Multiple myeloma immunoglobulin lambda translocations portend poor prognosis

Multiple myeloma is a malignancy of antibody-secreting plasma cells. Most patients benefit from current therapies, however, 20% of patients relapse or die within two years. To better understand and identify these ‘high-risk’ cases, we analyzed the translocation landscape of myeloma from 795 newly-diagnosed patients by whole genome sequencing from the CoMMpass study. Translocations involving the immunoglobulin lambda (IgL) locus were identified in 10% of patients, and were indicative of poor prognosis. Importantly, 70% of IgL translocations co-occurred with hyperdiploid disease, a marker of standard risk, potentially resulting in the misclassification of IgL-translocated myeloma. Most IgL-translocations coincided with focal amplifications that were centered on the 3’ enhancer. Patients with IgL-translocations failed to benefit from immunomodulatory imide drugs (IMiDs), which target the lymphocyte-specific transcription factor IKZF1 that is bound to the IgL 3’ enhancer at some of the highest levels in the myeloma epigenome. These data implicate IgL-translocation as a driver of poor prognosis which may be due in part to IMID resistance. Several myeloma cell lines were characterized for chromatin accessibility