Genetic lesions associated with chronic lymphocytic leukemia transformation to Richter syndrome

Bcor loss promotes Richter transformation of chronic lymphocytic leukemia associated with Notch1 activation in mice

Richter's transformation (RT) is an aggressive lymphoma occurring upon progression from chronic lymphocytic leukemia (CLL). Despite advances in deciphering the RT genetic architecture, the mechanisms driving this disease remain unknown. BCOR disruptive mutations were found in CLL and frequently associated with NOTCH1 aberrations, a common feature in CLL and RT. We engineered mice to knock-out Bcor in B and CLL cells of Eμ-TCL1 mice. Bcor loss resulted in alterations of the B cell compartment and favored CLL transformation into an aggressive lymphoma with reduced survival in Eμ-TCL1 mice. RNA-sequencing demonstrated a molecular signature reminiscent of human RT and implied the involvement of the T cell tumour microenvironment in the disease onset. Bcor deficiency was associated with Notch1 activation in splenic CD19 + CD5+ cells to accelerate Eμ-TCL1 mice lymphoproliferation. Notch1 inhibition progressively reduced circulating CD19+ CD5+ and RT cells infiltrating the spleen of diseased mice with concomitant reduction of PD-1 expressing T cells and improved survival. Our data demonstrated an interplay between the tumour suppressor activity of Bcor and Notch1 in RT pathogenesis with potential for tumour targeting. This model represented a new platform to uncover promising alternatives for this incurable tumour.

"Accelerated" chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL): unraveling the biological gray zone of CLL/SLL in the era of novel therapies

Accelerated chronic lymphocytic leukemia/small lymphocytic lymphoma (A-CLL/SLL) is a histologically aggressive subtype of CLL/SLL that lies in between conventional CLL/SLL (C-CLL/SLL) and Richter transformation (RT) on the biological spectrum. Although the histologic criteria for A-CLL/SLL were defined 14 years ago, the clinical and genetic characteristics and survival outcomes of these patients have yet to be studied in the era of novel therapies. We retrospectively analyzed the clinicopathologic, genetic, and survival characteristics of 34 patients with confirmed tissue diagnosis of A-CLL/SLL and compared them with 120 patients with C-CLL/SLL. Patients with A-CLL/SLL had significantly higher frequencies of B-symptoms, anemia and thrombocytopenia, splenomegaly, higher LDH, and more advanced Rai stages. A-CLL/SLL showed a significantly higher frequency of TP53 mutations (55.0% vs. 11.5%;p < 0.0001) and deletions (38.2% vs. 8.3%;p < 0.0001), lower isolated del(13q) (5.8% vs. 27.5%;p < 0.0001), and increased incidence of RT (11.76% vs. 0.83%;p = 0.0025). The overall survival of patients with A-CLL/SLL was significantly lower than C-CLL/SLL (median survival: 6.17 years vs. not reached; 2 and 5-year survival rates: 75.5% vs. 94.7% and 53.3% vs. 93.7%, respectively; p < 0.0001); however, novel agents have improved the outcomes dramatically compared to the previously published data in the pre-BTKi era. Our results support the categorization of A-CLL/SLL as a distinct biologically aggressive subtype of CLL/SLL and highlight the need to revise the diagnostic criteria utilizing a multifaceted approach that integrates the overall pathobiological profile of the disease, in addition to the histology.

Updates on the Treatment of Richter's Syndrome, Including Novel Combination Approaches

Richter's syndrome (RS) or transformation of chronic lymphocytic leukemia (CLL) into a more aggressive lymphoma (e.g., diffuse large B cell lymphoma, DLBCL) is a distinct disease that portends an overall poor prognosis and remains a challenge for clinicians to identify and treat effectively. This review of the current literature focuses on the pathology, diagnosis, and management of Richter's syndrome. Clonally related RS has been found to have a worse prognosis than unrelated disease and the genomic profile of DLBCL-RS differs from that of de novo DLBCL. The standard of care therapy for RS has historically been chemoimmunotherapy; consolidative stem cell transplants have a role in improving durability of disease response. Given generally poor response rates to chemotherapy, there have been recent investigations into combination treatments with immune checkpoint inhibitors and small molecule targeted therapies, which have had mixed results. Additional studies are evaluating the use of bispecific antibodies, chimeric antigen receptor T cell therapy, and antibody drug conjugates. RS remains difficult to manage; however, advancements in the understanding of the underlying pathology of transformation and continued investigations into new therapies demonstrate promise for the future.

Molecular Mechanisms in the Transformation from Indolent to Aggressive B Cell Malignancies

Histological transformation (HT) into aggressive lymphoma is a turning point in a significant fraction of patients affected by indolent lymphoproliferative neoplasms, namely, chronic lymphocytic leukemia (CLL), follicular lymphoma (FL), marginal zone lymphomas (MZLs), and lymphoplasmacytic lymphoma (LPL) [...].

Management strategies for patients with chronic lymphocytic leukaemia harbouring complex karyotype

Chronic lymphocytic leukaemia (CLL) is a heterogeneous disease characterised by the uncontrolled proliferation of mature lymphocytes. A subset of CLL patients harbouring complex karyotype (CK) presents with poor prognosis and limited treatment options. This review aims to discuss the current understanding of such patient subset, including its molecular landscape, diagnostic approaches, treatment modalities and emerging therapies. Furthermore, it outlines strategies for personalised management to improve clinical outcomes in this challenging patient population.

New classifications of B-cell neoplasms: a comparison of 5th WHO and International Consensus classifications

In 2024, the World Health Organization (WHO) launched a new classification of lymphoid neoplasms, a revision of the previously used Revised 4th Edition of their classification (WHO-4R). However, this means that two classifications are now in simultaneous use: the 5th Edition of the WHO classification (WHO-5) and the International Consensus Classification (ICC). Instead of a comprehensive review of each disease entity, as already described elsewhere, this review focuses on revisions made in both the WHO-5 and ICC from WHO-4R and discrepancies between them regarding B-cell neoplasms. Similarities include cutaneous marginal zone lymphoma, cold agglutinin disease, non-primary effusion lymphoma-type effusion-based lymphoma, and gray zone lymphoma. Differences include plasma cell neoplasms, high-grade B-cell lymphoma (double hit lymphoma), follicular lymphoma, LPD with immune deficiency and dysregulation, extranodal large B-cell lymphoma, transformations of indolent B-cell lymphomas, and diffuse large B-cell lymphoma, not otherwise specified. Understanding the similarities and differences between the two latest classifications will aid daily diagnostic practice and future research on lymphoid neoplasms.

The preclinical discovery and development of zanubrutinib for the treatment of chronic lymphocytic leukemia

INTRODUCTION

The history of treating chronic lymphocytic leukemia (CLL) inflected in 2014 with the Food and Drug Administration's (FDA) approval of ibrutinib, the first-in-class small molecule inhibitor of the Bruton's tyrosine kinase (BTK). Zanubrutinib is a 2nd generation covalent BTK inhibitor developed and manufactured by BeiGene.

