0.85; P = 0.0013 and 0.0023; respectively). No significant relationships with xanthine oxidase and N-acetyl transferase activity, also assessed by a caffeine test, were found. This study suggests that clozapine is metabolised by CYP1A2 to a major extent.

Caffeine metabolism in a healthy Spanish population: N-acetylator phenotype and oxidation pathways

We studied the oxidative and N-acetylator caffeine metabolic profile in 107 healthy Spanish volunteers. Smokers had significantly higher N-1- and N-3-demethylations activities than nonsmokers (p = 0.03 and p = 0.02, respectively), and the three caffeine demethylations indexes were strongly correlated with each other (r > 0.7; p < 0.001). Our in vivo studies suggest that CYP1A2 is involved, at least in part, in the primary N-demethylations of caffeine. A non-normal and possibly bimodal distribution was detected in the xanthine oxidase activity (p = 0.04), with about 4% of subjects deficient of this metabolic activity. The population exhibited a trimodal distribution of acetylator phenotype determined by use of the 5-acetylamino-6-amino-3-methyluracil/1-methylxanthine ratio (normality test; p = 0.004). Seventy subjects (65.4%) were phenotyped as slow acetylators. The mutated gene frequency was 0.81, which is similar to other white populations.

Frequency of S-mephenytoin hydroxylation deficiency in 373 Spanish subjects compared to other Caucasian populations

We have investigated the prevalence of poor metabolisers (PM) of S-mephenytoin in 373 unrelated, healthy Spanish Caucasian subjects, based on the enantiomeric S/R mephenytoin ratio in urine collected 0-8 h and 24-32 h after intake of the racemic drug. Five of the subjects were PM (1.34%, 95% confidence interval 0.18-2.59%), a prevalence lower than in 6 other Caucasian populations, but only significantly lower than in studies in France and Switzerland (P < 0.01). We suggest that this difference might be due to the use of different phenotyping procedures.

Debrisoquine oxidation in an Italian population: a study in healthy subjects and in schizophrenic patients

The debrisoquine oxidation phenotype was assessed in 137 healthy Italian volunteers and in 41 drug-free schizophrenic patients. A bimodal distribution of the urinary debrisoquine/4-hydroxydebrisoquine metabolic ratio was observed in healthy volunteers. Ten subjects were identified as poor metabolizers, yielding a frequency of 7.3% which is similar to that reported in other European countries. The prevalence of the poor metabolizer phenotype was 9.8% among schizophrenic patients. This indicates that there is no association between polymorphic drug oxidation and schizophrenic disorder. Treatment with chlorpromazine (100 or 150 mg daily) significantly increased the debrisoquine metabolic ratio in nine patients (P less than 0.01). These results confirm that neuroleptics of the phenothiazine class inhibit the oxidative metabolism of debrisoquine.

Polymorphic oxidation of debrisoquine in lung cancer patients

Oxidative polymorphism of debrisoquine (DBQ) was assessed in 84 patients (81 male) with histologically proven bronchogenic carcinoma and in 143 healthy male smokers. 80 (95%) patients and 133 (93%) controls, with a metabolic ratio (MR) below 12.6, were classified as extensive metabolisers of DBQ (no significant difference between patients and controls). Only 1 of the 73 patients with epidermoid or microcytic carcinomas was classified as a poor metaboliser (PM) (P = 0.031 compared with controls). 63 patients (75%) and 110 controls (77%) showed a very fast oxidative rate, with MR values under 1 (not significant). The EM phenotype of DBQ might be a secondary genetic risk factor for developing bronchogenic carcinoma in male smokers.