Journal Club
Oram RA, Jones AG, Besser RE, Knight BA, Shields BM, Brown RJ, Hattersley AT,
McDonald TJ.
The majority of patients with long-duration type 1 diabetes are insulin
microsecretors and have functioning beta cells.
Diabetologia. 2013 Oct 12. [Epub ahead of print]
de Zeeuw D, Akizawa T, Audhya P, Bakris GL, Chin M, Christ-Schmidt H,
Goldsberry A, Houser M, Krauth M, Heerspink HJ, McMurray JJ, Meyer CJ,
Parving HH, Remuzzi G, Toto RD, Vaziri ND, Wanner C, Wittes J, Wrolstad D,
Chertow GM; the BEACON Trial Investigators.
Bardoxolone Methyl in Type 2 Diabetes and Stage 4 Chronic Kidney Disease.
N Engl J Med. 2013 Nov 9. [Epub ahead of print]
2013年11月21日 8:30-8:55
８階 医局
埼玉医科大学 総合医療センター 内分泌・糖尿病内科
Department of Endocrinology and Diabetes,
Saitama Medical Center, Saitama Medical University
松田 昌文
Matsuda, Masafumi
ng/ml
C-pep 3617g=1mol ng/ml
3.617ng=1pmol, 1ng=0.276pmol
R. A. Oram : A. G. Jones : R. E. J. Besser : B. A. Knight : B. M. Shields : A. T.
Hattersley (*) : T. J. McDonald (*) NIHR Exeter Clinical Research Facility, University of
Exeter Medical School, Barrack Road, Exeter, UK e-mail: [email protected] email: [email protected] R. J. Brown : T. J. McDonald Department of Blood
Sciences, Royal Devon and Exeter NHS Foundation Trust, Exeter, UK
Diabetologia DOI 10.1007/s00125-013-3067-x
Aims/hypothesis
Classically, type 1 diabetes is thought to proceed
to absolute insulin deficiency. Recently developed
ultrasensitive assays capable of detecting Cpeptide under 5 pmol/l (18pg/ml) now allow very
low levels of C-peptide to be detected in patients
with long-standing type 1 diabetes. It is not known
whether this low-level endogenous insulin
secretion responds to physiological stimuli. We
aimed to assess how commonly low-level
detectable C-peptide occurs in long-duration type
1 diabetes and whether it responds to a meal
stimulus.
Methods
We performed a mixed-meal tolerance test in 74
volunteers with long-duration (>5 years) type 1
diabetes, i.e. with age at diagnosis 16 (9–
23)years (median [interquartile range]) and
diabetes duration of 30 (19–41) years. We
assessed fasting and stimulated serum C-peptide
levels using an electrochemiluminescence assay
(detection limit 3.3 pmol/l), and also the urinary Cpeptide:creatinine ratio (UCPCR).
We recruited 74 participants who had had type 1
diabetes for longer than 5 years. Participants had
either been diagnosed at less than 30 years of
age (n =68) or when older than 30 years and with
islet autoantibodies present (n =6). All patients
had been on insulin since diagnosis. Of the 74
participants, 38 (51%) were male. Age at
diagnosis was 16 (9–23)years, median
(interquartile range [IQR]), and duration of
diabetes was 30 (19–41)years, with BMI of 25
(23–28)kg/m2, HbA1c 7.9 (7.2–9.0)% (63 [55–75]
mmol/mol), insulin dose 0.55 (0.44–0.69)units per
kg of body weight per day and an estimated GFR
of 89 (82–102)ml min−1 1.73 m−2.
