Plasma cell leukemia: A multicenter retrospective study of 150 patients.

8014 Background: Despite the use of novel induction regimens, stem cell transplantation (SCT), and maintenance therapy, plasma cell leukemia (PCL) remains a challenging disease with a dismal prognosis. Currently, there is no agreed standard of care management for PCL. We conducted a multicenter retrospective analysis of the clinical presentation, treatment, and outcomes of 150 patients with PCL. Methods: Data of patients diagnosed with pPCL or sPCL between 01/2010 and 01/2021 were entered into a study-specific REDCap database from 7 different U.S. academic sites. PCL was defined as ≥ 5% circulating plasma cells. Clinical data included baseline patient characteristics, clinical presentation, treatment, therapeutic response, and survival outcomes. Overall survival (OS) curves were plotted using the Kaplan-Meier method. Cox proportional hazards regression tested associations between patient characteristics and OS, generating hazard ratios (HR) and 95% confidence intervals (CI), adjusted for PCL type (primary or secondary) and SCT. Results: The analytical cohort included 93 pPCL and 57 sPCL patients. Median age at diagnosis was 60 years. High-risk cytogenetics were found in 56.7% of the patients where it was documented. Of the 79 patients with a documented induction regimen, 58.2% received a proteasome inhibitor triplet, 22.8% received a VTD-Pace like conventional chemotherapy, and 3% received a daratumumab quadruplet regimen. SCT (autologous or allogeneic) was done in 56.1% of the patients. The median OS for all patients, those with pPCL, and those with sPCL was 20.3, 36.6, and 3.2 months, respectively. Secondary PCL was associated with worse survival outcomes compared with pPCL (HR, 2.46; 95% CI, 1.51-3.98; p<0.001) (Table). Median OS was better in patients treated with a proteasome inhibitor triplet regimen vs VTD PACE-like combination (28.2 versus 12.6 months). OS was prolonged among patients who underwent any type of SCT compared with those who did not undergo SCT (44.0 versus 5.7 months, p<0.001). Conclusions: This multicenter retrospective study is one of the largest PCL analyses performed to date and reveals the clinical practice patterns of treatment and survival of PCL patients across the U.S. in the novel treatment era. The survival analysis reinforces the poor prognosis in sPCL patients and the continued need for novel treatment approaches in this patient population. While limited by retrospective design, this analysis suggests prolonged survival with transplantation in both pPCL and sPCL. Table: see text