Phase III BENEGENE-2 study of PF 06838435 meets primary endpoint in haemophilia B
Pfizer announced positive top-line results from the Phase III BENEGENE-2 study (NCT03861273) evaluating PF 06838435 (fidanacogene elaparvovec), an investigational gene therapy, for the treatment of adult males with moderately severe to severe haemophilia B. The BENEGENE-2 study met its primary endpoint of non-inferiority and superiority in the annualized bleeding rate (ABR) of total bleeds post-fidanacogene elaparvovec infusion versus prophylaxis regimen with Factor IX (FIX), administered as part of usual care
The results demonstrated superiority with a mean ABR for all bleeds of 1.3 for the 12 months from week 12 to month 15 compared to an ABR of 4.43 during the lead-in pre-treatment period of at least six months, resulting in a 71% reduction in ABR (p<0.0001) after a single dose of 5e11 vg kg of fidanacogene elaparvovec. key secondary endpoints demonstrated a 78% reduction in treated abr (p="0.0001)" and a 92% reduction in annualized infusion rate (p><0.0001). mean fix activity was 27% at 15 months by one-stage synthasil assay and 25% at 24 months. the mean steady-state fix:c was significantly higher than the pre-specified threshold of 5% (p><0.0001).
Fidanacogene elaparvovec was generally well-tolerated, with a safety profile consistent with Phase I/II results. Fourteen serious adverse events (SAEs) were reported in seven (16%) patients, with two assessed as related to treatment, a duodenal ulcer hemorrhage occurring in the setting of corticosteroid use, and an immune-mediated elevation of liver aminotransferase levels. No deaths, SAEs associated with infusion reactions, thrombotic events, or FIX inhibitors were reported.
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