Monoclonal B-cell lymphocytosis, monoclonal gammopathy of undetermined significance, and T-cell clones of uncertain significance: are these premalignant conditions sharing a common identity?

Genomic instability and genetic heterogeneity in aging: insights from clonal hematopoiesis (CHIP), monoclonal gammopathy (MGUS), and monoclonal B-cell lymphocytosis (MBL)

Aging is a multifaceted process characterized by a gradual decline in physiological function and increased susceptibility to a range of chronic diseases. Among the molecular and cellular mechanisms driving aging, genomic instability is a fundamental hallmark, contributing to increased mutation load and genetic heterogeneity within cellular populations. This review explores the role of genomic instability and genetic heterogeneity in aging in the hematopoietic system, with a particular focus on clonal hematopoiesis of indeterminate potential (CHIP), monoclonal gammopathy of undetermined significance (MGUS), and monoclonal B-cell lymphocytosis (MBL) as biomarkers. CHIP involves the clonal expansion of hematopoietic stem cells with somatic mutations. In contrast, MGUS is characterized by the presence of clonal plasma cells producing monoclonal immunoglobulins, while MBL is characterized by clonal proliferation of B cells. These conditions are prevalent in the aging population and serve as measurable indicators of underlying genomic instability. Studying these entities offers valuable insights into the mechanisms by which somatic mutations accumulate and drive clonal evolution in the hematopoietic system, providing a deeper understanding of how aging impacts cellular and tissue homeostasis. In summary, the hematopoietic system serves as a powerful model for investigating the interplay between genomic instability and aging. Incorporating age-related hematological conditions into aging research, alongside other biomarkers such as epigenetic clocks, can enhance the precision and predictive power of biological age assessments. These biomarkers provide a comprehensive view of the aging process, facilitating the early detection of age-related diseases and hopefully enabling personalized healthcare strategies.

cyTRBC1 evaluation rapidly identifies sCD3-negative peripheral T-cell lymphomas and reveals a novel type of sCD3-negative T-cell clone with uncertain significance

The flow cytometry-based evaluation of TRBC1 expression has been demonstrated as a rapid and specific method for detecting T-cell clones in sCD3-positive TCRαβ+ mature T-cell lymphoma. The aim of the study was to validate the utility of surface (s) TRBC1 and cytoplastic (cy) TRBC1 assessment in detecting clonality of sCD3-negative peripheral T-cell lymphomas (PTCLs), as well as exploring the existence and characteristics of sCD3-negative clonal T-cell populations with uncertain significance (T-CUS). Evaluation of sTRBC1 and cyTRBC1 were assessed on 61 samples from 37 patients with sCD3-negative PTCLs, including 26 angioimmunoblastic T-cell lymphoma (AITL) patients and 11 non-AITL patients. The sCD3-negative T-CUS were screened from 1602 patients without T-cell malignancy and 100 healthy individuals. Additionally, the clonality of cells was further detected through T-cell gene rearrangement analysis. We demonstrated the monotypic expression patterns of cyTRBC1 in all sCD3-negative PTCLs. Utilizing the cyTRBC1 evaluation assay, we identified a novel and rare subtype of sCD3-negative T-CUS for the first time among 13 out of 1602 (0.8%) patients without T-cell malignancy. The clonality of these cells was further confirmed through T-cell gene rearrangement analysis. This subset exhibited characteristics such as sCD3-cyCD3 + CD4 + CD45RO+, closely resembling AITL rather than non-AITL. Further analysis revealed that sCD3-negative T-CUS exhibited a smaller clone size in the lymph node and mass specimens compared to AITL patients. However, the clone size of sCD3-negative T-CUS was significantly lower than that of non-AITL patients in both specimen groups. In conclusion, we validated the diagnostic utility of cyTRBC1 in detecting sCD3-negative T-cell clonality, provided a comprehensive analysis of sCD3-negative T-CUS, and established a framework and provided valuable insights for distinguishing sCD3-negative T-CUS from sCD3-negative PTCLs based on their phenotypic properties and clone size.

A tower of babel of acronyms? The shadowlands of MGUS/MBL/CHIP/TCUS

With the advent of outperforming and massive laboratory tools, such as multiparameter flow cytometry and next-generation sequencing, hematopoietic cell clones with putative abnormalities for a variety of blood malignancies have been appreciated in otherwise healthy individuals. These conditions do not fulfill the criteria of their presumed cancer counterparts, and thus have been recognized as their precursor states. This is the case of monoclonal gammopathy of unknown significance (MGUS), the first blood premalignancy state described, preceding multiple myeloma (MM) or Waldenström macroglobulinemia (WM). However, in the last 2 decades, an increasing list of clonopathies has been recognized, including monoclonal B cell lymphocytosis (MBL), which antecedes chronic lymphocytic leukemia (CLL), clonal hematopoiesis of indeterminate potential (CHIP) for myeloid neoplasms (MN), and T-cell clones of uncertain significance (TCUS) for T-cell large chronic lymphocytic leukemia (LGLL). While for some of these entities diagnostic boundaries are precisely set, for others these are yet to be fully defined. Moreover, despite mostly considered of "uncertain significance," they have not only appeared to predispose to malignancy, but also to be capable of provoking set of immunological and cardiovascular complications that may require specialized management. The clinical implications of the aberrant clones, together with the extensive knowledge generated on the pathogenetic events driving their evolution, raises the question whether earlier interventions may alter the natural history of the disease. Herein, we review this Tower of Babel of acronyms pinpointing diagnostic definitions, differential diagnosis, and the role of genomic profiling of these precursor states, as well as potential interventional strategies.

The constitutive activation of STAT3 gene and its mutations are at the crossroad between LGL leukemia and autoimmune disorders

Type T Large Granular Lymphocyte Leukemia (T-LGLL) is a chronic disorder characterized by the abnormal proliferation of clonal cytotoxic T cells. The intriguing association of T-LGLL with autoimmune and inflammatory diseases, the most prominent example being rheumatoid arthritis, raises questions about the underlying pathophysiologic relationships between these disorders which share several biological and clinical features, most notably neutropenia, which is considered as a clinical hallmark. Recent progress in molecular genetics has contributed to a better understanding of pathogenetic mechanisms, thus moving our knowledge in the field of LGL leukemias forward. Focusing on the constitutive activation of STAT3 pathway and the well-established role of STAT3 mutations in T-LGLL, we herein discuss whether the T cell clones occurring in comorbid conditions are the cause or the consequence of the immune-inflammatory associated events. Overall, this review sheds light on the intricate relationships between inflammation and cancer, emphasizing the importance of the STAT3 gene and its activation in the pathophysiology of these conditions. Gaining a deeper understanding of these underlying mechanisms seeks to pave the way for the development of novel targeted therapies for patients affected by inflammation-related cancers.