Trial Outcomes & Findings for Pimavanserin for the Treatment of Irritability Associated With Autism Spectrum Disorder (NCT NCT05523895)

Last Updated: 2025-08-24

Results Overview

The Aberrant Behavior Checklist (ABC) is a caregiver-rated scale comprised of 5 empirically-derived subscales encompassing 58 items that describe various behavior problems. It measures domains of irritability, lethargy/social withdrawal, stereotypic behavior, hyperactivity/noncompliance, and inappropriate speech. ABC-I is one of the subscales and comprises of 15 items. Minimum score is 0, maximum is 45. A score for each item ranges from 0 indicating "not at all a problem" to 3 indicating "the problem is severe in degree". Subscale scores are calculated by summing the items within that subscale. Higher scores indicate greater impairment.

Recruitment status

COMPLETED

Study phase

PHASE2/PHASE3

Target enrollment

237 participants

Primary outcome timeframe

6 weeks

Results posted on

2025-08-24

Participant Flow

Participant milestones

Participant milestones
Measure	Placebo Pimavanserin-matching placebo, given as 1 capsule once daily	Pimavanserin Low Dose Pimavanserin given as 1 capsule once daily. Patients aged 5-12 years: 10 mg/day; patients aged 13-17 years: 20 mg/day	Pimavanserin High Dose Pimavanserin given as 1 capsule once daily. Patients aged 5-12 years: 20 mg/day; patients aged 13-17 years: 34mg/day
Overall Study STARTED	78	78	81
Overall Study COMPLETED	74	67	75
Overall Study NOT COMPLETED	4	11	6

Reasons for withdrawal

Reasons for withdrawal
Measure	Placebo Pimavanserin-matching placebo, given as 1 capsule once daily	Pimavanserin Low Dose Pimavanserin given as 1 capsule once daily. Patients aged 5-12 years: 10 mg/day; patients aged 13-17 years: 20 mg/day	Pimavanserin High Dose Pimavanserin given as 1 capsule once daily. Patients aged 5-12 years: 20 mg/day; patients aged 13-17 years: 34mg/day
Overall Study Adverse Event	2	1	1
Overall Study Lost to Follow-up	0	1	2
Overall Study Noncompliance with study drug	1	1	1
Overall Study Protocol Violation	0	2	0
Overall Study Withdrawal by Subject	1	3	1
Overall Study Not further specified	0	3	1

Baseline Characteristics

Pimavanserin for the Treatment of Irritability Associated With Autism Spectrum Disorder

