Innate CD8 T-cells as a potential predictive biomarker for deep molecular response in chronic myeloid leukemia patients.

In chronic myeloid leukemia (CML), the role of immune effectors has been suggested in the achievement of a sustained deep molecular response (DMR) and treatment-free remission (TFR) after tyrosine kinase inhibitor (TKI) discontinuation. A contributory role of the distinct new innate CD8 T-cell pool in control of CML residual disease after TKI cessation was recently highlighted. Here, we evaluated longitudinally whether innate CD8 T-cells predict CML therapy success in a cohort of newly diagnosed CML patients treated in the DASA-PegIFN clinical trial. After 3 months of treatment (M3), we observed a significant increase in innate CD8 T-cell frequency as compared to diagnosis, together with an early shift within the pool of CD8 T-cells toward an innate/memory phenotype. We also found that patients with high innate CD8 T-cell frequency at M3 achieved DMR earlier and at higher rates than patients with low innate CD8 T-cell frequency. Remarkably, this signature pre-existed at the time of diagnosis, suggesting the possible role of the patient's initial individual immune status. High innate CD8 T-cell frequency was also associated with maintaining DMR stability for 2 years. Taken together, our findings highlight innate CD8 T-cells as a potential marker for CML therapy success and TFR eligibility.