Promoting multidisciplinary care for patients with unresectable hepatocellular carcinoma (HCC): Findings from a quality improvement initiative across two community cancer centers

528

Background: Evolving treatment paradigms in HCC are increasing the need for multidisciplinary coordination and a focus on patient-centered care. Identifying real-world challenges HCC care teams face in implementing these critical practices is necessary to inform educational interventions and optimize patient outcomes. Methods: In March–April 2021, 22 health care professionals (HCPs) who treat HCC at 2 US community oncology clinics completed surveys assessing practice patterns, challenges, and confidence related to multidisciplinary and patient-centered care in HCC and participated in interdisciplinary audit and feedback sessions. Patient charts evaluated pre- and post-intervention assessed changes in clinical practice. Inclusion criteria included confirmed HCC diagnosis, age ≥ 18 years, and ≥ 2 visits in the one-year chart abstraction period. Results: Participants represented the interprofessional HCC care team: medical oncologists (38%), gastroenterologists (8%), hepatologists (4%), internal medicine (17%), advanced practice professionals (4%), and nurses (29%). Baseline and follow-up patient charts included 50% and 47% Stage II-III HCC patients and 50% and 53% Stage IV HCC patients, respectively. Top reported barriers to multidisciplinary tumor board use were ineffective interdepartmental coordination/collaboration (43%) and low volume of referrals (38%). HCPs aimed to resolve these gaps through improved collaboration between multidisciplinary teams (33%) and earlier referrals to a medical oncologist (29%). Providing patient-centered supportive care was identified by 33% of HCPs as the top challenge in HCC patient care. Of HCPs surveyed, 77% estimated that ≤ 25% of patients are evaluated for/referred to distress/behavioral health services. Chart audits after educational intervention and action plan implementation showed improvements in supportive care utilization (see table). A critical component of patient-centered care, shared decision-making (SDM) was reported by 24% of HCPs. HCPs reported patient resistance to SDM (33%) and low patient health literacy (29%) as top barriers to SDM. Chart documentation of HCP participation in SDM increased post intervention (see table). Conclusions: In current real-world practice, HCC care teams report challenges in interdisciplinary collaboration and referrals, providing supportive care, and involving patients in SDM. These identified gaps represent key opportunities for future interventions to improve HCC care. [Table: see text]

Exploratory circulating biomarker analyses: lenvatinib + pembrolizumab (L + P) in a phase 1b trial in unresectable hepatocellular carcinoma (uHCC)

4084

Background: In a phase 1b trial (NCT03006926), L + P had promising antitumor activity as first-line (1L) therapy in uHCC. We present exploratory biomarker analyses of circulating angiogenic factors and cytokines/chemokines related to the mechanism of action of L + P (ie, pharmacodynamic [PD] biomarkers), as well as biomarker correlations with clinical outcomes in patients (pts) with uHCC, from this trial. Methods: Pts received lenvatinib 12 mg/d (bodyweight [BW] >60 kg) or 8 mg/d (BW < 60 kg) PO + pembrolizumab 200 mg IV Q3W. Tumors were assessed using mRECIST or RECIST v1.1 per independent imaging review. Peripheral blood samples were collected before administration of study drug at baseline, cycle (C) 2, day (D) 1, C3D1, C4D1, and off-treatment. 43 Biomarkers were assayed in serum from 100 1L uHCC pts (excluding 4 pts from the dose-limiting toxicity part of the trial with prior sorafenib). Of these 43, 31 biomarkers (for which ≤20% of samples had measurements above/below the quantification limit of the assay) were included in the analyses. Changes in biomarker levels from baseline were evaluated via 1-sample Wilcoxon signed-rank test. Associations were explored between changes in biomarker levels and maximum tumor shrinkage (MTS) via the Spearman’s rank correlation test, objective response (OR; complete response + partial response) via the Wilcoxon rank sum test, and PFS via Cox regression analysis and log rank test. Data cutoff date for clinical endpoints was 7 August 2020. Results: Levels of PD biomarkers related to angiogenic signaling (VEGF increase/ANG2 decrease), FGF signaling (increase in FGF23/FGF19), and IFNγ signaling (increase in IFNγ, CXCL9/10/11) were changed significantly (adjusted P< 0.05) with L + P (C2D1–C4D1; except for FGF19 at C3D1). Significant decreases of TIMP1 and increases of MCP1 were observed at C4D1 during treatment; these were associated with greater MTS. Greater decreases in TIMP1 and greater increases in MCP1 were observed in pts with OR vs others. Changes in levels of the PD biomarkers ANG2, IL10, and VEGFR2 were found to be associated with PFS by dichotomized analysis. With tertile 2 cutoff, median PFS for pts in the group with greater decreases of ANG2 was 13.9 months vs 9.6 months for pts in the group with lesser decreases of ANG2 (unadjusted P= 0.002; HR 2.65, 95% CI 1.39–5.08). Conclusions: These are the first exploratory biomarker analyses for the single-arm study of L + P in pts with uHCC. Changes in serum biomarkers associated with angiogenic-, FGF-, and IFNγ-signaling pathways indicated target engagement of L + P. Decreases in TIMP1 and increases in MCP1 were associated with MTS and OR. Associations were found between longer PFS and a greater decrease in levels of ANG2. Angiogenesis inhibition and modulation of cancer immune response were observed with L + P. Further validation from independent studies is warranted. Clinical trial information: NCT03006926.

Safety of weight-based dosing of nivolumab with or without ipilimumab by body mass index (BMI) stratified by sex across 14 CheckMate clinical trials

e15114

Background: Associations between obesity and cancer risk, prognosis, and therapeutic outcomes have been extensively researched. However, the impact of BMI on safety in patients receiving immunotherapy has not been well described. Methods: A descriptive, retrospective analysis examined associations between BMI (kg/m2) (underweight/normal, BMI < 25; overweight, 25 ≤ BMI < 30; obese, BMI ≥ 30) and incidence of any-grade and grade 3/4 immune-mediated adverse events (imAEs) in patients receiving ≥ 1 dose of nivolumab 3 mg/kg as monotherapy (NIVO3; n = 2746). Data were pooled from CheckMate clinical trials across 8 tumor types. Data from nivolumab in combination with ipilimumab cohorts (n = 1026) and safety analyses by specific imAEs and tumor types will be presented. Results: Select NIVO3 monotherapy cohort patient demographics were: 68.5% male, median age of 61 years, median 10 doses received, and median BMI of 25.3 kg/m2. Results showed a trend towards higher incidence of any-grade, but not grade 3/4, imAEs in obese vs overweight and obese vs underweight/normal BMI patients (Table). BMI associations with imAE incidence were consistent with the overall trend across pre-defined subsets, including smoking status, age, and ECOG performance status. Both male and female patients had an increased incidence of any-grade imAEs with obesity; however, obese female patients had a higher incidence of grade 3/4 imAEs vs underweight/normal BMI (Table). Conclusions: This was a novel analysis of BMI and safety in 2746 patients across 8 tumor types in CheckMate clinical trials who were treated with nivolumab monotherapy. While obese patients showed a trend towards higher incidence of any-grade imAEs than those with overweight and underweight/normal BMI, incidence of grade 3/4 imAEs was consistent across BMI categories. Clinical trial information: CheckMate 017,026,057,025,039,205,040,066,067,141,275,142,016,214 (NCT numbers do not fit in field) . [Table: see text]

A phase Ib study of lenvatinib (LEN) plus pembrolizumab (PEMBRO) in unresectable hepatocellular carcinoma (uHCC)

4519

Background: LEN is a multikinase inhibitor of VEGFR 1–3, FGFR 1–4, PDGFRα, RET, and KIT, approved for first line (1L) treatment of uHCC. PEMBRO, an anti-PD-1 monoclonal antibody, was granted accelerated approval for the treatment of patients (pts) with HCC after sorafenib therapy. We assessed the safety and efficacy of LEN + PEMBRO in uHCC. Methods: In this phase 1b trial (NCT03006926), pts received LEN 12 mg/day (bodyweight [BW] ≥60 kg) or 8 mg/day (BW <60 kg) orally + PEMBRO 200 mg IV on Day 1 of a 21-day cycle. Primary endpoints were safety and tolerability for Part 1 and objective response rate (ORR) and duration of response (DOR) by mRECIST and RECIST v1.1 per independent imaging review (IIR) in the 1L setting for Part 2. Results: 104 pts (part 1, n=6; part 2, n=98) were enrolled. No DLTs were reported in Part 1; 100 pts were included in the 1L analysis of LEN + PEMBRO–4 pts (part 1) excluded due to prior sorafenib. At data cutoff (October 31, 2019) and median follow-up of 10.6 months, 37 pts continued treatment (LEN only, n=3; both drugs, n=34); median duration of treatment was 7.9 months (LEN, 7.6 months; PEMBRO, 7.4 months). Median OS was 22.0 months (95% CI 20.4–not estimable [NE]), median PFS was 8.6 months (95% CI 7.1–9.7), and ORR was 36% (95% CI 26.6–46.2) (RECIST v1.1 per IIR). Additional efficacy outcomes are shown in the table. Treatment-emergent adverse events (TEAEs) occurred in 99% of pts (grade ≥3, 85%; grade ≥4, 23%). The most common grade ≥3 TEAE was hypertension (18% of pts). Treatment-related AEs (TRAEs) occurred in 95% of pts (grade ≥3, 67%; grade ≥4, 4%). The most common grade ≥3 TRAE was hypertension (17% of pts). 36% of pts had serious TRAEs and 3 pts died from a TRAE (acute respiratory failure/acute respiratory distress syndrome, n=1; intestinal perforation, n=1; abnormal hepatic function, n=1). Conclusions: LEN + PEMBRO has promising antitumor activity with a tolerable safety profile. An ongoing phase 3 trial (NCT03713593) is assessing LEN + PEMBRO vs LEN alone as 1L therapy for uHCC. Clinical trial information: NCT03006926 . [Table: see text]

Baseline liver function and outcomes in the phase III REFLECT study in patients with unresectable hepatocellular carcinoma (uHCC)

524

Background: Lenvatinib (LEN) is approved for first-line treatment of uHCC. Baseline (BL) liver function (Child-Pugh score [CPS] and albumin-bilirubin grade [ALBI]) was prognostic in uHCC patients (pts) who received sorafenib (SOR) but has not been assessed with LEN in uHCC. Here, we report post hoc analysis of BL liver function and efficacy/safety outcomes from the phase 3 REFLECT study. Methods: Overall survival (OS), progression-free survival (PFS), objective response rate (ORR), and safety were stratified by BL ALBI or CPS. OS and PFS were estimated by Kaplan–Meier method. Independent radiologic review utilized mRECIST criteria for ORR. Safety was assessed using NCI-CTCAE, version 4.0. Results: Liver function measured by ALBI and CPS seemed to be prognostic for OS and ORR. Median OS was longer in ALBI grade 1 (ALBI-1) vs grade 2 (ALBI-2) pts or for CPS-5 vs CPS-6 on either treatment arm and was longer for LEN vs SOR. ORR was higher in pts with better ALBI or CPS and for LEN vs SOR. Rates of treatment-emergent adverse events grade ≥3 were lower with better BL liver function (ALBI-1 vs ALBI-2: 70% vs 86%; CPS-5 vs CPS-6: 72% vs 86%). Study-drug withdrawal, dose reduction, and dose interruption occurred more often in pts with worse BL liver function. Conclusions: This post hoc analysis suggests ALBI (by OS, PFS and ORR) and CPS (by ORR) may be prognostic in uHCC pts and that BL liver function may be linked with efficacy/safety outcomes. This analysis also found that LEN provided benefit vs SOR for uHCC, regardless of BL liver function. The benefit of LEN may be underestimated, as more ALBI-2 pts and fewer ALBI-1 pts received LEN vs SOR. Clinical trial information: NCT01761266.

