Transcriptional characterization of a prospective series of primary plasma cell leukemia revealed genes associated with tumor progression and poorest outcome

Plasma cell leukemia (PCL) is a rare form of plasma cell dyscrasia that presents either as a progression of previously diagnosed multiple myeloma (MM), namely secondary PCL (sPCL), or as the initial manifestation of disease, namely primary PCL (pPCL). Although presenting signs and symptoms include those seen in MM, pPCL is characterized by several aspects that clearly define more aggressive course. To provide insights into the biology of pPCL, we have investigated the transcriptional profiles of a cohort of 21 newly-diagnosed, homogeneously treated pPCL patients included in a multicenter prospective clinical trial. All but one pPCL had one of the main IGH translocations, whose associated transcriptional signatures resembled those observed in MM. A 503-gene signature was identified that distinguished pPCL from MM, from which emerged 28 genes whose trend in expression levels was found associated with the progressive stages of plasma cell dyscrasia in a large dataset of cases from multiple institutions, including samples from normal donors throughout PCL. The transcriptional pattern of the pPCL series was then evaluated in association with outcome. Three genes were identified having expression levels correlated with response to the first-line treatment with lenalidomide/dexamethasone, whereas a 27-gene signature was identified associated with overall survival independently of molecular alterations, hematological parameters and renal function. Overall, our data contribute to a fine dissection of pPCL and may provide novel insights into the molecular definition of a subgroup of high-risk pPCL.

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Todoerti K, Agnelli L, Fabris S, Lionetti M, Tuana G, Mosca L, Lombardi L, Grieco V, Bianchino G, D'Auria F, Statuto T, Mazzoccoli C, De Luca L, Petrucci MT, Morabito F, Offidani M, Di Raimondo F, Falcone A, Omede' P, Tassone P, Boccadoro M, Palumbo A, Neri A, Musto P