AREAS COVERED

In this review, the authors trace the arc of zanubrutinib development from the preclinical phase through the two landmark phase 3 studies in the CLL space, ALPINE and SEQUOIA. The authors cover contemporary management strategies in CLL and highlight the areas of need that zanubrutinib was designed to mitigate.

EXPERT OPINION

Zanubrutinib entered a fray of novel, exciting therapies for CLL. As the second of two 2nd generation covalent BTK inhibitors its path to prominence in CLL management was narrow. Emphasis during development on kinase selectivity and enhanced bioavailability identified a molecule with superior efficacy and tolerability; hierarchical endpoints in trial design allowed for efficient acquisition of comparative data. Zanubrutinib is endorsed by the National Comprehensive Cancer Network as a preferred, category 1 recommended treatment choice for CLL. Future efforts in combination therapies and response-directed treatment breaks will hopefully lead to still further improvements in use.

Advances in the understanding of molecular genetics and therapy of Richter transformation in chronic lymphocytic leukemia

Richter's transformation (RT) is defined as the evolution of chronic lymphocytic leukemia (CLL) or small lymphocytic lymphoma (SLL) into an aggressive lymphoma, most commonly diffuse large B-cell lymphoma. This complication is rare and aggressive, with poor prognosis and dismal survival. Clonal relationship with the underlying CLL/SLL, observed in ∼80% of cases, represents one of the main factors affecting prognosis. Treatment has been historically based on chemoimmunotherapy, but frequent mutations in genes involved in cell survival and proliferation-such as TP53, NOTCH1, MYC, CDKN2A-confer resistance to standard treatments. During the last years, advances in the knowledge of the biological mechanisms underlying RT allowed to identify genetic and molecular lesions that can potentially be targeted by novel selective agents. Pathway and checkpoint inhibitors, bispecific antibodies and CAR T-cell therapy are currently under investigation and represent promising treatment options. This review summarizes current biological evidence and available data on novel therapeutic agents.

NF-ΚB Activation as a Key Driver in Chronic Lymphocytic Leukemia Evolution to Richter's Syndrome: Unraveling the Influence of Immune Microenvironment Dynamics

Background/Objectives: Chronic lymphocytic leukemia (CLL) is the most common adult leukemia in Western countries and it can progress to Richter's syndrome (RS), a more aggressive condition. The NF-κB pathway is pivotal in CLL pathogenesis, driven mainly by B-cell receptor (BCR) signaling. However, recent evidence indicates that BCR signaling is reduced in RS, raising questions about whether and how NF-κB activity is maintained in RS. This study aims to elucidate the triggers and dynamics of NF-κB activation and the progression from CLL to RS. Methods: Integrated single-cell RNA sequencing data from peripheral blood samples of four CLL-RS patients were analyzed. NF-κB pathway activity and gene expression profiles were assessed to determine changes in NF-κB components and their targets. Tumor microenvironment composition and cell-cell communication patterns were inferred to explore NF-κB regulatory mechanisms. Results: RS samples showed increased proportions of malignant cells expressing NF-κB components, including NFKB1, NFKB2, RELA, IKBKG, MAP3K14, CHUK, and IKBKB, with significantly higher expression levels than in CLL. Enhanced NF-κB pathway activity in RS cells was associated with targets involved in immune modulation. The tumor microenvironment in RS displayed significant compositional changes, and signaling inference revealed enhanced cell-cell communication via BAFF and APRIL pathways, involving interactions with receptors such as BAFF-R and TACI on RS cells. Conclusions: The findings from this study reveal an active state of NF-κB in RS and suggest that this state plays a critical role in the evolution of CLL to RS, which is modulated by alternative signaling pathways and the influence of the tumor microenvironment.

A Rare Case of Richter Transformation to Both Clonally Unrelated and Clonally Related Diffuse Large B-Cell Lymphoma in the Same Patient

Richter transformation (RT) is a rare sequelae of chronic lymphocytic leukemia (CLL)/small lymphocytic lymphoma (SLL). The clonal relationship of the RT to the underlined CLL/SLL is an important prognostic factor as clonally related RT has a worse prognosis than that of clonally unrelated RT. The development of more than one RT in the same patient is exceedingly rare and prior reports have shown cases consisting of RT to diffuse large B-cell lymphoma (DLBCL) and a subsequent or synchronous Hodgkin lymphoma. Here, we present a rare case of RT first to a clonally unrelated DLBCL and subsequently a clonally related DLBCL. Additionally, we retrospectively conducted next-generation sequencing studies of both RT's and found different mutational landscapes, including more clinically aggressive mutations identified in the clonally related RT. To our knowledge, this is the first reported case of clonally related and clonally unrelated RT, both of which are DLBCL, in the same patient.

Multiple omics levels of chronic lymphocytic leukemia

Chronic lymphocytic leukemia (CLL) is a lymphoproliferative malignancy characterized by the proliferation of functionally mature but incompetent B cells. It is the most prevalent type of leukemia in Western populations, accounting for approximately 25% of new leukemia cases. While recent advances, such as ibrutinib and venetoclax treatment have improved patient outlook, aggressive forms of CLL such as Richter transformation still pose a significant challenge. This discrepancy may be due to the heterogeneity of factors contributing to CLL development at multiple -omics levels. However, information on the omics of CLL is fragmented, hindering multi-omics-based research into potential treatment options. To address this, we aggregated and presented a selection of important aspects of various omics levels of the disease in this review. The purpose of the present literature analysis is to portray examples of CLL studies from different omics levels, including genomics, epigenomics, transcriptomics, epitranscriptomics, proteomics, epiproteomics, metabolomics, glycomics and lipidomics, as well as those identified by multi-omics approaches. The review includes the list of 102 CLL-associated genes with relevant genomics information. While single-omics studies yield substantial and useful data, they omit a significant level of complex biological interplay present in the disease. As multi-omics studies integrate several different layers of data, they may be better suited for complex diseases such as CLL and have thus far yielded promising results. Future multi-omics studies may assist clinicians in improved treatment choices based on CLL subtypes as well as allow the identification of novel biomarkers and targets for treatments.

