Impact of contemporary patterns of chemotherapy utilization on survival in patients with advanced cancer of the urinary tract: a Retrospective International Study of Invasive/Advanced Cancer of the Urothelium (RISC)

Background

Cisplatin-based combination chemotherapy is the standard treatment of advanced urinary tract cancer (aUTC), but 50% of patients are ineligible for cisplatin according to recently published criteria. We used a multinational database to study patterns of chemotherapy utilization in patients with aUTC and determine their impact on survival.

Patients and methods

This was a retrospective study of patients with: UTC (bladder, renal pelvis, ureter or urethra); advanced disease (stages T4b and/or N+ and/or M+); urothelial, squamous or adenocarcinoma histology. Primary objective was overall survival (OS). Eligibility-for-cisplatin was defined by Eastern Cooperative Oncology Group performance status ≤ 1, creatinine clearance ≥ 60 ml/min, no hearing loss, no neuropathy and no heart failure. Cox regression multivariate analyses were used to establish independent associations of cisplatin versus noncisplatin-based chemotherapy on OS.

Results

1794 patients treated between 2000 and 2013 at 29 centers were analyzed. Median follow-up was 29.1 months. About 1333 patients (74%) received first-line chemotherapy: the use of first-line chemotherapy was associated with longer OS: [hazard ratio (HR): 1.91, 95% confidence interval (CI): 1.67-2.20]. Type of first-line chemotherapy received was: cisplatin-based 669 (50%), carboplatin-based 399 (30%) and other 265 (20%). Cisplatin use was an independent favorable prognostic factor (HR: 1.54, 95% CI: 1.35-1.77). This benefit was independent of baseline characteristics or comorbidities but was associated with eligibility-for-cisplatin: eligible patients treated with cisplatin lived longer than those who were not (HR: 1.74, 95% CI: 1.36-2.21), while such benefit was not observed among ineligible patients. About 26% of patients who did not receive cisplatin were eligible for this agent. Median OS of ineligible patients was poor irrespective of the chemotherapy used.

Conclusions

The importance of applying published criteria of eligibility-for-cisplatin was confirmed in a multinational, real-world setting in aUTC. The reasons for deviations from these criteria set targets to improve adherence. Effective therapies for cisplatin-ineligible patients are needed.

Genetic counselors' (GC) knowledge, awareness, understanding of clinical next-generation sequencing (NGS) genomic testing

Genomic tests are increasingly complex, less expensive, and more widely available with the advent of next-generation sequencing (NGS). We assessed knowledge and perceptions among genetic counselors pertaining to NGS genomic testing via an online survey. Associations between selected characteristics and perceptions were examined. Recent education on NGS testing was common, but practical experience limited. Perceived understanding of clinical NGS was modest, specifically concerning tumor testing. Greater perceived understanding of clinical NGS testing correlated with more time spent in cancer-related counseling, exposure to NGS testing, and NGS-focused education. Substantial disagreement about the role of counseling for tumor-based testing was seen. Finally, a majority of counselors agreed with the need for more education about clinical NGS testing, supporting this approach to optimizing implementation.

Attitudinal barriers to participation in oncology clinical trials: factor analysis and correlates of barriers

Patient participation in cancer clinical trials is low. Little is known about attitudinal barriers to participation, particularly among patients who may be offered a trial during an imminent initial oncology consult. The aims of the present study were to confirm the presence of proposed subscales of a recently developed cancer clinical trial attitudinal barriers measure, describe the most common cancer clinical trials attitudinal barriers, and evaluate socio-demographic, medical and financial factors associated with attitudinal barriers. A total of 1256 patients completed a survey assessing demographic factors, perceived financial burden, prior trial participation and attitudinal barriers to clinical trials participation. Results of a factor analysis did not confirm the presence of the proposed four attitudinal barriers subscale/factors. Rather, a single factor represented the best fit to the data. The most highly-rated barriers were fear of side-effects, worry about health insurance and efficacy concerns. Results suggested that less educated patients, patients with non-metastatic disease, patients with no previous oncology clinical trial participation, and patients reporting greater perceived financial burden from cancer care were associated with higher barriers. These patients may need extra attention in terms of decisional support. Overall, patients with fewer personal resources (education, financial issues) report more attitudinal barriers and should be targeted for additional decisional support.

Abstract P1-01-13: Patterns of definitive axillary management in the era prior to reporting ACOSOG Z0011: comparison between NCCN Centers and hospitals in Michigan

Background: The results of the ACOSOG- Z0011 trial have had potential practice changing implications for the management of patients with positive sentinel lymph node (SLN) undergoing lumpectomy and radiation for breast cancer. However, some evidence suggests a shift in axillary management even prior to the initial report of data supporting sentinel lymph node biopsy (SLNB) alone in mid-2010. We analyzed data in the National Comprehensive Cancer Network (NCCN) outcomes database from NCCN centers and the Michigan Breast Oncology Quality Initiative (MiBOQI) hospitals to examine institutional practice patterns with respect to use of completion axillary dissection (CALND) for SLN positive breast cancer in the years leading up to publication of these trial results. We hypothesized that CALND would be omitted more frequently in women treated at NCCN centers compared to those treated at MiBOQI programs.

Methods: We identified 2,172 women with clinical T1/T2 N0 breast cancer who underwent breast surgery and SLNB and had a positive SLN from 2007 through 2010 at one of 12 participating NCCN centers or 12 MiBOQI sites. Patient and tumor characteristics, definitive breast procedure, year of diagnosis, and institutional affiliation were analyzed as predictors of use of SLNB alone in univariate Chi-Square and multivariable logistic regression models.

Results: CALND was omitted in 314 (14.5%) of the 2,172 patients. Over time, there was a dramatic increase in the use of SLNB alone (12% in 2007 to 23% in 2010). In the univariate analyses, increased patient age, later year of diagnosis, lower T stage, and lower pathologic N stage were significant predictors of use of SLNB alone (all p < .0001). There was no association between definitive breast surgery type, hormone receptor status, Her-2 Neu status, or institutional affiliation and use of SLNB alone. In the multivariable model, older age at diagnosis, later year of diagnosis, and lower pathologic N stage remained significant independent predictors of SLNB alone. There were no significant differences in rates of omission of CALND between NCCN and MIBOQI sites.

