A Study to Evaluate a Single Intravenous (IV) Dose Using a New Manufactured Clone and Single Ascending Doses of Subcutaneous (SC) Injections

The four doses will be studied in sequential cohorts of 8 subjects each, starting with the IV dose, followed by the subcutaneous doses in ascending order of dose. Within each cohort, subjects will be randomized to either active drug or matching placebo in a 3:1 ratio (6 active and 2 placebo). All subjects in each arm will be confined for 8 days and followed for a minimum of 90 days up to 9 months if necessary. Subjects who have study drug terminated should remain in the study, if possible and have scheduled procedures and follow-up. Subjects who have detectable blood levels of ASP2408 after Day 90 will be unblinded and followed monthly until ASP2408 levels are below the limit of quantification. In addition, subjects who have persistent anti-ASP2408 antibodies after Day 90 will be unblinded and followed every 30 (± 3) days for up to 9 months until the level of these antibodies are declining, no longer detectable, and/or have no clinical consequence.