Subjects would sequentially enroll in one of three cohorts. Subjects in the first cohort would receive a single 30-mg subcutaneous injection of TK006. If no safety signals are observed in the first cohort after 28 days, subjects would enroll in the second cohort and receive a single 60-mg subcutaneous injection of TK006. After an 28-day period for observation of safety of the second dose, subjects would enroll in the third cohort and receive a single 120-mg subcutaneous injection of TK006.