A rare case of Richter transformation with breast involvement: A case report and literature review

Richter transformation (RT) represents the development of intrusive lymphoma in individuals previously or concurrently diagnosed with chronic lymphocytic leukemia (CLL) and is characterized by lymph node enlargement. However, cases involving extra-nodal organ involvement as the first symptom are rare. There are no reports of RT with breast lesions as the first symptom. Nonspecific and atypical clinical manifestations represent key challenges in the accurate diagnosis and appropriate treatment of RT. This case report describes an elderly female patient who presented with breast lesions as the first RT symptom. The patient was admitted with a painless mass in the left breast. Examination revealed multiple lymphadenopathies and abnormally high white blood cell levels. The patient was diagnosed with CLL after hematological tests, assessments of bone marrow morphology, and tissue biopsy. Mammography and B-ultrasonography showed solid space-occupying lesions (BI-RADS category 5) in the left breast. Initially, the patient declined a breast biopsy and was therefore prescribed ibrupotinib treatment, which showed limited efficacy. A needle biopsy of the affected breast indicated the presence of diffuse large B-cell lymphoma. Based on auxiliary and pathological examinations and medical history, the final diagnosis was RT with breast involvement. Zanubrutinib with rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone treatment provided initial control; however, the treatment strategy required adjustment because of the patient's fluctuating condition. The current status of the patient is marked as stable, showing an overall achievement of partial alleviation. The patient is in the process of receiving follow-up treatment. We also performed a comprehensive literature review on RT, with particular emphasis on its biological paradigm, prognosis implications, existing therapeutic approaches, and emerging directions in treatment modalities.

Molecular Subtypes and the Role of TP53 in Diffuse Large B-Cell Lymphoma and Richter Syndrome

Diffuse large B-cell lymphoma (DLBCL) is the most common lymphoid malignancy and a heterogeneous entity comprised of several biologically distinct subtypes. Recently, novel genetic classifications of DLBCL have been resolved based on common mutational patterns indicative of distinct pathways of transformation. However, the complicated and costly nature of the novel classifiers has precluded their inclusion into routine practice. In view of this, the status of the TP53 gene, which is mutated or deleted in 20-30% of the cases, has emerged as an important prognostic factor for DLBCL patients, setting itself apart from other predictors. TP53 genetic lesions are particularly enriched in a genetic subtype of DLBCL that shares genomic features with Richter Syndrome, highlighting the possibility of a subset of DLBCL arising from the transformation of an occult chronic lymphocytic leukemia-like malignancy, such as monoclonal B-cell lymphocytosis. Patients with TP53-mutated DLBCL, including those with Richter Syndrome, have a particularly poor prognosis and display inferior responses to standard chemoimmunotherapy regimens. The data presented in this manuscript argue for the need for improved and more practical risk-stratification models for patients with DLBCL and show the potential for the use of TP53 mutational status for prognostication and, in prospect, treatment stratification in DLBCL.

Mouse models of CLL: In vivo modeling of disease initiation, progression, and transformation

Chronic lymphocytic leukemia (CLL) is a highly complex disease characterized by the proliferation of CD5+ B cells in lymphoid tissues. Current modern treatments have brought significant clinical benefits to CLL patients. However, there are still unmet needs. Patients relapse on Bruton's tyrosine kinase inhibitors and BCL2 inhibitors and often develop more aggressive diseases including Richter transformation (RT), an incurable complication of up to ∼10% patients. This evidence underscores the need for improved immunotherapies, combination treatment strategies, and predictive biomarkers. A mouse model that can recapitulate human CLL disease and certain components of the tumor immune microenvironment represents a promising preclinical tool for such purposes. In this review, we provide an overview of CRISPR-engineered and xenograft mouse models utilizing either cell lines, or primary CLL cells suitable for studies of key events driving the disease onset, progression and transformation of CLL. We also review how CRISPR/Cas9 established mouse models carrying loss-of-function lesions allow one to study key mutations driving disease progression. Finally, we discuss how next generation humanized mice might improve to generation of faithful xenograft mouse models of human CLL.

Venetoclax plus dose-adjusted R-EPOCH (VR-DA-EPOCH) or G-EPOCH bridging to subsequent cellular therapy for the patients with transformed lymphoma a single center clinical experience

Indolent lymphoma, including chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL) and follicular lymphoma (FL), can undergo histological transformation into an aggressive subtype, typically diffuse large B-cell lymphoma (DLBCL). The prognosis of transformed lymphoma is poor. In this study, we reported the efficacy and toxicity of a combination of venetoclax, dose-adjusted rituximab or obinutuzumab, etoposide, prednisone, vincristine, doxorubicin, and cyclophosphamide (VR-DA-EPOCH or VG-DA-EPOCH) in 11 patients with biopsy-proven histology transformation into DLBCL, including 8 patients with RT and 3 with transformed FL (tFL). The study was conducted between October 2019 and March 2023 at our single center. The median age of participants at enrolment was 53 years. Six patients (85.7%, 6/7) achieved complete remission (CR) at the end of treatment. The best overall response rate (ORR) and CR rate were both 72.7%, respectively. Two patients received autologous hemopoietic stem cell transplant (ASCT) while two patients received ASCT concurrently with CAR-T therapy for consolidation. With a median follow-up of 13.5 (range, 2.4-29.8) months after enrollment, the median event-free survival, progression-free survival, and overall survival were 9.4, 11.5, and 17.5 months, respectively. Hematologic toxicities of grade ≥3 consisted of neutropenia (90.9%, 10/11), thrombocytopenia (63.6%, 7/11), and febrile neutropenia (54.5%, 6/11). In conclusion, VR-DA-EPOCH or VG-DA-EPOCH was a promising strategy to achieve an early remission, bridging to cellular therapy within this population.

A genetic profiling guideline to support diagnosis and clinical management of lymphomas

The new lymphoma classifications (International Consensus Classification of Mature Lymphoid Neoplasms, and 5th World Health Organization Classification of Lymphoid Neoplasms) include genetics as an integral part of lymphoma diagnosis, allowing better lymphoma subclassification, patient risk stratification, and prediction of treatment response. Lymphomas are characterized by very few recurrent and disease-specific mutations, and most entities have a heterogenous genetic landscape with a long tail of recurrently mutated genes. Most of these occur at low frequencies, reflecting the clinical heterogeneity of lymphomas. Multiple studies have identified genetic markers that improve diagnostics and prognostication, and next-generation sequencing is becoming an essential tool in the clinical laboratory. This review provides a "next-generation sequencing" guide for lymphomas. It discusses the genetic alterations of the most frequent mature lymphoma entities with diagnostic, prognostic, and predictive potential and proposes targeted sequencing panels to detect mutations and copy-number alterations for B- and NK/T-cell lymphomas.

