Dheeraj Kalladka

Human neural stem cells in patients with chronic ischaemic stroke (PISCES): a phase 1, first-in-man study

BACKGROUND CTX0E03 is an immortalised human neural stem-cell line from which a drug product (CTX-DP) was developed for allogeneic therapy. Dose-dependent improvement in sensorimotor function in rats implanted with CTX-DP 4 weeks after middle cerebral artery occlusion stroke prompted investigation of the safety and tolerability of this treatment in stroke patients. METHODS We did an open-label, single-site, dose-escalation study. Men aged 60 years or older with stable disability (National Institutes of Health Stroke Scale [NIHSS] score ≥6 and modified Rankin Scale score 2-4) 6-60 months after ischaemic stroke were implanted with single doses of 2 million, 5 million, 10 million, or 20 million cells by stereotactic ipsilateral putamen injection. Clinical and brain imaging data were collected over 2 years. The primary endpoint was safety (adverse events and neurological change). This trial is registered with ClinicalTrials.gov, number NCT01151124. FINDINGS 13 men were recruited between September, 2010, and January, 2013, of whom 11 (mean age 69 years, range 60-82) received CTX-DP. Median NIHSS score before implantation was 7 (IQR 6-8) and the mean time from stroke was 29 (SD 14) months. Three men had subcortical infarcts only and seven had right-hemisphere infarcts. No immunological or cell-related adverse events were seen. Other adverse events were related to the procedure or comorbidities. Hyperintensity around the injection tracts on T2-weighted fluid-attenuation inversion recovery MRI was seen in five patients. At 2 years, improvement in NIHSS score ranged from 0 to 5 (median 2) points. INTERPRETATION Single intracerebral doses of CTX-DP up to 20 million cells induced no adverse events and were associated with improved neurological function. Our observations support further investigation of CTX-DP in stroke patients. FUNDING ReNeuron Limited.

Alteplase versus tenecteplase for thrombolysis after ischaemic stroke (ATTEST): a phase 2, randomised, open-label, blinded endpoint study.

BACKGROUND In most countries, alteplase given within 4·5 h of onset is the only approved medical treatment for acute ischaemic stroke. The newer thrombolytic drug tenecteplase has been investigated in one randomised trial up to 3 h after stroke and in another trial up to 6 h after stroke in patients selected by advanced neuroimaging. In the Alteplase-Tenecteplase Trial Evaluation for Stroke Thrombolysis (ATTEST), we aimed to assess the efficacy and safety of tenecteplase versus alteplase within 4·5 h of stroke onset in a population not selected on the basis of advanced neuroimaging, and to use imaging biomarkers to inform the design of a definitive phase 3 clinical trial. METHODS In this single-centre, phase 2, prospective, randomised, open-label, blinded end-point evaluation study, adults with supratentorial ischaemic stroke eligible for intravenous thrombolysis within 4·5 h of onset were recruited from The Institute of Neurological Sciences, Glasgow, Scotland. Patients were randomly assigned (1:1) to receive tenecteplase 0·25 mg/kg (maximum 25 mg) or alteplase 0·9 mg/kg (maximum 90 mg). Treatment allocation used a mixed randomisation and minimisation algorithm including age and National Institutes of Health Stroke Scale score, generated by an independent statistician. Patients were not informed of treatment allocation; treating clinicians were aware of allocation but those assessing the primary outcome were not. Imaging comprised baseline CT, CT perfusion, and CT angiography; and CT plus CT angiography at 24-48 h. The primary endpoint was percentage of penumbra salvaged (CT perfusion-defined penumbra volume at baseline minus CT infarct volume at 24-48 h). Analysis was per protocol. This study is registered with ClinicalTrials.gov, number NCT01472926. FINDINGS Between Jan 1, 2012, and Sept 7, 2013, 355 patients were screened, of whom 157 were eligible for intravenous thrombolysis, and 104 patients were enrolled. 52 were assigned to the alteplase group and 52 to tenecteplase. Of 71 patients (35 assigned tenecteplase and 36 assigned alteplase) contributing to the primary endpoint, no significant differences were noted for percentage of penumbral salvaged (68% [SD 28] for the tenecteplase group vs 68% [23] for the alteplase group; mean difference 1·3% [95% CI -9·6 to 12·1]; p=0·81). Neither incidence of symptomatic intracerebral haemorrhage (by SITS-MOST definition, 1/52 [2%] tenecteplase vs 2/51 [4%] alteplase, p=0·55; by ECASS II definition, 3/52 [6%] vs 4/51 [8%], p=0·59) nor total intracerebral haemorrhage events (8/52 [15%] vs 14/51 [29%], p=0·091) differed significantly. The incidence of serious adverse events did not differ between groups (32 in the tenecteplase group, three considered probably or definitely related to drug treatment; 16 in the alteplase group, five were considered drug-related). INTERPRETATION Neurological and radiological outcomes did not differ between the tenecteplase and alteplase groups. Evaluation of tenecteplase in larger trials of patients with acute stroke seems warranted. FUNDING The Stroke Association.

