Clinical Trial Details
— Status: Completed
Administrative data
| NCT number |
NCT00140010 |
| Other study ID # |
04/Q0108/87 |
| Secondary ID |
2004-001141-15 |
| Status |
Completed |
| Phase |
Phase 2
|
| First received |
August 29, 2005 |
| Last updated |
May 19, 2009 |
| Start date |
April 2005 |
| Est. completion date |
March 2007 |
Study information
| Verified date |
May 2009 |
| Source |
University of Cambridge |
| Contact |
n/a |
| Is FDA regulated |
No |
| Health authority |
United Kingdom: Medicines and Healthcare Products Regulatory Agency |
| Study type |
Interventional
|
Clinical Trial Summary
ABSTRACT:
Delayed ischemic deficits (DID) and strokes caused by low cerebral blood flow (CBF) are
major sources of poor outcome following aneurysmal subarachnoid hemorrhage (SAH). DID are
often accompanied by vasospasm and abnormalities in cerebrovascular autoregulation, an
important reflex involved in the defense against low CBF. Assessment of vasospasm and
impaired autoregulation can be conveniently measured non-invasively by use of transcranial
Doppler (TCD) and the transient hyperaemic response test (THRT). Vasospasm and abnormalities
in the THRT can predict those patients who are at risk of developing DID. In this study, the
investigators wish to explore the neuroprotective and angiogenic effects of systemic
erythropoietin (EPO) therapy on vasospasm and autoregulation following SAH, and examine
whether any improvements translate into reduced incidences of DID and poor outcome. Eighty
patients with SAH will be recruited over one year to receive three doses in the first week
of either intravenous epoetin beta 30000 IU or placebo (0.9% saline) 50 ml/30 min as part of
a randomized, double-blind, placebo-controlled trial. The investigators propose daily TCD
assessment for detecting vasospasm and abnormal autoregulation. Outcome measures will
examine the influence of EPO therapy on the incidence, severity, and duration of vasospasm,
abnormal autoregulation, and DID.
PURPOSE:
This study is a randomized, double-blind, placebo-controlled clinical trial investigating
the potentially beneficial effects of systemic recombinant human erythropoietin therapy
(Epoetin beta, NeoRecormon®, Roche, 30000IU/50 ml/30 min, three times in the first week) on
cerebral autoregulation and incidence of delayed ischemic deficits (DID) following
aneurysmal subarachnoid haemorrhage (SAH).
HYPOTHESIS Systemic recombinant human erythropoietin therapy can be used safely following
SAH to ameliorate vasospasm, improve cerebral autoregulation, reduce DID, and facilitate
neurological recovery.
Description:
BACKGROUND:
1. Delayed ischaemia deficits in subarachnoid haemorrhage
Seven thousand patients suffer SAH each year within the UK with young adults (<55
years) being equally affected. Cerebral vasospasm and related cerebral ischemia are the
major causes of delayed morbidity and mortality in patients who survive the initial SAH
episode. Previous studies have revealed that immediate low cerebral blood flow (CBF)
accompanies SAH, particularly in those in coma. However, for better grade patients the
low CBF is often delayed and associated with cerebral vasospasm [Knuckey 1985].
Vasospasm often precedes the onset of DID which commonly occurs in the 2nd week after
SAH [Knuckey 1985]. Autoregulation is the most accomplished reflex mechanism and
reflects an intrinsic ability of the cerebral vessels to dilate in an attempt to
maintain constant CBF in the face of poor cerebral perfusion. Following SAH, impairment
of autoregulation affects prognosis [Lam 2000]. Indeed, daily assessment of
autoregulation can help to identify patients at high risk of clinical deterioration
[Smielewski 1997].
Autoregulation can be conveniently measured non-invasively from the bedside using
transcranial Doppler (TCD). Direct measures of middle cerebral artery flow velocities
(FV) are predictive of DID; elevated mean FV (>120cms/sec) and increased ratio of mFV
between MCA and extracranial internal carotid artery (ICA) (Lindegaard ratio >3) being
associated with cerebral vasospasm and higher incidence of adverse events [Lindegaard
1988]. The rapid increase of FV with time is also predictive, as is the relationship
between FV and spontaneous changes in blood pressure (correlation index Mx) [Czosnyka
2000].
