Should Undetectable Minimal Residual Disease Be the Goal of Chronic Lymphocytic Leukemia Therapy?

MicroRNA Signatures: Illuminating Minimal Residual Disease Monitoring in Juvenile Myelomonocytic Leukemia - A Review

Juvenile myelomonocytic leukemia (JMML) is an aggressive pediatric myelodysplastic/myeloproliferative neoplasm characterized by RAS pathway mutations and significant heterogeneity. Minimal residual disease (MRD) monitoring is crucial for evaluating treatment response and predicting relapse risk. MicroRNA (miRNAs), small non-coding RNAs with pivotal roles in gene regulation, have emerged as promising biomarkers for JMML MRD detection. This review explores the mechanistic role of miRNAs in JMML pathogenesis, emphasizing their diagnostic, prognostic, and therapeutic potential. Dysregulated miRNA profiles correlate with distinct JMML subgroups and disease progression, suggesting utility in non-invasive MRD monitoring. Emerging evidence highlights miR-150-5p as a tumor suppressor targeting STAT5b and its therapeutic potential in ameliorating JMML's aberrant signaling pathways. We compare traditional MRD methods, such as flow cytometry and polymerase chain reaction (PCR), with miRNA-based techniques, underscoring the latter's superior sensitivity, specificity, and non-invasiveness. Recent advances in miRNA profiling technologies, including next-generation sequencing and digital PCR, enable precise detection of residual leukemic cells and support personalized treatment approaches. Despite significant progress, challenges persist in standardizing miRNA-based assays and validating their clinical utility. Ethical considerations, including patient privacy and informed consent, remain critical for integrating miRNA diagnostics into routine care. This review provides a comprehensive synthesis of current knowledge on miRNA signatures in JMML, illuminating their transformative potential in MRD monitoring and paving the way for innovative therapeutic strategies.

Cluster of Differentiation Markers and Human Leukocyte Antigen Expression in Chronic Lymphocytic Leukemia Patients: Correlations and Clinical Relevance

Chronic lymphocytic leukemia (CLL) is a distinct category of lymphoproliferative disorder characterized by the clonal expansion of mature B cells, followed by their accumulation in primary and secondary lymphoid organs. Cluster of differentiation (CD) markers such as CD79b, CD45, CD23, CD22 and CD81 serve as reliable prognostic indicators in CLL as well as the human leukocyte antigen (HLA) with its well-documented associations with various cancers. This study aims to investigate, for the first time, potential connections between HLA typing and CD marker expression in CLL. Although it is one of the most prevalent neoplasms, there is a need for biomarkers that can improve survival. This study included 66 CLL patients and 100 controls, with all samples analyzed using biochemical methods, flow cytometry, and cytomorphology. Next-generation sequencing was performed for HLA typing. The results indicate that several CD markers are statistically associated with different HLA alleles, specifically CD45 with HLA-C*07:01:01; CD79b with HLA-DPA1*02:01:02; CD23 with HLA-B*39:01:01; CD22 with HLA-B*49:01:01, HLA-C*07:01:01, HLA-DPB1*02:01:02, and HLA-DRB1*07:01:01; and CD81 with HLA-DPB1*04:02:01, HLA-DQA1*01:04:01, and HLA-DQB1*05:03:01. In conclusion, this research demonstrates significant statistical links between HLA genes and immunophenotypic markers in CLL patients, shedding new light on the immunological context of CLL.

Research Topic: Measurable Residual Disease in Hematologic Malignancies. Can digital droplet PCR improve measurable residual disease monitoring in chronic lymphoid malignancies?

Minimal/measurable residual disease (MRD) monitoring is progressively changing the management of hematologic malignancies. The possibility of detecting the persistence/reappearance of disease in patients in apparent clinical remission offers a refined risk stratification and a treatment decision making tool. Several molecular techniques are employed to monitor MRD, from conventional real-time quantitative polymerase chain reaction (RQ-PCR) to next generation sequencing and digital droplet PCR (ddPCR), in different tissues or compartments through the detection of fusion genes, immunoglobulin and T-cell receptor gene rearrangements or disease-specific mutations. RQ-PCR is still the gold standard for MRD analysis despite some limitations. ddPCR, considered the third-generation PCR, yields a direct, absolute, and accurate detection and quantification of low-abundance nucleic acids. In the setting of MRD monitoring it carries the major advantage of not requiring a reference standard curve built with the diagnostic sample dilution and of allowing to reduce the number of samples below the quantitative range. At present, the broad use of ddPCR to monitor MRD in the clinical practice is limited by the lack of international guidelines. Its application within clinical trials is nonetheless progressively growing both in acute lymphoblastic leukemia as well as in chronic lymphocytic leukemia and non-Hodgkin lymphomas. The aim of this review is to summarize the accumulating data on the use of ddPCR for MRD monitoring in chronic lymphoid malignancies and to highlight how this new technique is likely to enter into the clinical practice.

