Additional Relevant Details In the phase 1/2 study, 87% of patients experienced attenuation of their disease compared to the expected rate of decline observed in available natural history data. The primary endpoint of the study is a standardized mobility (motor) and language score using a CLN2 disease-specific rating scale. The scale separately measures performance of mobility and language with normal function in each being a score of 3 and no function being a score of 0. The highest score possible is 6. Natural history of the disease shows an average of 2.1 units of decline over 48 weeks in 41 untreated patients followed longitudinally.1  The mean decline in 21 evaluable subjects receiving cerliponase alfa treatment was 0.43 units over 48 weeks (p < 0.0001 compared to a 2-point/48 week decline derived from available natural history). Of the 23 evaluable subjects, two were not included in the rate of decline evaluation, as these subjects entered the study with the maximum motor-language score of 6, were not actively declining prior to treatment initiation and remained at 6 during the treatment period.      Brain Magnetic Resonance Imaging (MRI) measurement showed that cerliponase alfa treatment attenuated cortical grey matter volume loss. In 23 treated patients, the mean total cortical grey matter volume decrease is 9.7% over 48 weeks. In a separate study of six untreated children with CLN2 disease, cortical grey matter volume decreased by 14.5% each year.2An interim analysis from an ongoing extension study suggests durability of therapeutic effect. The mean change from baseline in the first nine patients receiving cerliponase alfa treatment was an improvement of +0.2 units over 72 weeks compared to the expected decline observed in a natural history cohort of approximately -3.13 units. Of those nine patients, three gained 1 point, five remained with a stable score and one lost 1 point. In the four patients who received cerliponase alfa for up to 88 weeks, the mean change from baseline was a decline of -0.5 units compared to the expected decline observed in a natural history cohort of approximately -3.83 units.