Effect of enzyme replacement therapy with imiglucerase on BMD in type 1 Gaucher disease

The effect of ERT with imiglucerase on BMD in type 1 GD was studied using BMD data from the International Collaborative Gaucher Group Gaucher Registry. Data were analyzed for 160 untreated patients and 342 ERT-treated patients. Imiglucerase significantly improves BMD in patients with GD, with 8 years of ERT leading to normal BMD.

The objective was to determine the effect of enzyme replacement therapy (ERT; Cerezyme, imiglucerase) on BMD in type 1 Gaucher disease (GD).

The study population included all adults (men, 18-70 years; women, 18-50 years) enrolled in the International Collaborative Gaucher Group (ICGG) Gaucher Registry for whom lumbar spine BMD measurements were available. BMD data with up to 8 years of follow-up were analyzed for 160 patients who received no ERT and 342 patients treated with ERT alone. BMD was assessed by DXA of the lumbar spine. Z scores for patients with GD were compared with a reference population. From the model's estimate, percent of patients by age and sex with osteoporosis (T score < or = -2.5) were calculated.

DXA Z scores for patients with GD in the no ERT (untreated) group were significantly below normal (y intercept = -0.80 Z score units, p < 0.001) and remained approximately 1 SD below the reference population over time (slope = -0.010 Z score units per year, p = 0.68). The DXA Z scores for patients with GD who received ERT at a dose of 60 U/kg/2 weeks were significantly lower than the reference population at baseline (y-intercept = -1.17 Z score units, p < 0.001), but improved significantly over time (slope = +0.132 Z score units per year, p < 0.001). A significant dose-response relationship was noted for the ERT group, with the slopes for the three main dosing groups of 15, 30, and 60 U/kg/2 weeks of +0.064, +0.086, and +0.132 Z score units per year, respectively. The BMD of patients with GD treated with ERT increased to -0.12 (60 U/kg/2 weeks), -0.48 (30 U/kg/2 weeks), and -0.66 (15 U/kg/2 weeks) SD of the mean of the reference population after 8 years of ERT, approaching the reference population. Estimated risk of osteoporosis of this GD population, if left untreated, ranged from approximately 10 to 30% in women and 10% to 25% in men.

ERT with imiglucerase (Cerezyme) may increase BMD in patients with GD. Response to treatment with imiglucerase is slower for BMD than for hematologic and visceral aspects of GD. A normal (age- and sex-adjusted) BMD should be a therapeutic goal for patients with type 1 GD.