A molecular circuit linking the BCR to the NAD biosynthetic enzyme NAMPT is an actionable target in Richter syndrome

ABSTRACT

This works defines, to the best of our knowledge, for the first time a molecular circuit connecting nicotinamide mononucleoside phosphoribosyl transferase (NAMPT) activity to the B-cell receptor (BCR) pathway. Using 4 distinct xenograft models derived from patients with Richter syndrome (RS-PDX), we show that BCR cross-linking results in transcriptional activation of the nicotinamide adenine dinucleotide (NAD) biosynthetic enzyme NAMPT, with increased protein expression, in turn, positively affecting global cellular NAD levels and sirtuins activity. NAMPT blockade, by using the novel OT-82 inhibitor in combination with either BTK or PI3K inhibitors (BTKi or PI3Ki), induces rapid and potent apoptotic responses in all 4 models, independently of their mutational profile and the expression of the other NAD biosynthetic enzymes, including nicotinate phosphoribosyltransferase. The connecting link in the circuit is represented by AKT that is both tyrosine- and serine-phosphorylated by PI3K and deacetylated by sirtuin 1 and 2 to obtain full kinase activation. Acetylation (ie, inhibition) of AKT after OT-82 administration was shown by 2-dimensional gel electrophoresis and immunoprecipitation. Consistently, pharmacological inhibition or silencing of sirtuin 1 and 2 impairs AKT activation and induces apoptosis of RS cells in combination with PI3Ki or BTKi. Lastly, treatment of RS-PDX mice with the combination of PI3Ki and OT-82 results in significant inhibition of tumor growth, with evidence of in vivo activation of apoptosis. Collectively, these data highlight a novel application for NAMPT inhibitors in combination with BTKi or PI3Ki in aggressive lymphomas.

The molecular map of CLL and Richter's syndrome

Clonal expansion of B-cells, from the early stages of monoclonal B-cell lymphocytosis through to chronic lymphocytic leukemia (CLL), and then in some cases to Richter's syndrome (RS) provides a comprehensive model of cancer evolution, notable for the marked morphological transformation and distinct clinical phenotypes. High-throughput sequencing of large cohorts of patients and single-cell studies have generated a molecular map of CLL and more recently, of RS, yielding fundamental insights into these diseases and of clonal evolution. A selection of CLL driver genes have been functionally interrogated to yield novel insights into the biology of CLL. Such findings have the potential to impact patient care through risk stratification, treatment selection and drug discovery. However, this molecular map remains incomplete, with extant questions concerning the origin of the B-cell clone, the role of the TME, inter- and intra-compartmental heterogeneity and of therapeutic resistance mechanisms. Through the application of multi-modal single-cell technologies across tissues, disease states and clinical contexts, these questions can now be addressed with the answers holding great promise of generating translatable knowledge to improve patient care.

Prognostication in chronic lymphocytic leukemia

Chronic lymphocytic leukemia (CLL) is the most common type of leukemia in Western countries. CLL is a highly heterogeneous disease: some patients may never require therapy and others relapse several times after different therapeutic strategies. Therefore, in CLL, prognostic markers are essential to capture high-risk patients for different clinical endpoints including early treatment requirement, early progression after BTK or BCL2 inhibitors and Richter transformation. In early stage CLL, different biological and clinical biomarkers have been identified to predict time to treatment requirement that could be used to identify the most appropriate population for early intervention clinical trial. However, at the moment, the standard of care for early stage CLL remains watch & wait since no survival benefit has been identified in clinical trials with chemoimmunotherapy and with BTK inhibitors. In patients requiring treatment TP53 disruptions identify high-risk patients who benefit the most from long-term continuous therapy with BTKi. On the opposite side of the spectrum, IGHV mutated patients devoid of TP53 disruption benefit the most from fixed-duration therapy with venetoclax-obinutuzumab. In between, the highly heterogenous subgroup of patients with IGHV unmutated genes represents the group in which further efforts are needed to identify additional prognostic biomarkers aimed at selecting patients who can benefit from fixed-duration and patients who can benefit from long term BTKi therapy. In the context of the aggressive transformation of CLL, namely Richter syndrome, the clonal relationship to the CLL counterpart represents the strongest prognostic biomarker. Clonally related Richter syndrome still represents an unmet clinical need which requires further efforts to identify new therapeutic strategies.

Richter's transformation: Transforming the clinical landscape

Richter transformation (RT) represents an aggressive histological transformation from chronic lymphocytic leukaemia, most often to a large B cell lymphoma. It is characterised by chemo-resistance and subsequent short survival. Drug development has struggled over recent years in light of the aggressive kinetics of the disease, lack of pivotal registrational trials and relative rarity of the phenomenon. In this review we will highlight the diagnostic and therapeutic challenges of managing patients with RT as well as taking a look to the future therapeutic landscape. Highly active therapies developed across B cell malignancies are starting to impact this field, with T-cell activation therapies (CAR-T, bispecific antibodies), antibody-drug conjugates, and novel small molecule inhibitor combinations (e.g. BTKi-BCL2i) being actively studied. We will highlight the data supporting these developments and look to the studies to come to provide hope for patients suffering from this devastating disease.

Richter transformation - retrospective treatment outcomes analysis in Polish Adult Leukemia Study Group

Richter transformation (RT) is defined as developing an aggressive lymphoma in 2-10% of patients suffering from chronic lymphocytic leukemia (CLL). So far, no complex analysis of RT demographics and treatment outcomes has been performed in Poland. Thus, the retrospective analysis of 124 patients with RT from Polish hematology centers was designed. Ninety-nine patients with diffuse large B-cell lymphoma (DLBCL-RT) were identified. The median overall survival (OS) for DLBCL-RT was 17.3 months, while for Hodgkin lymphoma (HL-RT)-21.3 months. In multivariate analysis, the independent factors of worse OS for DLBCL-RT were: prior CLL therapy, ECOG stage ≥2, and elevated serum LDH activity. Patients who proceeded to hematopoietic stem cell transplantation (HSCT) achieved better results. The median OS in allogeneic HSCT recipients was not reached, while in autologous HSCT median OS was 51.3 months. In conclusion, our study represents the largest dataset of patients diagnosed with RT in Poland and confirms its dismal prognosis.

Noncoding mutations cause super-enhancer retargeting resulting in protein synthesis dysregulation during B cell lymphoma progression

Whole-genome sequencing of longitudinal tumor pairs representing transformation of follicular lymphoma to high-grade B cell lymphoma with MYC and BCL2 rearrangements (double-hit lymphoma) identified coding and noncoding genomic alterations acquired during lymphoma progression. Many of these transformation-associated alterations recurrently and focally occur at topologically associating domain resident regulatory DNA elements, including H3K4me3 promoter marks located within H3K27ac super-enhancer clusters in B cell non-Hodgkin lymphoma. One region found to undergo recurrent alteration upon transformation overlaps a super-enhancer affecting the expression of the PAX5/ZCCHC7 gene pair. ZCCHC7 encodes a subunit of the Trf4/5-Air1/2-Mtr4 polyadenylation-like complex and demonstrated copy number gain, chromosomal translocation and enhancer retargeting-mediated transcriptional upregulation upon lymphoma transformation. Consequently, lymphoma cells demonstrate nucleolar dysregulation via altered noncoding 5.8S ribosomal RNA processing. We find that a noncoding mutation acquired during lymphoma progression affects noncoding rRNA processing, thereby rewiring protein synthesis leading to oncogenic changes in the lymphoma proteome.