[Table: see text]

Nivolumab monotherapy in patients with advanced platinum-resistant urothelial carcinoma: Efficacy and safety update from CheckMate 275

4524

Background: In the open-label, single-arm, phase 2 CheckMate 275 trial, objective response rate (ORR) for patients (pts) with metastatic urothelial carcinoma (mUC) with nivolumab (NIVO) was 20.4% with minimum follow-up of 21.3 mo. Here, we report updated efficacy and safety data with minimum follow-up of 33.7 mo. Methods: Pts with platinum-resistant locally advanced or metastatic urothelial carcinoma received NIVO 3 mg/kg until disease progression or unacceptable toxicity. The primary endpoint was ORR by blinded independent review committee (BIRC) by RECIST v1.1 (including duration of response [DOR]). Secondary endpoints included progression-free survival (PFS) by BIRC, overall survival (OS), and ORR per investigator. Efficacy was evaluated in all treated pts and by tumor PD-L1 expression. Safety and PFS by investigator were exploratory endpoints. Results: ORR by BIRC was 20.7% (95% CI 16.1–26.1) including 18 (7%) complete responses (CR; with 1 additional CR since the last report; Table). ORR per investigator was similar (24.8%). Median DOR by BIRC was 20.3 mo (95% CI 11.5–31.3). Of 56 pts with best overall response (BOR) of CR or partial response (PR), 59% had a DOR ≥12 mo. Median PFS (mPFS) was 1.9 mo per BIRC (95% CI 1.9–2.3; Table) and 2.0 mo per investigator (95% CI 1.9–2.5). Median OS (mOS) was 8.6 mo (95% CI 6.1–11.3; Table). 12, 24, and 36-mo OS rates were 40%, 30%, and 22%. While efficacy was numerically higher in pts with tumor PD-L1 expression ≥1%, efficacy was observed in all pts (Table). Any-grade treatment-related adverse events occurred in 69% of pts (grade 3–4, 25%), mostly (59%) within the first 3 mo of initiating therapy. Conclusions: With long-term follow-up from CheckMate 275, NIVO continues to provide durable antitumor activity in pts with mUC. No new safety signals were noted. Clinical trial information: NCT02387996. [Table: see text]

Quality-adjusted life years assessment using cabozantinib for patients with advanced hepatocellular carcinoma (aHCC) in the CELESTIAL trial

207

Background: In patients previously treated for aHCC, cabozantinib (cabo) led to longer overall survival and progression-free survival vs placebo (pbo) in the randomized, phase 3 CELESTIAL trial (NCT01908426; N = 707). CELESTIAL was stopped early for benefit at the second interim analysis. This post hoc analysis estimated the incremental quality-adjusted life years (QALYs) accrued in CELESTIAL. Methods: Health utility was elicited at each study visit using the EQ-5D-5L quality of life questionnaire. (completed by 82–100% of patients overall). UK crosswalk tariffs were applied for health states. Cumulative QALYs by patient were calculated by linear interpolation; for patients who were censored (31% of patients; including 9% within 100 days of randomization), the last observed utility value was carried forward to study end. The difference in restricted mean QALYs was calculated using generalized linear models, accounting for baseline utility, and with 0.06–0.08 QALYs considered the minimal important difference. Results: At day 50 after randomization (acute treatment phase), cabo was associated with a small reduction in mean total QALYs vs pbo (difference −0.003; 95% CI −0.005 to −0.002; p ≤ 0.001; n = 601 [cabo, n = 389; pbo, n = 212]). At day 100, there was a numerical benefit in mean total QALYs for cabo (difference +0.007; 95% CI −0.001 to 0.015; p = 0.103; n = 627 [cabo, n = 410; pbo, n = 217]), and at day 150 the difference was +0.032 QALYs (95% CI 0.017 to 0.047; p ≤ 0.001; n = 629 [cabo, n = 412; pbo, n = 217]) in favor of cabo. Over the entire follow-up, patients randomized to cabo accrued a mean of +0.092 (95% CI 0.016 to 0.169; p = 0.018; n = 700 [cabo, n = 465; pbo, n = 235]) additional QALYs compared with those receiving pbo. Using alternative Devlin weights for health states, the mean accrued QALYs with cabo was +0.115 vs pbo (95% CI 0.032 to 0.198; p = 0.007). Conclusions: Cabo was associated with an initial, small reduction in health utility. However, with continued treatment, health utility increased and at the end of the study there was a clinically and statistically significant benefit in mean QALYs in favor of cabo. Clinical trial information: NCT01908426.

Meta-analysis of individual patient safety data from six randomized, placebo-controlled trials with the antiangiogenic VEGFR2-binding monoclonal antibody ramucirumab

BACKGROUND

Ramucirumab, the human immunoglobulin G1 monoclonal antibody receptor antagonist of vascular endothelial growth factor receptor 2, has been approved for treating gastric/gastroesophageal junction, non-small-cell lung, and metastatic colorectal cancers. With the completion of six global, randomized, double-blind, placebo-controlled, phase III trials across multiple tumor types, an opportunity now exists to further establish the safety parameters of ramucirumab across a large patient population.

MATERIALS AND METHODS

An individual patient meta-analysis across the six completed phase III trials was conducted and the relative risk (RR) and associated 95% confidence intervals (CIs) were derived using fixed-effects or mixed-effects models for all-grade and high-grade adverse events (AEs) possibly related to vascular endothelial growth factor pathway inhibition. The number needed to harm was also calculable due to the placebo-controlled nature of all six registration standard trials.

RESULTS

A total of 4996 treated patients (N = 2748 in the ramucirumab arm and N = 2248 in the control, placebo arm) were included in this meta-analysis. Arterial thromboembolic events [ATE; all-grade, RR: 0.8, 95% CI 0.5-1.3; high-grade (grade ≥3), RR: 0.9, 95% CI 0.5-1.7], venous thromboembolic events (VTE; all-grade, RR: 0.7, 95% CI 0.5-1.1; high-grade, RR: 0.7, 95% CI 0.4-1.2), high-grade bleeding (RR: 1.1, 95% CI 0.8-1.5), and high-grade gastrointestinal (GI) bleeding (RR: 1.1, 95% CI 0.7-1.7) did not demonstrate a definite increased risk with ramucirumab. A higher percentage of hypertension, proteinuria, low-grade (grade 1-2) bleeding, GI perforation, infusion-related reaction, and wound-healing complications were observed in the ramucirumab arm compared with the control arm.

CONCLUSIONS

Ramucirumab may be distinct among antiangiogenic agents in terms of ATE, VTE, high-grade bleeding, or high-grade GI bleeding by showing no clear evidence for an increased risk of these AEs in this meta-analysis of a large and diverse patient population. Ramucirumab is consistent with other angiogenic inhibitors in the risk of developing certain AEs. Clinical Trial Numbers: NCT00917384 (REGARD), NCT01170663 (RAINBOW), NCT01168973 (REVEL), NCT01183780 (RAISE), NCT01140347 (REACH), and NCT00703326 (ROSE).

Phase III trial of lenvatinib (LEN) vs sorafenib (SOR) in first-line treatment of patients (pts) with unresectable hepatocellular carcinoma (uHCC)

4001

Background: SOR is the only approved agent in uHCC and new options are needed. LEN, an inhibitor of vascular endothelial growth factor receptors 1‒3, fibroblast growth factor receptors 1‒4, platelet derived growth factor receptor α, RET, and KIT, showed activity in uHCC in a phase II trial. We report a phase III trial of LEN vs SOR as first-line therapy for uHCC. Methods: In this randomized, open-label, noninferiority (NI) study, pts had uHCC, ≥ 1 measurable target lesion, Barcelona Clinic Liver Cancer stage B or C, Child-Pugh class A, ECOG PS ≤ 1, and no prior systemic therapy. Pts were randomized 1:1 to LEN (body weight ≥ 60 kg: 12 mg/day; < 60 kg: 8 mg/day) or SOR 400 mg twice daily. The primary endpoint was overall survival (OS). The OS hazard ratio (HR) and its 95% CI were estimated with a stratified Cox proportional hazard model. The predefined NI margin was 1.08. Secondary efficacy endpoints were progression-free survival (PFS), time to progression (TTP) and objective response rate (ORR) by modified RECIST. Type I error rates for secondary efficacy endpoints were controlled with a fixed sequence procedure at 2-sided α = 0.05 after OS NI was claimed. Results: 954 Pts enrolled (LEN: 478; SOR: 476). Efficacy outcomes are shown in the table. A similar number of pts in both arms had treatment-emergent adverse events (TEAEs). Most common LEN TEAEs were hypertension (42%), diarrhea (39%), decreased appetite (34%), decreased weight (31%), and fatigue (30%). Median (range) treatment duration was 5.7 mos (0−35.0) for LEN and 3.7 mos (0.1−38.7) for SOR. 13% Of LEN-treated and 9% of SOR-treated pts discontinued due to adverse events. 33% Of LEN-treated and 39% of SOR-treated pts received second-line therapy. Conclusions: LEN is noninferior in OS, and achieves statistically significant and clinically meaningful improvements in PFS, TTP, and ORR, as first line therapy for uHCC. TEAEs were consistent with the known LEN safety profile. Clinical trial information: NCT01761266. [Table: see text]

