A Trial of Centanafadine Efficacy and Safety in Adults With Attention-deficit/Hyperactivity Disorder and Comorbid Anxiety

Inclusion Criteria:

1. Participants between 18 and 65 years of age, inclusive.

2. Diagnosis of ADHD per the DSM-5 criteria and confirmed using the ACDS Version 1.2 atscreening.

3. AISRS total score of ≥ 28 at baseline.

4. Diagnosis of GAD or SAD per DSM-5 criteria and confirmed using the MINI atscreening.

5. HAM-A total score ≥ 20 at baseline.

6. CGI-S-ADHD and CGI-S-anxiety rating ≥ 4 at baseline.

7. Body mass index from 18.0 to 40.0 kg/m2 (inclusive).

8. Ability to provide written, informed consent prior to initiation of anytrial-related procedures, and ability, in the opinion of the principal investigator,to comply with all the requirements of the trial.

Exclusion Criteria:

1. In the clinical opinion of the investigator, participant has not derived significanttherapeutic benefit from 2 or more ADHD therapies of 2 different classes (eg,amphetamine and methylphenidate, or amphetamine and atomoxetine) given with anacceptable dose and duration during adulthood (aged 18 years or older).

2. In the opinion of the investigator, participant has not derived significanttherapeutic benefit from 2 or more anxiety therapies of 2 different classes (eg,selegiline and duloxetine, or buspirone and lorazepam) given with an acceptable doseand duration during adulthood (aged 18 years or older).

3. Current use of prohibited psychotropic medications that cannot be discontinued 2weeks prior to randomization. Fluoxetine is prohibited within 28 days ofrandomization.

4. Subjects who have started individual or group psychotherapy within the past 3 monthsprior to screening (ongoing psychotherapy that is not expected to change infrequency or type during the trial is permissible).

5. Any disorder that is the primary focus of treatment other than ADHD.

6. Psychosis, bipolar disorder, MDD, post-traumatic stress disorder, dementia,obsessive compulsive disorder, personality disorders, substance/medication inducedanxiety, anxiety disorder due to another medical condition, specific phobia if thisis the primary reason for treatment, selective mutism.

7. Participant is, in the investigator's judgment, at significant risk for suicide. Aparticipant with a Columbia-Suicide Severity Rating Scale (C-SSRS) ideation score of 4 or 5 within the last 6 months or participants who answer "Yes" on any of the 5C-SSRS Suicidal Behavior Items (actual attempt, interrupted attempt, abortedattempt, preparatory acts, or behavior) within the past year must be excluded.

8. Participants with a positive drug test at baseline for ADHD and anxiety medicationincluding methylphenidate, amphetamine, or for drugs of abuse. Participants with apositive drug screen for confirmed prescription or over-the-counter (OTC) use ofADHD and anxiety medications at screening will be required to undergo a washoutperiod.

9. Participants with evidence of current substance use disorder or history in the past 12 months.

10. Participants with epilepsy, a history of epilepsy, or a history of seizure, exceptfor a single childhood febrile seizure, a single seizure post brain injury, or asingle seizure due to alcohol withdrawal.

11. Participants who are partially hospitalized or receiving inpatient care or have anyother medical or physical condition(s) that, in the opinion of the investigator, mayprevent the participant from completing the trial or would go against theparticipant's best interest with participation in the trial. This would include anysignificant illness or unstable medical condition that could lead to difficultycomplying with the protocol.

12. The following laboratory test and ECG results are exclusionary at screening:

13. Platelets ≤ 75,000/mm3

14. Hemoglobin ≤ 9 g/dL

15. Neutrophils, absolute ≤ 1000/mm3

16. AST > 2 × upper limit of normal

17. ALT > 2 × upper limit of normal

18. Creatinine ≥ 2 mg/dL

19. HbA1c ≥ 7%

20. QTcF ≥ 450 msec for males or ≥ 470 msec for females

21. Abnormal free thyroxin (T4), unless discussed with and approved by the medicalmonitor (Note: free T4 is measured only if result for thyroid stimulatinghormone [TSH] is abnormal)

22. Participants presenting with, or having a history of, uncontrolled hypertension (systolic blood pressure > 150 mmHg or diastolic blood pressure > 95 mmHg) orsymptomatic hypotension, or orthostatic hypotension which is defined as a decreaseof ≥ 30 mmHg in systolic blood pressure or a decrease of ≥ 20 mmHg in diastolicblood pressure after at least 3 minutes standing compared with the previous supineblood pressure, or development of symptoms.

23. Participants with a history of any prior exposure to centanafadine.

24. Participants who have participated in other clinical trials involvinginvestigational drugs within 180 days prior to screening or who have participated inmore than 2 interventional clinical trials involving investigational drugs withinthe past year.

25. Participants of childbearing potential who are breast-feeding and/or have a positivepregnancy test result prior to receiving IMP.

26. Participants of reproductive potential / POCBP who do not agree to practice 2different highly effective methods of birth control or remain fully abstinent fromsexual activity with the potential for conception, per the guidelines in Section 10.3.

27. Participants who do not agree to refrain from donating sperm or eggs from trialscreening through 90 days for sperm and 30 days for eggs after the last dose of IMP.

28. Participants who have an allergy to the IMP or any component of the IMP.