Brain repair: cell therapy in stroke.

Stroke affects one in every six people worldwide, and is the leading cause of adult disability. Some spontaneous recovery is usual but of limited extent, and the mechanisms of late recovery are not completely understood. Endogenous neurogenesis in humans is thought to contribute to repair, but its extent is unknown. Exogenous cell therapy is promising as a means of augmenting brain repair, with evidence in animal stroke models of cell migration, survival, and differentiation, enhanced endogenous angiogenesis and neurogenesis, immunomodulation, and the secretion of trophic factors by stem cells from a variety of sources, but the potential mechanisms of action are incompletely understood. In the animal models of stroke, both mesenchymal stem cells (MSCs) and neural stem cells (NSCs) improve functional recovery, and MSCs reduce the infarct volume when administered acutely, but the heterogeneity in the choice of assessment scales, publication bias, and the possible confounding effects of immunosuppressants make the comparison of effects across cell types difficult. The use of adult-derived cells avoids the ethical issues around embryonic cells but may have more restricted differentiation potential. The use of autologous cells avoids rejection risk, but the sources are restricted, and culture expansion may be necessary, delaying treatment. Allogeneic cells offer controlled cell numbers and immediate availability, which may have advantages for acute treatment. Early clinical trials of both NSCs and MSCs are ongoing, and clinical safety data are emerging from limited numbers of selected patients. Ongoing research to identify prognostic imaging markers may help to improve patient selection, and the novel imaging techniques may identify biomarkers of recovery and the mechanism of action for cell therapies.

Stem cell therapy in stroke: designing clinical trials.

Stroke is a common and disabling condition that represents a potentially attractive target for regenerative therapy. Stem cells from a wide range of origins have been investigated in studies using animal models of stroke, with evidence that neural or mesenchymal cells migrate to the site of ischemic injury after intravascular or intraparenchymal delivery, and that a proportion of cells survive and differentiate into cells with characteristics of neurons or glia. In some studies there is evidence of electrical function of transplanted cells. Some studies report improvements in neurological function with cell implantation even when undertaken up to 30 days after the stroke is induced. Few clinical trials have been undertaken to date, with two studies of a teratocarcinoma-derived cell line delivered by direct brain injection, and two of bone-marrow derived mesenchymal stem cells delivered intravascularly. Ongoing trials of other cell lines are exploring safety. There are considerable difficulties in designing future efficacy trials, some being generic to the field of regenerative treatment in stroke, and some that are specific to stem cells or their mode of delivery.

Impact of Computed Tomography Perfusion Imaging on the Response to Tenecteplase in Ischemic Stroke: Analysis of 2 Randomized Controlled Trials.