SWOG S1310: Randomized phase II trial of single agent MEK inhibitor trametinib vs. 5-fluorouracil or capecitabine in refractory advanced biliary cancer

4016

Background: No standard treatment options are available for patients with advanced BC who fail gemcitabine/platinum therapy. The rationale for evaluation of trametinib was based on the presence of MAPK alterations and on earlier promising results with other MEK inhibitors in BC. Methods: Pts with histologically proven BC who progressed on gemcitabine/platinum were randomized to trametinib (2mg qd) (Arm A) vs infusional 5FU at 2400 mg/m2 over 46 hours or capecitabine (1000 mg/m2PO days 1-14 BID) (Arm B). Patients were stratified by planned chemotherapy 5FU/LV vs capecitabine; and disease site: cholangiocarcinoma vs gallbladder. The primary endpoint was overall survival (OS). Secondary endpoints included progression-free survival (PFS) and response rate (RR). 80 eligible patients (40 for each arm) were needed to detect an improvement in median OS from 5 months to 8.25 months (1.65 HR). A planned interim futility analysis of objective response was performed on the first 14 pts registered to the trametinib arm. Results: The study was stopped early based on the lack of measurable response in the trametinib arm. 53 pts were randomized (27 pts in Arm A vs 26 pts in Arm B). Median age was 62 years and the primary sites of tumor were cholangiocarcinoma (77%) and gallbladder (23%). Median OS was 4.3 months (95% CI 3.1-5.1) for Arm A, and 8.0 months (95% CI 3.2-14.6) for Arm B with a HR of 2.02 (95% CI 1.01-4.03, p=0.05). The median PFS was 1.3 months (95% CI 1.2-1.5) for arm A and 2.8 months (95% CI 1.4-6.9) for arm B with a HR of 2.95 (95% CI 1.38-6.30, p=0.01). Overall RR was 8% (95% CI 0%, 19%) in Arm A vs 10% (95% CI 0%, 23%) in Arm B (p>0.99), and 8% vs 45% had stable disease. Eight pts in Arm A experienced treatment-related ≥ grade 3 toxicities, including one death due to vomiting/dehydration. Seven pts in Arm B experienced treatment-related grade 3 toxicities; no higher grade toxicities were reported. Conclusions: To our knowledge, this is the first prospective randomized study of a targeted agent versus chemotherapy for the second line treatment of BC. In this unselected population, the lack of response to trametinib resulted in early closure. The PFS and OS for trametinib were inferior to 5FU. Clinical trial information: 02042443.

Health-related quality of life as a marker of treatment benefit with nivolumab in platinum-refractory patients with metastatic or unresectable urothelial carcinoma from CheckMate 275

4526

Background: CheckMate 275 (NCT02387996), a phase II, single-arm study of nivolumab (3 mg/kg every 2 weeks) treatment in platinum-refractory patients (pts) with metastatic urothelial carcinoma, showed an objective response rate of 19.6% (95% CI, 15.0%–24.9%) with manageable toxicity. The objective of this analysis was to examine the impact of nivolumab on health-related quality of life (HRQoL) in the study. Methods: HRQoL was measured using the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire (EORTC QLQ-C30) and three-level EQ-5D (EQ-5D-3L) and visual analog scale (VAS). Questionnaires were completed at baseline and every 8 weeks thereafter for the first 48 weeks. The analysis cohort included pts with scores recorded at baseline and ≥1 postbaseline assessments while on treatment. Data were analyzed using mixed models, adjusting for baseline score. Results: Of the 270 patients treated with nivolumab, 168 (62%) had an assessment at baseline and ≥1 postbaseline assessment and were included in HRQoL analyses. Completion rates at baseline were 97% for both questionnaires. Statistically significant ( P< 0.05) improvements in mean scores for the EORTC QLQ-C30 subscales measuring role, emotional, and social functioning; global health status/quality of life; nausea/vomiting; pain; dyspnea; insomnia; appetite loss; constipation; and diarrhea were observed at ≥1 time points. With the exception of cognitive functioning, no significant worsening in subscale scores was observed in the EORTC QLQ-C30. Statistically significant and clinically meaningful improvement (based on a minimally important difference of 7) in EQ-5D VAS was noted between weeks 17 and 41. EQ-5D-3L utility index scores based on the UK tariff remained stable during treatment. Conclusions: Results of CheckMate 275 indicate that pts with metastatic or unresectable urothelial carcinoma whose disease progressed or recurred after treatment with a platinum agent exhibited stable, or in some cases statistically significantly improved, HRQoL while being treated with nivolumab, as measured by EORTC QLQ-C30 and EQ-5D-3L. Clinical trial information: NCT02387996.

Ramucirumab as Second-Line Treatment in Patients With Advanced Hepatocellular Carcinoma: Analysis of REACH Trial Results by Child-Pugh Score

Importance

REACH is the first phase 3 trial to provide information on hepatocellular cancer (HCC) in the second-line (postsorafenib) setting categorized by Child-Pugh score, a scoring system used to measure the severity of chronic liver disease. This exploratory analysis demonstrates the relationship between a potential ramucirumab survival benefit, severity of liver disease, and baseline α-fetoprotein (αFP).

Objective

To assess treatment effects and tolerability of ramucirumab by Child-Pugh score in patients with HCC enrolled in the REACH trial.

Design, Settings, and Participants

Randomized, double-blind, phase 3 trial of ramucirumab and best supportive care vs placebo and best supportive care as second-line treatment in patients with HCC enrolled between November 4, 2010 and April 18, 2013, from 154 global sites. Overall, 643 patients were randomized and included in this analysis; 565 patients considered Child-Pugh class A (Child-Pugh scores 5 and 6) and 78 patients considered class B (Child-Pugh scores 7 and 8).

Interventions

Ramucirumab (8 mg/kg) or placebo intravenously plus best supportive care every 2 weeks.

Main Outcomes and Measures

Overall survival (OS), defined as time from randomization to death from any cause.

Results

In the randomized population of 643 patients (mean [SD] age, 62.8 [11.1] years) in this analysis, a potential ramucirumab OS benefit was observed for patients with a Child-Pugh score of 5 (hazard ratio [HR], 0.80; 95% CI, 0.63-1.02; P = .06) but no apparent benefit for patients with Child-Pugh scores of 6 or 7 and 8. In patients with baseline αFP levels of 400 ng/mL (to convert ng/mL to μg/L, multiply by 1.0) or more, a ramucirumab OS benefit was significant for a score of Child-Pugh 5 (HR, 0.61; 95% CI, 0.43-0.87; P = .01) and Child-Pugh 6 (HR, 0.64; 95% CI, 0.42-0.98; P = .04), but was not significant for Child-Pugh 7 and 8. The overall safety profile of ramucirumab, regardless of Child-Pugh score, was considered manageable. Regardless of treatment arm, patients with Child-Pugh scores of 7 and 8 experienced a higher incidence of grade 3 or higher treatment-emergent adverse events, including ascites and asthenia, and special-interest events, including liver injury and/or failure and bleeding, compared with patients with Child-Pugh scores of 5 or 6.

Conclusions and Relevance

In unselected patients, a trend for ramucirumab survival benefit was observed only for patients with a Child-Pugh score of 5. In patients with baseline αFP levels of 400 ng/mL or more, a ramucirumab survival benefit was observed for Child-Pugh scores of 5 and 6. Ramucirumab had a manageable toxic effect profile. These results support the ongoing REACH-2 study of ramucirumab in patients with advanced HCC with underlying Child-Pugh A cirrhosis and baseline αFP levels of 400 ng/mL or more.

Trial Registration

clinicaltrials.gov Identifier: NCT01140347.

Interim results of a randomized phase II study of PEGPH20 added to nab-paclitaxel/gemcitabine in patients with stage IV previously untreated pancreatic cancer

439

Background: Poor outcome in pancreatic cancer (PDA) is associated partly with stromal hyaluronan (HA) accumulation, which compromises chemotherapy perfusion. PEGPH20, PEGylated recombinant human hyaluronidase, potentiates chemotherapy by depleting HA in tumors. Methods: In an ongoing, phase II, open-label, randomized study of PEGPH20+nab-paclitaxel (Nab)+Gemcitabine (Gem) (PAG) vs Nab+Gem (AG) in previously untreated stage IV PDA, pts receive PEGPH20 3 µg/kg twice weekly (C1), then weekly (C2+) with standard AG dosing. HA status was tested retrospectively. After a temporary clinical hold (Apr-Jul 2014) for an imbalance in thromboembolic (TE) events (29% PAG vs 15% AG), the protocol was amended to exclude high-TE-risk pts and add enoxaparin (LMWH) prophylaxis. Endpoints are PFS and TE events (primary); PFS and ORR by HA level and OS (secondary). Efficacy and safety data through Dec 2014 are for pts enrolled up to clinical hold (Stage 1); TE data are through Sep 2015 (Stage 2). Results: 135 pts were treated (74 PAG, 61 AG). PFS results are shown below (median follow-up 7 mo). In HA-high pts receiving PAG vs AG, ORR was 52% (1 CR) vs 24% (P=.038); ORR was 37% vs 38% in HA-low pts. OS was 12 mo vs 9 mo (HR=0.62) despite 12/23 PAG pts discontinuing PEGPH20 at clinical hold. Common ADRs (PAG vs AG) included peripheral edema (58% vs 31%), muscle spasms (55% vs 1.6%), and neutropenia (32% vs 18%). TE events were: Stage 1 42% vs 25% (no LMWH); Stage 2 (with LMWH; 40 mg/d or 40 mg/d increased to 1 mg/kg/d) 28% vs 29%; (1 mg/kg/d) 5% vs 6%; overall (40 mg/d or 1 mg/kg/d) 13% each arm (to be updated). Conclusions: Pts with HA-high tumors receiving PAG, vs AG, showed significant improvements in PFS and ORR and a trend toward improved OS. PAG was well tolerated, with TE events reduced with LMWH prophylaxis. A global phase III trial of PAG will initiate Q1 2016. Clinical Trial Information: NCT01839487. Clinical trial information: NCT01839487. [Table: see text]

A randomized phase II open label multi-institution study of the combination of bevacizumab (B) and erlotinib (E) compared to sorafenib (S) in the first-line treatment of patients (pts) with advanced hepatocellular carcinoma (HCC)