Cytogenomics of B-cell non-Hodgkin lymphomas: The "old" meets the "new"

For the routine diagnosis of haematological neoplasms an integrative approach is used considering the morphology, and the immunophenotypic, and molecular features of the tumor sample, along with clinical information. The identification and characterization of recurrent chromosomal aberrations mainly detected by conventional and molecular cytogenetics in the tumor cells has a major impact on the classification of lymphoid neoplasms. Some of the B-cell non-Hodgkin lymphomas are characterized by particular chromosomal aberrations, highlighting the relevance of conventional and molecular cytogenetic studies in their diagnosis and prognosis. In the current genomics era, next generation sequencing provides relevant information as the mutational profiles of haematological malignancies, improving their classification and also the clinical management of the patients. In addition, other new technologies have emerged recently, such as the optical genome mapping, which can overcome some of the limitations of conventional and molecular cytogenetics and may become more widely used in the cytogenetic laboratories in the upcoming years. Moreover, epigenetic alterations may complement genetic changes for a deeper understanding of the pathogenesis underlying B-cell neoplasms and a more precise risk-based patient stratification. Overall, here we describe the current state of the genomic data integrating chromosomal rearrangements, copy number alterations, and somatic variants, as well as a succinct overview of epigenomic changes, which altogether constitute a comprehensive diagnostic approach in B-cell non-Hodgkin lymphomas.

[Clinical and molecular biological characterization of patients with accelerated chronic lymphocytic leukemia]

Objective: To investigate the clinical and molecular biological characteristics of patients with accelerated chronic lymphocytic leukemia (aCLL) . Methods: From January 2020 to October 2022, the data of 13 patients diagnosed with aCLL at The First Affiliated Hospital of Nanjing Medical University were retrospectively analyzed to explore the clinical and molecular biological characteristics of aCLL. Results: The median age of the patients was 54 (35-72) years. Prior to aCLL, five patients received no treatment for CLL/small lymphocytic lymphoma (SLL), while the other patients received treatment, predominantly with BTK inhibitors. The patients were diagnosed with aCLL through pathological confirmation upon disease progression. Six patients exhibited bulky disease (lesions with a maximum diameter ≥5 cm). Positron emission tomography (PET) -computed tomography (CT) images revealed metabolic heterogeneity, both between and within lesions, and the median maximum standardized uptake value (SUVmax) of the lesion with the most elevated metabolic activity was 6.96 (2.51-11.90). Patients with unmutated IGHV CLL accounted for 76.9% (10/13), and the most frequent genetic and molecular aberrations included +12 [3/7 (42.9% ) ], ATM mutation [6/12 (50% ) ], and NOTCH1 mutation [6/12 (50% ) ]. Twelve patients received subsequent treatment. The overall response rate was 91.7%, and the complete response rate was 58.3%. Five patients experienced disease progression, among which two patients developed Richter transformation. Patients with aCLL with KRAS mutation had worse progression-free survival (7.0 month vs 26.3 months, P=0.015) . Conclusion: Patients with aCLL exhibited a clinically aggressive course, often accompanied by unfavorable prognostic factors, including unmutated IGHV, +12, ATM mutation, and NOTCH1 mutation. Patients with CLL/SLL with clinical suspicion of disease progression, especially those with bulky disease and PET-CT SUVmax ≥5, should undergo biopsy at the site of highest metabolic uptake to establish a definitive pathological diagnosis.

Cytogenomic features of Richter transformation

BACKGROUND

Richter transformation (RT) is the development of aggressive lymphoma in patients with chronic lymphocytic leukemia (CLL) or small lymphocytic lymphoma (SLL). This rare disease is characterised by dismal prognosis. In recent years, there has been a deeper understanding of RT molecular pathogenesis, and disruptions of apoptosis (TP53) and proliferation (CDKN2A, MYC, NOTCH1) has been described as typical aberrations in RT.

RESULTS

A single-institution cohort of 33 RT patients were investigated by karyotyping, fluorescence in situ hybridization and single nucleotide polymorphism/copy number (CN) arrays. Most of RTs were typically manifested by diffuse large B-cell lymphoma, not otherwise specified, among the remaining cases one was classified as high-grade B-cell lymphoma with 11q aberrations. The most frequent alterations (40-60% of cases) were represented by MYC rearrangement/gain, deletions of TP53 and CDKN2A, IGH rearrangement and 13q14 deletion. Several other frequent lesions included losses of 14q24.1-q32.33, 7q31.33-q36.3, and gain of 5q35.2. Analysis of 13 CLL/SLL-RT pairs showed that RT arised from the CLL/SLL by acquiring of 10 ~ 12 cytogenetic or CN lesions/case, but without acquisition of loss of heterozygosity regions. Our result affirmed the higher genetic complexity in RT than CLL/SLL and confirmed the linear features of RT clonal evolution as predominant.

CONCLUSIONS

Cytogenomic profile was concordant with the literature data, however the role of IGH rearrangement, 14q deletion and 5q35.2 gain need to be explored. We anticipate that further characterization of RT lesions will probably facilitate better understanding of the RT clonal evolution.

From genetics to therapy: Unraveling the complexities of Richter transformation in chronic lymphocytic leukemia

Richter transformation (RT) refers to the progression of chronic lymphocytic leukemia, the most prevalent leukemia among adults, into a highly aggressive lymphoproliferative disorder, primarily a diffuse large B-cell lymphoma. This is a severe complication that continues to be a therapeutic challenge and remains an unmet medical need. Over the last five years, significant advances have occurred in uncovering the biological processes leading to the RT, refining criteria for properly diagnose RT from other entities, and exploring new therapeutic options beyond the ineffective chemotherapy. This review summarizes current knowledge in RT, including recent advances in the understanding of the pathogenesis of RT, in the classification of RT, and in the development of novel therapeutic strategies for this grave complication.

DLBCL arising from indolent lymphomas: How are they different?

Transformation to diffuse large B-cell lymphoma (DLBCL) is a recognized, but unpredictable, clinical inflection point in the natural history of indolent lymphomas. Large retrospective studies highlight a wide variability in the incidence of transformation across the indolent lymphomas and the adverse outcomes associated with transformed lymphomas. Opportunities to dissect the biology of transformed indolent lymphomas have arisen with evolving technologies and unique tissue collections enabling a growing appreciation, particularly, of their genetic basis, how they relate to the preceding indolent lymphomas and the comparative biology with de novo DLBCL. This review summarizes our current understanding of both the clinical and biological aspects of transformed lymphomas and the outstanding questions that remain.

