Authors
Maria D’Amato, Claudia Baratè, Clara Bono, Gaspare Tancredi, Francesca Guerrini, Edoardo Benedetti, Sara Galimberti.
Introduction
The fixed-duration treatment Rituximab (R)- Venetoclax (Ven) has revolutionized the treatment of chronic lymphocytic leukemia (CLL), achieving a 7-years overall survival rate of 69.6%, allowing for measurable residual disease (MRD) eradication. Sensitive techniques are vital for accurate MRD evaluation and response assessment.
Aim
The “Dedalus” protocol evaluates MRD using flow cytometry (MFC) and next-generation sequencing (NGS) in relapsed/refractory CLL patients treated with fixed-duration therapy R-Ven, correlating MRD status with clinical and immunological outcomes.
Materials & methods
Twenty-two CLL patients were analyzed using ERIC-compliant flow cytometry and the Lymphotrack NGS panel to detect IgH clonality with a sensitivity of 10⁻⁵. Additionally, advanced ultrasound techniques were employed to assess response. Immunological profiles and MRD were analyzed at 1, 6, 12, and 18 months or upon treatment discontinuation.
Results/Outputs
Among the 22 patients, 20 achieved complete response (CR), with MRD undetectable in 15 patients at the first checkpoint by both methods. Two patients remained in partial response (PR): in these cases, NGS outperformed MFC, detecting residual IgH clonality (3-45 clonal cell equivalents/10⁶ cells) when flow was negative. MRD detection by NGS mirrored clinical outcomes better than flow. The detection limits were 10⁻⁴ for MFC and up to 10⁻⁵ for NGS in 15% of tests. Immunologically, Ven induced significant and sustained depletion of B cells and a reduction in CD4+ T cells, altering the CD4/CD8 ratio in 25% of cases.
Conclusions
The study underscores the efficacy of R-Ven and highlights the superior accuracy of NGS over MFC in MRD detection. While MFC remains cost-effective and widely used, NGS provides deeper insights into residual disease. Future studies may explore digital PCR for IgH rearrangements as a non-invasive MRD biomarker, alongside investigations into Ven’s immunomodulatory effects in larger cohorts.
Keywords : Leukemia relapsed/refractory venetoclax
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