P1-11-02: Racial/Ethnic Differences in Adjuvant Trastuzumab Receipt for Women with Breast Cancer within the National Comprehensive Cancer Network

Background Racial/ethnic disparities in breast cancer care are well documented. Although adjuvant trastuzumab has been shown to improve disease outcomes for women with Human Epidermal Growth Factor Receptor 2 (HER2)-positive cancers, the ‘real world’ utilization and toxicity of adjuvant trastuzumab are unknown. Because therapy involves one year of treatment and the costs of treatment are high, a risk for treatment disparity exists. We examined differences in receipt and completion of adjuvant trastuzumab by race/ethnicity, education, employment, and insurance for women diagnosed with HER2−positive breast cancer.

Methods Using the National Comprehensive Cancer Network (NCCN) Breast Cancer Outcomes Database, we identified 1,146 women with stage I-III HER-2 positive breast cancer who presented to participating NCCN institutions during 2005–2008. In multivariable logistic analyses, we assessed the effect of race/ethnicity on the likelihood of trastuzumab therapy, and among women who initiated trastuzumab, the likelihood of completing ≥ 270 days of therapy, adjusting for center, diagnosis year, age, insurance, comorbidity, education, employment, and tumor characteristics. We also examined reasons for discontinuation of therapy among those who stopped treatment prematurely.

Results Among patients eligible for this analysis, 75% women were Caucasian, 9% were African-American, and 9% were Hispanic. Most women had managed care insurance (71%) and were employed/student (52%). About one-third (36%) had a college degree and 39% had a high school education or less. Overall, most women (82%) received neo/adjuvant trastuzumab and there were no racial/ethnic differences in receipt of therapy (adjusted odds ratio [OR] 1.11, 95% confidence interval [CI] .72-1.71 for African-American and OR 1.39, 95% CI .76-2.54 for Hispanic, versus Caucasian women). Among the 769 women who initiated neo/adjuvant trastuzumab and had ≥ 365 days of follow-up, 84% completed ≥ 270 days of trastuzumab. Rates of completion were lower for African-American (72%) and Hispanic (82%) women than Caucasian women (85%). In adjusted analyses, African-American women but not Hispanic women had lower odds of completing therapy compared with Caucasian women (OR .45, 95% CI .29-.70, p=0.0003). Indemnity insurance (versus managed care) was associated with lower odds of trastuzumab completion, as was having a high school education or less (versus college education). Among the 123 women who did not complete trastuzumab, 26% stopped early for toxicity, and this occurred more frequently for African-American women than Caucasian women (50% vs. 21%), but small sample precluded a meaningful test for statistical significance.

Conclusion: Compared with Caucasian women, African-American women had similar rates of initiation of adjuvant trastuzumab but much lower rates of completion that were not explained by differences in education, employment, or insurance. Because of the significant benefits conferred by adjuvant trastuzumab therapy for HER2−positive breast cancer, interventions to assure completion of therapy could lead to improved outcomes. Further exploration of racial differences in toxicity and tolerance of therapy are also warranted.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P1-11-02.

P5-12-05: (In-)Efficiencies in the Preoperative Imaging Evaluation of the Medicare Breast Cancer Patient

Introduction: Breast cancer evaluation requires a combination of physical examination and imaging for preoperative diagnosis and assessment of surgical treatment options. While imaging remains a critical component of that assessment, the burden of patient (pt) return visits for imaging is unknown.

Methods: Medicare claims linked to Surveillance Epidemiology End Results data were reviewed for women developing breast cancer between 1992 and 2005. The preoperative interval was defined as the period from the first physician encounter for a breast-related diagnosis until therapeutic surgery. Pts without ≥6 mos of data prior to that interval, those having DCIS or Stage IV disease, and those having preoperative chemotherapy or radiotherapy were excluded. Imaging modality counts exclude image-guidance claims for biopsies.

Results: Among 353,265 Medicare pts developing breast cancer between 1992 and 2005, 67,751 women >65 y of age had invasive, nonmetastatic breast cancer, and simultaneous breast surgery (lumpectomy or mastectomy) with lymph node staging. Median age was 75 y and preoperative interval length was 27 d. In the 6 mos before the preoperative interval, mammograms (MMGs), breast ultrasounds (USs), and breast MRIs were performed exclusive of the preoperative interval in 34,192 (50.5%), 16,936 (25.0%), and 180 (0.3%) pts respectively, while during the preoperative interval, MMGs, USs, and MRIs were performed in an additional 30,414 (44.9%), 17,983 (26.5%), and 1,409 (2.1%) respective pts. Imaging was performed on ≥2 separate dates during the preoperative interval in 4.9% of pts in 1992, rising to 19.4% in 2005 (trend, p<0.0001). During that interval, there were ≥2 encounter dates for MMGs in 7.0% of pts, rising from 3.9% in 1992 to 8.8% in 2005 (trend, p<0.0001); for US, 3.6% overall, rising from 0.2% in 1992 to 6.6% in 2005 (trend, p<0.0001). Multiple MRI encounters were rare, occurring in 0.2% overall, and increasing to 0.6% in 2005 (trend, p<0.0001), while single MRI use increased from <0.1% in 1994 to 8.3% in 2005 (trend, p<0.0001). In the preoperative interval, use of more than one imaging modality on any given date increased from 4.3% in 1992, to 27.1% in 2005. Among those with imaging, there was low correlation between number of imaging dates and number of modalities on any given date (rs= 0.13, p<0.0001). MMGs accounted for 71.9% of the days where one modality was performed alone, but MRI was performed alone 94.1% of the time. The total number of imaging dates in the preoperative interval was inversely related to age (p<0.0001). Differences in the mean number of imaging dates by race and stage were minor and all <0.3 days.

Conclusion: Preoperative Medicare breast imaging claims on multiple dates have been increasing substantially since 1992, suggesting that the patient's time burden for such evaluation is increasing. This trend is present despite the fact that multiple imaging modalities are being performed more frequently on the same date. Efforts to further consolidate preoperative breast imaging visits to lower that burden should be undertaken where possible in the Medicare population, for whom advanced age, in itself, may provide its own challenges.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P5-12-05.