SOHO State of the Art Updates and Next Questions | Treatment of Richter's Transformation

Richter's transformation (RT) is a rare condition, represented by the development of an aggressive lymphoma arising from underlying chronic lymphocytic leukemia/small lymphocytic lymphoma. The management of RT remains challenging, necessitating combined therapeutic strategies to achieve favorable outcomes. Traditional treatment options for RT have involved intensive chemotherapy regimens, often with limited success due to the high-risk nature of the disease. However, recent advances in the understanding of RT pathogenesis have led to the emergence of novel targeted therapies that show promising results. Noncovalent Bruton tyrosine kinase inhibitors, T-cell-engaging bispecific antibodies, chimeric antigen receptor T-cells, and conjugated monoclonal antibodies may hold promise for improved outcomes in RT, especially when combined in a multitargeted fashion. Further prospective randomized trials and collaborative efforts are warranted to optimize treatment algorithm and ultimately improve patient outcomes in this dismal condition. This review provides a comprehensive overview of the current treatment options for RT.

Refining prognosis in chronic lymphocytic leukemia with normal Fluorescence in situ hybridization results

Fluorescence in situ hybridization (FISH) to detect the recurrent cytogenetics abnormalities deletion 13q, trisomy 12, deletion 11q, and deletion 17p is important for prognostication in chronic lymphocytic leukemia (CLL). A subset of patients are negative for each of these abnormalities (normal 12/13/11/17 FISH), and outcomes are heterogenous within this group. To elucidate variables important for prognostication in this subgroup we conducted a retrospective analysis of 280 treatment-naïve CLL patients with normal standard CLL FISH results. In a multivariable model, advanced Rai stage (p = 0.04, hazard ratio [HR] 1.24 (95% confidence interval [CI] 1.01-1.53)), unmutated immunoglobulin heavy chain gene (IGHV) (p < 0.0001, HR 5.59 (95% CI 3.63-8.62)) and IGH rearrangement by FISH (p = 0.02, HR 2.56 (95% CI 1.20-5.48)) were significantly associated with shorter time to first treatment. In a multivariable model for overall survival, increasing age at 5-year increments (p < 0.0001, HR 1.55 (95% CI 1.25-1.93)), unmutated IGHV (p = 0.01, HR 5.28 (95% CI 1.52-18.35)) and gain of REL (p = 0.01, HR 4.08 (5% CI 1.45-11.49)) were significantly associated with shorter survival. Our study identifies variables important for refining prognosis for CLL patients with normal standard CLL FISH results.

Richter syndrome: novel insights into the biology of transformation

Although the genetic landscape of chronic lymphocytic leukemia (CLL) has been broadly profiled by large-scale sequencing studies performed over the past decade, the molecular basis of the transformation of CLL into aggressive lymphoma, or Richter syndrome (RS), has remained incompletely characterized. Recent advances in computational methods of clonal deconvolution, as well as extensive sample collection efforts in this rapidly progressive malignancy, have now enabled comprehensive analysis of paired CLL and RS samples and have led to multiple new studies investigating the genetic, transcriptomic, and epigenetic origins of RS. In parallel, new genetically engineered and xenograft mouse models have provided the opportunity for gleaning fresh biological and mechanistic insights into RS development and stepwise evolution from antecedent CLL. Altogether, these studies have defined RS driver lesions and CLL risk lesions and identified pathways dysregulated in transformation. Moreover, unique molecular subtypes of RS have been revealed, including a disease marked by profound genomic instability with chromothripsis/chromoplexy and whole genome duplication. Novel profiling approaches, including single-cell DNA and transcriptome sequencing of RS biopsy specimens and cell-free DNA profiling of patient plasma, demonstrate promise for the timely identification of RS clones and may translate to noninvasive identification and early diagnosis of RS. This review summarizes the recent scientific advances in RS and supports the integrated study of human genomics with mouse modeling to provide an advanced understanding of the biological underpinnings of transformation. These recent studies have major implications for much-needed novel therapeutic strategies for this still largely incurable malignancy.

Immunophenotypic and genomic landscape of Richter transformation diffuse large B-cell lymphoma

Integrated clinicopathological and molecular analyses of Richter transformation of diffuse large B-cell lymphoma subtype (RT-DLBCL) cases remain limited. This study group included 142 patients with RT-DLBCL. Morphological evaluation and immunophenotyping, using immunohistochemistry and/or multicolour flow cytometry, were performed. The results of conventional karyotyping, fluorescence in situ hybridisation analysis and mutation profiling performed using next generation sequencing were reviewed. Patients included 91 (64.1%) men and 51 (35.9%) women with a median age of 65.4 years (range 25.4-84.9 years) at the time of RT-DLBCL diagnosis. Patients had CLL for a median of 49.5 months (range 0-330 months) before onset of RT-DLBCL. Most cases (97.2%) of RT-DLBCL had immunoblastic (IB) morphology, the remainder had a high grade morphology. The most commonly expressed markers included: CD19 (100%), PAX5 (100%), BCL2 (97.5%), LEF1 (94.7%), CD22 (90.2%), CD5 (88.6%), CD20 (85.7%), CD38 (83.5%), MUM1 (83.3%), CD23 (77%) and MYC (46.3%). Most (51/65, 78.4%) cases had a non-germinal centre B-cell immunophenotype. MYC rearrangement was detected in 9/47 (19.1%) cases, BCL2 rearrangement was detected in 5/22 (22.7%) cases, and BCL6 rearrangement was detected in 2/15 (13.3%) cases. In comparison to CLL, RT-DLBCL had higher numbers of alterations involving chromosomes 6, 17, 21, and 22. The most common mutations detected in RT-DLBCL involved TP53 (9/14, 64.3%), NOTCH1 (4/14, 28.6%) and ATM (3/14, 21.4%). Among RT-DLBCL cases with mutant TP53, 5/8 (62.5%) had TP53 copy number loss, and among those, such loss was detected in the CLL phase of the disease in 4/8 (50%) cases. There was no significant difference in overall survival (OS) between patients with germinal centre B-cell (GCB) and non-GCB RT-DLBCL. Only CD5 expression correlated significantly with OS (HR=2.732; 95% CI 1.397-5.345; p=0.0374). RT-DLBCL has distinctive morphological and immunophenotypic features, characterised by IB morphology and common expression of CD5, MUM1 and LEF1. Cell-of-origin does not seem to have prognostic implications in RT-DLBCL.

