## 3 Results  
Phase A: Dose levels were escalated from 0.4 mg/dose to 20 mg/dose. The only adverse test item-related finding was observed at a dose level of 20 mg/animal:  
The Phase A female (Animal P0101F) was prematurely sacrificed on Day 29 due to apparent neurological findings at 20-mg dose (paralysis of arms and legs, missing tendon reflexes). In autopsy, no microscopic correlate to this finding could be identified. A test item-related finding of neuronal vacuolation was noted in the cerebral cortex and hippocampus of this animal's brain; this finding is common with intratheally delivered ASOs and was considered not responsible for the paralysis of the animal. Following single escalating intrathecal doses of NVP-13 at dose levels up to 20 mg/animal, plasma and CSF concentrations of NVP-13 generally increased with dose. However, the observed changes in NVP-13 exposure relative to the increases in dose level were inconsistent, probably due to inter-animal variability and the small number of animals (\(n=1/\text{sex}\)) used. Tissue concentrations were measured after final dosing on the day of necropsy (day 36) in kidneys, liver and including spinal cord. NVP-13 reaches CNS regions of interest following repeated intrathecal administrations with escalating doses. Phase B: Following single intrathecal doses of NVP-13, at dose levels of 0.8 and 4 mg/animal, the median plasma T\({}_{\text{max}}\) value was 0.5 h at both dose levels. Concentrations declined after T\({}_{\text{max}}\), but remained above the LLOQ (1.00 ng/mL) at the final sampling time point (24 h after dosing). Concentrations of NVP-13 in plasma and CSF generally increased with dose level. The observed increases in NVP-13 plasma exposure, as assessed using mean C\({}_{\text{max}}\) and AUC\({}_{\text{(0-t)}}\) values, were dose-proportional. On Day 14, the highest mean tissue concentrations of NVP-13 were observed in the kidneys. The tissue distribution pattern observed for Day 29 was similar to that on Day 14; however, relatively high levels of NVP-13 were also present in the lumbar spinal cord at both dose levels and in liver at 0.8 mg/animal. The highest mean tissue concentrationsmeasured for Day 29 represented approximately 30% and 25% of those measured for Day 14, at the 0.8 and 4 mg/animal dose levels, respectively. Phase C: Following repeated single intrathecal doses of NVP-13, at dose levels of 0.4 and 4 mg/animal/occasion for up to 13 weeks, median Tmax values in plasma were between 0.5 and 24 h after dosing. Plasma concentrations remained quantifiable at the last sampling time point (24 h after dosing) for all animals on each dosing occasion. Concentrations of NVP-13 in plasma and CSF increased with dose level. The observed increases in NVP-13 plasma exposure were dose-proportional. No accumulation of NVP-13 in plasma was observed. Exposure remained consistent throughout the dosing period at the 0.4 mg/animal/occasion dose level, and decreased with increasing number of 4 mg/animal/occasion doses. For both dose levels, the highest concentrations of NVP-13 in tissues were measured in the lumbar spinal cord and kidney cortex. Mean concentrations in other areas of the brain and in kidney medulla reached NVP-13 levels between approximately 10 and 33% of maximum mean tissue levels, whilst concentrations in the liver represented less than 10% of maximum mean levels. To assess NVP-13 concentrations within CNS regions, AEX-HPLC analysis was performed in all three phases of the present study. In all phases, NVP-13 was detectable within the main regions of interest, namely the spinal cord (lumbar, thoracic, and cervical), the hippocampus and the subventricular zone (Figure 3A, Figures 5A,B and 10). Figure 3: **Central NVP-13 tissue concentrations (Phase A). ** NVP-13 reaches central nervous system regions of interest following repeated intrathecal administrations with escalating doses. The NVP-13 tissue concentrations decreased with increasing distance from the injection side (lumbar spinal cord) (**A**).