Roger Mills
Analyst · JMP Securities
Thank you, Tom. My remarks today will focus mainly on our lead Phase III PDP program with pimavanserin.
Our primary focus in this program is on the ongoing pivotal Phase III trial, referred to as the -020 Study. This study incorporates several design enhancements that were guided by previous data in our PDP program. -020 is a randomized multicenter, double-blind placebo-controlled study designed to evaluate the efficacy, tolerability and safety of pimavanserin in patients with PDP.
Let me take a moment to highlight key elements of the -020 protocol and the study enhancements that are designed to mitigate placebo response and reduce data variability. This study is being conducted exclusively in North America and is expected to enroll about 200 patients over approximately 50 clinical sites. Importantly, the geographic focus enables us to use a small centralized group of highly-trained independent raters to conduct blinded assessments at the primary endpoint at all study sites. Our previous experience indicated that this centralized rating approach help to mitigate placebo response, enhance precision and reduce data variability.
Patients initially participate in the screening phase, which includes a brief psychosocial therapy program. This is designed to help patients adapt to participating in a clinical trial setting, help manage symptoms during the screening phase and poll initial placebo responses ahead of the baseline assessment. This also may allow more severe patients to be enrolled by offering non-pharmacologic support. To participate in the study, patients are required to have moderate to severe psychosis as measured by the Neuropsychiatric Inventory Scale or NPI screening and the Scale for the Assessment of Positive Symptoms or SAPS at the time of the baseline assessment. Criteria for study entry was heightened based on our observation of a larger placebo response in patients with mild psychotic symptoms in previous studies. Patients must have both adequate severity and frequency of symptoms to be included. The baseline SAPS score is assessed independently from the NPI, which provides an important check and balance. We believe the strengthened criteria for enrollment, together with the brief psychosocial therapy, have been effective in enabling sites to enroll patients with the desired clinical profile and to filter outpatients with milder psychotic symptoms who are more likely to respond to placebo.
We've continued to observe the patients enrolling in the -020 Study, to date, have, on average, exhibited a greater severity of psychosis at study entry relative to patients in our earlier trials. This is exactly what we'd hope to achieve with the design enhancement and we believe provides patients with the right profile to help position the study for success.
We've also seen an increase in subjects that do not qualify for randomization at the conclusion of screening due to inadequate severity of symptoms.
Upon qualifying, patients are randomized on a one-to-one basis to receive either 40 milligrams of pimavanserin or placebo once daily for 6 weeks. They also continue to receive stable doses of their existing dopamine replacement therapy used to manage the motor symptoms of Parkinson's disease. The primary endpoint of the study is antipsychotic efficacy as measured using 9 items from the hallucinations and delusions domains of SAPS, which best reflect the expression of the psychosis in patients with Parkinson's disease.
The 9-item SAPS is supported by our observation that when we applied this scale for the data in our previous PDP studies, we saw a clear reduction in variability, enhanced sensitivity and an improved effect size relative to the use of the larger 20-item SAPS. Importantly, as expected, we have observed that the blinded baseline data from patients enrolled in the -020 Study, to date, supports our early analysis, which indicated that the 9-item SAPS best captures the expression of PDP symptoms.
You may recall that the FDA was supportive of the -020 Study design and accepted the 9-item SAPS as a primary endpoint in the study. This pivotal study is powered at a standard 90% to provide statistically significant antipsychotic efficacy as measured using the 9-item SAPS. Motoric tolerability is a key secondary endpoint in the trial and is measured using parts 2 and 3 of the Unified Parkinson's Disease Rating Scale or UPDRS.
Overall, we remain convinced that the optimized -020 Study design should significantly improve the likelihood of achieving a successful outcome, and we are pleased to see that the design enhancements appear to be operating as planned.
We continue to make solid progress with the study enrollment while maintaining our focus on ensuring that we enroll patients with the desired clinical profile. Based on our progress and past experience, we anticipate reporting top line results from the -020 Study near the end of the third quarter this year.
Let me now turn to another important ongoing study in our PDP program: our Phase III open-label safety extension study referred to as the -015 Study. This large study involves patients who complete the -020 study as well as patients from previous Phase III PDP trials and who, in the opinion of the treating physician, may benefit from continued treatment with pimavanserin.
Once again, I'm pleased to report that the overwhelming majority of patients who complete the treatment phase in the -020 Study have elected to roll over into the -015 Study. This study is allowing us to generate a large amount of valuable long-term safety data regarding the use of pimavanserin in patients with PDP.
Overall in our Phase III and Phase II extension studies, we have now accumulated over 670 patient years of exposure in this patient population. Importantly, we far exceeded ICH guidelines required for 1-year exposures with over 200 patients having been treated for one year or longer.
We also have well over 100 patients that have been treated with pimavanserin for at least 2 years and our longest single patient exposure is 7 years.
We're encouraged to see that many patients have remained on treatment with pimavanserin for long periods of time, and we've continued to receive encouraging feedback from investigators regarding patients' experiences with pimavanserin. Our experience to date suggests that a long-term administration of pimavanserin appears to be generally safe and well-tolerated in this often fragile and elderly population. We believe that the favorable safety profile observed to date provides support for the potential of pimavanserin to offer significant advantages relative to current antipsychotics used off-label for the treatment of PDP.
PDP is a serious disorder that develops in up to 60% of patients with Parkinson's disease and deeply affects their quality of life, contributes substantially to the burden of Parkinson's disease and is the major cause of nursing home placements among Parkinson's patients. The FDA has not approved any drug to treat PDP. The neurologists currently face very difficult challenges in managing patients with this debilitating disease. We believe pimavanserin, with its innovative and well-tolerated non-dopaminergic profile, have the opportunity to be a first-in-class therapy that will effectively treat psychosis in Parkinson's patients without compromising motor control.
Let me now touch briefly on our other product candidates. As Tom mentioned earlier, during the first quarter, we extended our ongoing discovery collaboration with Allergan, which is focused on glaucoma and related ophthalmic conditions. You may recall that our long-standing alliance with Allergan has already resulted in 2 clinical stage product candidates that provide the potential for new treatments in the areas of chronic pain and glaucoma.
Our fourth clinical program, AM-831, advanced into Phase I development late last year in collaboration with Meiji Seika Pharma. AM-831 addresses schizophrenia, and is designed to provide a unique combination of antipsychotic and pro-cognitive activities through antagonism of D2, of 5-HT2A receptors, coupled with stimulation of muscarinic M1 receptors.
Behind these 4 clinical programs, we have continued to advance 2 preclinical programs that may pave the way for new breakthroughs in the treatment of Parkinson's and other neurological disorders.
First, we're excited to expand on promising initial research findings in our Nurr1 program through the new grant mentioned earlier from the Michael J. Fox Foundation. Secondly, our ER-beta compounds have exhibited neuroprotective and anti-inflammatory properties in preclinical models and may have the ability to slow down the progression of Parkinson's disease. These compounds may also address symptoms of chronic, inflammatory and neuropathic pain. Ongoing studies in this area are being funded by a grant from the National Institute of Neurological Disorders and Stroke.
Let me now turn the call back over to Tom.