Big stride in gene therapy for hemophilia B in China.

In a recent issue of Lancet Haematology , Xue et al 1 reported an adeno-associated virus (AAV)-based gene therapy in 10 patients with hemophilia B (HB) from China. BBM-H901, a novel vector comprised of an engineered liver-tropic AAV cap- sid (AAV843), synthesized liver-specific promoter and CpG reduced factor IX (FIX) Padua coding sequence, was infused in 10 patients (baseline FIX coagulation activity [FIX:C] were less than 2 IU/dL) after 1 week of prophylactic prednisone pretreat- ment (1 mg/kg per day). After a median follow-up of 58 weeks, mean FIX:C reached 36.9 ± 20·5 IU/dL. No FIX inhibitors or serious adverse events were observed. All patients developed high titer neutralizing antibodies against vector capsid. The concentrations of alanine aminotransferase and aspartate aminotransferase in plasma were below the upper limit of normal range in 8 patients. No FIX concentrate infusion was needed after gene therapy for these patients. This is a huge step forward in the treatment of HB in China.