337

Background: HCC is the 2nd most common cancer worldwide. Most pts present with advanced disease and require systemic therapy. S, a multi-targeted tyrosine kinase inhibitor (TKI) is the only approved drug for HCC. B is a mAb that binds circulating ligand of the transmembrane VEGF receptor; E is a TKI that inhibits EGFR signal transduction. Published single-arm trial data suggest clinical benefit from B+E in HCC. Methods: The study was designed to estimate the HR for OS of B+E vs S with its 95% confidence interval for a sample size of 90 evaluable pts. A difference in OS favoring the B+E arm with a HR of 0.67 was expected and of interest, based on median OS for B+E and S of 15 and 11 mos. seen in previous trials.Secondary endpoints include event-free survival (EFS), toxicity, and RR. Eligible pts had advanced HCC, Childs-Pugh Class A-B7, no prior systemic therapy, preserved organ function, ECOG PS 0-2. Patients were randomized 1:1 to receive S 400 mg orally twice daily, continuously, or B 10 mg/kg IV every 14 days and E 150 mg orally daily. Treatment cycles were 28 days, restaging every 2 cycles by investigator-assessed RR per RECIST 1.1 and subsequent independent radiologic review. Results: A total of 95 pts were registered, 43 in the S arm and 47 in the B+E arm. Pts who received at least 1 dose of study drug(s) were evaluable. Data are summarized in the table. Conclusions: Based on initial data analysis, the OS of advanced HCC pts treated with B+E is consistent with that of S, and the toxicity profile and EFS of B+E compare favorably to S. Clinical trial information: NCT00881751. [Table: see text]

The DASH Study: A phase 1b study of dalantercept plus sorafenib in advanced hepatocellular carcinoma

TPS495

Background: The activin receptor-like kinase (ALK1) pathway is a novel target in angiogenesis that promotes blood vessel maturation and stabilization. ALK1 binds to the ligand bone morphogenetic protein 9 (BMP9) which is overexpressed in hepatocellular carcinoma (HCC) compared to normal hepatocytes. Dalantercept is an ALK1 receptor fusion protein that binds BMP9 and acts as a ligand trap. Sorafenib, a multi-kinase and vascular endothelial growth factor receptor tyrosine kinase inhibitor (VEGFR TKI), is the standard therapy for advanced HCC. In a preclinical model of HCC, simultaneous blockade of ALK1 and VEGF signaling with dalantercept and sorafenib resulted in additive tumor growth inhibition. In a completed Phase 1 study in thirty-seven subjects with solid tumors, dalantercept monotherapy demonstrated preliminary anti-tumor activity and a safety profile that was generally non-overlapping with VEGFR TKIs. Methods: An open label, multi-center, dose escalating, phase 1b study to evaluate dalantercept plus sorafenib in subjects with advanced HCC is ongoing. The primary endpoint includes the evaluation of the safety and tolerability of dalantercept plus sorafenib and determination of the recommended phase 2 dose levels of the combination. Secondary endpoints include assessments of the pharmacokinetic profile of the combination, preliminary activity including response rate using RECIST 1.1 and time to progression, and pharmacodynamic biomarkers in the serum and tissue including ALK1 and BMP9 expression. In the first two cohorts of 3-6 subjects each, the dalantercept dose levels will be 0.6 and 0.9 mg/kg, respectively, administered subcutaneously (SC) every 3 weeks in combination with sorafenib 400 mg PO once daily. In cohort three, 3-6 subjects will receive dalantercept dose level 0.9 mg/kg SC every 3 weeks with sorafenib 400 mg PO twice daily. Patient safety data through day 22 will be evaluated prior to escalation to the next cohort. An expansion cohort will enroll 10-20 subjects at or below the maximum tolerated dose level. Key eligibility criteria: histologically confirmed advanced HCC, Child-Pugh A liver disease, ECOG performance status of 0-1, and no prior systemic therapy in the advanced setting. Clinical trial information: NCT02024087.

Ramucirumab (RAM) as second-line treatment in patients (pts) with advanced hepatocellular carcinoma (HCC): Analysis of patients with elevated α-fetoprotein (AFP) from the randomized phase III REACH study

232

Background: REACH was a global, multicenter, randomized, double-blind, phase 3 study evaluating the efficacy and safety of RAM as a single agent for the treatment of pts with advanced HCC after prior sorafenib therapy. The primary outcome for REACH was presented at ESMO 2014. The overall survival (OS) HR for the ITT population (RAM 283; placebo [PBO] 282) was 0.866 (95% CI 0.717, 1.046; p=0.1391); median OS was 9.2m for RAM vs 7.6m for PBO. The pre-specified subgroup analysis of baseline AFP (cutoff 400 ng/mL) suggested AFP is a predictive marker for RAM survival benefit. Methods: Pre-specified subgroup analysis was performed based on baseline AFP with a cutoff of 400 ng/mL. Additional analyses were conducted using stratified/unstratified cox regression models and corresponding log rank test to evaluate the relationship between baseline AFP and RAM treatment effect. Results: In 250 pts with baseline AFP ≥400 ng/mL (RAM 119; PBO 131), OS HR was 0.67 (95% CI 0.51–0.90; p=0.0059). Median OS was 7.8m for RAM vs 4.2m for PBO. In 417 pts with a baseline AFP ≥1.5 × upper limit of normal (ULN; RAM 205; PBO 212), mOS was 8.6m for RAM vs 5.7m for PBO and the HR was 0.749 (95% CI: 0.603, 0.930) (p=0.0088). The interaction testing of baseline AFP and RAM treatment effect on OS using both cutoffs (400 ng/mL and 1.5 xULN) are significant (p-value = 0.0272 and 0.0372, respectively). The safety profile in these pt populations was similar to that observed in the overall safety population. Additional REACH analyses demonstrating the predictive value of baseline AFP for RAM treatment effect on OS will be presented. Conclusions: A clinically meaningful improvement in OS was observed in populations with a baseline AFP ≥400 ng/mL or ≥1.5 × ULN. Additional analyses demonstrated a consistent RAM OS benefit for the pt population with baseline AFP over a wide range of values above the normal range. Baseline AFP is a likely predictive marker for RAM OS benefit. Clinical trial information: NCT01140347.

Phase IIb randomized trial of Pexa-Vec (pexastimogene devacirepvec; JX-594), a targeted oncolytic vaccinia virus, plus best supportive care (BSC) versus BSC alone in patients with advanced hepatocellular carcinoma who have failed sorafenib treatment (TRAVERSE)

TPS4161^

Background: Pexa-Vec is a targeted oncolytic and immunotherapeutic vaccinia virus engineered to express human granulocyte-macrophage colony stimulating factor (GM-CSF). Direct oncolysis plus GM-CSF expression stimulates tumor vascular disruption and anti-tumor immunity (Nature Rev Cancer, 2009). Pexa-Vec was well-tolerated in Phase 1 trials and was shown to replicate in metastatic tumors following intratumoral (IT) or intravenous (IV) administration (Lancet Oncol, 2008 and Nature, 2011). A randomized high vs low dose Phase 2 trial in 30 patients with advanced HCC, demonstrated prolonged survival in the high-dose Pexa-Vec arm (median survival 14.1 mo vs. 6.7 mo; Hazard Ratio 0.39, p=0.02) (AASLD Annual Meeting, 2011, LB1). Methods: TRAVERSE is a Phase 2b randomized, open-label, multi-center trial in patients with advanced HCC who have failed sorafenib treatment. Approximately 120 patients will be randomized 2:1 to Pexa-Vec plus BSC versus BSC, respectively. Randomization will be stratified by region (Asian vs. non-Asian); sorafenib intolerant vs refractory; and presence vs absence of extra-hepatic disease. The primary objective is to determine overall survival. Main inclusion criteria are advanced HCC having failed sorafenib (intolerance or radiographic progression during or < 3 months following last sorafenib), Child-Pugh A-B7 (no ascites), acceptable hematologic function. Assuming a median overall survival of 4.0 months with BSC and a target hazard ratio of 0.57 (corresponding to an experimental arm median survival of 7.0 months), 73 events (deaths) will provide 70% power at 1-sided alpha = 0.05 to detect a difference in overall survival between the treatment groups using a stratified logrank test. Patients randomized to Pexa-Vec will receive a dose of 109 plaque forming units (pfu) IV on Day 1 followed by five IT treatments between Day 8 and Week 18. Enrollment has begun on this study with clinical trial registry number of NCT01387555. Clinical trial information: NCT01387555.

A QTc study of cabazitaxel in patients with advanced solid tumors

e15115

Background: Cabazitaxel (Cbz) improves overall survival in patients (pts) with metastatic castration-resistant prostate cancer (mCRPC) after docetaxel failure, compared with mitoxantrone (HR 0.70; 95% CI 0.59–0.83; p<0.0001). Following Cbz approval for the treatment of mCRPC, this study was undertaken to evaluate any effect of Cbz on the QTc interval. Methods: This prospective, multinational, open-label study (NCT01087021) enrolled pts with advanced solid tumors (without other therapeutic options). Cbz 25 mg/m² IV was administered on Day 1 Q3W. QTc and other ECG intervals were assessed on Day 1 of Cycle 1. Triplicate ECGs were obtained from 12-lead Holter recordings and concomitant serial blood samples were collected for pharmacokinetic (PK) analysis. The primary endpoint was change from baseline in the corrected QTc interval (according to the Fridericia formula [QTcF]). Results: A total of 96 pts were enrolled; 32 pts under the original protocol (6-h Holter) and 64 pts following protocol amendment 1, which extended ECG and PK monitoring (24-h Holter). Median age was 63 yrs (69.8% male), 30.5% and 57.9% of pts were ECOG PS 0 and 1 respectively; 33 pts (34.4%) had prostate cancer. Screening ECG was abnormal but not clinically significant in 39.6% of pts. The majority (n=65) of pts received ≥ 3 treatment cycles; safety and ECG parameters were evaluated in 95 and 94 pts, respectively. In the 24-h Holter group (n=63), the maximum least squares (LS) mean change from baseline in QTcF was 4.8 msec (90% CI 2.1–7.5), returning to baseline by 24 h. Similar results were observed in the overall population (n=94). At Cmax, Cbz concentration had no effect on QTcF change from baseline; the mean (CV%) Cmax (n=91) and AUC (n=92) were 276 ng/ml (63%) and 1245 ng.h/ml (82%). The LS mean change from baseline in heart rate increased up to 24 h but remained < 10 beats per minute. The most common grade 3/4 AEs were neutropenia (27.4%), febrile neutropenia (12.6%), fatigue (12.6%) and dehydration (5.3%). No grade 3/4 cardiac AEs were reported. Of the 6 deaths reported, 1 (infection) was study drug related. Conclusions: Cbz had no significant effect on QTc interval in pts with advanced tumors. The Cbz safety profile is consistent with previous findings and with other taxane-based therapies.