Baseline characteristics by cohort

Baseline characteristics by cohort
Measure	Placebo n=78 Participants Pimavanserin-matching placebo, given as 1 capsule once daily	Pimavanserin Low Dose n=78 Participants Pimavanserin given as 1 capsule once daily. Patients aged 5-12 years: 10 mg/day; patients aged 13-17 years: 20 mg/day	Pimavanserin High Dose n=81 Participants Pimavanserin given as 1 capsule once daily. Patients aged 5-12 years: 20 mg/day; patients aged 13-17 years: 34mg/day	Total n=237 Participants Total of all reporting groups
Age, Continuous	9.8 years STANDARD_DEVIATION 2.88 • n=5 Participants	9.8 years STANDARD_DEVIATION 3.54 • n=7 Participants	9.8 years STANDARD_DEVIATION 3.11 • n=5 Participants	9.8 years STANDARD_DEVIATION 3.18 • n=4 Participants
Age, Customized 5-12 years	63 Participants n=5 Participants	61 Participants n=7 Participants	64 Participants n=5 Participants	188 Participants n=4 Participants
Age, Customized 13-17 years	15 Participants n=5 Participants	17 Participants n=7 Participants	17 Participants n=5 Participants	49 Participants n=4 Participants
Sex: Female, Male Female	21 Participants n=5 Participants	19 Participants n=7 Participants	13 Participants n=5 Participants	53 Participants n=4 Participants
Sex: Female, Male Male	57 Participants n=5 Participants	59 Participants n=7 Participants	68 Participants n=5 Participants	184 Participants n=4 Participants
Race (NIH/OMB) American Indian or Alaska Native	1 Participants n=5 Participants	1 Participants n=7 Participants	0 Participants n=5 Participants	2 Participants n=4 Participants
Race (NIH/OMB) Asian	1 Participants n=5 Participants	5 Participants n=7 Participants	6 Participants n=5 Participants	12 Participants n=4 Participants
Race (NIH/OMB) Native Hawaiian or Other Pacific Islander	1 Participants n=5 Participants	0 Participants n=7 Participants	0 Participants n=5 Participants	1 Participants n=4 Participants
Race (NIH/OMB) Black or African American	8 Participants n=5 Participants	12 Participants n=7 Participants	11 Participants n=5 Participants	31 Participants n=4 Participants
Race (NIH/OMB) White	61 Participants n=5 Participants	56 Participants n=7 Participants	58 Participants n=5 Participants	175 Participants n=4 Participants
Race (NIH/OMB) More than one race	0 Participants n=5 Participants	0 Participants n=7 Participants	0 Participants n=5 Participants	0 Participants n=4 Participants
Race (NIH/OMB) Unknown or Not Reported	6 Participants n=5 Participants	4 Participants n=7 Participants	6 Participants n=5 Participants	16 Participants n=4 Participants
Region of Enrollment Hungary	6 participants n=5 Participants	7 participants n=7 Participants	5 participants n=5 Participants	18 participants n=4 Participants
Region of Enrollment United States	39 participants n=5 Participants	38 participants n=7 Participants	40 participants n=5 Participants	117 participants n=4 Participants
Region of Enrollment Poland	18 participants n=5 Participants	19 participants n=7 Participants	21 participants n=5 Participants	58 participants n=4 Participants
Region of Enrollment Italy	2 participants n=5 Participants	3 participants n=7 Participants	5 participants n=5 Participants	10 participants n=4 Participants
Region of Enrollment France	6 participants n=5 Participants	1 participants n=7 Participants	4 participants n=5 Participants	11 participants n=4 Participants
Region of Enrollment Australia	4 participants n=5 Participants	1 participants n=7 Participants	2 participants n=5 Participants	7 participants n=4 Participants
Region of Enrollment Serbia	3 participants n=5 Participants	5 participants n=7 Participants	3 participants n=5 Participants	11 participants n=4 Participants
Region of Enrollment Spain	0 participants n=5 Participants	4 participants n=7 Participants	1 participants n=5 Participants	5 participants n=4 Participants

PRIMARY outcome

Timeframe: 6 weeks

Population: Full Analysis Set: all randomized patients who received at least one dose of study drug and have a baseline value and at least one post-baseline value for the ABC-I subscale score.

Outcome measures

Outcome measures
Measure	Placebo n=72 Participants Pimavanserin-matching placebo, given as 1 capsule once daily	Pimavanserin Low Dose n=64 Participants Pimavanserin given as 1 capsule once daily. Patients aged 5-12 years: 10 mg/day; patients aged 13-17 years: 20 mg/day	Pimavanserin High Dose n=74 Participants Pimavanserin given as 1 capsule once daily. Patients aged 5-12 years: 20 mg/day; patients aged 13-17 years: 34mg/day
Change From Baseline at Week 6 in Caregiver-rated Aberrant Behavior Checklist Irritability (ABC-I) Subscale Score	-9.6 score on a scale Standard Error 1.06	-11.2 score on a scale Standard Error 1.09	-11.2 score on a scale Standard Error 1.05

Adverse Events

Placebo

Serious events: 1 serious events

Other events: 11 other events

Deaths: 0 deaths

Pimavanserin Low Dose

Serious events: 0 serious events

Other events: 17 other events

Deaths: 0 deaths

Pimavanserin High Dose

Serious events: 0 serious events

Other events: 16 other events

Deaths: 0 deaths

Serious adverse events

Serious adverse events
Measure	Placebo n=78 participants at risk Pimavanserin-matching placebo, given as 1 capsule once daily	Pimavanserin Low Dose n=77 participants at risk Pimavanserin given as 1 capsule once daily. Patients aged 5-12 years: 10 mg/day; patients aged 13-17 years: 20 mg/day	Pimavanserin High Dose n=81 participants at risk Pimavanserin given as 1 capsule once daily. Patients aged 5-12 years: 20 mg/day; patients aged 13-17 years: 34mg/day
Immune system disorders Hypersensitivity	1.3% 1/78 • Number of events 1 • From screening to end of safety follow-up, which was to be performed at 10 weeks, i.e. 4 weeks after last dose of study drug	0.00% 0/77 • From screening to end of safety follow-up, which was to be performed at 10 weeks, i.e. 4 weeks after last dose of study drug	0.00% 0/81 • From screening to end of safety follow-up, which was to be performed at 10 weeks, i.e. 4 weeks after last dose of study drug