P1-08-05: Age and Survival in Women with Early Stage Breast Cancer: An Analysis Controlling for Tumor Subtype

Background: Previous research has suggested that young age at diagnosis is an independent risk factor for breast cancer recurrence and death in women with early stage breast cancer. However, young women are more likely to have aggressive subtypes of breast cancer. No prior studies have adequately controlled for tumor phenotype, including HER-2/neu (HER2) status, in particular. Recent evidence has suggested that the prognostic effect of young age varies by tumor subtype.

Methods: We examined data from women with newly diagnosed Stage 1–3 breast cancer presenting to one of 8 NCCN centers between January 2000 and December 2007. Multivariate Cox proportional hazards models were used to assess the relationship between age and breast cancer specific survival, controlling for known prognostic factors and treatment. In addition, we conducted stratified analyses by estrogen receptor (ER) and HER2 status.

Results: 19,633 women with Stage 1–3 breast cancer eligible for analysis including 2,177 (11%) who were age 40 years or younger at diagnosis. Younger women were more likely to be non-white or Hispanic, more educated, employed, and to have higher stage, high grade, ER-negative, progesterone receptor (PR) negative, and HER2−positive disease, and treated with chemotherapy and trastuzumab (all variables P< 0.0001 by Chi-Square test). 5-year survival among younger women was 94.1 (95% Confidence Interval [CI] 92.9−95.3) and 96.3 (95% CI 95.9−96.6) for older women. In a multivariate Cox proportional hazards model controlling for sociodemographic, disease, and treatment characteristics, women age < 40 or younger at diagnosis had increased mortality compared to older women (Hazard Ratio [HR] 1.26, 95% CI 1.02−1.56). In stratified analyses, age 40 or less was associated with increased mortality among women with ER-positive disease (HR 1.44, 95% CI 1.01−2.05), but was not among those with ER-negative disease (HR 1.15, 95% CI 0.85−1.55). Younger age was associated with a statistically significant increase in mortality among women with HER2−negative disease (HR 1.29, 95% CI 1.00−1.68), but this difference did not reach statistical significance among those with HER2−positive disease (HR 1.30, 95% CI 0.82−2.09). Conclusions: The effect of age on short-term survival of women with early breast cancer appears to vary by breast cancer subtype, particularly ER status. Further research to elucidate differences in breast cancer biology and efficacy of therapy within tumor types by age is warranted.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P1-08-05.

P4-20-02: Inflammatory Breast Cancer (IBC) in the National Comprehensive Cancer Network (NCCN): The Disease, the Recurrence Pattern and the Outcome

Background

Inflammatory breast cancer (IBC) is a unique clinicopathologic entity that is characterized by rapid progression and aggressive behavior from the onset. The clinical presentation consists of erythema, rapid enlargement of the breast, skin ridging, and a characteristic peau d'orange appearance of the skin secondary to dermal lymphatic tumor involvement. Because of its uncommon presentation leading to frequent misdiagnosis, most reports are from small single institution series which describe a predictable pattern of recurrence in spite of appropriate multidisciplinary treatments. We sought to confirm these observations using the large multi-institutional National Comprehensive Cancer Network (NCCN) outcomes database.

Methods: Patients (pts) with newly diagnosed IBC treated between 1999 and 2009 at 12 participating NCCN institutions were identified. The clinical diagnoses of IBC was based on the AJCC definition and staged as clinical T4d, N0-3, M0-1. The baseline pathological characteristics included histological type, estrogen receptor (ER), progesterone-receptor (PR), and HER-2/neu status. Pts were classified as receiving multimodality therapy if they received two of the following three treatments: surgery (lumpectomy or mastectomy), perioperative (neoadjuvant or adjuvant) systemic therapy, or perioperative radiation therapy.

Results: We identified a cohort of 673 pts with newly diagnosed IBC with a median follow-up of 28.9 months. Of which 195 (29%) had metastatic disease at presentation. The median age at presentation was 52.6 years. Caucasians were 79.4% of the cohort, African American 9.7%, and 11.0% other ethnic groups. Invasive ductal type comprised 84% of histologies. Biomarker assessment revealed ER+ (44.7%), PR+ (34.3%), and Her2/neu+ (33.4%). LVI was documented in 53.3%. Of stage III patients, 75.7% pts received perioperative radiation, 82% received perioperative systemic therapy and 70.7% underwent surgery. All three modalities were received by 64.4% of women. Of the stage III pts, 203 recurred. The most frequent sites of recurrence for were CNS (20.2%), bone (17.2%), chest wall (13.8%), lung (12.3%), liver (11.3%), distant (7.4%) and regional lymph nodes (6.9%). With a median of 30 and 20 months of follow-up for stage III & IV respectively, the median survival was 66 months (95% CI 54–107) for stage III pts and 26 months (95% CI: 22–33) for stage IV Among the 82% of stage III pts who received multimodality therapy, the 5 year and 10 year OS of 62% and 47%.

Discussion: This is a large retrospective multiinstitutional study that confirms the aggressive clinical features, recurrence patterns and adverse prognosis of IBC described in previous single institution series. Even with aggressive multimodal therapy, the long term survival of IBC shorter is than non-IBC. Future investigations are needed to address the aggressive biology of IBC to improve diagnosis and therapy.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P4-20-02.

Meeting the 12 lymph node (LN) benchmark in colon cancer

BACKGROUND

Examining >or=12 LN in colon cancer has been suggested as a quality metric. The purpose of this study was to determine whether the 12 LN benchmark is achieved at NCCN centers compared to a US population-based sample.

METHODS

Patients with stage I-III disease resected at NCCN centers were identified from a prospective database (n = 718) and were compared to 12,845 stage I-III patients diagnosed in a SEER region. Age, gender, location, stage, number of positive nodes were compared for NCCN and SEER data in regards to number of nodes evaluated. Multivariate logistic regression models were developed to identify factors associated with evaluating 12 LNs.

RESULTS

92% of NCCN and 58% of SEER patients had >or=12 LN evaluated. For patients treated at NCCN centers, factors associated with not meeting the 12 LN target were left-sided tumors, stage I disease and BMI >30.

