Treatment with intracerebroventricular (ICV)-delivered cerliponase alfa enzyme 
replacement therapy (ERT) in a Phase 1/2 study of 24 subjects with CLN2 disease 
resulted in a meaningful preservation of motor and language (ML) function and 
was well tolerated. Treatment was associated with anti-drug antibody (ADA) 
production in the cerebrospinal fluid (CSF) of 6/24 (25%) and in the serum of 
19/24 (79%) of clinical trial subjects, respectively, over a mean exposure of 
96.4 weeks (range 0.1-129 weeks). Neutralizing antibodies (NAb) were not 
detected in the CSF of any of the subjects. No events of anaphylaxis were 
reported. Neither the presence of serum ADA nor drug-specific immunoglobulin E 
was associated with the incidence or severity of hypersensitivity adverse 
events. Serum and CSF ADA titers did not correlate with change in ML score. 
Therefore, the development of an ADA response to cerliponase alfa is not 
predictive of an adverse safety profile or poor treatment outcome.