Mixed-meal tolerance test
Participants attended the Exeter National Institute for Health
Research (NIHR) Clinical Research, having fasted from midnight,
not taken their usual morning insulin and fully emptied their
bladder upon waking. Fasting blood was taken for measurement
of C-peptide, creatinine, glucose, HbA1c, and GAD and islet
antigen 2 autoantibodies, and a second void urine sample was
collected for UCPCR determination. Participants were given a
standard mixed meal (Ensure Plus HP; Abbott Nutrition,
Columbus, OH, USA) consisting of 6 ml/kg (maximum 360 ml)
water and containing per 100 ml: 15.9 g carbohydrate, 7.9 g
protein, 3.3 g fat and 125 kJ energy. Blood was taken for Cpeptide and glucose analysis at 90 min post-completion of the
mixed meal, with urine being collected for UCPCR determination
at 120 min. All participants were asked to provide a home urine
sample in a boric acid container, taken 2 h after an evening meal
(and having voided the bladder before the meal). Serum and urine
samples were stored at −80°C for subsequent analysis.
C-peptide analysis
We analysed serum C-peptide with a direct electrochemiluminescence immunoassay using mouse monoclonal antiC-peptide antibody (Roche Diagnostics, Mannheim, Germany) on
an E170 analyser (Roche). The reported limit of detection is
3.3 pmol/l with a CV of 0.6% at 33 pmol/l.
We compared our Roche assay with another assay, Ultrasensitive
C-peptide ELISA (Mercodia, Sylveniusgatanm, Sweden), which is
a solid-phase two-site enzyme immunoassay that uses a
peroxidase-TMB (3,3′,5,5′-tetramethybenzidine) label on an
automated ELISA system (Dynex DSX; Launch Diagnostics,
Longfield, UK). The comparison involved dual analysis of 67
samples selected for having low levels of serum C-peptide. The
reported limit of detection is 1.5 pmol/l with a CV of 5.5% at
37 pmol/l.
Urinary C-peptide was analysed on the E170 analyser (Roche) as
previously described.
C-pep 3617g=1mol ng/ml
3.617ng=1pmol, 1ng=0.276pmol
3.617ng/ml
1ng/ml
18pg/ml
The effect of a meal stimulus on serum C-peptide levels in participants with detectable insulin
(n = 54). (a) Paired fasting and mixed meal results for all patients with detectable C-peptide. Each
line represents an individual patient. (b) Results for all patients with fasting C-peptide below 30
pmol/l (n = 36). Of 54 patients, (80%) had a serum C-peptide value that rose after the mixed meal.
None had a fall in the C-peptide value after the meal
Results
Post-stimulation serum C-peptide was detectable
at very low levels (>3.3 pmol/l) in 54 of 74 (73%)
patients. In all patients with detectable serum Cpeptide, C-peptide either increased (n =43, 80%)
or stayed the same (n =11) in response to a meal,
with no indication of levels falling (p <0.0001).
With increasing disease duration, absolute Cpeptide levels fell although the numbers with
detectable C-peptide remained high (68%, i.e. 25
of 37 patients with >30 years duration). Similar
results were obtained for UCPCR.
Conclusions/interpretation
Most patients with long-duration type 1 diabetes
continue to secrete very low levels of
endogenous insulin, which increase after meals.
This is consistent with the presence of a small
number of still functional beta cells and implies
that beta cells are either escaping immune attack
or undergoing regeneration.
Message
インスリン分泌が平均30年の病歴の１型糖尿病
患者でも若干残っているということだが。
インスリン分泌が足らないのは勿論だが「残っ
ている」というのが大切らしい。
Reactive oxygen species (ROS)
The dimeric Kelch-like ECH-associated protein-1 (KEAP1) receptor contacts one NRF2 (nuclear factor (erythroid-derived-2)-like2) molecule at two distinct N-terminal sites. The KEAP1–cullin-3 (CUL3) complex constantly targets NRF2 for proteosomal
degradation through ubiquitylation of NRF2 Lys residues that are located at its N terminus, between the two KEAP1 interaction sites.