CONCLUSIONS

>or=12 LN are almost always evaluated in NCCN patients. In contrast, this target is achieved in 58% of SEER patients. With longer follow-up of the NCCN cohort we will be able to link this quality metric to patterns of recurrence and survival and thereby better understand whether increasing the number of nodes evaluated is a priority for cancer control.

Effect of lymph node retrieval rates on the utilization of adjuvant chemotherapy in stage II colon cancer

BACKGROUND

Failing to meet the benchmark of 12 lymph nodes in resection specimens is an indication for adjuvant chemotherapy in stage II colon cancer.

METHODS

Among consecutive eligible patients with pathologic stage II colon cancer treated at eight NCI-designated comprehensive cancer centers between September 1, 2005 and February 19, 2008, we analyzed receipt of adjuvant chemotherapy, with less than 12 versus 12+ lymph nodes removed and examined the primary explanatory variable of interest.

RESULTS

Among 258 patients, 46% received adjuvant chemotherapy. An oxaliplatin-containing regimen was used 67% of the time. Younger age (<50 years, P < 0.001), presence of lymphovascular invasion (P = 0.007), and higher T stage (P = 0.007) were independently associated with adjuvant chemotherapy use. There was significant inter-institutional variability in practice with the proportion receiving treatment ranging from 17% to 64% (P < 0.05). Notably, presence of less than 12 lymph nodes in the surgical specimen was a strong predictor of treatment (P = 0.008).

CONCLUSIONS

Adjuvant chemotherapy use after resection of stage II colon cancer is common, but by no means standard practice at National Comprehensive Cancer Network (NCCN) institutions. More attention to achieving the recommended benchmark for lymph node dissection has the potential to decrease exposure to the toxicity of adjuvant treatment.

Delineation of the interactions between the chemotherapeutic agent eribulin mesylate (E7389) and human CYP3A4

PURPOSE

Eribulin mesylate (E7389), a structurally simplified, synthetic analog of the marine natural product halichondrin B, acts by inhibiting microtubule dynamics via mechanisms distinct from those of other tubulin-targeted agents. Eribulin is currently in Phase III clinical trials for the treatment of metastatic breast cancer. Since drug-induced modulation of cytochrome P450 enzymes, particularly CYP3A4, is a frequent cause of drug-drug interactions, we examined the effects of eribulin on the activity and expression of hepatic and recombinant CYP3A4 (rCYP3A4) in vitro.

METHODS

Identification of the enzyme(s) responsible for eribulin metabolism was based on compound depletion and metabolite formation in reaction mixtures containing subcellular liver fractions or primary human hepatocytes, plus recombinant Phases I and II metabolic enzymes. The role of the enzyme(s) identified was confirmed using enzyme-selective inhibitors and the correlation with prototypic enzyme activity. The effect of eribulin on enzymatic activity was characterized using both microsomal preparations and recombinant enzymes, while the possible modulation of protein expression was evaluated in primary cultures of human hepatocytes.

RESULTS

Eribulin was primarily metabolized by CYP3A4, resulting in the formation of at least four monooxygenated metabolites. In human liver microsomal preparations, eribulin suppressed the activities of CYP3A4-mediated testosterone and midazolam hydroxylation with an apparent K (i) of approximately 20 microM. Eribulin competitively inhibited the testosterone 6beta-hydroxylation, nifedipine dehydration, and R-warfarin 10-hydroxylation activities of rCYP3A4, with an average apparent K (i) of approximately 10 microM. These inhibitions were reversible, with no apparent mechanism-based inactivation. Eribulin did not induce the expression or activities of CYP1A and CYP3A enzymes in human primary hepatocytes, and clinically relevant concentrations of eribulin did not inhibit CYP3A4-mediated metabolism of various therapeutic agents, including carbamazepine, diazepam, paclitaxel, midazolam, tamoxifen, or terfenadine.

CONCLUSIONS

Eribulin was predominantly metabolized by CYP3A4. Although eribulin competitively inhibited the testosterone 6beta-hydroxylation, nifedipine dehydration, and R-warfarin 10-hydroxylation activities of rCYP3A4, it did not induce or inhibit hepatic CYP3A4 activity at clinically relevant concentrations. As eribulin does not appear to affect the metabolism of other therapeutic agents by CYP3A4, our data suggest that eribulin would not be expected to inhibit the metabolism of concurrently administered drugs that are metabolized by CYP3A4, suggesting a minimal risk of drug-drug interactions in the clinical setting.

Quantitative liquid chromatography/mass spectrometry/mass spectrometry warfarin assay for in vitro cytochrome P450 studies

A sensitive assay using high-performance liquid chromatography tandem mass spectrometry (MS/MS) has been established for the quantitative analysis of cytochrome P450 form-specific activities using warfarin as a probe substrate. Four metabolites, 6-, 7-, 8-, and 10-hydroxywarfarin, were chromatographically resolved within 10 min using gradient mobile phases. The mass spectrometry was operated under negative ionization mode. The MS/MS product ion spectra of warfarin and the metabolites were generated using collision-activated dissociation and interpreted. The abundant product ions of the metabolites were selected for quantification applying multiple reaction monitoring. Quantification was based on a quadratic or power curve of the peak area ratio of the metabolite over the internal standard against the respective concentration of the metabolite. This assay has been validated from 2 to 1000 nM for 10-hydroxywarfarin and from 2 to 5000 nM for 6-, 7-, and 8-hydroxywarfarin and successfully applied to evaluate cytochrome P450-mediated drug-drug interactions in vitro using human hepatocytes and liver microsomal preparations.

