Comparison of time to therapy initiation, therapeutic strategies and survival in patients with MDS IB1, IB2 and AML-MR using data of the duesseldorf registries

In 2022, the ICC redefined AML by lowering marrow blast count to 10% herewith integrating former MDS IB2 into AML. To evaluate the clinical implications of this reclassification, we analyzed data of our Duesseldorf registries regarding different aspects in patients with MDS IB1, IB2 or AML-MR and included 928 patients suffering from IB1 (213 patients), IB2 (279 patients) and AML-MR (436 patients). We analyzed time to initiation of treatment as well as treatment strategies and survival times. Time to initiation of therapy was significantly shorter in patients with AML-MR compared to MDS IB2 and IB1 (0.5 vs. 2 vs. 5 months, p < 0.001). Median overall survival was 12 months in patients with AML-MR, 19 months in MDS IB2 and 27 months in MDS IB1 (p < 0.001). Regarding most intensive treatment, median overall survival did not differ significantly in patients undergoing allografting or induction chemotherapy but was significantly longer (p < 0.001) in patients with MDS IB1 or IB2 compared to AML-MR receiving HMA (29 vs. 20 vs. 9 months), low dose chemotherapy (18 vs. 11 vs. 1 months) or BSC only (16 vs. 9 vs. 2 months). The significantly longer time to treatment initiation together with the prolonged median overall survival and survival following treatment with hypomethylating agents (HMAs) or low-dose chemotherapy suggests biologically relevant differences between AML-MR and MDS-IB2 that may not support their classification as a single disease entity.