Other adverse events

Other adverse events
Measure	Placebo n=78 participants at risk Pimavanserin-matching placebo, given as 1 capsule once daily	Pimavanserin Low Dose n=77 participants at risk Pimavanserin given as 1 capsule once daily. Patients aged 5-12 years: 10 mg/day; patients aged 13-17 years: 20 mg/day	Pimavanserin High Dose n=81 participants at risk Pimavanserin given as 1 capsule once daily. Patients aged 5-12 years: 20 mg/day; patients aged 13-17 years: 34mg/day
Gastrointestinal disorders Nausea	1.3% 1/78 • Number of events 1 • From screening to end of safety follow-up, which was to be performed at 10 weeks, i.e. 4 weeks after last dose of study drug	5.2% 4/77 • Number of events 6 • From screening to end of safety follow-up, which was to be performed at 10 weeks, i.e. 4 weeks after last dose of study drug	1.2% 1/81 • Number of events 1 • From screening to end of safety follow-up, which was to be performed at 10 weeks, i.e. 4 weeks after last dose of study drug
Infections and infestations Upper respiratory tract infection	5.1% 4/78 • Number of events 4 • From screening to end of safety follow-up, which was to be performed at 10 weeks, i.e. 4 weeks after last dose of study drug	9.1% 7/77 • Number of events 7 • From screening to end of safety follow-up, which was to be performed at 10 weeks, i.e. 4 weeks after last dose of study drug	6.2% 5/81 • Number of events 6 • From screening to end of safety follow-up, which was to be performed at 10 weeks, i.e. 4 weeks after last dose of study drug
Metabolism and nutrition disorders Decreased appetite	0.00% 0/78 • From screening to end of safety follow-up, which was to be performed at 10 weeks, i.e. 4 weeks after last dose of study drug	5.2% 4/77 • Number of events 4 • From screening to end of safety follow-up, which was to be performed at 10 weeks, i.e. 4 weeks after last dose of study drug	2.5% 2/81 • Number of events 2 • From screening to end of safety follow-up, which was to be performed at 10 weeks, i.e. 4 weeks after last dose of study drug
Nervous system disorders Headache	5.1% 4/78 • Number of events 4 • From screening to end of safety follow-up, which was to be performed at 10 weeks, i.e. 4 weeks after last dose of study drug	6.5% 5/77 • Number of events 5 • From screening to end of safety follow-up, which was to be performed at 10 weeks, i.e. 4 weeks after last dose of study drug	6.2% 5/81 • Number of events 6 • From screening to end of safety follow-up, which was to be performed at 10 weeks, i.e. 4 weeks after last dose of study drug
Nervous system disorders Somnolence	5.1% 4/78 • Number of events 4 • From screening to end of safety follow-up, which was to be performed at 10 weeks, i.e. 4 weeks after last dose of study drug	2.6% 2/77 • Number of events 3 • From screening to end of safety follow-up, which was to be performed at 10 weeks, i.e. 4 weeks after last dose of study drug	4.9% 4/81 • Number of events 4 • From screening to end of safety follow-up, which was to be performed at 10 weeks, i.e. 4 weeks after last dose of study drug

Additional Information

Sr. Dir. Medical Information and Medical Communications

Acadia Pharmaceuticals Inc.

Phone: 858-261-2289

Email: [email protected]

Results disclosure agreements

Principal investigator is a sponsor employee Investigator may publish the study results, relative to their own patients, only after review, comment and approval by the sponsor. No publication of confidential information shall be made without the sponsor's prior written consent. At least 60 days prior to submitting a manuscript or prior to any public presentation, a copy of the manuscript or presentation will be provided to the Sponsor for review and comment. The sponsor has 60 days to review and comment.
Publication restrictions are in place

Restriction type: OTHER