Poor outcome despite modern treatments: A retrospective study of 99 patients with primary and secondary plasma cell leukemia

Background Plasma cell leukemia (PCL) is a rare monoclonal gammopathy, associated with short survival. Because of its very low incidence, only a few cohorts have been reported and thus, information on this disease is scarce. The goal of this study was to better understand the clinical features, prognostic factors, and efficacy of modern treatments in both primary PCL (pPCL) and secondary PCL (sPCL). Methods We performed a retrospective, multicenter study of patients diagnosed with PCL, defined as circulating plasma cells ≥20% of total leukocytes and/or ≥2 × 109/L. Results We identified 99 eligible PCL patients, of whom 33 were pPCL and 66 were sPCL. The median progression‐free survival (PFS) to frontline treatment and overall survival (OS) were, respectively, 4.8 (95% CI, 0.4–9.2) and 18.3 months (95% CI, 0.0–39.0) for pPCL and 0.8 (95% CI, 0.5–1.1) and 1.2 months (95% CI, 0.9–1.5) for sPCL (both p