Dear Editor Extrachromosomal DNA (ecDNA), a major focal oncogene amplification mode found across cancer, has recently regained attention as an emerging cancer hallmark 1,2 , with a pervasive presence across cancers 3,4 . With technical advancements such as high-coverage sequencing and live-cell genome imaging, we can now investigate ecDNA's behaviors and functions 5-7 . However, we still lack an understanding of how to eliminate ecDNA. We observed depletion of cells containing ecDNA during lentiviral but not transposon-based transduction while we sought to investigate the mechanism of ecDNA behavior. This discovery may provide critical information on utilizing a lentiviral system in emerging ecDNA research. Additionally, this observation suggests specific sensitivities for cells with ecDNA.