(PA-353) Analysis of Clinical Characteristics and Prognostic Factors in Patients with Primary Plasma Cell Leukemia

Current evidence on the prognostic benefits of novel agents such as proteasome inhibitors, immunomodulators, and autologous hematopoietic stem cell transplantation for primary plasma cell leukemia (pPCL) remains insufficient. Existing prognostic studies predominantly rely on retrospective data, while the prognostic value of minimal residual disease (MRD) requires further validation.

Methods:   This single-center retrospective cohort study enrolled 38 pPCL patients and 569 newly diagnosed multiple myeloma (NDMM) controls without circulating plasma cells treated at the First Affiliated Hospital of Sun Yat-sen University between January 2014 and April 2024. Clinical characteristics, genetic profiles, treatment responses, and survival outcomes were compared between groups using electronic medical records and follow-up data. For the pPCL cohort, Cox regression analyses identified independent prognostic factors to construct a scoring system, with Kaplan-Meier methodology and log-rank tests evaluating risk stratification efficacy.

Results:   

pPCL patients demonstrated significantly poorer clinical indicators and higher cytogenetic abnormality rates, particularly 1q21 amplification (76.3% vs. 40.5%, p< 0.001). The transplantation group achieved superior post-treatment MRD negativity (60.0% vs. 13.0%, p=0.004). pPCL patients exhibited inferior long-term outcomes compared to NDMM controls (median PFS: 35.30 vs. 67.87 months, p=0.001; median OS: 38.30 vs. 78.80 months, p< 0.001).

No significant prognostic differences emerged among pPCL patients stratified by R-ISS staging. Univariate Cox regression identified shared adverse prognostic factors for both PFS and OS: 1q21+ (PFS: HR=5.508, p=0.025; OS: HR=4.723, p=0.043), LDH >400 U/L (PFS: HR=4.199, p=0.004; OS: HR=4.370, p=0.007), bone marrow SUVmax≥7.2 (PFS: HR=3.608, p=0.022; OS: HR=4.346, p=0.012), and non-paramedullary extramedullary disease (PFS: HR=4.649, p=0.010; OS: HR=6.057, p=0.005). Post-treatment MRD negativity (PFS: HR=0.179, p=0.008; OS: HR=0.241, p=0.028) and transplantation (PFS: HR=0.192, p=0.003; OS: HR=0.144, p=0.002) emerged as favorable prognostic factors. Multivariate analysis confirmed paramedullary extramedullary disease as an independent adverse factor for both endpoints (PFS: HR=11.529, p=0.002; OS: HR=11.622, p=0.004).

Prognostic heterogeneity was observed among pPCL patients. After excluding 5 cases with extremely poor prognosis associated with extramedullary involvement, a prognostic stratification system incorporating 1q21+, LDH >400 U/L, bone marrow SUVmax≥7.2, transplantation status, and post-treatment MRD negativity was developed. Patients scoring ≥4 points demonstrated exceptional outcomes.

Conclusions:   

The conventional R-ISS staging system failed to effectively stratify pPCL prognosis. A novel scoring system (≥4 points) based on 1q21 amplification, LDH levels, bone marrow SUVmax, transplantation status, and MRD status successfully identified a subgroup with excellent prognosis.