I support what Cathy said. With orphan diseases—rare diseases—one of the challenges in studying drugs is the size of the population you're studying. Globally there may be fewer than 1,000 patients suffering from it.
Normally, in clinical trials that approve drugs for market authorization for sale, we're looking at phase three clinical trials with 3,000 to 5,000 patients, where statistics and the size of the studies allow us to have a better understanding of the performance and the risk associated. With rare diseases, we're talking about potentially 10, 20 or 30 Canadians with this condition.
The trials are often designed to be global, with many sites. There are challenges around who would be a controlled group and whether there is a controlled group. Often the participants are also the control group. We're faced with unique kinds of challenges around showing if there is effectiveness and safety with the drug. Globally we work on what is the evidentiary bar we would allow access to. As Cathy said, we also have to put in place conditions that allow us to continue to monitor the performance of the drug and whether the promising effectiveness that's shown in these early trials is borne out by more real-world use.