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Host – Dan Keller

Hello, and welcome to Episode Ninety-six of Multiple Sclerosis Discovery, the podcast of the MS Discovery Forum. I'm Dan Keller.

Today's interview features Drs. Bibiana Bielekova, who is an investigator at the National Institutes of Health, and Mika Komori, a postdoctoral fellow in her lab. We caught up with the two physician-researchers at the ACTRIMS meeting in New Orleans earlier this year. At the meeting, Dr. Komori talked about a new and more sensitive way to evaluate what may be happening in the brains and spinal cords of people with progressive MS.

In a recent study, she examined samples of cerebral spinal fluid, or CSF, collected through a thin needle near the base of the spine. She was scouting for immunological biomarkers of progressive MS. In the analysis, a molecule called CD27, mostly from T cells, stood out, as did another marker specific to B cells. Even more revealing was the ratio of the CD27 molecule to the T cells. T cells are a big player in relapsing MS and not usually associated with the progressive, more neurodegenerative forms of MS. The unexpected results raise new questions about why immune-modulating drugs do not seem to be effective against progressive MS.

If validated, the new test may lead to better diagnosis and treatment of people with MS and other neurological disorders. And it may speed up clinical trials in progressive MS and reduce their cost. In fact, the same research team used their new biomarker test in a small phase 2 study of the anti-B cell drug, rituximab, delivered both intravenously in the blood and intrathecally in the spinal column. Unfortunately, the new biomarker test showed that the double delivery system did not work as expected to eliminate inflammatory B cells trapped in the brains of people with progressive MS. They stopped the study early for lack of efficacy.

In a change to our usual podcast format, Dr. Bielekova interviewed Dr. Komori about the specifics of the study and put the results in a larger context. Midway through the interview, Carol Morton, a past editor of MS Discovery Forum, asked both doctor-scientists about what the new test means for treating patients.

Interviewer – Dr. Bibiana Bielekova

As a physician, when we see patients, we don't really know what's happening in their brains, right? We are using some tools that are supposed to help us to identify like, for example, MRI, but they are not perfect. So, how did you choose to address that problem?

Interviewee – Dr. Mika Komori

So, when I saw patients, I can't tell them that the drug, which are now available, is effective or not, especially for progressive MS patients, because currently so far all big clinical trials, they didn't show any effects on them. Because of that result, we think progressive MS patients don't have any intrathecal inflammation. So far we believe MS – multiple sclerosis – is inflammatory disease, but we don't know if it's true for progressive MS or not.

Dr. Bielekova

Yes, and, in fact, it is because these tools are not that ideal, right? So, in fact, by using the tools that are available, such as MRI or these cerebrospinal fluid markers that have been developed more than 40 years ago, the conclusion is that there isn't inflammation in progressive MS, right, because all of them are basically decreased, with exception of IgG index which, as you said, remains stable for many, many years. So somebody who had, for example, infection during childhood can have elevated IgG index for the rest of their life.

So that was really the reason why we wanted to develop something that is more sensitive. And also, I think, the question really was, does cerebrospinal fluid reflect what's happening in the brain tissue? And can we somehow develop technology that can tell us what is happening in the brain tissue without taking, of course, the biopsy, which is extremely invasive, and we cannot really use it in people, right? So how did you address that problem?

Dr. Komori

We developed a very good way to measure soluble biomarkers in the CSF with a new technique called Meso Scale Discovery.

Dr. Bielekova

So I think we should probably step back a little bit and say that our goal was to really look at the biomarkers that can point towards a specific cell, right? Because there are proteins that can be released by all immune cells, such as for example, chemokines, and, in fact, the vast majority of cytokines. But we were especially interested in looking at the proteins than can specifically point to one particular cell type, and so you did something else to really measure that, right? In fact, we all helped you to do that because it was so difficult, right? So we employed the whole lab to do the separation of cells. And then you were looking at which cells are producing these biomarkers.

Dr. Komori

Right.

Dr. Bielekova

So tell us about those three that really panned out as the best.

Dr. Komori

When we see the results of soluble CD27, soluble CD14, and soluble CD21, soluble CD27 correctly identified all inflammatory neurological disease and also only negative for noninflammatory neurological disease patients.

Dr. Bielekova

Whereas all of the traditional markers together, if we put all of them together, they could identify only about two-thirds of the patients. We were really surprised, because – I mean, the field believed, as Mika had said, right, based on the fact you no longer have contrast-enhancing lesions; the treatments no longer work; you don't have clear cytosis, meaning a large number of white blood cells in the cerebrospinal fluid – the field and us, we believed that what we are going to see, once Mika unblinds these two cohorts of close to 200 patients each that we will see that progressive patients have significantly lower amount of inflammation. But that's not what she saw. She saw something completely different and surprising. So what did you see?

Dr. Komori

Well we saw almost comparable level of intrathecal inflammation in both PPMS/SPMS to RRMS.

Dr. Bielekova

Not almost, right? There wasn't any statistically significant difference.

Dr. Komori

No.

Dr. Bielekova

So on the group level, we saw the same level.

Dr. Komori

Absolutely. Yes, and it was so significant compared to a healthy donor and noninflammatory neurological diseases. So all healthy donor and neuro-inflammatory neurological diseases, they didn't have high level of especially soluble CD27. But almost 90% of each MS subtypes had very high soluble CD27.

Dr. Bielekova

But when you did the ratios…

Dr. Komori

Then we did the ratio and calculated soluble CD27 per T cell in CSF. We found that even higher level of ratio results in progressive MS patients, both in primary progressive and secondary progressive. And for our MS patients the ratio is almost comparable to healthy donor and noninflammatory neurological diseases. That means, although we don't see many immune cells in the CSF for progressive MS patients, those cells are in the CNS tissue. And it cannot move, but just shedding the soluble markers like soluble CD27 into the CSF. And we can detect that marker when we measure the CSF.

Dr. Bielekova

And I think it really nicely ties with the beautiful pathology studies that have been published that demonstrate that patients with progressive MS no longer have this very dense inflammation around the vessel, which is the type inflammation that is capable of opening blood-brain barrier, right? Which means that that's the type of inflammation that is associated with contrast-enhancing lesions. But instead, when pathologists looked at normal-appearing white matter, they could see, you know, one T cell here, one T cell there, right? It's really difficult to quantify it on the pathology level, because they never assay the whole brain. But your assay is, in fact, looking at the entire brain. And what your assay is saying is that the number of cells is basically the same in all of these different stages of MS disease process. What is really different is where they are located, right?

So, in relapsing/remitting MS, they are located in the perivascular aggregates, not much in the normal appearing white matter. That's where they open the blood-brain barrier. But in the progressive MS they are located in the brain. And I think our conclusion was that, in fact, this may be the major reason why current treatments are not working for progressive MS, because basically we would expect that only those drugs can work in progressive MS that have very good penetrance into the brain tissue.

Now, I think that we also have to realize that just the presence of the cells in the tissue doesn't tell us that they are pathogenic, right? So it may be that they are there, but something else is driving disability. But on the other hand, the data we have, for example, from recently announced ocrelizumab trial is really suggesting that these cells are indeed pathogenic, right? So I think that we can say that progressive MS is neurodegenerative disease only if we can eliminate inflammation from the brain of progressive MS patients, and it does not translate into stopping disability or significantly inhibiting disability.

But the data that we have published, and we are still collecting, are really suggesting that current treatments, in fact, do not eliminate cells from the brain of progressive MS patients, right? So I think the question of compartmentalized inflammation versus neurodegeneration ...