Early achievement and maintenance of the therapeutic goals using velaglucerase alfa in type 1 Gaucher disease.

Introduction: Therapeutic goals have been described to monitor achievement, maintenance and continuity of therapeutic response in patients with type 1 Gaucher disease receiving enzyme replacement therapy.

Aim: To benchmark the impact of velaglucerase alfa treatment against therapeutic goals for 5 key clinical parameters of type 1 Gaucher disease (anemia, thrombocytopenia, hepatomegaly, splenomegaly and skeletal pathology).

Methods: In an open-label Phase I/II study, twelve adults with symptomatic type 1 Gaucher disease and intact spleens received velaglucerase alfa for 9 months (60 U/kg infusion every other week [EOW]). Eleven patients completed the study and 10 enrolled in a long-term extension. After 1 year, patients who achieved ≥ 2 hematological or organ goals began step-wise dose reduction from 60 to 45 then 30 U/kg EOW. Data for anemia, thrombocytopenia, hepatomegaly, splenomegaly and skeletal pathology at baseline and 4 years are available for 8 patients (3 male, 5 female). The proportion of patients at goal for anemia, thrombocytopenia, hepatomegaly and splenomegaly at baseline was compared with the proportion achieving each goal at 4 years. The proportion achieving the skeletal pathology goal was determined on the basis of Z-score improvement from baseline to 4 years. The proportion of patients who achieved all 5 goals at 4 years was compared with the proportion at goal for all 5 parameters at baseline.

Results: At baseline, no patient was at goal for all clinical parameters. After 1 year of treatment, all patients maintained goals present at baseline, and all achieved ≥ 2 goals. All 8 patients began step-wise dose reduction from 60 to 30 U/kg EOW between 15 and 18 months. By year 4 of treatment, all patients met goals for all 5 clinical parameters; therefore 100% achievement was seen for each of the 5 long-term, therapeutic goals.

Discussion: In this velaglucerase alfa Phase I/II and extension study, clinically meaningful achievement of each long-term, therapeutic goal was observed for each patient, despite dose reduction after 1 year. This is the first report of a cohort where all patients receiving ERT for type 1 Gaucher disease achieved all 5 of these long-term, therapeutic goals within 4 years of starting treatment and after ≥ 2years dose reduction.