Primary plasma cell leukemia: Clinical and laboratory presentation, gene-expression profiling and clinical outcome with Total Therapy protocols

To determine whether primary plasma cell leukemia (PPCL) remains a high-risk multiple myeloma feature in the context of contemporary therapy and gene-expression profiling (GEP), we reviewed records of 1474 patients with myeloma, who were enrolled in Total Therapy protocols or treated identically off protocol. A total of 27 patients (1.8%) were classified as having PPCL. As a group, these patients more often had low hemoglobin, high beta-2-microglobulin, high lactate dehydrogenase, low albumin and cytogenetic abnormalities. Among 866 patients with GEP results, the PPCL group more often had disease that was classified as high risk, and in CD-1 and MF molecular subgroups. Regardless of the therapeutic protocol, patients with PPCL had shorter median overall survival (OS; 1.8 years), progression-free survival (PFS; 0.8 years) and complete response duration (CRD; 1.3 years) than the remainDer, whose clinical outcomes had improved markedly with successive protocols. Multivariate analyses of pretreatment parameters showed that PPCL was a highly significant independent adverse feature linked to OS, PFS and CRD. In GEP analyses, 203 gene probes distinguished PPCL from non-PPCL; the identified genes were involved in the LXR/RXR activation, inositol metabolism, hepatic fibrosis/hepatic stellate-cell activation and lipopolysaccharide/interleukin-1-mediated inhibition of RXR function pathways. Different treatment approaches building on these genomic differences may improve the grave outcome of patients with PPCL.