Novel combination approaches with targeted agents in frontline chronic lymphocytic leukemia

Targeted therapies have revolutionized the frontline treatment landscape for patients with chronic lymphocytic leukemia (CLL) and have largely displaced a reliance on chemoimmunotherapy when treating this disease. Multiple randomized trials have documented the efficacy of oral therapy with the Bruton tyrosine kinase inhibitors ibrutinib and acalabrutinib (and zanubrutinib, pending a supplemental new drug application in CLL), as well as BCL2 inhibition using venetoclax. In this review, the authors highlight novel therapeutic strategies for using these agents in combination, either as doublet therapy or as triplet therapy, with anti-CD20 antibodies. First, the current treatment landscape is outlined, and the data are reviewed for continuous and time-limited therapeutic approaches, which constitute the current standard of care. Then, more recent reports are described from phase 2 and 3 studies exploring different combination strategies of Bruton tyrosine kinase and BCL2 inhibition for treatment-naive patients. In addition, relevant differences are emphasized between patient characteristics (e.g., patient fitness and the presence of high-risk disease features) and study methodology (e.g., dosing schedule, randomization, and assessment of measurable residual disease) across trials. Finally, the authors revisit the currently available data for these approaches in the context of ongoing studies and future planned trials, evaluating their potential impact on the frontline treatment landscape for CLL in the years to come.

High-Throughput immunogenetics for precision medicine in cancer

Cancer is characterized by an extremely complex biological background, which hinders personalized therapeutic interventions. Precision medicine promises to overcome this obstacle through integrating information from different 'subsystems', including the host, the external environment, the tumor itself and the tumor micro-environment. Immunogenetics is an essential tool that allows dissecting both lymphoid cancer ontogeny at both a cell-intrinsic and a cell-extrinsic level, i.e. through characterizing micro-environmental interactions, with a view to precision medicine. This is particularly thanks to the introduction of powerful, high-throughput approaches i.e. next generation sequencing, which allow the comprehensive characterization of immune repertoires. Indeed, NGS immunogenetic analysis (Immune-seq) has emerged as key to both understanding cancer pathogenesis and improving the accuracy of clinical decision making in oncology. Immune-seq has applications in lymphoid malignancies, assisting in the diagnosis e.g. through differentiating from reactive conditions, as well as in disease monitoring through accurate assessment of minimal residual disease. Moreover, Immune-seq facilitates the study of T cell receptor clonal dynamics in critical clinical contexts, including transplantation as well as innovative immunotherapy for solid cancers. The clinical utility of Immune-seq represents the focus of the present contribution, where we highlight what can be achieved but also what must be addressed in order to maximally realize the promise of Immune-seq in precision medicine in cancer.

Multiparametric Flow Cytometry for MRD Monitoring in Hematologic Malignancies: Clinical Applications and New Challenges

Simple Summary

In hematologic cancers, Minimal Residual Disease (MRD) monitoring, using either molecular (PCR) or immunophenotypic (MFC) diagnostics, allows the identification of rare cancer cells, readily detectable either in the bone marrow or in the peripheral blood at very low levels, far below the limit of classic microscopy. In this paper, we outlined the state-of-the-art of MFC-based MRD detection in different hematologic settings, highlighting main recommendations and new challenges for using such method in patients with acute leukemias or chronic hematologic neoplasms. The combination of new molecular technologies with advanced flow cytometry is progressively allowing clinicians to design a personalized therapeutic path, proportionate to the biological aggressiveness of the disease, in particular by using novel immunotherapies, in view of a modern decision-making process, based on precision medicine.

Abstract

Along with the evolution of immunophenotypic and molecular diagnostics, the assessment of Minimal Residual Disease (MRD) has progressively become a keystone in the clinical management of hematologic malignancies, enabling valuable post-therapy risk stratifications and guiding risk-adapted therapeutic approaches. However, specific prognostic values of MRD in different hematological settings, as well as its appropriate clinical uses (basically, when to measure it and how to deal with different MRD levels), still need further investigations, aiming to improve standardization and harmonization of MRD monitoring protocols and MRD-driven therapeutic strategies. Currently, MRD measurement in hematological neoplasms with bone marrow involvement is based on advanced highly sensitive methods, able to detect either specific genetic abnormalities (by PCR-based techniques and next-generation sequencing) or tumor-associated immunophenotypic profiles (by multiparametric flow cytometry, MFC). In this review, we focus on the growing clinical role for MFC-MRD diagnostics in hematological malignancies—from acute myeloid and lymphoblastic leukemias (AML, B-ALL and T-ALL) to chronic lymphocytic leukemia (CLL) and multiple myeloma (MM)—providing a comparative overview on technical aspects, clinical implications, advantages and pitfalls of MFC-MRD monitoring in different clinical settings.