The impact of biomarkers of malignancy (IMWG SLiM criteria) in myeloma in a real-world population: Clinical characteristics, therapy and outcomes from the Australian and New Zealand Myeloma and Related Diseases Registry (ANZ MRDR).

A decade after International Myeloma Working Group (IMWG) biomarkers (SLiM criteria) were introduced, this real-world study examined their impact on diagnosis, therapy and outcomes in myeloma. Using the ANZ MRDR, 3489 newly diagnosed patients from 2013 to 2023, comprising 3232 diagnosed by CRAB ('CRAB patients', including 1758 who also satisfied ≥1 SLiM criteria) and 257 by SLiM ('SLiM patients') criteria were analysed. CRAB patients had higher R-ISS and lower performance status, with no difference in cytogenetic risk. SLiM patients had improved progression-free survival (PFS, 37.5 vs. 32.2 months, hazard ratio [HR] 1.31 [1.08-1.59], p = 0.003), overall survival (80.9 vs. 73.2 months, HR 1.64 [1.26-2.13], p < 0.001) and PFS2 (54.6 vs. 40.3 months, HR 1.51 [1.22-1.86], p < 0.001) compared with CRAB patients, partially explained by earlier diagnosis, with no differential impact between the plasma cell and light-chain criteria on PFS. However, 34% of CRAB patients did not manifest SLiM characteristics, raising the possibility that SLiM features are associated with different biological behaviours contributing to a better prognosis, for example, improved PFS2 in SLiM patients suggested less disease resistance at first relapse. These data support earlier initiation of therapy by SLiM. The superior survival outcomes of SLiM versus CRAB patients highlight the importance of defining these subgroups when interpreting therapeutic outcomes at induction and first relapse.