Phase 1 TAK-915 Single-Dose Positron Emission Tomography (PET) Occupancy Study

The drug being tested in this study is called TAK-915. TAK-915 is being tested to examine the
degree and duration of brain phosphodiesterase 2A (PDE2A) enzyme occupancy/target engagement
as a function of TAK-915 plasma concentration in order to guide dosing and schedule for
future clinical studies in schizophrenia. This study will look at PDE2A brain enzyme
occupancy in the putamen as a function of TAK-915 plasma concentration, as assessed using the
positron emission tomography (PET) ligand [18F]MNI-794 after single dosing of TAK-915.

The study will enroll approximately 16 patients in total and within that total, allow up to 5
dose levels and up to 6 subjects per dose level. All participants will receive a single dose
of TAK-915 on Day 1. The initial TAK-915 dose level to be studied is 100 mg. Subsequent dose
levels may be lower or higher and will be determined through dose level review meetings
(DLRMs) following approximately every 2 participants and based on prior occupancy, duration
of occupancy, safety, tolerability, and available pharmacokinetic (PK) data.

This single center trial will be conducted in the United States. The overall time to
participate in this study is up to 55 days. Participants will make multiple visits to the
clinic, and will be contacted by telephone 22 days after last dose of study drug for a
follow-up assessment.

Inclusion Criteria:

1. Is a healthy male, or female of non-childbearing potential, aged between 18 and 55
years, inclusive.

2. Weighs at least 45 kg and has a body mass index (BMI) between 18.0 and 30.0 kg/m^2.

Exclusion Criteria:

1. Has a known history or evidence of a clinically significant disorder (including
neurologic and psychiatric) or disease that in the opinion of the study investigator
would pose a risk to the participant's safety or interfere with the study evaluation,
procedures, or completion.

2. Contraindication to magnetic resonance imaging (MRI) based on the standard MRI
screening questionnaire.

3. Have had exposure to any radiation >15 millisievert (mSv)/year (eg, occupational or
radiation therapy) within the previous year prior to Baseline imaging.

4. Has a known hypersensitivity to any component of the formulation of TAK-915 or related
compounds, or to [18F]MNI-794 or to any of its components.

5. Clinically significant abnormal findings on brain MRI scan or findings on brain MRI
that may interfere with the interpretation of the positron emission tomography (PET)
imaging.

6. Use of any herbal or prescription medications within 30 days prior to Baseline Imaging
Check-in; use of any over-the-counter medications or vitamin supplements within 7 days
prior to Baseline Imaging Check-in.