Based on our previous work, we initiated a medicinal chemistry program aimed at modifying the structure of the pyrimidine diamine to further increase the inhibitory activity of BCL6, ultimately obtaining the highly effective BCL6 inhibitor YK01 with [1,2,4]triazoline [1,5-a] pyrimidine structural skeleton, and evaluated its biological functions and possible mechanism in inhibiting GBM. This evidence concerns the gene BCL6 and glioblastoma.