A QTc study of cabazitaxel in patients with advanced solid tumors

257

Background: Cabazitaxel (Cbz) improves overall survival in patients (pts) with metastatic castration-resistant prostate cancer (mCRPC) after docetaxel failure, compared with mitoxantrone (HR 0.70; 95% CI 0.59–0.83; P < 0.0001). Following Cbz approval for the treatment of mCRPC, this study was undertaken to evaluate any effect of Cbz on the QTc interval.

Methods: This prospective, multinational, open-label study ( NCT01087021 ) enrolled pts with advanced solid tumors (without other therapeutic options). Cbz 25 mg/m² IV was administered on Day 1 Q3W. QTc and other ECG intervals were assessed on Day 1 of Cycle 1. Triplicate ECGs were obtained from 12-lead Holter recordings and concomitant serial blood samples were collected for pharmacokinetic (PK) analysis. The primary endpoint was change from baseline in the corrected QTc interval (according to the Fridericia formula QTcF).

Results: A total of 96 pts were enrolled; 32 pts under the original protocol (6-h Holter) and 64 pts following protocol amendment 1, which extended ECG and PK monitoring (24-h Holter). Median age was 63 yrs (69.8% male), 30.5% and 57.9% of pts were ECOG PS 0 and 1 respectively; 33 pts (34.4%) had prostate cancer. Screening ECG was abnormal but not clinically significant in 39.6% of pts. The majority (n = 65) of pts received ≥ 3 treatment cycles; safety and ECG parameters were evaluated in 95 and 94 pts, respectively. In the 24-h Holter group (n = 63), the maximum least squares (LS) mean change from baseline in QTcF was 4.8 msec (90% CI 2.1–7.5), returning to baseline by 24 h. Similar results were observed in the overall population (n = 94). At Cmax, Cbz concentration had no effect on QTcF change from baseline; the mean (CV%) Cmax (n = 91) and AUC (n = 92) were 276 ng/ml (63%) and 1245 ng.h/ml (82%). The LS mean change from baseline in heart rate increased up to 24 h but remained < 10 beats per minute. The most common Grade 3/4 AEs were neutropenia (27.4%), febrile neutropenia (12.6%), fatigue (12.6%) and dehydration (5.3%). No Grade 3/4 cardiac AEs were reported. Of the 6 deaths reported, 1 (infection) was study drug related.

Conclusions: Cbz had no significant effect on QTc interval in pts with advanced tumors. The Cbz safety profile is consistent with previous findings and with other taxane-based therapies.

Phase II trial of weekly patupilone in patients with castration-resistant prostate cancer

BACKGROUND

Drug resistance mechanisms can reduce response rate and duration in men with castration-resistant prostate cancer (CRPC) receiving docetaxel-based therapy. Patupilone (epothilone B), a microtubule-targeting agent, may be unaffected by some resistance mechanisms. Therefore, a phase II study assessed the patupilone safety and activity in CRPC patients with and without previous chemotherapy.

METHODS

CRPC patients received patupilone 2.5 mg/m(2) weekly for 3 weeks of a 4-week cycle. Patients were required to have measurable disease or prostate-specific antigen (PSA) progression (levels>20 ng/ml).

RESULTS

All 45 enrolled patients (median age, 69 years) were safety and response assessable. Sixty-four percent had previous chemotherapy (55% had previous taxane therapy). Patients received a median of three patupilone cycles. Patupilone was generally well tolerated. Ten (22%) patients experienced grade 3 diarrhea, six (13%) grade 3 fatigue, and one (2%) grade 3 neuropathy with no neutropenia or thrombocytopenia incidence. Six (13%) patients had >or= 50% decline in PSA (three had previous taxane therapy). No patient with measurable disease had a response. Median overall survival was 13.4 months.

CONCLUSIONS

The safety profile of weekly patupilone in CRPC patients compares favorably with that of other microtubule inhibitors. At the dose and schedule tested, patupilone demonstrated minimal activity in CRPC.

Day-long subcutaneous infusion of exenatide lowers glycemia in patients with type 2 diabetes

Exenatide (exendin-4) is an incretin mimetic with potential antidiabetic activity. This study examined the effects of a continuous subcutaneous (SC) infusion of exenatide (0.2, 0.4, 0.6, or 0.8 microg/kg/day) or placebo (PBO) on glycemic control over 23 h intervals. Twelve subjects with type 2 diabetes treated with metformin and/or diet received 10 infusions (4 exenatide, 6 PBO) on consecutive days. Exenatide was given in a dose-increasing design with at least one placebo infusion between each exenatide infusion, and with meals and a snack provided during the first 14 h of infusion. Plasma exenatide concentrations were dose-proportional. Plasma glucose (4-23 h) was lower in all exenatide arms compared to placebo (p<0.0001). The change in insulin/glucagon ratio and amylin concentrations from pre-infusion to post-infusion was increased (p<0.005, p<0.05, respectively) in the combined exenatide arms, but remained unchanged in the placebo groups. Nausea and vomiting were the most common treatment emergent adverse events. Exenatide infusion also appeared to have positive effects on beta-cell and alpha-cell function as measured by proinsulin/insulin ratios and mean glucagon concentrations. In summary, exenatide lowered plasma glucose during both prandial and fasting states when delivered as a continuous SC infusion over twenty-three hours, suggesting that exenatide can provide day-long glycemic control in patients with type 2 diabetes.

Vascular function, insulin resistance and fatty acids

Over the past 10 years it has become clear that intact vascular function, especially at the level of the endothelium, is paramount in the prevention or delay of cardiovascular disease. It has also become clear that insulin itself, in addition to its metabolic actions, directly effects vascular endothelium and smooth muscle. Insulin, at normal physiologic concentrations, causes changes in skeletal muscle blood flow in healthy, insulin-sensitive subjects. Insulin's effect on the endothelium is mediated through its own receptor and insulin signalling pathways, resulting in the increased release of nitric oxide. Insulin's vascular actions are impaired in insulin-resistant conditions such as obesity, Type II (non-insulin-dependent) diabetes mellitus and hypertension, which could contribute to the excessive rates of cardiovascular disease in these groups. Insulin-resistant states of obesity and Type II diabetes show a multitude of metabolic abnormalities that could cause vascular dysfunction. Non-esterified fatty acid levels increase long before hyperglycaemia becomes present. Raised non-esterified fatty acids impair insulin's effect on glucose uptake in skeletal muscle and the vascular endothelium and thus could have detrimental effects on the vasculature, leading to premature cardiovascular disease.

Repeatability characteristics of simple indices of insulin resistance: implications for research applications

The objectives of this study were to evaluate test characteristics, such as normality of distribution, variation, and repeatability, of simple fasting measures of insulin sensitivity and to use the results to choose among these measures. Duplicate fasting samples of insulin and glucose were collected before 4 h of euglycemic hyperinsulinemic clamping using insulin infusion rates ranging from 40-600 mU/m2 x min. Currently recommended estimates of insulin sensitivity, including the fasting insulin, 40/insulin, the homeostasis model assessment, the logarithmic transformation of the homeostasis model assessment, and the Quantitative Insulin Sensitivity Check Index, were evaluated. The normality of distribution and the variability of the tests (coefficient of variation and discriminant ratio) were compared between the measures and against the "gold standard" hyperinsulinemic clamp. Data from 253 clamp studies in 152 subjects were examined, including 79 repeated studies for repeatability analysis. In subjects ranging from lean to diabetic, the log transformed fasting measures combining insulin and glucose had normal distributions and test characteristics superior to the other simple indices (logarithmic transformation of the homeostasis model assessment coefficient of variation, 0.55; discriminant ratio, 13; Quantitative Insulin Sensitivity Check Index coefficient of variation, 0.05; discriminant ratio, 10) and statistically comparable to euglycemic hyperinsulinemic clamps (coefficient of variation, 0.10; discriminant ratio, 6.4). These favorable characteristics helped explain the superior correlations of these measures with the hyperinsulinemic clamps among insulin-resistant subjects. Furthermore, therapeutic changes in insulin sensitivity were as readily demonstrated with these simple measures as with the hyperinsulinemic clamp. The test characteristics of the logarithmic transformation of the homeostasis model assessment and the Quantitative Insulin Sensitivity Check Index are superior to other simple indices of insulin sensitivity. This helps explain their excellent correlations with formal measures both at baseline and with changes in insulin sensitivity and supports their broader application in clinical research.

Impaired glucose tolerance as a disease

Current criteria for diagnosing diabetes, based on fasting plasma glucose levels during administration of the oral glucose tolerance test (OGTT), are poorly sensitive and are only modestly predictive of microvascular risk. The period after administration of OGTT is far more predictive and more closely resembles the postprandial state where microvascular risk is elevated. However, persons who do not yet exhibit symptoms of diabetes may nonetheless have impaired glucose tolerance or dysglycemia, whereby macrovascular disease can develop at a glucose level lower than the threshold for microvascular disease and can progress in a graded fashion. This article reviews the factors that may cause dysglycemia (including insulin resistance and obesity) and how diet, blood pressure control, and the use of statins or glycemic/insulin sensitizing may reduce cardiovascular risk in this prediabetic population.

Polycystic ovary syndrome is associated with endothelial dysfunction

BACKGROUND

We recently reported endothelial dysfunction as a novel cardiovascular risk factor associated with insulin resistance/obesity. Here, we tested whether hyperandrogenic insulin-resistant women with polycystic ovary syndrome (PCOS) who are at increased risk of macrovascular disease display impaired endothelium-dependent vasodilation and whether endothelial function in PCOS is associated with particular metabolic and/or hormonal characteristics.

METHODS AND RESULTS

We studied leg blood flow (LBF) responses to graded intrafemoral artery infusions of the endothelium-dependent vasodilator methacholine chloride (MCh) and to euglycemic hyperinsulinemia in 12 obese women with PCOS and in 13 healthy age- and weight-matched control subjects (OBW). LBF increments in response to MCh were 50% lower in the PCOS group than in the OBW group (P:<0.01). Euglycemic hyperinsulinemia increased LBF above baseline by 30% in the PCOS and 60% in OBW group (P:<0.05 between groups). Across all subjects, the maximal LBF response to MCh exhibited a strong inverse correlation with free testosterone levels (r=-0.52, P:<0.007). This relationship was stronger than with any other parameter, including insulin sensitivity.

