Here, it was found that the targeting of PLK1 with the PLK1 selective inhibitor volasertib (BI 6727) exerted anti-tumour effects against a range of cultured DMG cell lines, with PLK1 inhibition leading to significant G2-to-M-phase cell cycle arrest and H3.1K27M-mutant DMG cell lines showing more sensitivity than their H3.3K27M counterparts. This evidence concerns the gene PLK1 and neoplasm.