In the Laitman article (2018), you applied the model to real patients. What were the main findings from that study?
DR. KRIEGER: Until now, the topographical model has been conceptual with a visual depiction, and I think it has been important as an educational tool and an aid to help shape our thinking about MS in a unified way.
The Laitman et al research, is the first time we have applied the concepts of the model to individual patients to confirm whether we could map individual patients’ MS histories in the topographical model and see if we could depict their clinical course this way. We found that we could.
One of the most important points that the topographical model makes is the idea that as progression occurs and reserve is lost, there is an unmasking of underlying disease. Meaning, all of the signs and symptoms that a patient has had during their relapse when they were accumulating lesions should be re-revealed or recapitulated when reserve is lost and progression occurs.
To confirm this, we mapped ten patients in the topographical model. We characterized their signs and symptoms of relapses during the relapsing phase and we found that the vast majority of these symptoms had redeclared themselves at the time that these patients developed SPMS. Furthermore, those symptoms were continuing to worsen in their pattern; that is in the pattern of their disease topography as the years have continued to pass since they developed SPMS.
This was the first empirical study in real patients to show that the principles of the topographical model held true. This recapitulation hypothesis of symptoms in progressive disease was borne out, and that can help to lay the groundwork for future empirical studies to see how this model can be used as a predictive tool.
How does this new theory of MS disease progression better inform treatment decisions than the disease course theories that currently exist?
DR. KRIEGER: We have had the clinical phenotypes for 20 years and it has been very helpful to us in the development of treatments that we have shown are effective for RRMS and in more recent years for PPMS. What we don’t really have is a way of personalizing and predicting the individual person’s disease trajectory.
Although we have prognostic factors that we know are important, such as age and MRI disease burden, there is still great uncertainty of the clinical course in the individual patient. If the topographical model can be further empirically validated using real world data, that could help us to predict what is going to happen to an individual patient. That can help us to make better treatment decisions for them because it could inform our treatment decisions in a more personalized way.
Is there any other recent research that supports these concepts?
DR. KRIEGER: We talk a lot about the need for biomarkers in MS to help us predict disease course and the topographical model makes the case that lesion location is a crucial biomarker. That is, the patient that has lesions in the spinal cord and the brain stem is more likely to have progressive signs and symptoms referable to those lesions.