Electrophiles and signals from reactive oxygen species (ROS) modify KEAP1 Cys residues, leading to zinc release and a
conformation that is non-permissible for ubiquitylation. An alternative speculative model proposes that two NRF2 molecules are each
contacted by the Kelch domain of dimeric KEAP1. Phosphorylation of Ser40 by phosphatidylinositol 3-kinase (PI3K), protein kinase
RNA (PKR)-like endoplasmic reticulum (ER) kinase (PERK) or protein kinase C (PKC) might also lead to ubiquitylation arrest. KEAP1
dimerizes through the broad complex–tramtrack–bric-a-brac (BTB) domain and interacts with NRF2 through the Kelch domain. The
KEAP1 intervening region (IVR) that carries reactive Cys residues is located between the BTB and Kelch domains. ARE, antioxidant
response element; CNC-bZIP, cap 'n' collar-basic leucine zipper; DGR, double glycine repeat; GSH, glutathione.
The Keap1–Nrf2 system. Under normal conditions, Nrf2 is constantly ubiquitinated
through Keap1 and degraded in the proteasome. Following exposure to electrophiles or
oxidative stress, Keap1 is inactivated. Stabilized Nrf2 accumulates in the nucleus and
activates many cytoprotective genes. Ub, ubiquitin.
http://www.frontiersin.org/Journal/10.3389/fonc.2012.00200/full
Bardoxolone methyl (also known as “RTA 402”
and “CDDO-methyl ester”) is an orallyavailable first-in-class synthetic triterpenoid. It
is an inducer of the Nrf2 pathway, which can
suppress oxidative stress and inflammation
Nuclear factor (erythroid-derived 2)-like
2, also known as NFE2L2 or Nrf2, is a
transcription factor that in humans is
encoded by the NFE2L2 gene. The Nrf2
antioxidant response pathway is "the
primary cellular defense against the
cytotoxic effects of oxidative stress."
Among other effects, NFE2L2 increases
the expression of several antioxidant
enzymes.
BEAM Study
N Engl J Med 2011; 365:327-336
the University of Groningen, Groningen, the Netherlands (D.Z., H.J.L.H.); Showa University School
of Medicine, Tokyo (T.A.); Reata Pharmaceuticals, Irving, TX (P.A., M.C., A.G., M.K., C.J.M.);
University of Chicago (G.L.B.) and AbbVie Pharmaceuticals (M.H.) — both in Chicago; Statistics
Collaborative, Washington, DC (H.C.-S., J.W., D.W.); University of Glasgow, Glasgow, United
Kingdom (J.J.M.); Rigshospitalet, University of Copenhagen, Copenhagen (H.-H.P.); Istituto di
Ricovero e Cura a Carattere Scientifico–Istituto di Ricerche Farmacologiche Mario Negri, Bergamo,
Italy (G.R.); University of Texas Southwestern Medical Center, Dallas (R.D.T.); University of
California, Irvine (N.D.V.); University of Würzburg, Würzburg, Germany (C.W.); and Stanford
University, Palo Alto, CA (G.M.C.).
N Engl J Med 2013. DOI: 10.1056/NEJMoa1306033
Background
Although inhibitors of the renin–
angiotensin–aldosterone system can
slow the progression of diabetic kidney
disease, the residual risk is high.
Whether nuclear 1 factor (erythroidderived 2)–related factor 2 activators
further reduce this risk is unknown.
Oxidative stress and impaired antioxidant capacity
intensify with the progression of chronic kidney disease.
In animals with chronic kidney disease, oxidative stress
and inflammation are associated with impaired activity of
the nuclear 1 factor (erythroid-derived 2)–related factor 2
(Nrf2) transcription factor. The synthetic triterpenoid
bardoxolone methyl and its analogues are the most
potent known activators of the Nrf2 pathway. Studies
involving humans, including persons with type 2
diabetes mellitus and stage 3b or 4 chronic kidney
disease, have shown that bardoxolone methyl can
reduce the serum creatinine concentration for up to 52
weeks.
Methods
We randomly assigned 2185 patients
with type 2 diabetes mellitus and stage
4 chronic kidney disease (estimated
glomerular filtration rate [GFR], 15 to
<30 ml per minute per 1.73 m2 of bodysurface area) to bardoxolone methyl, at
a daily dose of 20 mg, or placebo. The
primary composite outcome was endstage renal disease (ESRD) or death
from cardiovascular causes.
