The invention relates to the preparation of a mutant chimeric antigen receptor (CAR) expressing cell with excellent target cell toxicity. The invention provides a genetically modified cell, which is introduced with a target binding region, a transmembrane region, and an intracellular signal encoding a human granulocyte-macrophage colony-stimulating factor (GM-CSF) receptor. The chimeric antigen receptor (CAR) protein of the delivery region is a polynucleotide, and the target binding region is the 21st glutamic acid in the amino acid sequence shown in SEQ ID NO: 1 being replaced with another amino group Acid variants.本發明係關於一種具有優異之靶細胞毒殺性之變異型嵌合抗原受體(CAR)表現細胞之製備。本發明提供一種基因修飾細胞，其係導入有編碼具有與人類粒細胞-巨噬細胞菌落刺激因子(GM-CSF)受體特異性地結合之標靶結合區、跨膜區、及細胞內訊號傳遞區之嵌合抗原受體(CAR)蛋白質之聚核苷酸者，且上述標靶結合區為序列編號1所表示之胺基酸序列中之第21號麩胺酸被置換為其他胺基酸之變異體。
