IFNB1 and in situ carcinoma: In the follow up of a placebo controlled CIS study comparing early interferon beta intramuscular treatment 10 years after randomization with delayed treatment Kinkel et al. reported that 18.4% had an EDSS ≥ 3.0.[23] In a study by Chung et al. conducted in a British cohort of untreated patients 30 years after CIS only 42% had remained ambulatory (EDSS scores of ≤ 3.5) and 34% developed SPMS [22].