Primary Plasma Cell Leukemia in the Era of Novel Agents: A Multicenter Study of the Japanese Society of Myeloma.

We investigated the treatment and outcome of Japanese patients with primary plasma cell leukemia (pPCL) in the era of novel agents and analyzed the risk factors affecting survival. Among 3,318 patients with symptomatic multiple myeloma (MM), 38 patients were diagnosed with pPCL. The median overall survival (OS) of the pPCL patients was 2.85 years, which was significantly extended compared with that in previous reports. The proportion of patients treated with novel agents was 61%. The OS of the patients treated with novel agents was significantly extended compared with that of patients treated without novel agents according to the generalized Wilcoxon test (2.85 vs. 1.16 years, p = 0.049). This statistical finding suggests that treatment with novel agents could have prevented early death in the patients with pPCL. Age was the only statistically significant prognostic factor associated with an inferior OS (hazard ratio 4.57). Five patients received maintenance therapy with novel agents, and their OS tended to be longer than that of the other patients without maintenance (4.45 vs. 2.85 years). Unlike MM, OS for pPCL has not been improved significantly over the last decade, especially in elderly patients. Therefore, it is important to establish the treatment strategy, particularly after induction treatment.