A Positron Emission Tomography Occupancy Study Using Ligand [11C]AS2471907 and Following Oral Dosing of ASP3662

This is a two-part study where Part 1 will assess the test/retest variability of the ligand
([11C]AS2471907). Part 2 will assess the level and time-course of enzyme occupancy following
ASP3662 dosing. Subjects will be confined to the clinic for up to 2 days.

Inclusion Criteria:

- Subject is of non-Asian descent.

- Subject has a body mass index (BMI) range of 18.5 to 32 kg/m2, inclusive and weighs
at least 50 kg at screening.

- Subject and his female spouse/partner who is of childbearing potential must be using
highly effective contraception1 consisting of 2 forms of birth control (at least one
of which must be a barrier method) starting at screening and continuing throughout
the study period and for 90 days after final study drug administration.

- Subject must not donate sperm starting at screening, throughout the study period and
for at least 90 days after final study drug administration.

- Subject agrees not to participate in another investigational study while on study
treatment.

Exclusion Criteria:

- Subject has a known or suspected hypersensitivity to ASP3662, [11C]AS2471907 or
intolerance of drugs with the same mechanism of action as ASP3662.

- Subject has an allergy to topical anesthetics, such as, lidocaine (if used for
catheter placement).

- Subject has previously participated in a clinical study with ASP3662 or part 1 of the
current study.

- Subject has any of the liver enzymes (aspartate aminotransferase [AST], alanine
transaminase [ALT], alkaline phosphatase [ALP], gamma-glutamyl transferase [GGT]) or
total bilirubin (TBIL) above the upper limit of normal (ULN). If any liver enzyme is
> 1 x ULN but ≤ 1.5 x ULN, the assessment may be repeated once during the screening
period or on check-in. If the repeated assessment is above the ULN, it is
exclusionary. If the initial value is > 1.5 x ULN, it cannot be repeated and is
exclusionary.

- Subject has any clinically significant history of allergic conditions.

- Subject with a history of a suicide attempt or suicidal behavior.

- Subject has a history of smoking within the past 6 months.

- Subject has any history or evidence of any clinically significant cardiovascular,
gastrointestinal (GI), endocrinologic, hematologic, hepatic, immunologic, metabolic,
urologic, pulmonary, neurologic, dermatologic, psychiatric, renal and/or other major
disease or malignancy, as judged by the investigator or designee.

- Subject has/had febrile illness or symptomatic viral, bacterial (including upper
respiratory infection) or fungal (non-cutaneous) infection within 1 week before
clinic check-in.

- Subject has any clinically significant abnormality following the investigator's
review of the physical examination, electrocardiogram (ECG) and protocol-defined
clinical laboratory tests at screening or clinic check-in.

- Subject has a mean pulse < 40 or > 90 beats per minute; mean systolic blood pressure
> 140 mmHg or mean diastolic blood pressure > 90 mmHg (measurements taken in
triplicate after subject has been resting in supine position for 10 minutes) at
screening. If the mean pulse or mean systolic blood pressure (SBP) or mean diastolic
blood pressure (DBP) is out of the range specified above, 1 additional triplicate
measurement may be taken at screening.

- Subject has a mean QTcF interval of > 430 msec at screening or check-in. If the mean
QTcF exceeds the limits above, 1 additional triplicate ECG can be taken at screening.
If this triplicate also gives an abnormal result, the subject should be excluded.

- Subject has a history of unexplained syncope, cardiac arrest, unexplained cardiac
arrhythmias or torsade de pointes, structural heart disease or a family history of
Long QT Syndrome.

- Subject has use of any prescribed or non-prescribed drugs (including vitamins,
natural and herbal remedies, e.g., St. John's wort) in the 2 weeks before study drug
administration, except for occasional use of acetaminophen (up to 2 g/day).

- Subject has history of consuming more than 14 units of alcoholic beverages per week
within 6 months prior to screening or has a history of alcoholism or drug/chemical or
substance abuse within the past 2 years prior to screening (Note: 1 unit = 12 ounces
of beer, 4 ounces of wine or 1 ounce of spirits/hard liquor) or the subject tests
positive at screening or clinic admission for alcohol or drugs of abuse
(amphetamines, barbiturates, benzodiazepines, cannabinoids, cocaine and opiates).

- Subject has any use of drugs of abuse within 3 months before screening or check-in.

- Subject has use of any inducer of metabolism (e.g., barbiturates, rifampin) in the 3
months prior to check-in.

- Subject has consumed any caffeine-containing product within 24 hours prior to
admission or grapefruit or star fruit within 7 days prior to admission.

- Subject has any significant blood loss, donated equal to 1 unit (450 mL) or more of
blood or received a transfusion of any blood or blood products within 60 days or
donated plasma within 7 days before check-in.

- Subject has a positive serology test for hepatitis B surface antigen, anti-hepatitis
A virus (Immunoglobulin M), anti-hepatitis C virus or anti-human immunodeficiency
virus (HIV) Type 1 or Type 2 at screening.

- Subject has participated in any interventional clinical study or has been treated
with any investigational drugs within 30 days or 5 half-lives, whichever is longer,
before the initiation of screening.

- Subject is an employee of the Astellas Group or vendors involved in the study.

- Additionally, a subject who meets the following imaging exclusion criteria will not
be included in this study:

- Subject who suffers from claustrophobia.

- Subject who has received a diagnostic or therapeutic radiopharmaceutical within
7 days prior to participation in this study.

- Participation in other research studies involving ionizing radiation within 1
year of the PET scans that would cause the subject to exceed the US Nuclear
Regulatory Commission yearly dose limits for healthy subjects, i.e., an
effective dose of 5 Roentgen equivalent man (rem) received per year.

- Subject with history of IV drug use which would prevent venous access for PET
tracer injection.

- Severe motor problems that prevent the subject from lying still for PET imaging.

- Subject who has chronic pain for any reason (e.g., as the result of rheumatoid
arthritis).

- Subject who has an MRI scan deemed to be structurally abnormal by the
investigator and thus precluding proper identification of the regions of
interest (ROIs) (e.g., cortical atrophy). The MRI scan for an individual subject
may be omitted if the required anatomical MRI scan for this subject is on file
and was performed within approximately 6 months prior to dosing, as part of
participation in an approved Yale Protocol.

- Subjects who has current, past or anticipated exposure to radiation in the work
place.