Kristen, thanks very much for the question. So the goal here is to develop a therapy, a disease modifying therapy for patients with Huntington's disease that is both effective and safe. So the safety of the product during development is of incredible importance. When we talk about Huntington lowering as a therapeutic strategy, it makes a lot of sense. It's well understood. Huntington's disease is a monogenic disease caused by the production of a toxic mutant Huntington protein. The goal of Huntington lowering is to decrease that protein that is causing the disease and, of course, there's a broad scientific literature substantiating that lowering mutant Huntington mutant protein is likely to result in clinical benefit. In the development of PTC518, we really followed the playbook established by Rare Disease [ph] for the development of a both safe and effective oral slicing agent for a whole brain disease like Huntington's disease. Therefore, in the development, it was incredibly important to ensure that we're lowering Huntington protein so that we can have the desired therapeutic effect one would expect for reducing the cause of the disease, but at the same time, wanting to make sure that we're doing so safely and that involves making sure that we have a molecule that is specific and is selected for the Huntington target, and it gets into the brain, gets to all regions of the brain because Huntington's disease is a whole brain disease and so when we look at these markers of safety like NFL, we're asking, are we seeing some harm to nerve cells, because the way that nerve cell injury can present itself is through NFL spikes and this is something that has been seen in development of a number of therapies, and it's the reason why, as you pointed out, NFL could be thought of as a marker of clinical benefit, but more importantly, Huntington's disease, over the shorter period of time on a clinical trial, it's really acknowledged to be more important as a marker of safety. Are we delivering therapeutic benefit without causing spikes that show that we may also be causing harm? So the fact that we've not seen any evidence of treatment related NFL spikes and we continue to observe that PTC518 one has been safe and well tolerated in the PIVOT-HD study is an incredibly important finding for patients and then to also say that we're having a desired biomarker effect of lowering Huntington protein in the blood, we're seeing lowering of Huntington protein in CSF, and importantly, as we reported, we're seeing early evidence of clinical benefit on key disease scales like total motor score and CUHDRS tell us that so far we're seeing that we're having the desired therapeutic benefit, while we hope for disease modifying therapy, but importantly, also having the safety that will be incredibly important for a successful therapy.