CONCLUSIONS

PCOS is characterized by (1) endothelial dysfunction and (2) resistance to the vasodilating action of insulin. This endothelial dysfunction appears to be associated with both elevated androgen levels and insulin resistance. Given the central vasoprotective role of endothelium, these findings could explain, at least in part, the increased risk for macrovascular disease in women with PCOS.

HbA1c measurement improves the detection of type 2 diabetes in high-risk individuals with nondiagnostic levels of fasting plasma glucose: the Early Diabetes Intervention Program (EDIP)

OBJECTIVE

Whereas new diagnostic criteria based on a fasting plasma glucose (FPG) of > 126 mg/dl (7.8 mmol/l) have improved the detection of diabetes, multiple reports indicate that many people with diabetes diagnosed by 2-h oral glucose tolerance test (OGTT) glucose measurements > or = 11.1 mmol/l (200 mg/dl) would remain undiagnosed based on this FPG criteria. Thus, improved methods to detect diabetes are particularly needed for high-risk individuals. We evaluated whether the combination of FPG and HbA1c measurements enhanced detection of diabetes in those individuals at risk for diabetes with nondiagnostic or minimally elevated FPG.

RESEARCH DESIGN AND METHODS

We analyzed FPG, OGTT, and HbA1c data from 244 subjects screened for participation in the Early Diabetes Intervention Program (EDIP).

RESULTS

Of 244 high-risk subjects studied by FPG measurements and OGTT, 24% of the individuals with FPG levels of 5.5-6.0 mmol/l (100-109 mg/dl) had OGTT-diagnosed diabetes, and nearly 50% of the individuals with FPG levels of 6.1-6.9 mmol/l (110-125 mg/dl) had OGTT-diagnosed diabetes. In the subjects with OGTT-diagnosed diabetes and FPG levels between 5.5 and 8.0 mmol/l, detection of an elevated HbA1c (>6.1% or mean + 2 SDs) led to a substantial improvement in diagnostic sensitivity over the FPG threshold of 7.0 mmol/l (61 vs. 45%, respectively, P = 0.002). Concordant FPG levels > or = 7.0 mmol/l (currently recommended for diagnosis) occurred in only 19% of our cohort with type 2 diabetes.

CONCLUSIONS

Diagnostic criteria based on FPG criteria are relatively insensitive in the detection of early type 2 diabetes in at-risk subjects. HbA1c measurement improves the sensitivity of screening in high-risk individuals.

Quantitative insulin sensitivity check index: a simple, accurate method for assessing insulin sensitivity in humans

Insulin resistance plays an important role in the pathophysiology of diabetes and is associated with obesity and other cardiovascular risk factors. The "gold standard" glucose clamp and minimal model analysis are two established methods for determining insulin sensitivity in vivo, but neither is easily implemented in large studies. Thus, it is of interest to develop a simple, accurate method for assessing insulin sensitivity that is useful for clinical investigations. We performed both hyperinsulinemic isoglycemic glucose clamp and insulin-modified frequently sampled iv glucose tolerance tests on 28 nonobese, 13 obese, and 15 type 2 diabetic subjects. We obtained correlations between indexes of insulin sensitivity from glucose clamp studies (SI(Clamp)) and minimal model analysis (SI(MM)) that were comparable to previous reports (r = 0.57). We performed a sensitivity analysis on our data and discovered that physiological steady state values [i.e. fasting insulin (I(0)) and glucose (G(0))] contain critical information about insulin sensitivity. We defined a quantitative insulin sensitivity check index (QUICKI = 1/[log(I(0)) + log(G(0))]) that has substantially better correlation with SI(Clamp) (r = 0.78) than the correlation we observed between SI(MM) and SI(Clamp). Moreover, we observed a comparable overall correlation between QUICKI and SI(Clamp) in a totally independent group of 21 obese and 14 nonobese subjects from another institution. We conclude that QUICKI is an index of insulin sensitivity obtained from a fasting blood sample that may be useful for clinical research.

Free fatty acid elevation impairs insulin-mediated vasodilation and nitric oxide production

The effect and time course of free fatty acid (FFA) elevation on insulin-mediated vasodilation (IMV) and the relationship of FFA elevation to changes in insulin-mediated glucose uptake was studied. Two groups of lean insulin-sensitive subjects underwent euglycemic-hyperinsulinemic (40 mU x m(-2) x min(-1)) clamp studies with and without superimposed FFA elevation on 2 occasions approximately 4 weeks apart. Groups differed only by duration of FFA elevation, either short (2-4 h, n = 12) or long (8 h, n = 7). On both occasions, rates of whole-body glucose uptake were measured, and changes in leg blood flow (LBF) and femoral vein nitric oxide nitrite plus nitrate (NOx) flux in response to the clamps were determined. Short FFA infusion did not have any significant effect on the parameters of interest. In contrast, long FFA infusion decreased rates of whole-body glucose uptake from 47.7 +/-2.8 to 32.2 +/- 0.6 micromol x kg(-1) x min(-1) (P < 0.01), insulin-mediated increases in LBF from 66 +/- 8 to 37 +/- 7% (P < 0.05), and insulin-induced increases in NOx flux from 25 +/- 9 to 5 +/- 9% (P < 0.05). Importantly, throughout all groups, FFA-induced changes in whole-body glucose uptake correlated significantly with FFA-induced changes in insulin-mediated increases in LBF (r = 0.706, P < 0.001), which indicates coupling of metabolic and vascular effects. In a different protocol, short FFA elevation blunted the LBF response to NG-monomethyl-L-arginine (L-NMMA), which is an inhibitor of NO synthase. LBF in response to L-NMMA decreased by 17.3 +/- 2.4 and 9.0 +/- 1.4% in the groups without and with FFA elevation, respectively (P < 0.05), which indicates that FFA elevation interferes with shear stress-induced NO production. Thus, impairment of shear stress-induced vasodilation and IMV by FFA elevation occurs with different time courses, and impairment of IMV occurs only if glucose metabolism is concomitantly reduced. These findings suggest that NO production in response to the different stimuli may be mediated via different signaling pathways. FFA-induced reduction in NO production may contribute to the higher incidence of hypertension and macrovascular disease in insulin-resistant patients.

Quantitative insulin sensitivity check index: a simple, accurate method for assessing insulin sensitivity in humans

Insulin resistance plays an important role in the pathophysiology of diabetes and is associated with obesity and other cardiovascular risk factors. The "gold standard" glucose clamp and minimal model analysis are two established methods for determining insulin sensitivity in vivo, but neither is easily implemented in large studies. Thus, it is of interest to develop a simple, accurate method for assessing insulin sensitivity that is useful for clinical investigations. We performed both hyperinsulinemic isoglycemic glucose clamp and insulin-modified frequently sampled iv glucose tolerance tests on 28 nonobese, 13 obese, and 15 type 2 diabetic subjects. We obtained correlations between indexes of insulin sensitivity from glucose clamp studies (SI(Clamp)) and minimal model analysis (SI(MM)) that were comparable to previous reports (r = 0.57). We performed a sensitivity analysis on our data and discovered that physiological steady state values [i.e. fasting insulin (I(0)) and glucose (G(0))] contain critical information about insulin sensitivity. We defined a quantitative insulin sensitivity check index (QUICKI = 1/[log(I(0)) + log(G(0))]) that has substantially better correlation with SI(Clamp) (r = 0.78) than the correlation we observed between SI(MM) and SI(Clamp). Moreover, we observed a comparable overall correlation between QUICKI and SI(Clamp) in a totally independent group of 21 obese and 14 nonobese subjects from another institution. We conclude that QUICKI is an index of insulin sensitivity obtained from a fasting blood sample that may be useful for clinical research.

Type II diabetes abrogates sex differences in endothelial function in premenopausal women

BACKGROUND

Obesity is a more potent cardiovascular risk factor (CVRF) in men than in women. Because traditional CVRFs cannot fully account for this sex difference, we tested the hypothesis that compared with men, women exhibit more robust endothelial function independent of obesity and that this sex difference is abrogated by diabetes.

METHODS AND RESULTS

We studied leg blood flow (LBF) responses to graded intrafemoral artery infusions of the endothelium-dependent vasodilator methacholine chloride (Mch) and the endothelium-independent vasodilator sodium nitroprusside (SNP) in groups of lean, obese (OB), and type II diabetic (DM) premenopausal women and age- and body mass index-matched men. LBF response to intrafemoral administration of L-NMMA, an inhibitor of nitric oxide synthase, was also assessed in normal men and women. Maximum LBF increments in response to Mch were 347+/-57% versus 231+/-22% in lean women versus men (P<0.05) and 203+/-25% versus 111+/-17% in OB women versus men (P<0.01), respectively. In DM, maximum LBF increments in response to Mch were 104+/-24% and 138+/-33% in women and men, respectively, (P=NS). LBF decrements in response to L-NMMA were 34.9+/-4.1% and 17.1+/-4.2% in women and men, respectively (P<0.01). The response to SNP was not different between sexes and groups.

CONCLUSIONS

Premenopausal nondiabetic women exhibit more robust endothelium-dependent vasodilation owing to higher rates of nitric oxide release than men. Given the protective vascular action of nitric oxide, this difference may partially explain the lower incidence of macrovascular disease in women. In premenopausal women, DM causes impairment of endothelial function beyond that observed with obesity alone and leads to endothelial dysfunction similar to that observed in DM men. These findings may help explain the similar rates of coronary artery disease and mortality in diabetic men and women.

Interaction between insulin sensitivity and muscle perfusion on glucose uptake in human skeletal muscle: evidence for capillary recruitment

Insulin and glucose delivery (muscle perfusion) can modulate insulin-mediated glucose uptake. This study was undertaken to determine 1) to what extent insulin sensitivity modulates the effect of perfusion on glucose uptake and 2) whether this effect is achieved via capillary recruitment. We measured glucose disposal rates (GDRs) and leg muscle glucose uptake (LGU) in subjects exhibiting a wide range of insulin sensitivity, after 4 h of steady-state (SS) euglycemic hyperinsulinemia (>6,000 pmol/l) and subsequently after raising the rate of leg blood flow (LBF) 2-fold with a superimposed intrafemoral artery infusion of methacholine chloride (Mch), an endothelium-dependent vasodilator. LBF was determined by thermodilution: LGU = arteriovenous glucose difference (AVGdelta) x LBF. As a result of the 114+/-12% increase in LBF induced by Mch, the AVGdelta decreased 32+/-4%, and overall rates of LGU increased 40+/-5% (P < 0.05). We found a positive relationship between the Mch-modulated increase in LGU and insulin sensitivity (GDR) (r = 0.60, P < 0.02), suggesting that the most insulin-sensitive subjects had the greatest enhancement of LGU in response to augmentation of muscle perfusion. In separate groups of subjects, we also examined the relationship between muscle perfusion rate and glucose extraction (AVGdelta). Perfusion was either pharmacologically enhanced with Mch or reduced by intra-arterial infusion of the nitric oxide inhibitor N(G)-monomethyl-L-arginine during SS euglycemic hyperinsulinemia. Over the range of LBF, changes in AVGdelta were smaller than expected based on the noncapillary recruitment model of Renkin. Together, the data indicate that 1) muscle perfusion becomes more rate limiting to glucose uptake as insulin sensitivity increases and 2) insulin-mediated increments in muscle perfusion are accompanied by capillary recruitment. Thus, insulin-stimulated glucose uptake displays both permeability- and perfusion-limited glucose exchange properties.

