A conjugate of a potent cytotoxic agent with a cell-surface receptor binding molecule having a formula (I), wherein T, L, m, n, Y, R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 , R 8 , R 9 , R 10 , R 12 , and R 13 are defined herein, can be used for targeted treatment of cancer, autoimmune disease, and infectious disease.