Reduced prognostic value of beta-2-microglobulin for time to first treatment in CLL patients with compromised kidney function.

Chronic lymphocytic leukemia (CLL) is the most common leukemia in adults and characterized by a highly heterogeneous clinical course. The CLL-IPI and the OCLL-1 scores are among the best validated tools to predict time-to-first-treatment. In both models, elevated beta-2-microglobulin plasma level (B2M) is an independent prognostic factor. Yet, B2M is commonly increased in patients with chronic kidney disease (CKD) per se and both models were not adjusted for CKD. We analyzed the clinical outcomes of 297 treatment-naive CLL patients between 2000 and 2022. B2M was more frequently elevated in CKD patients and lost prognostic significance at the threshold > 2.5 mg/L. Both CLL-IPI and OCLL-1 failed to facilitate prognostic segregation in CKD patients. 22.2% of CKD patients were assigned to a higher CLL-IPI risk group due to elevated B2M. Our results suggest that both models overestimate the risk for disease progression and need to be interpreted with caution in CKD patients.