Acute-stress-induced facilitation of the hypothalamic-pituitary-adrenal axis

It has been hypothesized that the hypothalamic-pituitary-adrenal (HPA) axis responds to a stressor by secreting facilitatory and inhibitory factors. During a stressor, the relative magnitude of secretion of these factors determines the responsiveness of the HPA axis to a subsequent stressor. Previous studies have suggested that corticosterone (B) secreted during the first stressor is an inhibitory factor. We hypothesized that the transient removal of the inhibitory factor, B, during the first stressor would result in the secretion of only facilitatory factors. This would cause the HPA axis to exist in a state of hyperresponsiveness, and to hypersecrete corticotropin (ACTH) and B in response to a second stressor. Therefore, our primary objective was to demonstrate stress-induced facilitation of the HPA axis response to a subsequent stressor. Male Sprague-Dawley rats were subjected to a 1-hour physical immobilization stressor (IMM) or administered a single dose of ACTH on day 1. B response during these treatments was markedly but transiently attenuated with an 100 mg/kg i.p. dose of aminoglutethimide (AG). Twenty-four hours later, rats were subjected to an intraperitoneal saline injection stressor. B and ACTH levels were measured 15 min after the injection stressor. Rats treated with AG plus IMM on day 1 hypersecreted B and ACTH after the injection stressor on day 2. These results suggest that immobilization stress induces facilitation of both pituitary and adrenal responses. Exogenous administration of ACTH- to AG-pretreated rats on day 1, in lieu of immobilization stress, did not affect the responsiveness of the HPA axis on day 2. This suggests that ACTH secreted during the first stressor does not play an important role in acute-stress-induced facilitation.

Structure-activity studies on 4-substituted-2-anilinopyrimidine corticotropin releasing factor (CRF) antagonists

Structure-activity studies around the 4-position of 2-anilinopyrimidine corticotropin releasing factor (CRF) antagonists suggest that there is a large lipophilic cavity in the rat CRF receptor, which can accommodate a wide variety of substituents at this position in contrast to the steric constraints observed for other positions on the 2-anilinopyrimidine core. The chemical syntheses and biological activities of 2-anilinopyrimidine CRF antagonists with carbon-linked substituents at the 4-position are reported. Significant improvements in rat pharmacokinetic parameters were achieved relative to those for the lead structure. While the lead compound 1 (rCRF Ki = 44 nM) afforded no detectable rat plasma levels after intraperitoneal (i.p.) or oral (p.o.) dosing, compounds 3-3 (rCRF Ki = 16 nM) and 3-4 (rCRF Ki 59 nM) gave high rat plasma levels at 30 mg/kg (i.p., p.o.) (Cmax = 1389 nM and 8581 nM (i.p.) respectively; Cmax = 113 nM and 988 nM (p.o.), respectively). Furthermore 3-3 and 3-4 had superior bioavailabilities at these doses (59 and 46% (i.p.), respectively; 2 and 10%, (p.o.), respectively).

Synthesis, corticotropin-releasing factor receptor binding affinity, and pharmacokinetic properties of triazolo-, imidazo-, and pyrrolopyrimidines and -pyridines

The synthesis and CRF receptor binding affinities of several new series of N-aryltriazolo- and -imidazopyrimidines and -pyridines are described. These cyclized systems were prepared from appropriately substituted diaminopyrimidines or -pyridines by nitrous acid, orthoester, or acyl halide treatment. Variations of amino (ether) pendants and aromatic substituents have defined the structure-activity relationships of these series and resulted in the identification of a variety of high-affinity agents (Ki's < 10 nM). On the basis of this property and lipophilicity differences, six of these compounds (4d,i,n,x, 8k, 9a) were initially chosen for rat pharmacokinetic (PK) studies. Good oral bioavailability, high plasma levels, and duration of four of these compounds (4d,i,n,x) prompted further PK studies in the dog following both iv and oral routes of administration. Results from this work indicated 4i,x had properties we believe necessary for a potential therapeutic agent, and 4i1 has been selected for further pharmacological studies that will be reported in due course.

Open-label, single-dose pharmacokinetic study of modafinil tablets: influence of age and gender in normal subjects

An open-label, single-center, single-dose, parallel-group study was performed in healthy young males and females as well as healthy elderly males to examine the influence of age and gender on the pharmacokinetics of modafinil following administration of a single 200 mg oral dose. Twelve subjects were enrolled in each of the following three groups: young males, young females, and elderly males. Each fasted (overnight) subject received 2 x 100 mg modafinil tablets. Blood and urine samples were collected at various times up to 72 hours postdose for the determination of plasma and urine levels of modafinil as well as the acid and sulfone metabolites. The plasma concentrations of the individual isomers, d- and l-modafinil, were also determined. Pharmacokinetic parameters were determined by noncompartmental methods. Modafinil was well tolerated at a single oral dose of 200 mg. The most commonly reported adverse events were headache, fever, pharyngitis, and asthenia. There were no clinically meaningful differences with respect to the incidence rate of treatment-emergent adverse events among the young female, young male, and old male groups. Modafinil was rapidly absorbed after oral dosing and slowly cleared (t1/2 approximately 11-14 hr) from the body. Modafinil acid was the major urinary metabolite, which accounted for 35% to 60% of the dose. Results from this study indicated that there were age and gender effects on modafinil clearance processes. In this regard, the clearance rate of modafinil in males decreased with age while young females cleared modafinil at a faster rate than young males. Stereospecific pharmacokinetics of modafinil were also demonstrated. The d-modafinil was eliminated three times faster than the l-modafinil.

A double-blind, placebo-controlled, ascending-dose evaluation of the pharmacokinetics and tolerability of modafinil tablets in healthy male volunteers

A randomized, double-blind, placebo-controlled, ascending-dose study was conducted to evaluate the pharmacokinetic and safety profiles of increasing modafinil doses (200 mg, 400 mg, 600 mg, 800 mg) administered orally over a 7-day period in normal healthy male volunteers. Eight subjects (six modafinil; two placebo) were randomized to each of the four dose groups. Modafinil or a placebo was administered once daily for 7 days. Serial blood samples were obtained following administration of the day 1 and day 7 doses for characterization of pharmacokinetics, and trough samples were obtained prior to dosing on days 2 through 6 to assess the time to reach the steady state. Pharmacokinetic parameters were calculated using noncompartmental methods. Modafinil steady state was reached after three daily doses. Modafinil pharmacokinetics were dose and time independent over the range of 200 mg to 800 mg. Steady-state pharmacokinetics of modafinil were characterized by a rapid oral absorption rate, a low plasma clearance of approximately 50 mL/min, a volume of distribution of approximately 0.8 L/kg, and a long half-life of approximately 15 hr. Modafinil was primarily eliminated by metabolism. Modafinil acid was the major urinary metabolite. Stereospecific pharmacokinetics of modafinil were demonstrated. The d-modafinil enantiomer was eliminated at a threefold faster rate than 1-modafinil. Modafinil 200 mg, 400 mg, and 600 mg doses were generally well tolerated. The modafinil 800 mg dose panel was discontinued after 3 days of treatment due to the observation of increased blood pressure and pulse rate. The safety data from this study suggest that the maximum tolerable single daily oral modafinil dose, without titration, may be 600 mg.

