CC100: Safety and Tolerability of Single Doses

Approximately 18 healthy subjects will be randomized to receive by mouth either 3 single
increasing doses of CC100 or 1 dose of placebo and 2 increasing doses of CC100. Dosing will
occur every 2 to 7 days for a study duration of 5 to 15 days from the 1st dose. Subjects
are required to stay in the Clinic for approximately 24 hours following each dose. Subjects
may choose to have an optional lumbar puncture following the 3rd dose of study drug.

Inclusion Criteria:

- Men must practice a reliable method of birth control during study and for 2 weeks
following study. Women must be non-fertile or post-menopausal.

Exclusion Criteria:

- Have serious or unstable illnesses as determined by the investigator.

- Have current or a history of asthma, or severe drug allergies or pollen allergy.

- Have used medications (except for calcium supplements or externally applied eye drops
or antibiotics) within 30 days prior to dosing or are expected to use other
medications during the study.

- Have had serious infectious disease affecting the brain within the preceding 5 years;
or have known or existing evidence of serious infection.

- Have laboratory test values that are considered clinically significant as determined
by the investigator.

- Have ECG abnormalities that are clinically significant.

- Have donated blood (a pint or more) or received an experimental drug within 30 days
prior to dosing.

- Have a history of chronic alcohol or drug abuse within the past 2 years.