Objective: A planned subgroup analysis of a phase 3 study was performed to evaluate the efficacy and safety of pimavanserin (PIM) in Parkinson’s disease psychosis (PDP) patients with global cognitive impairment.

Background: PDP is frequent, distressing, a leading cause of institutionalization, complicates PD management and is linked to increased morbidity, incident dementia and mortality. PIM, a selective serotonin receptor (5-HT_2A) inverse agonist/antagonist, is newly FDA-approved for the treatment of hallucinations and delusions associated with PDP.

Methods: In Study 020, a 6-week FDA registration study, 199 patients with baseline Mini-Mental State Examination (MMSE) score ≥21, moderate-severe psychosis, and on stable PD meds, were randomized to PIM (34 mg/day) or placebo (PBO) for 6 weeks. This subgroup analysis evaluates efficacy and safety between two groups: those with MMSE total score ≥21 but <25 (cognitively impaired; equivalent to Montreal Cognitive Assessment [MoCA] score 15-19) and those with score ≥25 (cognitively normal; equivalent to MoCA score 20-30). Safety assessments were performed on the full safety dataset (i.e., three 6-week placebo-controlled studies) including 614 subjects (PIM=382, PBO=231).

Results: Overall, patients in the PIM group experienced a statistically significant improvement in SAPS-PD scores from baseline to Day 43 compared with PBO (‑5.79 vs. ‑2.73; p=0.001). In the subgroup analysis stratifying by baseline MMSE score, the change from baseline to Day 43 compared with PBO in the cognitively-impaired group (N=50) was numerically larger (‑7.11 vs. ‑0.47; p=0.002). In the full safety dataset examining cognitively‑impaired patients, there were no between-group (PIM vs. PBO) differences in any treatment-emergent adverse event (TEAE) (57.6% vs. 56.1%) or serious TEAE (6.8% vs. 5.3%). The most common TEAEs occurring at ≥5% in either group were fall (7.4% vs. 10.5%), confusional state (6.5% vs. 1.8%), and orthostatic hypotension (0.0% vs. 8.8%).

Conclusions: In this subgroup analysis of PDP patients, the treatment effect of PIM on SAPS-PD was larger in the cognitively-impaired group, with similar TEAE and serious TEAE rates. These results hold promise for cognitively-impaired patients that will be further elucidated in future studies.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/use-of-pimavanserin-in-patients-with-parkinsons-disease-psychosis-subgroup-analysis-of-efficacy-and-safety-in-patients-with-and-without-cognitive-impairment/