Genomic Aberrations and Survival of Patients with Light-Chain-Only Multiple Myeloma Undergoing Autologous Stem Cell Transplantation

The majority of patients with multiple myeloma (MM) have intact immunoglobulin, but in a subset of patients (∼15%), their tumors produce monoclonal light chains only (LCO). Although specific genomic aberrations have emerged as a major prognostic factor in MM, their incidence and prognostic impact on LCO myeloma patients are not clear. We therefore investigated a cohort of 86 LCO MM cases diagnosed and treated with autologous stem cell transplantation at our institution. Overall, genomic risk factors del(13q), del(17p), t(4;14), 1p loss, and 1q21 gain were detected by cytoplasmic fluorescence in situ hybridization (cIg-FISH) in 40.6%, 18.5%, 11.9%, 18.8%, and 25% of the cases, respectively. Patients with del(13q) and 1q gains had a significantly shorter overall survival (OS) (median 80.4 vs 56.2 months, P = .021; median 77.9 vs 26.9 months, P = .006, respectively) and shorter progression-free survival (PFS) (median 33.4 vs 15.8 months, P = .002; median 33.4 vs 19.1 months, P = .011, respectively) than those without the genetic abnormalities. In addition, 1p loss was significantly associated with shorter PFS (median 37.9 vs 18.2 months, P = .001). There was no significant difference in PFS or OS in patients with or without t(4;14) or del(17p). On multivariate analysis, del(13q) was an independent prognostic factor for PFS and OS.