Comparison of the single-dose pharmacokinetics and tolerability of modafinil and dextroamphetamine administered alone or in combination in healthy male volunteers

An open-label, randomized, crossover study was performed in healthy male volunteers to evaluate the potential pharmacokinetic and pharmacodynamic interactions and tolerability of single oral doses of modafinil (200 mg) and dextroamphetamine (10 mg). Blood samples were collected for determination of plasma levels of modafinil, the acid and sulfone metabolites of modafinil, and dextroamphetamine at intervals through 48 hours after administration for each treatment. Vital signs (blood pressure and pulse rate) were measured through 48 hours, and electrocardiograms were measured through 24 hours after administration. Pharmacokinetic parameters were determined using noncompartmental methods. The data collected in this study of 24 healthy volunteers suggest that concomitant administration of single oral doses of modafinil and dextroamphetamine has no clinically significant effects on the pharmacokinetic profile of either agent. Although there was a slightly greater incidence of adverse events when modafinil and dextroamphetamine were administered together, the concomitant administration of the two drugs was well tolerated.

Single-dose pharmacokinetics of modafinil and methylphenidate given alone or in combination in healthy male volunteers

Modafinil is a novel wake-promoting agent being developed for treatment of excessive daytime sleepiness associated with narcolepsy. An open, 3 x 3 Latin square, randomized, cross-over study was performed in healthy males to compare the pharmacokinetics of single-dose oral modafinil (200 mg) and methylphenidate (40 mg) administered alone or in combination. Blood samples were obtained for analysis of d- and l-threo-methylphenidate and modafinil and its acid and sulfone metabolites. Pharmacokinetic parameters were determined by noncompartmental methods, but could not be evaluated for modafinil sulfone due to plasma levels that were close to the assay quantitation limit. Although sporadic differences in plasma concentrations were observed between treatments, coadministration of modafinil and methylphenidate did not significantly alter the plasma concentrations of modafinil, modafinil acid, modafinil sulfone, or methylphenidate enantiomers compared with administration of these agents alone. Half-life (t1/2), maximum concentration (Cmax), area under the concentration-time curve (AUC0-infinity), total clearance (Cl/F), and apparent volume of distribution (Vd/F) for modafinil and t1/2, Cmax, and AUC0-infinity for modafinil acid were not affected by concomitant administration of methylphenidate. Small but statistically significant increases in time to Cmax (tmax) were observed for modafinil and modafinil acid after methylphenidate coadministration compared with modafinil alone. Modafinil coadministration did not significantly alter the pharmacokinetics of d- or l-threo-methylphenidate, except for a small decrease in Vd/F of l-threo-methylphenidate. Concomitant methylphenidate may cause a delay in the oral absorption of modafinil, but this delay might not be relevant clinically. Coadministration did not alter the extent of oral absorption and disposition of either agent. Therefore, a pharmacokinetic interaction between modafinil and methylphenidate would be unlikely.

Pharmacological and pharmacokinetic evaluation of EXP3312, an orally-active non-peptide angiotensin II-receptor antagonist

EXP3312, 2-n-propyl-4-chloro-1-[(2'-(1H-tetrazol-5-yl)-biphenyl-4-yl) methyl]imidazole-5-carboxylaldehyde, is a non-peptide angiotensin II (AII) AT1-receptor antagonist. In the rabbit isolated aorta EXP3312 inhibited the contractile response to AII competitively with a pA2 value of 8.24. In renal hypertensive rats EXP3312 reduced blood pressure with intravenous and oral ED30 values of 0.19 and 0.14 mg kg-1, respectively. It also reduced blood pressure in frusemide-treated dogs when administered orally at 1 and 3 mg kg-1. In rats and dogs, the absolute oral bioavailability of EXP3312 averaged 60 and 28%, respectively. When EXP3312 was administered intravenously to rats and dogs the plasma elimination half-lives were 1.20 and 2.52 h, respectively. In rats and dogs EXP3312 was metabolized to an active metabolite M1, 2-n-propyl-4-chloro-1-[(2'-(1H-tetrazol-5-yl)-biphenyl-4-yl) methyl]imidazole-5-carboxylic acid. M1 is about ten times more potent than EXP3312 in renal hypertensive rats; the intravenous ED30 value was 0.02 mg kg-1. Because high plasma levels of M1 were found in rats after oral administration of EXP3312, it is likely that M1 contributes to the long duration of the antihypertensive effects of EXP3312 in renal hypertensive rats. The results show that EXP3312 is potent, orally active, competitive and selective AT1-receptor antagonist and a potent antihypertensive agent; it is likely to be therapeutically useful in the treatment of hypertension and congestive heart failure.

Pharmacokinetics and metabolism of EXP921, a novel cognitive enhancer, in rats

EXP921, 5,5-bis(4-pyridinylmethyl)-5H-cyclopenta[2,1-b:3,4-b']-dipyridine, was a potential drug candidate for the improvement of cognitive performance in patients with Alzheimer's-type dementia. It has been shown to improve cognitive performance in rodent and primate models of learning and memory. To characterize the disposition of EXP921, the pharmacokinetics and metabolism of this compound were studied in rats after oral and intravenous administrations. EXP921 exhibited good bioavailability, 43% at 3 mg/kg and 61% at 10 mg/kg and was rapidly eliminated with a terminal half-life ranging from 1.28 to 2.29 hr after oral doses. Absorption from oral doses was rapid, as peak plasma levels were reached within 1 hr. A major metabolite was identified in plasma as the pyridinyl mono-N-oxide of EXP921. This metabolite (EXP696) was rapidly formed, and significant levels were detected in rat plasma after oral or intravenous administration. Its terminal half-life was slightly longer than that of EXP921. EXP696 was found to be reduced back to EXP921, demonstrating that the N-oxidation at the pyridyl ring is reversible. The interconversion favored the oxidation of EXP921 to EXP696. Two additional metabolites were identified in rat plasma at doses higher than or equal to 30 mg/kg. They result from despicolylation, followed by hydroxylation in the cyclopentane ring.

