Pivotal data from XTEND-1 phase III study demonstrates once-weekly efanesoctocog alfa provides superior bleed protection compared to prior factor prophylaxis.

The study met the primary efficacy endpoint, with once-weekly efanesoctocog alfa prophylaxis providing clinically meaningful bleed protection for people with severe haemophilia A. The median and mean annualised bleeding rates (ABR) were 0.00 (IQR: 0.00 - 1.04) and 0.71 (SD: 1.43) respectively. The study also met the key secondary endpoint, demonstrating superior bleed protection (p<0.0001) over prior factor viii prophylaxis with an estimated abr reduction of 77 per cent and a mean abr of 0.69 compared to 2.96 on prior prophylaxis, based on an intra-patient comparison (n = "78)." in a subset of participants (n = "17)" studied at baseline and week 26, mean factor viii levels remained in the normal to near-normal range (>40 IU/dL) for the majority of the week, and at 15 IU/dL at day seven post dosed, providing increased factor activity level protection for patients with once-weekly prophylaxis.

Data show adults and adolescents treated with once-weekly efanesoctocog alfa experienced statistically significant and clinically meaningful improvements in physical health (p=0.0001), pain intensity (p=0.0276), and joint health (p=0.0101) when comparing week 52 and baseline measurements. Moreover, efanesoctocog alfa was effective at treating bleeds, including in target joints; 96.7 per cent of bleeds were resolved with a single 50 IU/kg dose. Efanesoctocog alfa was well tolerated and inhibitor development to factor VIII was not detected. The most common treatment-emergent adverse events (greater than 5 per cent of participants overall) were headache, arthralgia, fall, and back pain.

Regulatory submission of the Biologics License Application to the US FDA occurred in June 2022 and submission in the EU will follow availability of data from the ongoing XTEND-Kids paediatric study, expected in 2023.