TPP1 and glycogen storage disease VI: Two clinical trials: an open label, single group study (Study 190–201; NCT01907087) and an extension study (Study 190–202; NCT02485899), have demonstrated a clinically significant difference between cerliponase alfa treatment and historical controls; treatment with cerliponase alfa was shown to result in a slower rate of decline of motor and language function in CLN2 disease patients.