The invention relates to inhibitors of glucosylceramide synthase (GCS) useful for the treatment metabolic diseases, such as lysosomal storage diseases, either alone or in combination with enzyme replacement therapy, and for the treatment of cancer.本發明有關一種神經醯胺葡萄糖神經醯胺合成酶(GCS)抑制劑,用於治療代謝疾病,例如溶酶體貯積疾病,單獨或與酵素替代療法組合,且用於治療癌症。