F8 gene variants influence the response to desmopressin in hemophilia A carriers

Desmopressin (DDAVP) is often administered to correct factor VIII (FVIII) levels in female hemophilia A carriers (HACs). However, the post-DDAVP FVIII pharmacokinetic profiles have been reported only in small series in HACs. Therefore, this study analyzed the post-DDAVP FVIII and von Willebrand factor (VWF) response in 361 HACs. A population pharmacokinetic/pharmacodynamic model was developed to analyze the VWF and FVIII levels by taking into account the F8 gene variants (n = 143 [39.6%] with null; and n = 218 [60.4%] with non-null variants), demographic and laboratory covariates. The before/after DDAVP mean basal, peak and recovery FVIII activity (FVIII:C) levels were 0.34 IU/mL (0.08-0.65), 1.13 IU/mL (0.19-2.69), and 2.85 IU/mL (1.06-7.13), respectively. Peak FVIII:C was ≥0.5 IU/mL in 95.6% (345/361) and ≥0.8 IU/mL in 78.7% (284/361) of patients. The covariate analysis showed a poorer DDAVP FVIII:C response for null than non-null F8 variants: lower mean FVIII:C peak (1.04 vs 1.23 IU/mL; P < 5 × 10-5) and patients percentage with normalized FVIII:C (91.6% vs 98.1%; P = .0068), higher mean FVIII:C clearance (5898.83 vs 2704.06 IU/h; P = 1.58 × 10-15), lower mean FVIII:C area under the curve during the first 12 hours (AUC0-12h =7.73 vs 9.06 IU/mL per hour; P < 5 × 10-6), and shorter mean time with FVIII:C ≥0.8 IU/mL (1.9 vs 4.1 hours; P < 6 × 10-6). HAC with body weight <35 kg had lower peak FVIII:C, higher FVIII:C clearance, lower AUC0-12h, and shorter time with FVIII:C ≥0.8 IU/mL than HAC with body weight 35 to 70 kg. In HACs, the post-DDAVP FVIII response is strongly influenced by the F8 genotype and body weight.