Nonprecipitous changes upon withdrawal from imiglucerase for Gaucher disease because of a shortage in supply

Because of an unpredicted and unavoidable shortage in global supplies of imiglucerase for Gaucher disease, we collected clinical and laboratory data from patients who were evaluated ≤ 6 months before drug withdrawal and then retested before/during reinstatement of therapy. Hemoglobin, platelet counts, and liver and spleen index volumes by ultrasound as well as chitotriosidase were evaluated as percent change over time and relative to dose-years of exposure to enzyme therapy. Deterioration was seen in all four clinical parameters and in chitotriosidase activity in most patients and even among patients who stopped for only 3 months. No patient consistently showed nondeterioration in all five parameters. Platelet counts were most sensitive to therapy withdrawal. There was no overt correlation between percent change in these parameters and dose-years of therapy. Although we no longer think that drug vacations should be considered as a form of maintenance for patients requiring enzyme therapy for Gaucher disease, but if necessary—for compelling personal reasons—one may be reassured that a short-term drug interruption is not likely to lead to irreversible complications or return to baseline values of critical clinical parameters.