Table 1. Gene therapy dose response in treated dogs with hemophilia B.

The table shows the age and weight at treatment of three dogs with hemophilia B (M57, O21, and O59), the infused dose of lentiviral vector in TU and physical particles (p24) per weight, the follow-up (FU) time in days, the whole blood clotting time (WBCT) in minutes, and the cFIX activity [determined by activated partial thromboplastin time (aPTT)]. Also shown are the cFIX antigen (determined by ELISA), the type of transgene contained in the infused lentiviral vector: wild-type (WT) cFIX, co-cFIX, or co-cFIXR338L (see also Fig. 1). When possible, results are presented as mean values ± SEM over time (with ranges in parentheses). The values of WBCT and cFIX activity and antigen are considered valid only if measured 27 days after the last canine plasma transfusion (to ensure washout of exogenous cFIX).

M57 (Hemil)O21 (Valentine)O59 (Enzo)
Age at treatment (months)82121
Weight at treatment (kg)202218
TransgeneWT cFIXco-cFIXco-cFIXR338L
TU/kg5.7x1082.3x1091.1x109
μg p24/kg4447174
FU (days)1831900637
WBCT (min)20.31 ± 0.91 (14.5–32)17.36 ± 0.66 (13.5–22.5)15.73 ± 0.5 (11–19.5)
cFIX activity (% normal)0.08 ± 0.01 (0.01–0.25)1.05 ± 0.12 (0.3–1.7)1.18 ± 0.08 (0.7–1.9)
cFIX antigen (% normal)0.05 ± 0.004 (0.01–0.09)0.6 ± 0.06 (0.2–0.85)0.16 ± 0.005 (0.14–0.2)