Currently the treatment of acute ischemic stroke (AIS) – the most common form of stroke – is focused on restoration of blood flow to the brain by thrombolysis and more recently by endovascular thrombectomy to reverse the ischemic events in the brain.
Stroke research in 2018
To date there is only one US Food and Drug Administration-approved thrombolytic drug treatment for AIS in the eight major markets (US, France, Germany, Italy, Spain, the UK, Japan and China), called Activase (alteplase), a tissue plasminogen activator (tPA), marketed by Roche (Genentech) and Boehringer Ingelheim, which can be administered within a 4.5-hour window after stroke.
Improving clinical outcomes
After decades of efforts on improving revascularisation, companies have shifted their focus towards the development of drugs that can improve clinical outcomes and restore neurological function in patients after AIS, highlighting the immense socio-economic need for reducing disability following ischemic events.
There are about 36 pipeline candidates under development, according to a recent report by GlobalData that offers a global drug forecast and market analysis of acute ischemic stroke to 2027.
Drugs developed to improve clinical outcomes include neuroprotective agents (44%), stem cell therapies (14%), and drugs for stroke recovery (11%).
Conversely, the AIS pipeline contains only three thrombolytic drugs and very few drugs for secondary stroke prevention. Development of these novel agents is challenging and a high attrition rate characterizes AIS clinical drug development. Nevertheless, developers demonstrated progress with their drugs designed for the treatment of AIS during 2018.
ZZ Biotech and Biogen
ZZ Biotech announced some encouraging results for the Phase II Rhapsody trial of its pipeline candidate, 3K3A-APC, which is a genetically engineered variant of the naturally occurring activated protein C (APC) designed to protect AIS patients from a brain haemorrhage that can develop following thrombolysis or mechanical thrombectomy. The Phase II trial established a maximally tolerated dose (MTD) of 540µg/kg, and a substantial reduction in cerebral haemorrhage volume and incidence was also reported.
Biogen demonstrated a particular commitment in 2018 to grow in the AIS space. On 4 September 2018, Biogen announced the enrollment of the first patient in the global Phase III clinical study, called CHARM, to evaluate intravenous glibenclamide designed for the prevention and treatment of severe cerebral edema (brain swelling) in AIS patients with large hemispheric infarction (LHI).
Furthermore, Biogen has also acquired a thrombolytic drug, TMS-007, from TMS Co Ltd, recognising the continued need for this type of drug in the AIS space, a need that was likewise strongly expressed by high-prescribing physicians who completed GlobalData’s surveys.
Stem cell therapies
Other interesting advances in 2018 involved stem cell therapies for improving clinical outcomes. On 31 July 2018, Athersys announced enrollment of the first patient who suffered an AIS event in the Phase III Masters-2 study of MultiStem.
MultiStem consists of undifferentiated adult human stem cells obtained from bone marrow (BM) or other non-embryonic tissue. In a Phase II study, MultiStem treatment was safe, well-tolerated, and showed better recovery when given earlier (within 24–36 hours post-stroke versus 48 hours) as compared to placebo in patients with cortical cerebral ischemic stroke.
Patients enrolled in the Masters-2 clinical trial receive a single intravenous (IV) dose of MultiStem cell therapy within 18–36 hours of stroke occurrence, in addition to the standard of care, and disability using modified Rankin Scale (mRS) scores will be compared to the placebo group.
MultiStem is also being developed for other indications and the company announced positive results, on 23 January 2019, from its exploratory clinical study of MultiStem for treatment of acute respiratory distress syndrome (ARDS), which showed a lower mortality rate compared to placebo.
Regeneration of damaged neuronal cells
SanBio’s SB623 is a regenerative cell medicine for patients with a chronic motor deficit due to AIS, designed to promote regeneration of the damaged neuronal cells. It consists of allogeneic mesenchymal stem cells (MSCs), prepared from allogeneic BM stromal cells isolated from healthy donors, which is implanted in the nerve tissue of the brain.
Despite positive results obtained in the Phase I/IIa study of SB623, which showed significant benefit in AIS patient outcomes, the results of the Phase IIb trial, announced on 29 January 2019, show that the trial, unfortunately, did not meet the primary endpoint of proportion of patients demonstrating at least 10 points of improvement from baseline at six months after treatment on the Fugl-Meyer Motor Scale (FMMS) compared to the placebo group.
Although no new drugs entered the AIS space during 2018 and despite some disappointing results, GlobalData expects that novel drugs designed to improve clinical outcomes of AIS patients will start launching from 2021, which along with the increasing prevalence of AIS will fuel AIS market growth.
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