Full transcript: [intro music] Host – Dan Keller Hello, and welcome to Episode Eighty-Six of Multiple Sclerosis Discovery, the podcast of the MS Discovery Forum. I’m Dan Keller. A hallmark of multiple sclerosis is a new brain lesion. The active inflammation normally goes away in about 4 to 6 weeks, disappearing from contrast-enhanced detection by MRI scans. More recently, in some people with MS, researchers have found smaller longer-lasting inflammatory lesions outside the brain, in the surrounding lining called the leptomeninges, as well as evidence that they may play a role in progressive disease. The tiny compartments are associated with more severe disability, worse outcomes, and nearby gray matter demyelination. Dr. Pavan Bhargava, a neuroimmunology fellow at the Johns Hopkins University MS Center in Baltimore, Maryland, has started a phase I trial to slow progressive disease by targeting the B cells in these follicles. He is testing an anti-B cell antibody called rituximab, using the drug intrathecally—that is, injecting it directly into the cerebrospinal fluid of patients with primary or secondary progressive MS, so that more of it reaches the inflamed pockets in the brain lining. We spoke at the ECTRIMS meeting last fall in Barcelona, where he described to me the rationale for this experimental treatment approach. Interviewee – Pavan Bhargava In 2004, what was noted was that in autopsies of MS patients, there were collections of lymphoid cells in the meninges, and these aggregates of lymphoid cells were noted to abut areas of the cortex that demonstrated demyelination. So this suggested that possibly these collections of B and T lymphocytes that were in the meninges might be driving some of the cortical demyelination that is seen commonly in patients who have progressive MS. So the idea behind using rituximab intrathecally is that we want to, first of all, get as much rituximab as possible into the CSF [cerebral spinal fluid] and into the brain, because when we give rituximab IV, less than 0.1% usually gets into the CNS [central nervous system]. So we're trying to target the B cells that are found in these lymphoid follicles, and we're trying to get as much of the rituximab into the CNS as possible. So that's the rationale behind using intrathecal rituximab in progressive MS patients. Interviewer – Dan Keller Do the patients you're selecting just have visible leptomeningeal lesions, or do they have to have abnormal CSF – IgG elevated or oligoclonal bands – or how are you selecting them? Dr. Bhargava So in our trial, we are selecting patients using an MRI finding that was described now a couple of years ago that on a time-delayed post-contrast flare image, in about a third of MS patients you can actually see contrast-enhancing lesions, not in the brain parenchyma, but actually in the leptomeninges. And a recent paper from the NIH showed that in a couple of these patients who had contrast-enhancing leptomeningeal lesions, when they came to autopsy they could identify clusters of lymphocytes and macrophages that corresponded to these contrast-enhancing leptomeningeal lesions. So in our study, we're basically screening progressive MS patients with an MRI, and are only including patients in this study who do have evidence of these leptomeningeal contrast-enhancing lesions, because we feel that this is a marker of leptomeningeal inflammation in these patients.   MSDF And have you run any patients yet? Dr. Bhargava So we have 5 patients currently in the study, of whom 4 have actually completed their treatment phase of the trial. And our goal in this study is to enroll 12 patients. And the primary outcome is safety. So, you know, we want to know that using rituximab intrathecally in MS is safe. But our secondary outcomes include looking at the change in the MRI lesions that we noted at baseline, and then we