A more sophisticated measure of abnormal cerebrovascular haemodynamics involves the
transient hyperaemic response test (THRT) [Giller 1991]. This is used routinely in our
department where we have demonstrated a relationship between an abnormal THRT and
clinical outcome following SAH [Lam 2000]. The THRT assesses the FV response to a
manual carotid compression (Figure 1) and can be repeated within a few minutes
providing a reliable and readily accessible method for assessing autoregulation. When
THRT is used for day-to-day assessments for the same patient, this test can provide a
valuable monitor of sequential changes in autoregulation.
2. Autoregulation after SAH
Autoregulation is often impaired after SAH, even in patients presenting in good
clinical grade [Voldby 1985]. An abnormal THRT response commonly develops either early
during days 0 to 3 (primary), or late around days 7 to 14 (secondary) after the initial
bleed. Primary abnormalities in THRT are far more common in poor grade patients, while
secondary abnormalities occur more regularly in the initially good grade patients who
later develop signs of DID with clinical deterioration [Ratsep 2002]. Routine and daily
assessment of autoregulation with TCD helps to identify patients at higher risk for
DID. This delay in the evolution of an abnormal autoregulation response in better grade
patients presents an opportunity to introduce early therapeutic strategies designed to
offset the potentially harmful effects. Indeed, routine use of plasma expansion is
already adopted with this aim in mind [Origitano 1990].
3. Therapeutic opportunity; why recombinant human erythropoietin?
Recently attention has been focused on potential therapeutic roles for endogenous brain
proteins possessing neuroprotective properties. This neuroprotective approach of using
erythropoietin (EPO) is aimed at protecting potentially viable brain tissue from apoptosis
[Ehrenreich 2002]. EPO, a 34-kDa hydrophobic sialoglycoprotein, is responsible for the
survival, proliferation, and differentiation of committed erythroid progenitor cells. It is
produced by foetal liver and adult kidney, which is accelerated during hypoxia [Lacombe
1999]. Because there is no pre-formed EPO storage, therefore, the control of EPO gene
transcription involves complex interactions with hypoxia-inducible factor 1 (HIF-1), a
transcription factor which is activated during hypoxia, hypoglycaemia, and seizures [Lacombe
1999].
EPO receptor (EPO-R), like other members of the haematopoietic receptor family, does not
possess an endogenous tyrosine kinase activity. However, its close association with Jak2
tyrosine kinase can induce a rapid tyrosine phosphorylation on a number of proteins [Lacombe
1999]. Hypoxia can induce an increased EPO-R expression, which in turn causes increased
sensitivity to EPO [Chin 2000].
Both EPO and EPO-R are ubiquitously distributed in neural tissues [Digicaylioglu 1995].
Except larger vessels, EPO-R is abundantly distributed in astrocytes, neurons, and cerebral
capillary endothelia [Marti 1996, Yamaji 1996, Bernaudin 1999, Brines 2000].
Immunohistochemistry shows that these distributions of EPO-R are consistent with the
anatomical location of blood-brain barrier (BBB) [Brines 2000]. Such a condensed
distribution of EPO-R within and surrounding the cerebral capillaries implies that a small
amount of EPO is sufficient to mediate physiological function in the central nervous system
[Chin 2000]. The increased production of EPO in response to hypoxia and anemia by astrocytes
and neurons corresponds to that which occurs in kidney and liver [Masuda 1994]. Thus, during
hypoxia, EPO acts directly on cerebral capillary endothelial cells as an angiogenic factor
through a paracrine mechanism from the astrocytes and an endocrine mechanism from the kidney
[Digicaylioglu 1995].
EPO protects nervous tissue under any conditions characterised by a relative deficiency of
ATP [Brine 2000]. This neuroprotective effect is achieved by several mechanisms.
1. EPO can induce expression of several glycolytic enzymes, which re-directs energy
metabolism toward favouring survival during oxygen deprivation [Digicaylioglu 1995].
2. During cerebral ischemia, the N-methyl-D-aspartate (NMDA) receptor-mediated glutamate
toxicity is the major cause of neuron death [Morishita 1997]. Glutamate toxicity is in
part mediated by nitric oxide (NO). EPO up-regulates the expression of antioxidant
enzymes on a transcriptional level in vascular smooth muscle cells [Kusano 1999], and
can potentially protect neurons from NO-generating agents [Sakanaka 1998]. Furthermore,
EPO can suppress the increase in Ca2+ concentration induced by glutamate and the nitric
oxide (NO)-induced apoptosis [Morishita 1997].