Immune evasion phenotype is common in Richter transformation diffuse large B-cell lymphoma variant

Immune checkpoint inhibitors (PD-1 inhibitors) have shown clinical activity in Richter transformation-diffuse large B-cell lymphoma variant (RT-DLBCL), thus providing for a novel therapeutic approach. The study group consists of 64 patients with RT-DLBCL. Expression of PD-1, PD-L1, CD30, and microsatellite instability (MSI) status (hMLH1, hMSH2, hMSH6, PMS1) was assessed using immunohistochemistry. EBV-encoded RNA (EBER) was evaluated using colorimetric in situ hybridization. PD-1 and PD-L1 expression levels were categorized on the basis of tumor cell expression as follows: negative (< 5%), positive to low-positive (5-50%), or high-positive (> 50%). An "immune evasion phenotype" (IEP) was defined as RT-DLBCL cases having high-positive expression of PD-1 and/or PD-L1 on tumor cells. The level of PD1-positive tumor-infiltrating lymphocytes (TILs) was estimated as a fraction of total lymphocytes and categorized as negative/low vs. brisk (> 20%). 28/64 (43.7%) patients were characterized as IEP+ RT-DLBCL. A brisk level of PD1+ TILs was significantly more common in IEP1+ compared with IEP- tumors (17/28, 60.7% vs. 5/34, 14.7%; p = 0.001). In addition, CD30 expression was significantly more common in IEP+ compared with IEP- RT-DLBCL (6/20, 30% vs. 1/27, 3.7%; p = 0.0320). Two (2/36; 5.5%) cases were positive for EBER, both IEP+. There was no significant difference between the two groups in terms of age, sex, or time to transformation. Assessment of mismatch repair proteins demonstrated absence of microsatellite instability (MSI) in all cases (18/18; 100%). Notably, patients with brisk PD1+ TILs had a significantly better OS compared to those with a negative/low infiltrate (p = 0.0285).

Extracellular Vesicles in Chronic Lymphocytic Leukemia: Tumor Microenvironment Messengers as a Basis for New Targeted Therapies?

In addition to intrinsic genomic and nongenomic alterations, tumor progression is also dependent on the tumor microenvironment (TME, mainly composed of the extracellular matrix (ECM), secreted factors, and bystander immune and stromal cells). In chronic lymphocytic leukemia (CLL), B cells have a defect in cell death; contact with the TME in secondary lymphoid organs dramatically increases the B cells' survival via the activation of various molecular pathways, including the B cell receptor and CD40 signaling. Conversely, CLL cells increase the permissiveness of the TME by inducing changes in the ECM, secreted factors, and bystander cells. Recently, the extracellular vesicles (EVs) released into the TME have emerged as key arbiters of cross-talk with tumor cells. The EVs' cargo can contain various bioactive substances (including metabolites, proteins, RNA, and DNA); upon delivery to target cells, these substances can induce intracellular signaling and drive tumor progression. Here, we review recent research on the biology of EVs in CLL. EVs have diagnostic/prognostic significance and clearly influence the clinical outcome of CLL; hence, from the perspective of blocking CLL-TME interactions, EVs are therapeutic targets. The identification of novel EV inhibitors might pave the way to the development of novel combination treatments for CLL and the optimization of currently available treatments (including immunotherapy).

The role of SF3B1 and NOTCH1 in the pathogenesis of leukemia

The discovery of new genes/pathways improves our knowledge of cancer pathogenesis and presents novel potential therapeutic options. For instance, splicing factor 3b subunit 1 (SF3B1) and NOTCH1 genetic alterations have been identified at a high frequency in hematological malignancies, such as leukemia, and may be related to the prognosis of involved patients because they change the nature of malignancies in different ways like mediating therapeutic resistance; therefore, studying these gene/pathways is essential. This review aims to discuss SF3B1 and NOTCH1 roles in the pathogenesis of various types of leukemia and the therapeutic potential of targeting these genes or their mutations to provide a foundation for leukemia treatment.

In Vivo Modeling of CLL Transformation to Richter Syndrome Reveals Convergent Evolutionary Paths and Therapeutic Vulnerabilities

Transformation to aggressive disease histologies generates formidable clinical challenges across cancers, but biological insights remain few. We modeled the genetic heterogeneity of chronic lymphocytic leukemia (CLL) through multiplexed in vivo CRISPR-Cas9 B-cell editing of recurrent CLL loss-of-function drivers in mice and recapitulated the process of transformation from indolent CLL into large cell lymphoma [i.e., Richter syndrome (RS)]. Evolutionary trajectories of 64 mice carrying diverse combinatorial gene assortments revealed coselection of mutations in Trp53, Mga, and Chd2 and the dual impact of clonal Mga/Chd2 mutations on E2F/MYC and interferon signaling dysregulation. Comparative human and murine RS analyses demonstrated tonic PI3K signaling as a key feature of transformed disease, with constitutive activation of the AKT and S6 kinases, downmodulation of the PTEN phosphatase, and convergent activation of MYC/PI3K transcriptional programs underlying enhanced sensitivity to MYC/mTOR/PI3K inhibition. This robust experimental system presents a unique framework to study lymphoid biology and therapy.

SIGNIFICANCE

Mouse models reflective of the genetic complexity and heterogeneity of human tumors remain few, including those able to recapitulate transformation to aggressive disease histologies. Herein, we model CLL transformation into RS through multiplexed in vivo gene editing, providing key insight into the pathophysiology and therapeutic vulnerabilities of transformed disease. This article is highlighted in the In This Issue feature, p. 101.

The end of the beginning: application of single-cell sequencing to chronic lymphocytic leukemia

Single-cell analysis has emerged over the past decade as a transformative technology informative for the systematic analysis of complex cell populations such as in cancers and the tumor immune microenvironment. The methodologic and analytical advancements in this realm have evolved rapidly, scaling from but a few cells at its outset to the current capabilities of processing and analyzing hundreds of thousands of individual cells at a time. The types of profiling attainable at individual cell resolution now range from genetic and transcriptomic characterization and extend to epigenomic and spatial analysis. Additionally, the increasing ability to achieve multiomic integration of these data layers now yields ever richer insights into diverse molecular disease subtypes and the patterns of cellular circuitry on a per-cancer basis. Over the years, chronic lymphocytic leukemia (CLL) consistently has been at the forefront of genomic investigation, given the ready accessibility of pure leukemia cells and immune cells from circulating blood of patients with this disease. Herein, we review the recent forays into the application of single-cell analysis to CLL, which are already revealing a new understanding of the natural progression of CLL, the impact of novel therapies, and the interactions with coevolving nonmalignant immune cell populations. As we emerge from the end of the beginning of this technologic revolution, CLL stands poised to reap the benefits of single-cell analysis from the standpoints of uncovering fresh fundamental biological knowledge and of providing a path to devising regimens of personalized diagnosis, treatment, and monitoring.

Molecular characterization of Richter syndrome identifies de novo diffuse large B-cell lymphomas with poor prognosis

Richter syndrome (RS) is the transformation of chronic lymphocytic leukemia (CLL) into aggressive lymphoma, most commonly diffuse large B-cell lymphoma (DLBCL). We characterize 58 primary human RS samples by genome-wide DNA methylation and whole-transcriptome profiling. Our comprehensive approach determines RS DNA methylation profile and unravels a CLL epigenetic imprint, allowing CLL-RS clonal relationship assessment without the need of the initial CLL tumor DNA. DNA methylation- and transcriptomic-based classifiers were developed, and testing on landmark DLBCL datasets identifies a poor-prognosis, activated B-cell-like DLBCL subset in 111/1772 samples. The classification robustly identifies phenotypes very similar to RS with a specific genomic profile, accounting for 4.3-8.3% of de novo DLBCLs. In this work, RS multi-omics characterization determines oncogenic mechanisms, establishes a surrogate marker for CLL-RS clonal relationship, and provides a clinically relevant classifier for a subset of primary "RS-type DLBCL" with unfavorable prognosis.

