PML and multiple sclerosis: Therefore, to provide further insights into molecular mechanisms in topoII-related leukemias, we analyzed a cohort of 12 patients collected from across Europe who developed APL following the use of single agent mitoxantrone to treat a benign condition, multiple sclerosis (MS), and in whom there was no history of previous cancer.38 Chromosome 15 breakpoints again were found to cluster at position 1484 within PML intron 6.