Author Interviews / 07.05.2019 Interview with: [caption id="attachment_49033" align="alignleft" width="200"]Lana Zhovtis Ryserson, MDAssistant Professor, Department of NeurologyNYU Langone Health Dr. Zhovtis Ryserson[/caption] Lana Zhovtis Ryserson, MD Assistant Professor, Department of Neurology NYU Langone Health What is the background for this study? What are the main findings? Response: Natalizumab is an effective therapy of relapsing remitting multiple sclerosis dosed at 300mg every 4 weeks. However it is associated with a potentially deadly infection - progressive multifocal leukoencephalopathy. In order to mitigate this risk, clinicians have adopted an approach of infusing the medication less frequently, a strategy which has become known as Extended Interval Dosing (EID). The TOUCH database is US mandatated risk evaluation and mitigation program which is the largest database available to assess PML risk for patients on EID schedule. Previous analysis of this database in 2017, showed a significant risk reduction of PML in patients utilizing extended interval dosing schedule. The aim of the current study was to update on this analysis with another year of data.