EPO has been shown to provide neurotrophic [Konishi 1993] and angiogenic effects [Yamaji
1996], and it has the potential for neural regeneration [Siren 2001]. These effects are
dose-dependent and unrelated to the nerve growth factor (NGF) [Konoshi Y 1993]. The
distributions of EPO and EPO-R correspond to the sequence of histopathological changes of
cerebral ischemia/infarction. In acute hypoxia (cardiac arrest), strong immunoreactivity of
EPO can be found in vascular endothelium, while the EPOR is expressed strongly in neurons
[Siren 2001]. After cerebral ischemia, EPO plays an important role in angiogenesis and glial
reaction. EPO immunoreactivity appears in the endothelium, intravascular inflammatory cells
and neurons of the penumbra. Also EPO-R is expressed in neurons, astrocytes and endothelial
cells [Bernaudin 1999, Siren 2001]. Because the expression of EPO-R precedes the
up-regulation of EPO synthesis [Bernaudin 1999], the sensitivity to EPO increases [Chin
2000]. In contrast, these changes are not detectable in non-ischemic cortex [Bernaudin
1999], indicating an increased potential for EPO to act where neurons are at risk [Siren
2001]. By protecting endothelial cells from apoptosis, EPO can increase cerebral blood flow,
improve microcirculation of the penumbra, and improve tissue oxygenation by angiogenesis,
thus significantly reduce the infarct volume [Bernaudin 1999, Siren 2001]. This angiogenesis
corresponds to the finding that under hypoxic conditions such as exposure to high altitudes,
the brain increases the mean microvascular density [Lamanna JC 1992]. In old infarcts, EPO
and EPO-R are strongly expressed in reactive astrocytes. Thus the EPO system may participate
in the repair process [Siren 2001]. The persistent up-regulation of EPO production by
astrocytes after stroke also provides rapidly available sources of EPO to make neurons more
tolerate ischemia [Siren 2001]. These endogenous neuroprotective mechanisms are insufficient
to cope with acute injuries, as severe ischemic insult can exhaust the EPO/EPO-R
neuroprotective capacity of the brain or the latency of de novo synthesis is too long.
Clinical application of EPO should be administered rapidly to provide additional
neuroprotection [Brines 2000].
Epoetin beta is a 165-aa glycoprotein manufactured by using recombinant DNA technology,
which contains the identical amino acid sequence of isolated human EPO and possesses the
same biological activity. It is similar to the endogenous EPO except for minor differences
in the pattern of 4 carbohydrate chains. [Brine 2000] The recombinant human EPO has been
widely used for treating anaemia associated with chronic renal insufficiency, HIV infection,
cancer, and surgery, and has an excellent safety record in wide clinical practice.
4. Why 90,000 IU Epoetin beta?
The safety and efficacy of epoetin beta for treating acute stroke (within 8 hours) in humans
have been confirmed in a double blind, randomized, placebo-controlled clinical trial, which
uses high dose intravenous epoetin beta (3,3000 IU/50 ml/30min/day, three days, with a
cumulative dose 100,000IU) [Ehrenreich 2002]. No associated changes in blood pressure,
haematocrit, haemoglobin, and red blood cell count are found in this trial [Ehrenreich
2002]. Only the reticulocyte count increases 29.2 ±10.0% on the 4th day after the last dose
of EPO [Ehrenreich 2002]. This systemic administration of EPO also has led to a 60- to
100-fold increase in CSF levels and does not require a breakdown of the blood-brain barrier
(BBB) [Ehrenreich 2002]. Patients who are treated with EPO have a lower and earlier surge of
serum S100 (secreted by reactive astrocytes and functional disturbances of membrane
integrity of brain cell membrane) and thereafter return to within the normal limits sooner
than the placebo [Ehrenreich 2002]. This earlier return of serum S100 towards the normal
level implies that the inflammatory processes and/or BBB integrity can be improved more
rapidly by systemic EPO therapy [Ehrenreich 2002]. The beneficial effects on stroke patients
continue throughout 30 days, particularly for those with moderate to severe strokes
[Ehrenreich 2002].