Background: We pooled 2 clinical trials of tenecteplase compared with alteplase for the treatment of acute ischemic stroke, 1 that demonstrated superiority of tenecteplase and the other that showed no difference between the treatments in patient clinical outcomes. We tested the hypotheses that reperfusion therapy with tenecteplase would be superior to alteplase in improving functional outcomes in the group of patients with target mismatch as identified with advanced imaging. Methods: We investigated whether tenecteplase-treated patients had a different 24-hour reduction in the National Institutes of Health Stroke Scale and a favorable odds ratio of a modified Rankin scale score of 0 to 1 versus 2 to 6 compared with alteplase-treated patients using linear regression to generate odds ratios. Imaging outcomes included rates of vessel recanalization and infarct growth at 24 hours and occurrence of large parenchymal hematoma. Baseline computed tomography perfusion was analyzed to assess whether patients met the target mismatch criteria (absolute mismatch volume >15 mL, mismatch ratio >1.8, baseline ischemic core <70 mL, and volume of severely hypoperfused tissue <100 mL). Patients meeting target mismatch criteria were analyzed as a subgroup to identify whether they had different treatment responses from the pooled group. Results: Of 146 pooled patients, 71 received alteplase and 75 received tenecteplase. Tenecteplase-treated patients had greater early clinical improvement (median National Institutes of Health Stroke Scale score change: tenecteplase, 7; alteplase, 2; P=0.018) and less parenchymal hematoma (2 of 75 versus 10 of 71; P=0.02). The pooled group did not show improved patient outcomes when treated with tenecteplase (modified Rankin scale score 0–1: odds ratio, 1.77; 95% confidence interval, 0.89–3.51; P=0.102) compared with alteplase therapy. However, in patients with target mismatch (33 tenecteplase, 35 alteplase), treatment with tenecteplase was associated with greater early clinical improvement (median National Institutes of Health Stroke Scale score change: tenecteplase, 6; alteplase, 1; P<0.001) and better late independent recovery (modified Rankin scale score 0–1: odds ratio, 2.33; 95% confidence interval, 1.13–5.94; P=0.032) than those treated with alteplase. Conclusions: Tenecteplase may offer an improved efficacy and safety profile compared with alteplase, benefits possibly exaggerated in patients with baseline computed tomography perfusion–defined target mismatch. Clinical Trial Registration: URL: http://www.clinicaltrials.gov. Unique identifier: NCT01472926. URL: https://www.anzctr.org.au. Unique identifier: ACTRN12608000466347.

How many stroke patients might be eligible for mechanical thrombectomy

Introduction Recent studies showed improved patient outcomes with endovascular treatment of acute stroke compared to medical care, including IV rtPA, alone. Seven trials have reported results, each using different clinical and imaging criteria for patient selection. We compared eligibility for different trial protocols to estimate the number of patients eligible for treatment. Patients and methods Patient data were extracted from a single centre database that combined patients recruited to three clinical studies, each of which obtained both CTA and CTP within 6 h of stroke onset. The published inclusion and exclusion criteria of seven intervention trials (MR CLEAN, EXTEND–IA, ESCAPE, SWIFT-PRIME, REVASCAT, THERAPY and THRACE) were applied to determine the proportion that would be eligible for each of these studies. Results A total of 263 patients was included. Eligibility for IAT in individual trials ranged from 53% to 3% of patients; 17% were eligible for four trials and under 10% for two trials. Only three patients (1%) were eligible for all studies. The most common cause of exclusion was absence of large artery occlusion (LAO) on CTA. When applying simplified criteria requiring an ASPECT score > 6, 16% were eligible for IAT, but potentially 40% of these patients were excluded by perfusion criteria and more than half by common NIHSS thresholds. Conclusion Around 15% of patients presenting within 6 h of stroke onset were potentially eligible for IAT, but clinical trial eligibility criteria have much more limited overlap than is commonly assumed and only 1% of patients fulfilled criteria for all recent trials.

Tenecteplase in ischemic stroke offers improved recanalization: Analysis of 2 trials.

