Use of Ambroxol as Therapy for Gaucher Disease

Abstract

Importance: Ambroxol was identified as an enhancer of stability and residual activity of several misfolded glucocerebrosidase variants in 2009.

Objectives: To assess hematologic and visceral outcomes, biomarker changes, and safety of ambroxol therapy for patients with Gaucher disease (GD) without disease-specific treatment.

Design, setting, and participants: Patients with GD who could not afford enzyme replacement therapy were enrolled and received oral ambroxol from May 6, 2015, to November 9, 2022, at Xinhua Hospital, affiliated with Shanghai Jiao Tong University School of Medicine, Shanghai, China. Thirty-two patients with GD (29 with GD type 1, 2 with GD type 3, and 1 with GD intermediate types 2-3) were enrolled. Of those, 28 patients were followed up for longer than 6 months; 4 were excluded due to loss of follow-up. Data analyses were performed from May 2015 to November 2022.

Intervention: An escalating dose of oral ambroxol (mean [SD] dose, 12.7 [3.9] mg/kg/d).

Main outcomes and measures: Patients with GD receiving ambroxol were followed up in a genetic metabolism center. Biomarkers of chitotriosidase activity and glucosylsphingosine level, liver and spleen volumes, and hematologic parameters were measured at baseline and various time points throughout the ambroxol treatment.

Results: A total of 28 patients (mean [SD] age, 16.9 [15.3] years; 15 male patients [53.6%]) received ambroxol for a mean (SD) duration of 2.6 (1.7) years. Two patients with severe symptoms at baseline experienced deterioration of hematologic parameters and biomarkers and were deemed nonresponders; clinical response was observed in the other 26 patients. After 2.6 years of ambroxol treatment, the mean (SD) hemoglobin concentration improved from 10.4 (1.7) to 11.9 (1.7) g/dL (mean [SD], 1.6 [1.7] g/dL; 95% CI, 0.8-2.3 g/dL; P < .001), and the mean (SD) platelet count improved from 69 (25) to 78 (30) × 103/µL (mean [SD], 9 [22] × 103/µL; 95% CI, -2 to 19 × 103/µL; P = .09). The mean (SD) spleen volume decreased from 17.47 (7.18) to 12.31 (4.71) multiples of normal (MN) (mean [SD], -5.16 [5.44] MN; 95% CI, -10.19 to -0.13; P = .04), and the mean (SD) liver volume decreased from 1.90 (0.44) to 1.50 (0.53) MN (mean [SD], -0.39 [0.42] MN; 95% CI, -0.75 to -0.04; P = .03). Biomarker median percentage changes from baseline were -43.1% for chitotriosidase activity (from 14 598 [range, 3849-29 628] to 8312 [range, 1831-16 842] nmol/mL/h; z = -3.413; P = .001) and -34.1% for glucosylsphingosine level (from 251.3 [range, 73.6-944.2] to 165.7 [range, 21.3-764.8] ng/mL; z = -2.756; P = .006). Patients were divided into subgroups according to age when initiating treatment; those who received treatment at a younger age (mean [SD] age, 6.3 [2.7] years) experienced more rapid improvements: hemoglobin concentration increased by 16.5% (from 10.3 [1.5] to 12.0 [1.5] g/dL; mean [SD] change, 1.6 [1.6] g/dL; 95% CI, 0.7-2.5 g/dL; P = .002), and platelet count increased by 12.0% (from 75 [24] to 84 [33] × 103/µL; mean [SD] change, 9 [26] × 103/µL; 95% CI, -5 to 24 × 103/µL; P = .17); whereas chitotriosidase activity decreased by 64.0% (from 15 710 [range, 4092-28 422] to 5658 [range, 1146-16 843] nmol/mL/h; z = -2.803; P = .005), and glucosylsphingosine level decreased by 47.3% (from 248.5 [range, 122.8-674.9] to 131.0 [range, 41.1-448.5] ng/mL; z = -2.385; P = .02). Three of the 28 patients experienced mild and transient adverse events.

Conclusions and relevance: In this case series of ambroxol repurposing among patients with GD, long-term treatment with ambroxol was safe and associated with patient improvement. Improvements in hematologic parameters, visceral volumes, and plasma biomarkers were larger among patients with relatively mild symptoms of GD and patients who received initial treatment at younger ages.

Figure 1.. Hematologic Improvement During Ambroxol Therapy

Hematologic improvement during ambroxol therapy excludes 5 splenectomized patients. A and C, Error bars indicate SE of the mean. No comparative analysis was performed at the time point with a 6-year treatment duration due to the small number of patients (n = 3). E and F, Whiskers indicate the minimum and maximum range; the line inside the box indicates the median value. To convert hemoglobin to grams per liter, multiply by 10.0; and platelets to ×10⁹ per liter, multiply by 1.0. ^aP < .05. ^bP < .01.

Figure 2.. Absolute Spleen and Liver Volume Changes in Individual Patients

Liver and spleen volume data before and after treatment were available for only 8 patients. Patient 1 was splenectomized. Due to the expense and time spent on testing, some patients did not undergo abdominal imaging to monitor spleen and liver volumes throughout therapy.

Figure 3.. Changes From Baseline in Disease-Related Biomarkers During Ambroxol Treatment

Chitotriosidase analysis excluded 10 patients with no chitotriosidase activity. A and C, Error bars indicate SE of the mean. No comparative analysis was performed at the time point with a 6-year treatment duration due to the small number of patients (n ≤ 3). E and F, 5 splenectomized patients were excluded; whiskers indicate the minimum and maximum range; the line inside the box indicates the median value. ^aP < .05. ^bP < .01.