Nonpeptide angiotensin II receptor antagonist: pharmacokinetics and pharmacodynamics in rats of EXP3174, an active metabolite of losartan

The pharmacokinetics and pharmacodynamics of EXP3174 (2-n-butyl-4-chloro-1-[(2'-(1H-tetrazole-5-yl)biphenyl-4- yl-)methyl]imidazole-5-carboxylic acid), an angiotensin II receptor antagonist, were studied in conscious rats. Elimination half-life, systemic clearance, and apparent volume of distribution of EXP3174 at a dose of 10 mg/kg i.v. were 2.9 h, 1.8 ml/min/kg, and 0.25 l/kg, respectively. Inhibition of the angiotensin II pressor response correlated with the log of the steady state plasma EXP3174 concentration in a sigmoidal fashion with an IC50 of about 200 ng/ml. When corrected for plasma protein binding, the IC50 (free) for EXP3174 was 0.4 ng/ml (0.9 nmol/l). This study indicates a predictable plasma concentration-effect relationship of EXP3174 in rats which would be helpful in designing more rational dosing schemes for pharmacodynamic studies.

Analysis of corticosterone in rat plasma by high-performance liquid chromatography

A sensitive and specific high-performance liquid chromatographic assay for the determination of corticosterone in rat plasma using dexamethasone as the internal standard is reported. Rat plasma (0.5 ml) is extracted with methylene chloride, washed with 0.1 M sodium hydroxide and then with water. The extract is analyzed by HPLC on a C18 column with ultraviolet absorbance detection at 254 nm. Pooled rat plasma was treated with activated decolorizing carbon to remove endogenous corticosterone, and was then used to prepare standards for the assay. Using 0.5 ml plasma for extraction, the detection limit of the assay is 10 ng/ml. The standard curve is linear over the concentration range 10-500 ng/ml. The recovery of corticosterone after extraction was independent of concentration and ranged from 87 to 95%. The coefficient of variation for intra-day and inter-day precision ranged from 2.4 to 7.4% and 2.1 to 8.7%, respectively. In addition, for concentrations ranging from 10 to 500 ng/ml the accuracy is within 5% of the spiked standards. The assay was utilized to examine the circadian rhythm of plasma corticosterone, and to examine the effect of immobilization stress on corticosterone levels in rats.

A pharmacokinetic evaluation of HIV protease inhibitors, cyclic ureas, in rats and dogs

The pharmacokinetics of a series of novel cyclic, non-peptide inhibitors of HIV protease were studied in rats or dogs after intravenous and oral administration. Six symmetrically substituted cyclic urea compounds (XK234, XM311, XM320, XM321, XM323, and XM412), which effectively inhibited HIV virus replication, with IC90 values of 0.03-1.0 microM (0.017-0.76 microgram mL-1), were evaluated. Plasma concentrations were measured in rats and dogs using specific and sensitive HPLC methods. In rats, the maximum plasma concentrations of 0.21-1.88 micrograms mL-1 were detected within 1 h of oral administration of 10 mg kg-1 of the compounds. The elimination half-lives ranged from 1.25 to 3.3 h in rats and the absolute oral bioavailability ranged from 18 to 100%. In dogs, the maximum plasma concentration and absolute oral bioavailability were 4.37 micrograms mL-1 and 48%, 1.07 micrograms mL-1 and 16%, and 1.48 mg ML-1 and 38% for XK234, XM311, and XM323, respectively. The data demonstrated that the maximum plasma concentrations of these cyclic ureas were several times higher than the IC90 for inhibition of viral replication after single doses of 10 mg kg-1 in rats and dogs. With this combination of high potency against virus replication and good oral bioavailability, these cyclic ureas represent a new class of compounds that are suitable for development as therapeutic agents for the treatment of HIV-associated diseases.

Pharmacokinetics of HIV protease inhibitor DMP 323 in rats and dogs

DMP 323 is a symmetrically substituted cyclic urea compound with demonstrated activity against human immunodeficiency virus (HIV) in vitro. DMP 323 has been measured in rat and dog plasma via liquid-liquid extraction and HPLC. The limit of quantitation is 10 ng/ml using 0.5 ml plasma. Following an intravenous dose of 5 mg/kg to rats, DMP 323 exhibited an apparent volume of distribution at steady-state of 6.36 liters/kg and clearance of 7.12 liters/hr/kg. The same dose administered intravenously to dogs resulted in apparent volume of distribution at steady-state and clearance values of 2.28 liters/kg and 1.48 liters/hr/kg, respectively. Elimination half-lives were 0.95 hr in rats and 1.80 hr in dogs. DMP 323 was rapidly absorbed from oral solution doses in rats (3, 5, and 10 mg/kg) and dogs (5 and 10 mg/kg), achieving maximum plasma concentrations in 1 hr or less in both species. Absolute bioavailability of DMP 323 from oral doses ranged from 15 to 27% in rats and from 37 to 38% in dogs. Pharmacokinetics were unchanged in rats and dogs over 8-day t.i.d. and 5-day b.i.d. multiple oral dose regimens, respectively. Oral doses administered to fed animals resulted in lower plasma concentrations of DMP 323 than the same doses administered to fasted animals. Because of its in vitro high potency and acceptable pharmacokinetics, DMP 323 seems to be a worthy candidate for further study in the effort to develop an inhibitor of HIV protease for use in the therapy of AIDS.

