Priya S. Kishnani

Gaucher disease type 1 (GD1) is known for phenotypic heterogeneity and varied natural history. Registrational clinical trials enrolled narrowly defined phenotypes, but greater diversity is encountered in clinical practice. We report real‐world outcomes with long‐term eliglustat treatment in adults with GD1 in the International Collaborative Gaucher Group Gaucher Registry. Among 5985 GD1 patients in the Registry as of January 6, 2023, 872 started eliglustat at ≥18 years old; of these, 469 met inclusion criteria. We compared clinical parameters at eliglustat initiation (i.e., baseline) and follow‐up in treatment‐naïve patients and used linear mixed models to estimate annual change from baseline in parameters among patients who switched to eliglustat after ≥1 year on enzyme replacement therapy. Over 4 years of follow‐up in non‐splenectomized treatment‐naïve patients, hemoglobin and platelet count increased, liver and spleen volume decreased, and total lumbar spine bone mineral density (BMD) Z‐score decreased slightly. Among non‐splenectomized switch patients, on average, hemoglobin decreased −0.030 (95% CI: −0.053, −0.008) g/dL ( N = 272) and platelet count increased 2.229 (95% CI: 0.751, 3.706) × 10 3 /mm 3 ( N = 262) annually up to 10 years; liver volume decreased (−0.009 [95% CI: −0.015, −0.003] MN) ( N = 102) and spleen volume remained stable (−0.070 [95% CI: −0.150, 0.010] MN) ( N = 106) annually up to 7 years; and total lumbar spine BMD Z ‐score increased 0.041 (95% CI: 0.015, 0.066) ( N = 183) annually up to 8 years. Among splenectomized switch patients, clinical parameters were stable over time. These long‐term, real‐world outcomes are consistent with the eliglustat clinical trials and emerging real‐world experience across the GD phenotypic spectrum.