ITI-1284 for Generalized Anxiety Disorder

Inclusion Criteria: * Provide written informed consent before the initiation of any study specific procedures; * At Screening, meet Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition, Text Revision (DSM-5-TR) diagnostic criteria for moderate or severe GAD (current GAD) as confirmed by the Investigator or Sponsor-approved rater using the Structured Clinical Interview for DSM-5 Clinical Trials Version (SCID-5-CT), and meets all of the following at Screening and Baseline: * HAM-A Total score of ≥ 22; * HAM-A Items 1 (anxious mood) and 2 (tension) scores ≥ 2; * CGI-S score of ≥ 4; * History of inadequate response (\< 50% improvement in anxiety symptoms as measured by the modified Antidepressant Treatment Response Questionnaire \[ATRQ\] for GAD) to at least 2 of the following GAD-approved treatments: paroxetine, venlafaxine XR, duloxetine, escitalopram, or buspirone taken at an adequate dose (that is, at least a minimum total daily dose of paroxetine 20 milligram \[mg\], venlafaxine XR 75mg, duloxetine 60 mg, escitalopram 10mg, or buspirone 20 mg) and duration (ie, for at least 6 weeks prior to Screening) for the treatment of ongoing GAD symptoms. Exclusion Criteria: * Within the patient's lifetime, has one of the following confirmed DSM-5-TR psychiatric diagnoses: * Schizophrenia, Schizoaffective Disorder, Schizophreniform Disorder or other psychotic disorder; * Bipolar Disorder; * MADRS total score \> 18 at Screening or Baseline; * In the opinion of the Investigator, the patient has a significant risk for suicidal behavior during his/her participation in the study or * At Screening, the patient scores "yes" on Suicidal Ideation Items 4 or 5 of the C-SSRS within 6 months prior to Screening or, at Baseline, the patient scores "yes" on Suicidal Ideation Items 4 or 5 since the Screening Visit; * At Screening, the patient has had 1 or more suicidal attempts within the 2 years prior to Screening; * At Screening or Baseline MADRS Item 10 score ≥ 5; or * The patient is considered to be an imminent danger to him/herself or others based on the assessment of the Investigator; * Lifetime history of failure to respond to \> 3 of the approved treatments for GAD (ie, paroxetine, venlafaxine XR, duloxetine, escitalopram, or buspirone) at an adequate dose (that is, at least a minimum total daily dose of paroxetine 20 mg, venlafaxine XR 75mg, duloxetine 60 mg, escitalopram 10mg, or buspirone 20 mg) and for an adequate duration (ie, at least 6 weeks)