The study will investigate the efficacy, safety and tolerability of continuous SC infusion (16 weeks) of ND0612 compared with placebo infusion. The treatment period will be comprised of a 4-week adjustment period during which time the ND0612 infusion dose will remain constant and the oral LD/DDI dose can be decreased or increased back up to the Baseline levels. All other anti-PD treatments must remain constant. During the maintenance period (Weeks 5 to 16) all anti-PD medication including the ND0612/placebo should remain constant.