GlaxoSmithKline (GSK) and Impax Pharmaceuticals, the branded products division of Impax Laboratories, Inc. announced top-line results of the ASCEND-PD phase III clinical study of IPX066 versus carbidopa-levodopa plus entacapone (CLE), in patients with advanced Parkinson’s disease (PD). IPX066 is an extended release capsule formulation of carbidopa-levodopa (CD-LD) under investigation for the treatment of the motor symptoms of PD.

The primary endpoint of this double blind crossover study was the percentage of “off time” during waking hours as measured by patient diary. “Off time” is the functional state when patients’ medication effect has worn off and there is a return of the motor symptoms of PD. Patients entered the study with a baseline “off time” of 36.1% (5.9 hours), and at the end of the randomized IPX066 treatment phase patients had “off time” of 24.0% (3.8 hours) during waking hours compared to 32.5% (5.2 hours) for CLE (p<0.0001). This represents a 33.5% decrease in percent “off time” for IPX066 from baseline vs. a 10% decrease for CLE.

“Impax Pharmaceuticals and GSK are excited to report these positive results for the ASCEND-PD trial which demonstrate an 84 minute improvement in “off time” over CLE therapy with a corresponding increase in “on time” without troublesome dyskinesia,” stated Dr Suneel Gupta, chief scientific officer, Impax Pharmaceuticals. “Consistent with our earlier ADVANCE-PD phase III study findings, this study also demonstrates that IPX066 provides efficacy across a range of clinically meaningful measures in advanced PD.  We are also pleased that the secondary endpoints supported the conclusion from the primary endpoint.”

During the double blind crossover period of this trial the Adverse Event (AE) rate for IPX066 was 20% compared to 14% for CLE. After randomisation two serious treatment-emergent adverse events were reported with both occurring on IPX066 therapy (sciatica and dehydration) and none on CLE. The most common AEs reported for IPX066 included: insomnia, confusional state, and dyskinesia (each event was reported by 3 subjects). The most common AE reported for CLE was: fall (reported by 2 patients on CLE).

Impax plans to submit these data as part of its New Drug Application (NDA) for IPX066 to the FDA, which is planned for the fourth quarter of 2011.  GSK plans to file the Marketing Authorisation Application for IPX066 in the European Union in 2012.

The ASCEND-PD study is a randomised, double-blind 2-treatment, 2-week crossover study of IPX066 and CLE (a combination treatment of carbidopa-levodopa and entacapone, an enzyme inhibitor of levodopa breakdown), and one of three phase III studies of IPX066. Study subjects taking a stable dose of CLE were converted to IPX066 over a six-week period, then randomised to one of the two treatments (IPX066 or CLE) for two weeks and then crossed over to the other treatment for an additional two weeks after a one-week washout with IPX066. The study enrolled 110 subjects, with 91 subjects entering the randomised comparative phase of the study. A total of 84 subjects completed the randomised double-blind comparative phase of the study. Following the comparative phase, subjects were enrolled into a six-month open-label extension study.

IPX066 is an investigational extended release capsule formulation of CD-LD which is intended to maintain consistent plasma concentration of levodopa for a longer duration versus immediate release levodopa, which may have an impact on fluctuations in clinical response. It is not approved or licensed anywhere in the world.

Results from the pivotal phase III studies of IPX066, ADVANCE-PD (in advanced PD) and APEX-PD (in early PD) have previously been announced and presented at the American Academy of Neurology and International Congress of Parkinson’s Disease and Movement Disorders Conference in April and June 2011, respectively. Open-label extension studies for subjects who have completed the ADVANCE-PD and APEX-PD are ongoing.

GSK and Impax Pharmaceuticals announced an agreement for the development and commercialisation of IPX066 in December 2010. Under the terms of the agreement, GSK received an exclusive license to register and commercialise IPX066 throughout the world except in the US and Taiwan.

Parkinson’s disease is a chronic neurodegenerative movement disorder affecting over three million people in the US, Europe, and Japan.

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