By activation of endothelial EPO receptors, the circulating EPO may appose inflammatory
pathways in cerebral arteries and attenuate vasospasm induced by SAH. In vivo studies have
found that systemic administration of EPO (i.p. 1000units/kg) immediately after SAH can
improve survival and motor functions [Buemi 2000]. The systemic delivery of EPO has the
advantage that it is universally available to the capillary endothelium in the whole brain,
in contrast to intraventricular injection, which is highly localized and not practical in
clinical settings [Brines 2000]. Because the concentration of EPO in CSF is independent of
the serum level and the extent of BBB disruption in patients suffering from aneurysmal SAH,
the EPO in CSF is predominantly produced by the brain in order to match its need [Springborg
2003]. Therefore, an early activation of endothelial EPO-R may be a potential therapeutic
strategy, which in fact has been proved by a reduction of S100 protein in CSF (a marker of
brain damage) and restoration of cerebral autoregulation (for at least 48 hours) after
systemic administration of recombinant human EPO [Springborg 2002]. Therefore, 90,000 Iuof
epoetin beta will be use to achieve the maximal effects on CBF and autoregulation in these
SAH patients to be studied.
QUESTIONS TO BE ANSWERED:
We wish to address the following hypotheses for SAH patients:
1. Systemic treatment with epoetin beta (90,000IU) is safe following SAH
2. Systemic treatment with epoetin beta reduces the incidence of abnormal FV and cerebral
autoregulation following SAH.
3. Systemic treatment with epoetin beta reduces the incidence of acute neurological
deterioration following SAH If primary endpoints are improved with epoetin beta
therapy, the data will be used to formulate the power calculation for design of a Phase
III clinical outcome study. However, we will assess clinical outcome at the end of the
trial and at discharge to detect any indication of adverse effect after EPO therapy.
Randomisation procedure:
Following informed consent, patients with angiography-positive aneurismal SAH will be
randomised to receive either intravenous epoetin beta 30,000IU or placebo (0.9% saline)
50ml/30min, three times in the first week after SAH (total dose 90,000IU). The number in
each group will be 40. For blinding, the Pharmacy Manufacture Unit (PMU) will prepare and
number identical vials containing either saline (0.9% NaCl) or epoetin beta reconstituted in
saline. The vials will be randomly assigned to patients upon enrollment with the contents of
each vial known only by the PMU. Trial medication will be started as soon as possible within
72 hours of the ictus. As approximately 70% of aneurysms will be treated with open clipping,
and the remainder with endovascular coils, we do not consider the method of treatment to
represent a contaminating factor, but it will be included in the final analysis. Location,
size, and morphology of the culprit aneurysm are not believed to affect outcome in our
institution.
Following randomisation and start of trial therapy the clinical management of each patient
will be as routine. Arterial blood pressure will be continuously monitored (Finapress, or
via radial arterial line).
Safety:
The full blood cell count, reticulocyte count, blood viscosity, coagulation profile, serum
biochemistry, serum iron levels, and C-reactive protein (CRP) at the time of admission will
be checked as clinical routine. Although EPO has effects of erythropoiesis and
thrombopoiesis, associated deterioration or adverse events have not been observed in
short-term treatment [Ehrenreich 2002]. However, in the face of any abnormalities the trial
drug will be stopped and the safety committee informed. A safety committee (chaired by Dr
Ken Smith, Consultant nephrologist) will review the safety data at monthly intervals or, if
concerns arise, on a patient-by-patient basis.
Primary outcome measures: Vasospasm and abnormalities in AR:
Trial patients will be examined daily with TCD (DWL, Germany) using a 2-MHz probe mounted on
a purposed head frame for two weeks since SAH ictus. The systolic, diastolic, and mean FV
will be recorded (trans-temporal) by a single user (MT). Vasospasm will be defined as mean
FV > 120 cm/sec and Lindegaard ratio >3 [Lindegaard 1988]. The regression index (Mx) between
mean FV and spontaneous changes in ABP will be calculated. Two carotid compressions lasting
5 seconds will be performed. The criteria for an acceptable THRT includes a sudden decrease
in middle cerebral artery FV at the onset of compression, a stable TCD signal during
compression, and a minimum of 30% decrease in FV with no blood pressure instability
[Smielewski 1997]. The THRT ratio (THRR) is calculated using the formula: THRR = FVs
(hyperaemia) / FVs(baseline), where FVs denotes systolic FV (Figure 1). THRR is classified
as normal (≥l.10) or impaired (<1.10), and will be repeated 2 minutes later. The average
value of the two tests will be recorded. Quality issues concerning the THRT response have
been extensively evaluated in this laboratory [Smielewski 1997].