The pharmacokinetics and pharmacodynamics of the angiotensin II receptor antagonist losartan potassium (DuP 753/MK 954) in the dog

The pharmacokinetics and plasma concentration-effect relationship for the nonpeptide angiotensin II (Ang II) receptor antagonist losartan potassium (losartan) have been determined with conscious and anesthetized dogs. The p.o. bioavailability of single doses of 5 to 20 mg/kg was low, 23 to 33%, and independent of the dose. Absorption was rapid, with peak plasma levels observed within 1 hr, and the Cmax and area under the concentration vs. time curve to infinity were proportional to the dose, P < .05. The elimination half-life, 108 to 153 min, was longer than that observed after a single i.v. dose, 41 min, and may reflect both continuous absorption and enterohepatic recirculation because the major route of excretion was via the bile. Single i.v. doses were eliminated rapidly, with a systemic plasma clearance of 22.2 ml/min/kg. When corrected for the blood:plasma distribution ratio, 0.66 to 0.72, the systemic clearance approximates hepatic blood flow, suggesting that clearance is primarily via hepatic metabolism and biliary excretion. Losartan was not distributed extensively to tissues; apparent volume of distribution at steady-state of 0.30 liters/kg and was highly but not extensively bound to plasma proteins; 2.7 to 2.9% unbound (free). The plasma concentration vs. blockade of exogenous Ang II-induced vasopressor response was also determined after a single 3-mg/kg i.v. dose of losartan with a sigmoidal Emax model. Blockade of the pressor response was rapid, 89% at 5 min, and declined to 11% at 240 min postdose. The relationship between concentration and effect was highly significant (r = 0.922, P < .01), with an IC50 (total) of 96 ng/ml.(ABSTRACT TRUNCATED AT 250 WORDS)

Rational design of potent, bioavailable, nonpeptide cyclic ureas as HIV protease inhibitors

Mechanistic information and structure-based design methods have been used to design a series of nonpeptide cyclic ureas that are potent inhibitors of human immunodeficiency virus (HIV) protease and HIV replication. A fundamental feature of these inhibitors is the cyclic urea carbonyl oxygen that mimics the hydrogen-bonding features of a key structural water molecule. The success of the design in both displacing and mimicking the structural water molecule was confirmed by x-ray crystallographic studies. Highly selective, preorganized inhibitors with relatively low molecular weight and high oral bioavailability were synthesized.

The pharmacokinetics and metabolism of DuP 532, a non-peptide angiotensin II receptor antagonist, in rats and dogs

DuP 532, 2-propyl-4-pentafluoroethyl-1-([2'-(1H-tetrazol-5-yl)biph eny l-4-]methyl) imidazole-5-carboxylic acid, is an orally active, non-peptide angiotensin II (AII) receptor antagonist. DuP 532 is more potent and longer acting than losartan, another AII receptor antagonist currently undergoing phase III clinical trials. The pharmacokinetics and the effect of the salt form on the bioavailability of DuP 532 were determined in rats and dogs. In rats, the absolute oral bioavailability and half-life averaged 8.0% and 3.5 h, respectively, after the sodium bicarbonate solution and 7.6% and 3.6 h, respectively, after the methyl cellulose suspension. In dogs, the absolute oral bioavailability averaged 13.4% after the sodium bicarbonate solution and 11.9% after hard gelatin capsules containing the neat powder. The data demonstrated that there were no differences in bioavailability between the free acid and the sodium salt of DuP 532 after oral administration to rats and dogs. The in vitro metabolism of 14C-DuP 532 was evaluated with rat, dog, and human liver microsomes. HPLC analyses with UV and radiochemical flow detection showed that recovery of DuP 532 was greater than 99%, suggesting that there was little if any metabolism by liver microsomal enzymes. Therefore, the low oral bioavailability in rats was probably due to poor absorption of DuP 532 from the GI tract rather than extensive metabolism.

Metabolism and disposition of EXP631--a novel antidepressant analgesic

EXP631, 4-(3-thienyl)-alpha, alpha,1-trimethyl-4-piperidine-methanol hemi-fumarate salt (I), is a centrally acting non-opioid analgesic compound with monoamine uptake blocking properties. EXP631 has analgesic effects in several animal models. It is intended to be used for the treatment of moderate to moderately severe acute and chronic pain. To characterize the disposition of EXP631, the plasma levels of EXP631 were determined in rats and dogs after single intravenous and oral doses. In rats, EXP631 was rapidly absorbed following a single oral solution dose of 5-20 mg kg-1 with maximum plasma levels detected within 1.2 h post dose. The absorption was complete with an oral bioavailability of 92-131%. The pharmacokinetics was dose independent as measured by either Cmax or AUC values. In fasted dogs, EXP631 was absorbed rapidly and well (F = 81%) from an oral solution with the maximum concentration detected at 20 min post dose. In fed dogs, the absorption from capsules was slower (1.38 h) compared to the solution, but the absorption was complete (F = 115%). An N-desmethyl metabolite (II) was found in both rat and dog plasma samples. The structure was confirmed by mass spectroscopy, nuclear magnetic resonance spectroscopy and comparative chromatographic retention times. The metabolite is inactive as an analgesic.

Effects of multiple doses of moricizine hydrochloride on its pharmacokinetics and hepatic microsomal enzymes in rats

We studied the influence of chronic moricizine hydrochloride (MRZ) treatment on the drug's pharmacokinetics and on drug metabolizing enzyme activities in rats. Separate groups of 8 rats (4 males and 4 females) were treated with 40 and 100 mg/kg oral MRZ once daily for 7 days and saline control for 7 days prior to the preparation of hepatic microsomal enzyme suspensions. Depending on the substrate, treatments with multiple oral MRZ increased or decreased hepatic microsomal enzyme activities. For the pharmacokinetic study, rats (4 males and 4 females) were treated with 40 mg/kg oral MRZ once daily for 7 days. A comparison of MRZ pharmacokinetics obtained on day 1 relative to day 7 revealed that both AUC0-t and AUC0-infinity increased about 7-fold in males and 2-fold in females. Cmax also increased about 5-fold from day 1 to day 7 in males. These increases in blood concentrations and AUC's are likely due to enzyme inhibition. Results obtained from female rats on days 1, 4 and 7 suggest that metabolic changes probably occur after the 4th day of dosing. Therefore, chronic MRZ treatment affected its pharmacokinetics and hepatic metabolizing enzyme activities in rats.