AstraZeneca passed a milestone in its effort to develop an effective treatment for ischaemic stroke yesterday after its developmental neuroprotectant Cerovive was cleared to continue in a pivotal study.

The trial – SAINT II – is a follow-up to an earlier study which had mixed results. In the earlier trial, Cerovive was found to be superior to placebo in reducing post-stroke disability, but was no better at improving neurological impairment. In light of these findings, AstraZeneca increased the size of SAINT II to boost its statistical power to detect improvements over placebo.

The Independent Data and Safety Monitoring Board (IDMB) and the trial’s steering committee yesterday gave the go-ahead for SAINT II to continue after an interim safety analysis yielded no worrying findings.

Ischaemic stroke has been something of a graveyard for product candidates, with a plethora of drugs discontinued because they either had no effect or worsened outcomes in stroke. To date only one product - Genentech's clotbuster Activase (alteplase) – has been approved to treat stroke patients, and use of this drug is limited because it must be delivered within two to three hours of the onset of symptoms, and most patients do not reach hospital so soon.

Cerovive conferred its benefit in the first SAINT I trial after being administered on average six hours after symptom onset. Roughly half of all stroke patients receive treatment within that time period.

Tomas Odergren, who heads the development programme for the drug at AstraZeneca, said the news was another encouraging sign that Cerovive is well tolerated in acute ischemic stroke patients, who have tended to be highly vulnerable to adverse effects of many other drug candidates tested to date.

AstraZeneca is hoping to file for approval of Cerovive in stroke in the first half of 2007.

Cerovive is licensed from US firm Renovis and is thought to work by trapping free radicals that cause oxidative damage to brain tissue in ischaemic stroke. No other neuroprotectant has ever shown any efficacy in a Phase III trial in this indication.