Objective: To test whether patients with complete vessel occlusion show greater recanalization at 24 hours and have improved clinical outcomes at 24 hours and 90 days when treated with tenecteplase compared to alteplase. Methods: Pooled clinical and imaging data from 2 phase 2 randomized trials comparing tenecteplase with alteplase allowed CT angiography (CTA) scans to be assessed centrally for occlusion status at baseline and at 24 hours post thrombolysis using the modified thrombolysis in cerebral infarction (TICI) scale. Twenty-four-hour poststroke NIH Stroke Scale (NIHSS) and 90-day modified Rankin Scale (mRS) scores were also compared between treatment groups using linear regression to generate odds ratios (ORs). Results: From 146 pooled patients, 69 had a TICI 0/1 occlusion overall at baseline. Tenecteplase-treated patients with a complete vessel occlusion had greater complete recanalization rates at 24 hours (71% for tenecteplase vs 43% for alteplase, p < 0.001). Patients with a TICI 0/1 occlusion who were treated with tenecteplase also showed greater early clinical improvement (median NIHSS change with tenecteplase was 9, interquartile range [IQR] 6, alteplase 1, IQR 1, p = 0.001) and higher rates of favorable 90-day outcomes (mRS 0–1 of tenecteplase compared with alteplase, OR 4.82, 95% confidence interval 1.02–7.84, p = 0.05). Conclusions: Tenecteplase may offer greater recanalization efficacy compared to alteplase, possibly exaggerated in patients with complete vessel occlusions on baseline CTA.

Coagulation and Fibrinolytic Activity of Tenecteplase and Alteplase in Acute Ischemic Stroke

Background and Purpose— We compared the fibrinolytic activity of tenecteplase and alteplase in patients with acute ischemic stroke, and explored the association between hypofibrinogenaemia and intracerebral hemorrhage. Methods— Venous blood samples from a subgroup of participants in the Alteplase–Tenecteplase Trial Evaluation for Stroke Thrombolysis (ATTEST) study were obtained at pretreatment, 3 to 12 hours, and 24±3 hours post-intravenous thrombolysis for analyses of plasminogen, plasminogen activator inhibitor-1, D-dimer, factor V, fibrinogen, and fibrin(ogen) degradation products, in addition to routine coagulation assays. Related sample Wilcoxon signed-rank tests were used to test the within-group changes, and independent Mann–Whitney tests for between-group differences. Results— Thirty patients were included (alteplase=14 and tenecteplase=16) with similar baseline demographics. Compared with baseline, alteplase caused significant hypofibrinogenaemia (P=0.002), prolonged prothrombin time (P=0.011), hypoplasminogenaemia (P=0.001), and lower factor V (P=0.002) at 3 to 12 hours after administration with persistent hypofibrinogenaemia at 24 hours (P=0.011), whereas only minor hypoplasminogenaemia (P=0.029) was seen in the tenecteplase group. Tenecteplase consumed less plasminogen (P<0.001) and fibrinogen (P=0.002) compared with alteplase. Conclusions— In patients with acute ischemic stroke, alteplase 0.9 mg/kg caused significant disruption of the fibrinolytic system, whereas tenecteplase 0.25 mg/kg did not, consistent with the trend toward lower intracerebral hemorrhage incidence with tenecteplase in the ATTEST study. Clinical Trial Registration— URL: http://www.clinicaltrials.gov. Unique identifier: NCT01472926.

