High NK Cell Levels at the End of Obinutuzumab Treatment Are Associated with Negative Minimal Residual Disease (MRD) in Chronic Lymphocytic Leukemia (CLL)

NK-cell antibody-dependent cell-mediated cytotoxicity (ADCC) is one of the main mechanisms of action of anti-CD20 monoclonal antibodies, which may affect the outcome of patients with chronic lymphocytic leukemia (CLL). We assessed whether high post-treatment NK-cell count in peripheral blood was associated with increased negative minimal residual disease (MRD) in patients receiving antibody-based therapy. Obinutuzumab forces the interaction between NK cells and CLL cells, making the number of NK cells critical for the efficacy of this monoclonal antibody. Normal NK cell counts after Obinutuzumab monotherapy are associated with achieving MRD-negative status. Group A, who did not achieve MRD-negative status, had a mean NK cell count of 36.86 cells/µL, while Group B, who achieved MRD-negative status, had a mean NK cell count of 202.29 cells/µL. NK-cell counts and MRD were measured three months after the completion of Obinutuzumab treatment. The differences were statistically significant (p < 0.05). These results underscore the relevance of evaluating NK-cell counts as a potential biomarker to predict the success of Obinutuzumab treatment. In conclusion, our study suggests that elevated NK-cell counts after Obinutuzumab treatment are associated with MRD-negative status in CLL patients.