Roger Mills
Analyst · JMP Securities
Thank you, and good afternoon. As Uli mentioned, our primary focus is on our lead pimavanserin program, most notably the ongoing pivotal Phase III trial referred to as the -020 Study. This study builds on the wealth of clinical experience we generate in our primavanserin PDP program. -020 is a randomized, multi-center, double-blind, placebo-controlled study designed to evaluate the efficacy, tolerability and safety of pimavanserin in patients with PDP. Importantly, it incorporates several design enhancements that were guided by previous data in our PDP program.
In December, we presented information regarding our optimization of the -020 Study design at the World Congress of Parkinson's Disease and Related Disorders. Let me take a minute to highlight key elements of the -020 protocol, and the study enhancements that are designed to mitigate placebo response and reduce variability.
The study is being conducted exclusively in North America and is expected to enroll about 200 patients over approximately 50 clinical sites. This geographic focus allows us to use a small centralized group of highly trained, independent raters to conduct blinded assessments of the primary endpoint at all study sites. Our previous experience has shown that this centralized rating approach helped to mitigate placebo response, enhance consistency and reduce data variability.
Patients initially participate in a screening phase, which includes a brief psychosocial therapy program. This program involves scripted interactions between each patient and their caregiver directed by a qualified member of the site. It is designed to help patients adapt to participating in a clinical trial setting, help manage symptoms during the screening phase and pull initial placebo responses ahead of the baseline assessment. This may also 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 at the screening and the Scale for the Assessment of Positive Symptoms or SAPS at the time of the baseline assessment. Criteria for study entry were tightened based on our observation of a larger placebo response in patients with more mild psychotic symptoms in previous studies. Patients must have both adequate severity and frequency of symptoms to be included. Importantly, the baseline SAPS score is assessed independently from the NPI, which provides an important check and balance. We believe that strength and 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 out patients with more mild psychotic symptoms, who are more likely to respond to placebo.
We continue to be pleased to observe that patients enrolling in the -020 Study to date have, on average, exhibited a greater severity of psychosis, a study entry relative to patients in our earlier trials. We also have seen an increase in subjects that did 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. Patients 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 delusion domains of SAPS, which best reflect the expression of psychosis in patients with Parkinson's disease.
The use of the 9-item SAPS is supported by our observation, that when we apply this scale to 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. In particular, as part of our poster presentation at the World Congress meeting in December, we highlighted results of our retrospective analysis of the U.S. data from our earlier -012 PDP trial using the 9-item SAPS, which demonstrated enhanced statistical separation of the 40-milligram pimavanserin arm from placebo. Importantly, 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 a measure to using the 9-item saps. Motoric tolerability is a key secondary endpoint in the trial and is measured using Parts II and III 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 design enhancements appear to be operating as planned. Additionally, we continue to make solid progress with study enrollment while maintaining our focus on ensuring that we enroll what we believe are patients with the right clinical profile to position the study for success. We also continue to be encouraged by the enthusiasm displayed by many of the investigators and sites. 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 Phase III PDP program, that is our Phase III open-label safety extension study, referred to as the -015 Study. This large study involves patients, who completed previous Phase III PDP trials as well as patients who complete the -020 Study, 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 rolled 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've now accumulated about 650 patient years of exposure in this patient population. Importantly, we far exceeded ICH guidelines required for 1 year exposures with over 200 patients having treated for 1 year or longer. We also now 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 remained on treatment with pimavanserin for long periods of time and its growing base of clinical experience continues to increase our confidence in the program. Additionally, our experience to date suggests that a long-term administration of pimavanserin appears to be generally safe and well tolerated in this fragile elderly patient population. We believe that 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. Let me now turn the call back over to Uli.