A Study of a N, N-dimethyltryptamine (DMT) Analog (CYB004) in Participants With Generalized Anxiety Disorder (GAD) With Depressive Symptoms

Inclusion Criteria: Aged between 21 to 65 years, inclusive, at Screening. Has a diagnosis of GAD (as defined in the Diagnostic and Statistical Manual of Mental Disorders, 5th edition [DSM-V] of moderate to severe degree), established through a full psychiatric work up. Has co-occurring symptoms of moderate to severe depression. Has a BMI of 18 to 37.5 kg/m2, inclusive at Screening. Is ≥60 kg. Is a non-smoker for at least the past 3 months prior to Screening. Has been on a stable dose of antidepressant/anxiolytic medication (no more than 50% change) in the last month prior to Screening and has had an inadequate response, as judged by the Investigator. Is willing to refrain from taking any benzodiazepines or buspirone (or other 5-HT1A agonist) during the 24 hours preceding each dosing visit. Is willing to refrain from taking monoamine oxidase inhibitors for 3 weeks prior to Screening, if applicable. Is negative for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) test at Screening and at Day -1. Provision of giving written informed consent, which includes compliance with the requirements and restrictions listed in the consent form. Exclusion Criteria: Has a primary DSM-5 psychiatric diagnosis other than GAD within the past 6 months established through a full psychiatric work-up. A secondary diagnosis of MDD may be permissible. Current or previously diagnosed schizophrenia spectrum or other psychotic disorders, including schizophrenia, schizoaffective disorder, schizotypal disorder, schizophreniform disorder or brief psychotic disorder; current or previous history of bipolar disorder, or current personality disorder. Current or previous diagnosis of treatment-resistant MDD, defined as failure to respond to 2 or more antidepressant treatments given at an adequate dose for an adequate duration. Currently receiving a monoamine oxidase inhibitor, tricyclic antidepressant, mirtazapine, or a mood stabilizer or has taken any of these medications in the last 3 weeks. Currently taking antipsychotic medication which are 5-HT2 antagonists or has taken such medication in the last 3 weeks. Clinically significant risk of suicidality, as determined through a comprehensive psychiatric interview. Clinically relevant history of abnormal physical health interfering with the study as determined by medical history and physical examinations obtained during Screening as judged by the Investigator (including [but not limited to], neurological, endocrine, cardiovascular, respiratory, gastrointestinal, hepatic, or renal disorder). Diagnosis of hypertension or an arrhythmia. History of hypothyroidism and/or current abnormal thyroid function tests. Clinically relevant abnormal laboratory results. Positive test for hepatitis B surface antigen (HBsAg), anti-hepatitis C antibody (anti- HCV) or human immunodeficiency virus I and II (anti-HIV I/II) at Screening. History or clinical evidence of any disease and/or existence of any surgical or medical condition which might interfere with the absorption, distribution, metabolism or excretion of the study drug. Any other concomitant disease or condition that could interfere with, or for which the treatment might interfere with the conduct of the study, or that would, in the opinion of the Investigator, pose an unacceptable risk to the participant in this study. Has a presence or relevant history of any of the following medical conditions: organic brain disorders (e.g., epilepsy, seizure, intracranial hypertension, intracranial bleed and aneurysmal disease, brain tumor or other medical conditions associated with seizures or convulsions). Consumes excessive amounts of caffeine (e.g., coffee, tea, caffeinated sodas) or methylxanthines (e.g., chocolate) based on the Investigator's determination and discretion. Has participated in a clinical study and has received a medication or a new chemical entity within 3 months prior to dosing of current study medication. Known sensitivity to DMT or ayahuasca. Is taking a prescription medicine (except for stable chronic dose of antidepressant medication(s), sedatives/hypnotics, and hormonal contraceptives, if applicable), certain herbal supplements (to be reviewed by the Investigator), or over-the-counter (OTC) medicine during the 28 days before dosing. Is taking or has taken over the counter (OTC) doses of 5-hydroxytryptophan or St John's Wort within 28 days prior to receiving the study drug. Donation of blood or plasma of >400 mL within 1 month prior to first dosing until 4 weeks after final dosing. For participants capable of producing sperm: Is not willing to abstain from sperm donation between first dosing and 3 months after final dosing. For participants capable: Is pregnant, breastfeeding or planning to conceive. Known difficulty with obtaining intravenous (IV) access. Not fluent in the English language. Other eligibility considerations (i.e., participant personal circumstances, behavior, and/or any current problem that might interfere with participation or that is incompatible with establishment of rapport or safe exposure to the study drug), as judged by the Investigator.