Clinical trials on a computer

The story: Everyone knows how expensive clinical trials are, and risky as well for the participants. The search is on for computer models good enough

Clinical trials on a computer

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• The story: Everyone knows how expensive clinical trials are, and risky as well for the participants. The search is on for computer models good enough to replace warm bodies for at least the preliminary phases of trials.
• New approaches: Scientists are investigating stent-like devices called intracranial flow diverters. These control the passage of blood through brain arteries and are used to treat cerebral aneurysms (bulges that form in an arterial wall), in which blood then accumulates. If a cerebral aneurysm bursts, it causes a so-called haemorrhagic stroke, damaging surrounding tissue by engulfing it in blood. Inserting a flow diverter directs the bloodstream away from the aneurysm, permitting blood already within the bulge to stay in place and clot, thus blocking the aneurysm up.

1. The researchers’ experimental “subjects” were computer models derived from detailed three-dimensional scans of the brains of 82 volunteers with cerebral aneurysms.
2. The team inserted software representations of flow diverters into these models and recorded the consequences for virtual blood flow through the virtual brains in question.
3. They then compared their results with those from three trials of the procedure carried out in the real world in recent years. They confirmed what these real trials had found—that the flow diverters do indeed encourage clots to form in aneurysms—and they rated the stents’ effectiveness at this task as similarly good.

• Ischaemic strokes: These are a consequence of a vessel getting blocked. This stops blood flowing to the part of the brain distal to the blockage, which then dies. The virtual trials showed that the risk of an ischaemic stroke did indeed rise if a flow-diverter was fitted near an arterial fork. It also predicted that patients with higher than normal blood pressure were at even greater risk of such fork-related strokes—a finding that had not (and still has not yet) been shown in the real world.
• Virtual or real: Though it is hard to imagine virtual trials of this sort completely replacing real ones, they could certainly reduce their number by suggesting in advance which avenues are worth exploring. They might also reduce the need for animal trials—and might indeed be more effective than these if they proved better models of human physiology than the laboratory mice now popular for the purpose.
• Advantages: Virtual trials bring other advantages, too. One is that the same procedure can be tested over and over again in the same “patient”, but with different variables. The observation about blood pressure which emerged was made this way. 

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