Pimavanserin Top-Line Results Phase III Parkinson s Disease Psychosis Trial (-020 Study) Creating the Next Generation of CNS Drugs

Pimavanserin Top-Line Results Phase III Parkinson s Disease Psychosis Trial (-020 Study) Creating the Next Generation of CNS Drugs

Forward-Looking Statement This presentation contains forward-looking statements. These statements relate to future events and involve known and unknown risks, uncertainties and other factors which may cause our actual results, performance or achievements to be materially different from any future results, performances or achievements expressed or implied by the forward-looking statements. Each of these statements is based only on current information, assumptions and expectations that are inherently subject to change and involve a number of risks and uncertainties. Forward-looking statements include, but are not limited to statements about (i) the plans for, including timing and progress of, clinical trials involving our product candidates, including pimavanserin; (ii) the application for or receipt of regulatory clearances and approvals, including any potential approval of pimavanserin as a first in class drug for PDP or potential approval for other indications; (iii) the benefits to be derived from and efficacy of our product candidates, including the clinical benefits of pimavanserin in PDP or other indications, the potential advantages of pimavanserin versus existing antipsychotics, and the potential for pimavanserin to represent a new class of superior antipsychotics; and (iv) our estimates regarding our cash position, capital requirements and our need for additional financing. In some cases, you can identify forward-looking statements by terms such as may, will, should, could, would, expects, plans, anticipates, believes, estimates, projects, predicts, potential and similar expressions (including the negative thereof) intended to identify forward looking statements. Given the risks and uncertainties, you should not place undue reliance on forward-looking statements. For a discussion of the risks and other factors that may cause our actual results, performance or achievements to differ, please refer to our annual report on Form 10-K for the year ended December 31, 2011, as well as our subsequent filings with the SEC. The forward-looking statements contained herein are made as of the date hereof, and we undertake no obligation to update them for future events. 2

Ph III -020 Study: Highlights Pivotal study evaluating 40 mg pimavanserin vs placebo in PDP patients Pimavanserin met the primary endpoint for antipsychotic efficacy: Highly significant separation from placebo on the 9-item SAPS-PD scale (p=0.001) Supported by highly significant improvement on CGI-I (p=0.001) Pimavanserin met the key secondary endpoint of motoric tolerability as measured by the UPDRS II+III scale Pimavanserin also showed significant improvements on nighttime sleep, daytime wakefulness and caregiver burden Pimavanserin was safe and well tolerated 3

Ph III -020 Study: Design Patient Pathway From Screening to Open-Label Treatment Screening 6-Week Blinded Treatment Period Long-Term Open-Label (1) BPST Run-In 40 mg PIM or PBO (1:1) 40 mg PIM NPI Baseline SAPS-PD 2-Week Visit 4-Week Visit 6-Week Endpoint (1) Patients who completed the 6-week treatment period of the -020 Study could elect to roll over into a Phase III open-label safety extension trial, the -015 Study. 4

Pimavanserin Met Primary Endpoint for Antipsychotic Efficacy Ph III -020 Study 0 SAPS-PD (ITT, N=185; change from baseline) SAPS-PD Improvement (LSM ± SE) -2-4 -6-8 SAPS-PD Improvement Change from Baseline to Day 43 (LSM + SE) 0-1 -2-3 -4-5 -6-7 Placebo -2.73 40 mg PIM -5.79 1 15 29 43 Placebo Study Day * p = 0.037 40 mg PIM ** p = 0.001 5

Pimavanserin Met Key Secondary Endpoint for Motoric Tolerability Ph III -020 Study Pimavanserin maintained motor function in PDP patients Both arms showed improvements in combined UPDRS II+III score (-1.69 for PBO, -1.40 for PIM) The treatment difference met the pre-specified criteria for noninferiority Pimavanserin conferred antipsychotic efficacy while maintaining motor control 6

Pimavanserin Improved Nighttime Sleep and Daytime Wakefulness Ph III -020 Study 0.5 Nighttime Sleep (ITT, N=185; change from baseline) 0.5 Daytime Wakefulness (ITT, N=185; change from baseline) SCOPA Improvement (LSM±SE) 0-0.5-1 -1.5-2 ** p = 0.001 * p = 0.045 SCOPA Improvement (LSM±SE) 0-0.5-1 -1.5-2 -2.5-3 1 15 29 43 Study Day Placebo 40 mg PIM -2.5-3 1 15 29 43 Study Day Placebo 40 mg PIM * p = 0.012 7

Pimavanserin Reduced Caregiver Burden Ph III -020 Study Caregiver Burden Improvement (LSM±SE) 2 1 0-1 -2-3 -4-5 -6 Caregiver Burden (ITT, N=185; change from baseline) ** p = 0.002 1 15 Study Day 29 43 Placebo 40 mg PIM 8

Preliminary Safety Findings Ph III -020 Study Consistent with our prior experience, pimavanserin was safe and well tolerated Treatment emergent AEs 5% Most common AEs were UTI (11.7% PBO, 13.5% PIM) and Fall (8.5% PBO, 10.6% PIM) Only 5 other AEs occurred with an incidence 5% in either arm (peripheral edema, hallucination, confusional state, nausea and headache) Most AEs were mild to moderate SAEs Only two SAEs occurred in more than 1 patient: UTI (1 PBO and 3 PIM) and psychotic disorder (0 PBO and 2 PIM) 3 deaths (1 PBO, 2 PIM), all were considered unrelated to study drug Pimavanserin s safety profile potentially offers important advantages compared to existing antipsychotics 9

The Treating Physician s Perspective Stuart Isaacson, M.D. Associate Professor of Neurology, FIU College of Medicine, Miami FL Director, Parkinson s Disease and Movement Disorders Center of Boca Raton 10

Pimavanserin Phase III PDP Program Next Steps Advance pimavanserin toward registration for PDP Continue preparations for confirmatory Phase III pivotal trial, - 021 Study Continue ongoing open-label safety extension trial (-015 Study) Present -020 data at future clinical meeting 11

Pimavanserin Phase III PDP Program Results of -020 Study confirm attractive clinical and safety profile of pimavanserin in PDP Pimavanserin s selective and non-dopaminergic profile enabled effective treatment of psychosis without compromising motor control and safety Differentiated from off-label use of existing antipsychotics Pimavanserin has potential to become first drug approved for patients with PDP Pimavanserin may represent a new class of superior antipsychotic drugs 12

Creating the Next Generation of CNS Drugs