The present invention relates to antisense oligonucleotides for modulating the activity of PRDM15 and use thereof in the treatment of cancer. In particular, said antisense oligonucleotides are capable of inducing the skipping of an exon of a PRDM15 mRNA. The present invention also relates to a method for determining prognosis in a patient with cancer, or selecting a therapeutic strategy for a patient with cancer, by assessing the level of PRDM15 nucleic acid, protein or activity in a sample.