Extension Study of Pimavanserin in Irritability Associated With Autism Spectrum Disorder

INCLUSION CRITERIA:

• Has completed the treatment period of study ACP-103-069

• Informed consent prior to the conduct of any study procedures

• Continues to be both clinically stable and not at imminent risk of suicide or injuryto self, others, or property

• Continues to be medically stable at enrollment

• For female patients only: unable to become pregnant or agree to use a highlyeffective non-hormonal method of contraception. Females of childbearing potentialmust have a negative pregnancy test

EXCLUSION CRITERIA:

• Patient or parent/legally accepted representative is judged by the Investigator tobe inappropriate for the study

• Requires treatment with a medication prohibited by the protocol, includingconcomitant psychotropic drugs targeting irritability, including those usedoff-label (clonidine, guanfacine, and propranolol; lithium, valproate), medicationsthat prolong the QT interval; and strong cytochrome P450 (CYP) 3A4 enzyme (CYP3A4)inhibitors and inducers

• At a significant risk of suicide, or is a danger to self or others

• At risk of significant violent behavior to the extent that participation would posean undue risk to other patients, caregivers, or others

• Positive urine drug test

• Serious and/or unstable psychiatric, neurologic, cardiovascular, respiratory,gastrointestinal, renal, hepatic, hematologic, or other medical disorder, includingcancer or malignancies

• Any change in medical or treatment status that may increase the risk associated withtaking pimavanserin, would interfere with safety assessments, or would confound theinterpretation of study results

• Clinically significant abnormal ECG of protocol-defined cardiac conductionabnormalities

• Weight <15 kg

• Additional inclusion/exclusion criteria apply. Subjects will be evaluated atscreening to ensure that all criteria for study participation are met.