Ipilimumab Induced Encephalitis: A Case Report

Background: Cytotoxic T-lymphocyte-associated protein-4 (CTLA-4) is a helper T cell protein receptor that down regulates the immune system when bound to antigen presenting cells. Ipilimumab selectively binds to CTLA-4 inhibiting the immune tolerance to tumour cells and has recently been approved for the treatment of metastatic melanoma. Autoimmune sequelae are side-effects of such immunomodulatory therapies. We describe the first case of ipilimumab induced delayed onset encephalitis. Case: A 71 year-old man with BRAF wild-type metastatic melanoma received ipilimumab as first-line therapy. He presented with generalised weakness and headache following cycle 2 of ipilimumab. Blood analyses confirmed panhypopituitarism and MRI showed lymphocytic infiltration of pituitary gland, confirming autoimmune hypophysitis. Hormone replacement and a course of dexamethasone resolved the initial symptoms. Two months later he developed myoclonic jerks, drowsiness and mood elevation. CSF protein was raised with normal white and no malignant cells. Ipilimumab was stopped and high dose methylprednisolone was intiated resulting in improvement within 24hours. Post methylprednisolone electroencephalogram showed normal background activity with no seizures. Discussion: Gastrointestinal (colitis, nausea), skin (pruritis, rash) and fatigue are the most common (30-40%) ipilimumab induced side effects. Endocrinopathies are reported in 1-2% of patients. CTLA-4 is expressed by pituitary gland thereby being susceptible for lymphocytic hypophysitis following ipilimumab. Neurological side effects are even rarer yet (<1%). Autoimmune encephalitis can be a delayed response and in our case was around 2 months after second dose of ipilimumab therapy. No cases of delayed onset ipilimumab induced encephalitis have been described as yet, but with increasing use of immune therapies which up-regulate T cells, rarer immune sequelae are likely to be on the rise. Conclusion: Ipilimumab caused delayed onset autoimmune encephalitis and hypophysitis that was steroid responsive. Multi-specialty approach with early intervention of a neurologist and endocrinologist is a must for improved identification, treatment and outcomes.

The Impact of CT Perfusion Imaging on the Response to Tenecteplase in Ischemic Stroke. Analysis of Two Randomized Controlled Trials

Background: We pooled 2 clinical trials of tenecteplase compared with alteplase for the treatment of acute ischemic stroke, 1 that demonstrated superiority of tenecteplase and the other that showed no difference between the treatments in patient clinical outcomes. We tested the hypotheses that reperfusion therapy with tenecteplase would be superior to alteplase in improving functional outcomes in the group of patients with target mismatch as identified with advanced imaging. Methods: We investigated whether tenecteplase-treated patients had a different 24-hour reduction in the National Institutes of Health Stroke Scale and a favorable odds ratio of a modified Rankin scale score of 0 to 1 versus 2 to 6 compared with alteplase-treated patients using linear regression to generate odds ratios. Imaging outcomes included rates of vessel recanalization and infarct growth at 24 hours and occurrence of large parenchymal hematoma. Baseline computed tomography perfusion was analyzed to assess whether patients met the target mismatch criteria (absolute mismatch volume >15 mL, mismatch ratio >1.8, baseline ischemic core <70 mL, and volume of severely hypoperfused tissue <100 mL). Patients meeting target mismatch criteria were analyzed as a subgroup to identify whether they had different treatment responses from the pooled group. Results: Of 146 pooled patients, 71 received alteplase and 75 received tenecteplase. Tenecteplase-treated patients had greater early clinical improvement (median National Institutes of Health Stroke Scale score change: tenecteplase, 7; alteplase, 2; P=0.018) and less parenchymal hematoma (2 of 75 versus 10 of 71; P=0.02). The pooled group did not show improved patient outcomes when treated with tenecteplase (modified Rankin scale score 0–1: odds ratio, 1.77; 95% confidence interval, 0.89–3.51; P=0.102) compared with alteplase therapy. However, in patients with target mismatch (33 tenecteplase, 35 alteplase), treatment with tenecteplase was associated with greater early clinical improvement (median National Institutes of Health Stroke Scale score change: tenecteplase, 6; alteplase, 1; P<0.001) and better late independent recovery (modified Rankin scale score 0–1: odds ratio, 2.33; 95% confidence interval, 1.13–5.94; P=0.032) than those treated with alteplase. Conclusions: Tenecteplase may offer an improved efficacy and safety profile compared with alteplase, benefits possibly exaggerated in patients with baseline computed tomography perfusion–defined target mismatch. Clinical Trial Registration: URL: http://www.clinicaltrials.gov. Unique identifier: NCT01472926. URL: https://www.anzctr.org.au. Unique identifier: ACTRN12608000466347.