Smoldering Multiple Myeloma (SMM) is a plasma cell disorder defined by the presence of ≥10% plasma cells in bone marrow and/or a monoclonal protein level of ≥3 g/dl in serum without organ damage. The aim of the study was to analyze the prognostic impact of chromosomal aberrations on time to progression (TTP) from SMM to symptomatic MM.
For selection of the patients, we used the same criteria as previously described by Kyle (Kyle et al., NEJM, 2007). We analyzed the prognostic value of 5 chromosomal abnormalities and hyper-/non-hyperdiploidy (HD and NHD, respectively) in a series of 231 patients with SMM by fluorescent in situ hybridization (FISH). Gains of at least 2 of the 3 chromosomes 5, 9, and 15 defined HD status.
Interphase-FISH analysis on CD138-enriched plasma cells detected gains of chromosomes 1q21 (29.4%) as well as deletions of chromosomes 13q14 (19.3%) and 17p13 (6.1%). Furthermore, the IgH-translocations t(4;14) and t(11;14) were observed in a frequency of 9.2% and 22.3%, respectively. The presence of t(4;14) was correlated with the serum heavy chain IgA (p<0.001). For the entire group, the median TTP was 4.9 years (95% CI, 3.9 – NA). Of all analyzed chromosomal abnormalities, del(17p13), t(4;14), and +1q21 showed a significant impact on TTP, whereas the presence of t(11;14) and del(13q14) was of no statistical significance. The median TTP for patients with del(17p13) was 2.7 years (vs. 4.9 years without, p=0.019), with t(4;14) 2.9 years (vs. 5.2 years without, p=0.021), and with +1q21 3.7 years (vs. 5.3 years without, p=0.013), respectively. In addition, HD was associated with a statistically shorter median TTP of 3.9 vs. 5.7 years in patients with NHD, respectively (p=0.036). A multivariate analysis identified t(4;14), +1q21, HD, reduction of uninvolved immunoglobulins (no.), and the risk score defined by Kyle et al. as independent factors for adverse outcome.
The study shows that the overall risk of progression in SMM is significantly influenced by markers for tumor burden (i.e. Kyle risk score) as well as the presence of the chromosomal aberrations del(17p13), t(4;14), and +1q21. Our findings provide evidence that specific chromosomal aberrations are not only associated with early tumor progression and drug resistance in patients with overt MM but also to drive transition from asymptomatic into symptomatic stage of disease.
No relevant conflicts of interest to declare.
Asterisk with author names denotes non-ASH members.