Positive Results Achieved from the WD-1603 Phase II Clinical Trial for Treatment of Parkinson’s Disease

As disease progresses, dopamine neurons are lost to the extent, then neuronal storage and sustained secretion of dopamine diminishes, thereby the therapeutic window becoming narrower, which make controlling of symptom a great challenge. Currently no cure exists for Parkinson’s disease, the main strategy for treatment of PD is to effectively control symptoms, while delaying the development of motor complications.

It’s a great challenge to achieve a steady LD plasma concentration, since LD’s absorption through LNAA (Large neutral amino acids) transporter is limited in the upper gastrointestinal tract.

WDP has developed a proprietary delivery platform, called the high-load/high-flux osmotic delivery system (Gi-Pump®), that can provide LD therapeutic coverage up to 16 hours of waking-up time for treatment of Parkinson’s disease.   

WD Pharma announced the successful completion of a Phase 2, randomized, parallel, double-blind, placebo-controlled, multi-center study of the efficacy and safety of WD-1603 in patients with Parkinson’s disease.

WD-1603 is a controlled-release delivery platform designed to generate prolonged and less fluctuated LD plasma concentrations. Patients with early PD were randomized into 4 treatment groups, 25/100 mg (low dose group, n=10), 25/150 mg (middle dose group, n=10), 2 x 25/100 mg (high dose group, n=10) or placebo treatment (n=10). Efficacy was assessed by blinded raters using MDS-UPDRS-II + III on Day -1 (baseline), 14, and 27 of each treatment group. The steady-state pharmacokinetics was evaluated on Day 28 for the WD-1603-treated groups.

As shown in Figure 5, the total scores of MDS-UPDRS-II + III were reduced by 7.2, 10.0, and 14.4 points on the 27th day after WD-1603 treatments at the low, middle, and high doses, respectively, compared with the baseline.

Figure 5. Changes from baseline in MDS-UPDRS Part Ⅱ+Ⅲ scores at various treatment periods. Data were LS mean change and SE (n=10). The p-values were calculated using an MMRM, mixed-effect model for repeated measures. *p<0.05, **p<0.01.

The steady-state LD plasma concentration-time curves of the three WD-1603 treatment groups (25/100 mg, 25/150 mg and 2 x 25/100 mg) were relatively flat, with their Fluctuation Indexes (FI) being 1.27, 1.08 and 1.10, respectively (Figure 6).

Figure 6. Pharmacokinetic profiles of LD plasma concentrations after dosing of WD-1603 (assessed on Day 28). Blood samples were collected between 0.25 h before and 9h after the second dosing. The third dosing was omitted on Day 28 in all groups. 

These FI values are lower than those LD oral formulations currently on the market. The results of this clinical trial showed the excellent efficacy and the safety of WD-1603 tablets. With their lower FIs, WD-1603 tablets are expected to slow down disease progression and to prolong “Honeymoon” period for PD patient at early stage.