Mice with gene disruption of both endothelial and neuronal nitric oxide synthase exhibit insulin resistance

Studies from our laboratory using acute pharmacologic blockade of nitric oxide synthase (NOS) activity have suggested that nitric oxide (NO) has an important role in regulating carbohydrate metabolism. We now report on insulin sensitivity in mice with targeted disruptions in endothelial NOS (eNOS) and neuronal NOS (nNOS) genes compared with their wild-type (WT) counterparts. Mice underwent hyperinsulinemic-euglycemic clamp studies after a 24-h fast, during an insulin infusion of 20 mU x kg(-1) x min(-1). Glucose levels were measured at baseline and every 10 min during the clamp. Insulin levels were measured at baseline and at the end of the clamp study. Glucose infusion rates (GIRs) during the last 30 min of the clamp study were in a steady state. Tritiated glucose infusion was used to measure rates of endogenous glucose output (EGO) both at baseline and during steady-state euglycemia. Glucose disposal rates (GDRs) were computed from the GIR and EGO. Fasting and steady-state glucose and insulin levels were comparable in the 3 groups of mice. No differences in fasting EGO were noted between the groups. GIR was significantly reduced (37%, P = 0.001) in the eNOS knockout (KO) mice compared with the WT mice, with values for the nNOS mice being intermediate. EGO was completely suppressed in the nNOS and WT mice during insulin infusion, but not in the eNOS mice. Even so, the eNOS mice displayed significantly reduced whole-body GDRs compared with those of the WT mice (82.67+/-10.77 vs. 103.67+/-3.47 mg x kg(-1) x min(-1), P = 0.03). eNOS KO mice are insulin resistant at the level of the liver and peripheral tissues, whereas the nNOS KO mice are insulin resistant only in the latter. These data indicate that NO plays a role in modulating insulin sensitivity and carbohydrate metabolism and that the eNOS isoform may play a dominant role relative to nNOS.

Dose-response relationship of insulin to glucose fluxes in the awake and unrestrained mouse

The purpose of the study was to use the hyperinsulinemic-euglycemic clamp technique to generate insulin dose-response curves for insulin suppression of endogenous glucose output (EGO) and stimulation of the glucose disposal rate (GDR) in conscious unstressed mice. Five groups of male ICR (Institute for Cancer Research) mice were studied (N = 43). The animals underwent surgery for implantation of a jugular vein catheter 2 to 3 days before the clamp and were fasted 6 hours before the study. Each group was clamped at a different insulin infusion rate of 0, 2.5, 10, or 20 mU/kg/min. 3H-3-glucose was infused for measurement of the glucose turnover rate (rate of appearance [Ra]). Blood samples were collected by milking a severed tail-tip. EGO was calculated as the difference between the Ra and glucose infusion rate (GIR), and the glucose clearance rate (GCR) as the GDR divided by the plasma glucose concentration. From the curves generated, half-maximal EGO and GCR were obtained at a plasma insulin concentration of 20 to 30 microU/mL, which was achieved at an insulin infusion rate of about 4 to 5 mU/kg/min. Maximal suppression of EGO and stimulation of the GCR occurred at an insulin infusion rate of 10 mU/kg/min. The establishment of normative curves for insulin-stimulated glucose metabolism in conscious mice facilitates the evaluation of glucose metabolism in a variety of mouse models of insulin resistance.

Dual energy X-ray absorptiometry assessment of fat mass distribution and its association with the insulin resistance syndrome

OBJECTIVE

To determine which dual energy X-ray absorptiometry (DXA)-derived indices of fat mass distribution are the most informative to predict the various parameters of the metabolic syndrome.

RESEARCH DESIGN AND METHODS

A total of 87 healthy men, 63 lean (% fat < or =26) and 24 obese (% fat >26), underwent DXA scanning to evaluate body composition with respect to the whole body and the trunk, leg, and abdominal regions from L1 to L4 and from L3 to L4. These regions were correlated with insulin sensitivity determined by the euglycemic-hyperinsulinemic clamp, insulin area under the curve after oral glucose tolerance test (AUC I); triglyceride; total, HDL, and LDL cholesterol; free fatty acids; and blood pressure. The analyses were performed in all subjects, as well as in lean and obese groups separately.

RESULTS

Among the various indices of body fat, DXA-determined adiposity in the abdominal cut at L1-4 level was the most predictive of the metabolic variables, showing significant relationships with glucose infusion rate ([GIR], mg kg(-1) lean body mass x min(-1)), triglyceride, and cholesterol, independent of total-body mass (r = -0.267, P<0.05; r = 0.316, P<0.005; and r = 0.319, P<0.005, respectively). Upon subanalysis, these correlations remained significant in lean men, whereas in obese men, only BMI and the amount of leg fat (negative relationship) showed significant correlations with triglyceride and cholesterol (r = 0.438, P<0.05; r = 0.458, P<0.05; r = -0.439, P<0.05; and r = -0.414, P<0.05, respectively). The results of a multiple regression analysis revealed that 47% of the variance in GIR among all study subjects was predicted by AUC I, fat L1-4, diastolic blood pressure (dBP), HDL, and triglyceride as independent variables. In the lean group, fat L1-4 alone accounted for 33% of the variance of GIR, whereas in obese men, AUC I and dBP explained 68% of the variance in GIR.

CONCLUSIONS

The DXA technique applied for the evaluation of fat distribution can provide useful information regarding various aspects of the insulin resistance syndrome in healthy subjects. DXA can be a valid, accurate, relatively inexpensive, and safer alternative compared with other methods to investigate the role of abdominal body fat distribution on cardiovascular risk factors.

Vascular reactivity

Endothelial dysfunction appears to be an integral aspect of the insulin resistance syndrome, independently of hyperglycemia. The ability of insulin to cause endothelium-derived nitric oxide (NO)-dependent vasodilation amplifies its overall effect of stimulating skeletal muscle glucose uptake and modulating vascular tone. The dose-dependent physiologic increase in skeletal muscle blood flow in response to insulin, which is highly associated with the rate of glucose metabolism, is impaired in insulin-resistant states. Insulin appears to mediate vasodilation by direct stimulation of release of NO from endothelium. Studies of the response to the endothelium-dependent vasodilator methacholine chloride in lean and obese nondiabetic subjects and obese subjects with type 2 diabetes mellitus indicate that there may be marked endothelial dysfunction very early in insulin resistance. The potent vasoprotective effects of NO mitigate various atherogenic processes, including vascular smooth muscle cell proliferation, platelet adhesion and thrombogenesis, lipid peroxidation, and monocyte adhesion to endothelial cells. The interaction between insulin and NO may contribute to the prominent outcomes of insulin resistance syndrome (viz., hypertension, thrombosis, and atherosclerosis).

Glucosamine infusion in rats rapidly impairs insulin stimulation of phosphoinositide 3-kinase but does not alter activation of Akt/protein kinase B in skeletal muscle

Glucosamine, a metabolite of glucose via the hexosamine biosynthetic pathway, potently induces insulin resistance in skeletal muscle by impairing insulin-induced GLUT4 translocation to the plasma membrane. Activation of phosphoinositide (PI) 3-kinase is necessary for insulin-stimulated GLUT4 translocation, and the serine/threonine kinase Akt/protein kinase B (PKB) is a downstream mediator of some actions of PI 3-kinase. To determine whether glucosamine-induced insulin resistance could be due to impaired signaling, we measured insulin receptor substrate (IRS)-1 and insulin receptor tyrosine phosphorylation; PI 3-kinase activity associated with IRS-1, IRS-2, and phosphotyrosine; and Akt activity and phosphorylation in skeletal muscle of rats infused for 2 h with glucosamine (6.0 mg x kg(-1) x min(-1)) or saline. Euglycemic-hyperinsulinemic clamp studies (12 mU x kg(-1) x min(-1) insulin) in awake rats showed that glucosamine infusion resulted in rapid induction of insulin resistance, with a 33% decrease in glucose infusion rate (P < 0.01). Tissues were harvested after saline alone (basal), 1 min after an insulin bolus (10 U/kg), or after 2 h of insulin clamp in saline- and glucosamine-infused rats. After 1 min of insulin stimulation, phosphorylation of IRS-1 and insulin receptor increased 6- to 8-fold in saline-infused rats and 7- to 10-fold in glucosamine-infused rats. In saline-infused rats, 1 min of insulin stimulation increased PI 3-kinase activity associated with IRS-1, IRS-2, or phosphotyrosine 7.6-, 6.4-, and 10-fold, respectively. In glucosamine-infused rats treated for 1 min with insulin, PI 3-kinase activity associated with IRS-1 was reduced 28% (P < 0.01) and that associated with phosphotyrosine was reduced 43% (P < 0.01). Insulin for 1 min stimulated Akt/PKB activity approximately 5-fold in both saline- and glucosamine-infused rats; insulin-induced hyperphosphorylation of Akt/PKB was not different between groups. Glucosamine infusion alone had no effect on tyrosine phosphorylation of the insulin receptor or IRS-1 or on stimulation of PI 3-kinase or Akt/PKB activity. However, 2 h of insulin clamp reduced PI 3-kinase activity associated with IRS-1, IRS-2, or phosphotyrosine to <30% of that seen with 1 min of insulin. No effect of glucosamine was seen on these signaling events when compared with 2 h of insulin clamp without glucosamine. Our data show that 1) glucosamine infusion in rats is associated with an impairment in the early activation of PI 3-kinase by insulin in skeletal muscle, 2) this insulin-resistant state does not involve alterations in the activation of Akt/PKB, and 3) prolonged insulin infusion under clamp conditions results in a blunting of the PI 3-kinase response to insulin.