The trial was terminated early because of
safety concerns, driven primarily by an
increase in cardiovascular events in the
bardoxolone methyl group.
Figure 2. Kaplan–Meier Plots of the Time to the First Event of the Discrete Secondary Outcomes.
Panel A shows the time to the first event of heart failure, defined as death due to heart failure or hospitalization for heart failure, among patients in the
bardoxolone methyl group and those in the placebo group. Panel B shows the time to the first event of the secondary composite outcome (nonfatal
myocardial infarction, nonfatal stroke, hospitalization for heart failure, or death from cardiovascular causes) in the two study groups. The first event was
nonfatal myocardial infarction in 17 patients in the bardoxolone methyl group and 11 in the placebo group, nonfatal stroke in 12 patients in the
bardoxolone methyl group and 8 in the placebo group, hospitalization for heart failure in 91 patients in the bardoxolone methyl group and 54 in the
placebo group, and death from cardiovascular causes in 19 patients in the bardoxolone methyl group and 13 in the placebo group.
Table S6. Physiological parameters during the trial
*0.05<p-value<0.01, **0.01<p-value<0.001, ***p-value<0.001.
†137 (placebo: 71, bardoxolone methyl: 66) patients have both valid baseline and Week 4 ABPM measurements.
Why were these adverse effects identified in the current
trial and not in the BEAM trial?
First, the number of patient-months of drug exposure in
the current trial was roughly 10 times that in the BEAM
trial.
Second, the population in the present trial had more
severe chronic kidney disease than did the population in
the BEAM trial. Observational studies have shown
significantly higher rates of death and cardiovascular
events, including heart failure, among patients with
stage 4 chronic kidney disease than among patients with
stage 3 chronic kidney disease.
Finally, our trial used an amorphous spray-dried
dispersion formulation of bardoxolone methyl at a fixed
dose rather than at an adjusted dose.
Results
The sponsor and the steering committee terminated the trial on the
recommendation of the independent data and safety monitoring
committee; the median follow-up was 9 months. A total of 69 of 1088
patients (6%) randomly assigned to bardoxolone methyl and 69 of
1097 (6%) randomly assigned to placebo had a primary composite
outcome (hazard ratio in the bardoxolone methyl group vs. the
placebo group, 0.98; 95% confidence interval [CI], 0.70 to 1.37;
P=0.92). In the bardoxolone methyl group, ESRD developed in 43
patients, and 27 patients died from cardiovascular causes; in the
placebo group, ESRD developed in 51 patients, and 19 patients died
from cardiovascular causes. A total of 96 patients in the bardoxolone
methyl group were hospitalized for heart failure or died from heart
failure, as compared with 55 in the placebo group (hazard ratio, 1.83;
95% CI, 1.32 to 2.55; P<0.001). Estimated GFR, blood pressure, and
the urinary albumin-to-creatinine ratio increased significantly and
body weight decreased significantly in the bardoxolone methyl group,
as compared with the placebo group.
Conclusions
Among patients with type 2 diabetes
mellitus and stage 4 chronic kidney disease,
bardoxolone methyl did not reduce the risk
of ESRD or death from cardiovascular
causes. A higher rate of cardiovascular
events with bardoxolone methyl than with
placebo prompted termination of the trial.
(Funded by Reata Pharmaceuticals; BEACON
ClinicalTrials.gov number, NCT01351675.)
Message
糖尿病でステージ4の慢性腎臓病（CKD）患
者2185人を対象に、転写因子Nrf2活性化剤
bardoxolone methylによる治療の効果を検
討（BEACON試験）。主要評価項目の末期腎
臓病または心血管死発生率は治療群、プラ
セボ群とも6％だった。プラセボ群に比べ、
治療群で心血管イベント発生率が高く、本
試験は中止された。