Secondary endpoint measures: Development of DID:
The clinical progress of each patient will be monitored daily. The development of a focal
neurological deficit and/or a drop in the Glasgow Coma Scale by 2 points or more following
vasospasm will be the criteria adopted to define an episode of DID [Pickard 1989]. Other
factors which can affect consciousness, including systemic infection and infection of
central nervous system, will be recorded for final analysis. Clinical outcomes will be
assessed at the end of the trial and at the time of discharge. Durations of hospitalisation
and NCCU stay will be observed.
Statistical Analysis:
The analysis will be performed by using statistical software, STATA (Texas, USA). Data will
be expressed as mean±standard deviation. The multivariate analysis will be performed on the
timings of vasospasm and abnormal AR, which will be computed as the number of days between
the date of diagnosis of SAH and the date of the first detection of vasospasm and abnormal
autoregulation in respect of variables likely to influence their occurrence: age, WFNS
grade, Fisher's grade on CT scans, and treatment procedures, intraventricular haemorrhage
and/or hydrocephalus by using the Cox Proportional Hazards regression. The measure of
outcome will be the hazards ratio (HR), which expresses the probability of vasospasm or
abnormal autoregulation for a specific category relative to the placebo group. Variables
associated with EPO treatment (haematocrits, erythrocyte counts, reticulocyte counts,
thrombocyte counts, serum iron levels, and viscosity) will be collected. The improvement in
fit due to each variable will be tested for statistical significance at the 5% level with
the likelihood ratio test. The test for departure from a linear trend (one degree of
freedom) was used to assess the potential linear trend in certain categorical variables.
Daily results from each patient will also be averaged to produce a patient-oriented database
to satisfy the independence assumption for linear regression. The day-to-day variations in
parameters will be calculated as the standard deviation divided by the average value from
all examinations in each patient.
Power analysis:
Our previous observations indicate that vasospasm and abnormal THRT occur in 64% and 90% SAH
of patients respectively. To demonstrate a 50% reduction in duration of vasospasm or
abnormal autoregulation with a power of 80% and a significance level of 5% we will require
examinations from 80 patients. This number of patients also has an 83% chance of
demonstrating a 50% reduction in the incidence of clinical DID in the first 2 weeks
following the ictus. The study is not powered to show a reduction in clinical endpoints
although trends will be sought to identify any potential adverse effects.
DETAILS OF ANY DIFFICULTIES THAT CAN BE FORESEEN
1. Patient recruitment:
The Neurosurgical Unit at Addenbrookes treats 80 aneurysmal SAH patients per annum.
Previous studies in our unit have shown high ascertainment, and we were the largest
contributor to the International Hypothermia for Aneurysm Surgery Trial (IHAST). We do
not foresee difficulties with recruitment.
2. Safety issues:
The safety and efficacy of using high dose intravenous epoetin beta (100,000IU) for
treating human acute stroke (within 8 hours) have been confirmed [Ehrenreich 2002]. The
therapeutic margin of EPO is very wide. Even at very high serum levels no adverse
effects have been observed [NeoRecormon information sheet, Roche].
3. Assessment of AR using TCD:
Quality control for THRT assessment has been vigorously addressed, failure to complete the
test is rare [Ratsep 2002]. The incidence of significant carotid atherosclerotic disease
precluding safe carotid compression is less than 1% [Lam 2000]. The test is well tolerated
and we know of no patient who requested to withdraw from the investigation in previous
studies due to discomfort etc.
FUTURE RESEARCH
Results from this phase II study will be used to design a phase III clinical outcome trial
using the Spontaneous Intracranial Haemorrhage Group mechanism. Any potential benefits may
extrapolate to other cerebrovascular conditions where low CBF states and loss of
autoregulation occur (e.g. acute cerebral vasculitis).