Central nervous system nitric oxide synthase activity regulates insulin secretion and insulin action

Systemic inhibition of nitric oxide synthase (NOS) with NG-monomethyl-L-arginine (L-NMMA) causes acute insulin resistance (IR), but the mechanism is unknown. We tested whether L-NMMA-induced IR occurs via NOS blockade in the central nervous system (CNS). Six groups of Sprague-Dawley rats were studied after chronic implantation of an intracerebroventricular (ICV) catheter into the lateral ventricle and catheters into the carotid artery and jugular vein. Animals were studied after overnight food deprivation, awake, unrestrained, and unstressed; all ICV infusion of L-NMMA or D-NMMA (control) were performed with artificial cerebrospinal fluid. ICV administration of L-NMMA resulted in a 30% rise in the basal glucose level after 2 h, while ICV D-NMMA had no effect on glucose levels. Insulin, epinephrine, and norepinephrine levels were unchanged from baseline in both groups. Tracer (3H-3-glucose)-determined glucose disposal rates during 2 h euglycemic hyperinsulinemic (300 microU/ml) clamps performed after ICV administration of L-NMMA were reduced by 22% compared with D-NMMA. Insulin secretory responses to a hyperglycemic clamp and to a superimposed arginine bolus were reduced by 28% in L-NMMA-infused rats compared with D-NMMA. In conclusion, ICV administration of L-NMMA causes hyperglycemia via the induction of defects in insulin secretion and insulin action, thus recapitulating abnormalities observed in type 2 diabetes. The data suggest the novel concept that central NOS-dependent pathways may control peripheral insulin action and secretion. This control is not likely to be mediated via adrenergic mechanisms and could occur via nonadrenergic, noncholinergic nitrergic neural and/or endocrine pathways. These data support previously published data suggesting that CNS mechanisms may be involved in the pathogenesis of some forms of insulin resistance and type 2 diabetes independent of adiposity.

Postprandial hyperglycaemia and alpha-glucosidase inhibitors

Fasting blood glucose level is usually used to diagnose diabetes, but is not a good predictor of postprandial hyperglycaemia, which is a more accurate measure of the metabolic defect underlying type 2 diabetes. Postprandial blood glucose levels may be elevated while fasting levels are normal, constituting an early stage in type 2 diabetes that can be termed 'postprandial diabetes'. Prevention of postprandial hyperglycaemia is important, as it is implicated in the development of macro- and microvascular complications associated with diabetes. The risk of cardiovascular disease is higher in individuals with postprandial hyperglycaemia, even without diabetes, than in individuals with normal postprandial blood glucose levels. Furthermore, postprandial hyperglycaemia is implicated in the development of type 2 diabetes. Even modest postprandial hyperglycaemia may lead to beta-cell dysfunction. Agents that reduce postprandial hyperglycaemia have a key role in the treatment of type 2 diabetes and pre-diabetic states. Most anti-diabetic agents that are currently available reduce fasting blood glucose levels, but have little impact on postprandial glycaemic excursions and thus do not normalize postprandial hyperglycaemia. However, new agents that control postprandial hyperglycaemia have been developed, for example, the alpha-glucosidase inhibitor acarbose. Such agents have a potential to reduce the progression of diabetes as well as macro- and microvascular complications.

Evidence for defects in the trafficking and translocation of GLUT4 glucose transporters in skeletal muscle as a cause of human insulin resistance

Insulin resistance is instrumental in the pathogenesis of type 2 diabetes mellitus and the Insulin Resistance Syndrome. While insulin resistance involves decreased glucose transport activity in skeletal muscle, its molecular basis is unknown. Since muscle GLUT4 glucose transporter levels are normal in type 2 diabetes, we have tested the hypothesis that insulin resistance is due to impaired translocation of intracellular GLUT4 to sarcolemma. Both insulin-sensitive and insulin-resistant nondiabetic subgroups were studied, in addition to type 2 diabetic patients. Biopsies were obtained from basal and insulin-stimulated muscle, and membranes were subfractionated on discontinuous sucrose density gradients to equilibrium or under nonequilibrium conditions after a shortened centrifugation time. In equilibrium fractions from basal muscle, GLUT4 was decreased by 25-29% in both 25 and 28% sucrose density fractions and increased twofold in both the 32% sucrose fraction and bottom pellet in diabetics compared with insulin-sensitive controls, without any differences in membrane markers (phospholemman, phosphalamban, dihydropyridine-binding complex alpha-1 subunit). Thus, insulin resistance was associated with redistribution of GLUT4 to denser membrane vesicles. No effects of insulin stimulation on GLUT4 localization were observed. In non-equilibrium fractions, insulin led to small GLUT4 decrements in the 25 and 28% sucrose fractions and increased GLUT4 in the 32% sucrose fraction by 2.8-fold over basal in insulin-sensitive but only by 1.5-fold in both insulin-resistant and diabetic subgroups. The GLUT4 increments in the 32% sucrose fraction were correlated with maximal in vivo glucose disposal rates (r = +0.51, P = 0.026), and, therefore, represented GLUT4 recruitment to sarcolemma or a quantitative marker for this process. Similar to GLUT4, the insulin-regulated aminopeptidase (vp165) was redistributed to a dense membrane compartment and did not translocate in response to insulin in insulin-resistant subgroups. In conclusion, insulin alters the subcellular localization of GLUT4 vesicles in human muscle, and this effect is impaired equally in insulin-resistant subjects with and without diabetes. This translocation defect is associated with abnormal accumulation of GLUT4 in a dense membrane compartment demonstrable in basal muscle. We have previously observed a similar pattern of defects causing insulin resistance in human adipocytes. Based on these data, we propose that human insulin resistance involves a defect in GLUT4 traffic and targeting leading to accumulation in a dense membrane compartment from which insulin is unable to recruit GLUT4 to the cell surface.

Glucosamine infusion in rats mimics the beta-cell dysfunction of non-insulin-dependent diabetes mellitus

Sustained hyperglycemia can cause peripheral insulin resistance and pancreatic beta-cell dysfunction and has been termed glucose toxicity or glucose-induced desensitization. Glucosamine, a product of glucose flux through the hexosamine biosynthetic pathway (HBP), causes insulin resistance in peripheral tissues and has been shown to cause abnormal glucose-insulin secretion coupling, and thus has been implicated in the pathogenesis of glucose toxicity. Here, we investigate whether glucosamine-induced insulin secretory dysfunction is specific to glucose or also extends to nonglucose secretagogues such as arginine. Two groups of 12 weight-matched Sprague-Dawley rats underwent hyperglycemic clamp studies (steady-state blood glucose, approximately 220 mg x dL(-1)) during infusion of normal saline or glucosamine 3.5 mg x kg(-1) x min(-1) over a 100-minute period. Insulin levels were measured at baseline and between 90 and 100 minutes. One hundred minutes into the hyperglycemic clamp, subgroups of seven rats each (saline- and glucosamine-infused rats) received a bolus of arginine (100 mg x kg(-1)) while the glucose infusion rate was unaltered. Glucose and insulin levels were measured at 1, 3, 5, 10, 15, and 30 minutes after the arginine bolus. Both groups had similar fasting glucose and insulin levels. At steady state (60 to 100 minutes), glucose levels were almost identical in both groups (223.58+/-3.94 v 224.58+/-4.34 mg x dL(-1)), but the glucose infusion rate (26.55+/-1.60 v 8.83+/-1.35 mg x kg(-1) x min(-1), P < .0001) and insulin level (41.36+/-6.47 v 18.04+/-2.95 mU x mL(-1), P < .0001) were markedly reduced in animals receiving glucosamine. Peak insulin levels 1 minute after the arginine bolus were lower in rats infused with glucosamine versus saline (274.00+/-30.38 v 176.25+/-20.12 microU x ml(-1), P=.0319). Total insulin secretion in response to arginine was significantly lower in the glucosamine group as determined by the area under the curve (1,268.09+/-142.27 v 706.77+/-84.79 microU x mL(-1) x min, P=.0054). In conclusion, glucosamine causes severe impairment in glucose-induced insulin secretion. Further, glucosamine-induced beta-cell secretory dysfunction extends to nonglycemic stimuli like arginine. This pattern of insulin secretory dysfunction is similar to that observed in patients with non-insulin-dependent diabetes mellitus (NIDDM). These data suggest that glucosamine may participate in the pathogenesis of glucose toxicity at the level of the beta cell in NIDDM patients.

Intrapericardial delivery of L-arginine reduces the increased severity of ventricular arrhythmias during sympathetic stimulation in dogs with acute coronary occlusion: nitric oxide modulates sympathetic effects on ventricular electrophysiological properties

BACKGROUND

Nitric oxide (NO) modulates autonomic effects on myocardial contractility and sinus and atrioventricular nodal function of the heart. Whether NO influences autonomic actions on ventricular electrophysiological properties and arrhythmogenesis is not known.

METHODS AND RESULTS

Four groups consisting of 43 autonomically denervated dogs were studied. To "superfuse" sympathetic nerves innervating the ventricles, test drugs were introduced into the pericardial sac for 30 minutes, and their effects on ventricular effective refractory period (ERP) and arrhythmia development were assessed before and during sympathetic stimulation (SS). In group 1 (n=12), ventricular ERPs showed no significant difference between control and superfusion with L-arginine, a NO precursor (222+/-20 versus 222+/-19 ms, P=.485). However, L-arginine significantly reduced SS-induced ERP shortening compared with control (9+/-7 versus 13+/-7 ms, P<.001). Simultaneous administration of N(G)-monomethyl-L-arginine (2 mg/mL) abolished the inhibitory effects of L-arginine (13+/-7 versus 13+/-7 ms, P=.885). In group 2 (n=15), the severity of ventricular arrhythmias significantly increased during SS. L-Arginine reduced this increase caused by SS. In group 3 (n=8), plasma norepinephrine spillover measured from the coronary sinus significantly increased during SS and was reduced by pericardial superfusion with L-arginine compared with control (6005.2+/-1525.6 versus 8503.4+/-2044.5 pg/min, P=.012). In group 4 (n=8), L-arginine pericardial superfusion significantly increased NO overflow measured from the coronary sinus during SS (93.25+/-59.20 versus 114.82+/-74.92 nmol/min, P=.043).

CONCLUSIONS

Pericardial L-arginine reduces ERP shortening and increased severity of ischemic ventricular arrhythmias during SS in dogs. NO-induced reduction of norepinephrine release in the heart may be one of the underlying mechanisms.