Single-center, open-label Phase 2b study will evaluate the PK, PD, efficacy and safety parameters of SC prophylaxis treatment regimens with CB2679d in adult subjects with hemophilia B. The study will enroll and dose subcutaneously, a total of 6 adult male subjects with severe congenital hemophilia B.~During the Treatment Period, the subject will receive an IV dose of 50 IU/kg followed 35 ± 5 minutes later by a SC dose of 100 IU/kg. Daily SC doses of 100 IU/kg will be administered until Day 28 (28 total SC doses). On Day 1, PK, PD, and safety assessments will be done at pre-IV dose and repeated 35 (± 5) minutes later prior to the SC dose. Subsequent PK, PD and safety assessments will be performed pre-dose on days 2, 3, 7, 14, 21 and 28.~During the Washout Period, PK, PD, and safety assessments will be done on Days 29, 30, 31, 32 and 33. Daily FIX activity levels will be measured, unless FIX activity level is known to be < 5%, as measured by local laboratory.~An End of Study visit will occur 30 days (± 2 days) after the last dose of study drug.
Phase 2b, single-center, open-label study designed to evaluate the pharmacokinetics, pharmacodynamics, efficacy and safety of subcutaneous (SC) prophylaxis treatment regimens with CB2679d in 6 adult, male subjects with severe congenital hemophilia B.