Purpose: Splenic marginal lymphoma (SMZL) is a rare indolent B-cell lymphoma with long survival. The minimal residual disease (MRD) detection in indolent B-cell lymphomas has shown power in predicting survival and even in guiding treatment duration in chronic lymphocytic leukemia. As almost all SMZL patients have bone marrow involvement (BMI) at diagnosis, we prospectively designed the MRD detection during treatment to study its prognostic value in SMZL.
Methods: SMZL patients who needed chemotherapy would regularly monitor the MRD status until undetectable MRD by multiparameter flow cytometry (MFC). Patients with MRD under 0.01% were defined as uMRD. Other clinical factors were also analysed as prognostic factors.
Results: In total, 71 patients with frontline therapy were enrolled in this study. There were 284 evaluable BM MRD samples. At end of treatment, 55 patients (77.4%) got uMRD, 10 patients had a MRD level of 0.01-1%, and 6 patients had a MRD level of ≥ 1%. The uMRD rate increased at the end of treatment. With a median follow-up of 50 (24-157) months, uMRD patients showed superior outcomes compared with MRD-positive patients. Patients with uMRD had a significant better progression free survival (PFS) compared to those with MRD. PR with positive-MRD after induction therapy was a significantly poor predictor for PFS and overall survival (OS). Multivariate prognostic analysis showed it was a powerful independent prognostic factor for PFS [HR=0.357 (95%CI 0.131-0.972), P=0.044].
Conclusion: uMRD in BM was an independent prognostic factor in SMZL patients, especially for the patients only achieving PR at the end of therapy.
No relevant conflicts of interest to declare.
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