Therapy-related myeloid neoplasms following treatment for multiple myeloma-a single center analysis.

Myelodysplastic syndromes (MDS) and acute myeloid leukemia (AML) can be late complications following mutagenic treatment. Limited data is available on the outcome of patients developing therapy-related MDS and AML after treatment for multiple myeloma (MM). We identified 250 patients with therapy-associated MDS or AML in the Duesseldorf MDS registry. Of those, 50 patients were previously diagnosed with multiple myeloma (mm-MDS/AML). We compared them to patients with de novo MDS (n = 4862) and to patients with MDS following other underlying diseases (tMDS) (n = 200). mm-MDS patients and tMDS patients showed similar karyotypes and degrees of cytopenia. However, mm-MDS patients had significantly higher blast counts and more often belonged to the high-risk group according to the International Prognostic Scoring System (IPSS) (both p < 0.05). Although the rate of progression to AML was similar in mm-MDS and tMDS, both transformed significantly more often than de novo MDS (p < 0.05). Median overall survival of patients with mm-MDS (13 months; range: 1-99) and tMDS (13 months; range 0-160) was also similar yet significantly shorter than patients with de novo MDS (32 months; range 0-345 months; p < 0.05). Furthermore, survival of mm-MDS patients was not affected by myeloma activity. Despite significantly more high-risk disease and higher blast cell counts, myeloma-associated MDS-patients show features akin to other tMDS. Survival is similar to other tMDS and irrespective of myeloma remission status or transformation to AML. Thus, patient outcome is not determined by competing clones but rather by MDS governing the stem cell niche.