[intro music]   Host – Dan Keller Hello, and welcome to Episode Ninety-seven of Multiple Sclerosis Discovery, the podcast of the MS Discovery Forum. I’m Dan Keller.   Today's interview features Dr. David Baker, Professor of Neuroimmunology at Queen Mary University of London in the UK. We spoke at the ECTRIMS conference last fall, where I asked him about his work with cannabinoid compounds – work that has led to a better understanding of the cannabinoid system as well as to candidate drug compounds to treat spasticity.   Interviewer – Dan Keller In terms of what you're doing now with cannabinoids, can you tell me what you are looking for, and what you've found?   Interviewee – David Baker Many, many years ago, we actually were probably the first people to show that cannabis can actually alleviate muscle stiffness in animal models of multiple sclerosis, which then kind of underpinned the push to look for cannabis in MS. So people with MS were smoking cannabis and perceiving benefit. The question was, why? And what they didn't really understand that there was going to be an unfolding biology. And a few years later after our first discovery that actually cannabinoids can cause relaxation of the muscles, we understood that the function of the cannabinoid system is to regulate nerve signaling. And so because the cannabinoid system does regulate the strength of synaptic signaling, then it's obvious that it can inhibit signs and symptoms because of this excessive neurostimulation. So at the time of that, then we realized that the receptor is a CB1 receptor, and the compound within cannabis is THC, and they're the same molecules that cause all the side effects. So you could never really disassociate away the high from the medical benefit. So we started to think, well, how can we try and get the medical benefit from the cannabinoid system and at the same time try and limit the side effect potential.   So what we thought is, well, if we can stop the cannabinoid molecules getting in the brain, then they won't cause the side effects. But maybe we can target the aberrant signaling in the spinal cord and the peripheral system to try and get the benefits. And so that was our intention. So we tried to make a CNS-excluded drug. And that's, in fact, what we did. We made a drug that was very, very water soluble, so you know, you use the mechanism of the blood-brain barrier to actually exclude it from the brain. So we made the compound, and a few weeks later, we kind of started putting it into animal models, not really doing it the pharmaceutical way, which would be a methodical testing. So we showed that it didn't cause any of the unwanted side effects that are associated with cannabis in the animals. And then we put it in a system where we had a spasticity in a multiple sclerosis relevant system, and the drug worked.   Now what we did know is that the drug was blocked by the activity of the CB1 receptor antagonist, so it looked like we'd made what we set out to make. So we were really excited. And from that point, we started to try and see if we could develop it as a drug. Unfortunately what we realized very quickly actually is that it doesn't work by the known cannabinoid receptor system, and I think what we stumbled across is a whole new biology of the cannabinoid system.   And so we've been developing this drug bit by bit. We set up a university spinout company to try and develop it as a pharmaceutical drug. And over the years, bit by bit, we've been pushing it forward. So it's very safe in animals. It has a massive therapeutic window. And with grant funding agencies etc. we've managed to be able to take it into phase I study where it passed with flying colors. We tested it in 60 healthy humans. And a few weeks ago, we started our first testing in people with multiple sclerosis. So we'll have to see how it works. But we ho