Emerging Therapies for the Management of Richter Transformation

Richter transformation (RT) refers to the development of an aggressive lymphoma in patients with underlying chronic lymphocytic leukemia/small lymphocytic lymphoma. Aside from a small subgroup of patients with clonally unrelated and previously untreated chronic lymphocytic leukemia, the disease responds poorly to standard therapies and prognosis is dismal. Recent developments in the understanding of the biology of RT and the advent of several targeted agents may result in improved outcomes for these patients. The purpose of this review is to analyze recent data on the pathogenesis and treatment of RT. We reviewed studies addressing the pathophysiology of RT and analyzed the data for frontline chemoimmunotherapy and emerging targeted therapies likely to play a significant role in the future management of RT. Several biologic and clinical factors may help identify those who are unlikely to respond to conventional chemoimmunotherapy; where possible, these patients should be managed with a novel approach. Emerging therapies for the management of RT include chimeric antigen receptor T-cell therapy, noncovalent Bruton tyrosine kinase inhibitors, and T-cell-engaging bispecific antibodies. The use of less toxic and more effective targeted therapies may result in improved outcomes. Larger, prospective clinical trials are required to confirm efficacy and safety of novel agents for the management of RT, particularly when used in combination with other targeted therapies and in addition to chemoimmunotherapy regimens.

Dysregulation of PRMT5 in chronic lymphocytic leukemia promotes progression with high risk of Richter's transformation

Richter's Transformation (RT) is a poorly understood and fatal progression of chronic lymphocytic leukemia (CLL) manifesting histologically as diffuse large B-cell lymphoma. Protein arginine methyltransferase 5 (PRMT5) is implicated in lymphomagenesis, but its role in CLL or RT progression is unknown. We demonstrate herein that tumors uniformly overexpress PRMT5 in patients with progression to RT. Furthermore, mice with B-specific overexpression of hPRMT5 develop a B-lymphoid expansion with increased risk of death, and Eµ-PRMT5/TCL1 double transgenic mice develop a highly aggressive disease with transformation that histologically resembles RT; where large-scale transcriptional profiling identifies oncogenic pathways mediating PRMT5-driven disease progression. Lastly, we report the development of a SAM-competitive PRMT5 inhibitor, PRT382, with exclusive selectivity and optimal in vitro and in vivo activity compared to available PRMT5 inhibitors. Taken together, the discovery that PRMT5 drives oncogenic pathways promoting RT provides a compelling rationale for clinical investigation of PRMT5 inhibitors such as PRT382 in aggressive CLL/RT cases.

Evolutionary history of transformation from chronic lymphocytic leukemia to Richter syndrome

Richter syndrome (RS) arising from chronic lymphocytic leukemia (CLL) exemplifies an aggressive malignancy that develops from an indolent neoplasm. To decipher the genetics underlying this transformation, we computationally deconvoluted admixtures of CLL and RS cells from 52 patients with RS, evaluating paired CLL-RS whole-exome sequencing data. We discovered RS-specific somatic driver mutations (including IRF2BP2, SRSF1, B2M, DNMT3A and CCND3), recurrent copy-number alterations beyond del(9p21)(CDKN2A/B), whole-genome duplication and chromothripsis, which were confirmed in 45 independent RS cases and in an external set of RS whole genomes. Through unsupervised clustering, clonally related RS was largely distinct from diffuse large B cell lymphoma. We distinguished pathways that were dysregulated in RS versus CLL, and detected clonal evolution of transformation at single-cell resolution, identifying intermediate cell states. Our study defines distinct molecular subtypes of RS and highlights cell-free DNA analysis as a potential tool for early diagnosis and monitoring.

A systematic review evaluating the efficacy of autologous hematopoietic transplantation for diffuse large B cell lymphoma-type Richter syndrome

Background

Chronic lymphocytic leukemia (CLL) can transform into fast growing lymphoma for diffuse large B-cell lymphoma (DLBCL) called Richter's syndrome (RS), which is commonly related to an existence of large B-cells with equal or larger size than macrophage nuclei or more than twice those of normal lymphocyte. We conducted a systematic review of the existing literature to assess the clinical efficacy of auto-HCT for patients with RS.

Methods

We searched 4 main databases; EMBASE, Google Scholar, Scopus, PubMed and Web of Science and was done on December 26, 2021. All analyses in this study were performed by Stata software and this review was reported in accordance with PRISMA 2020.

Results

Data was extracted from 4 articles; the total number of patients was reported to be 110. Based on the meta-analysis findings, pooled overall survival rate was 56.36% (95%CI= (46.98-65.31). In figure 2, the forest plot of combined results is shown.

Conclusion

Despite the use of common treatment regimens such as chemo immunotherapy and the availability of novel therapies including B-cell receptor inhibitors and rituximab-cyclophosphamide-hydroxydaunorubicin-Oncovin-prednisone (CHOP-R) regimen, the status of disease progression and recovery in RS cases is still not strong enough.

Genomic landscape of mature B-cell non-Hodgkin lymphomas - an appraisal from lymphomagenesis to drug resistance

BACKGROUND

Mature B-cell non-Hodgkin lymphomas are one of the most common hematological malignancies with a divergent clinical presentation, phenotype, and course of disease regulated by underlying genetic mechanism.

MAIN BODY

Genetic and molecular alterations are not only critical for lymphomagenesis but also largely responsible for differing therapeutic response in these neoplasms. In recent years, advanced molecular tools have provided a deeper understanding regarding these oncogenic drives for predicting progression as well as refractory behavior in these diseases. The prognostic models based on gene expression profiling have also been proved effective in various clinical scenarios. However, considerable overlap does exist between the genotypes of individual lymphomas and at the same time where additional molecular lesions may be associated with each entity apart from the key genetic event. Therefore, genomics is one of the cornerstones in the multimodality approach essential for classification and risk stratification of B-cell non-Hodgkin lymphomas.

CONCLUSION

We hereby in this review discuss the wide range of genetic aberrancies associated with tumorigenesis, immune escape, and chemoresistance in major B-cell non-Hodgkin lymphomas.

Old and New Facts and Speculations on the Role of the B Cell Receptor in the Origin of Chronic Lymphocytic Leukemia

The engagement of the B cell receptor (BcR) on the surface of leukemic cells represents a key event in chronic lymphocytic leukemia (CLL) since it can lead to the maintenance and expansion of the neoplastic clone. This notion was initially suggested by observations of the CLL BcR repertoire and of correlations existing between certain BcR features and the clinical outcomes of single patients. Based on these observations, tyrosine kinase inhibitors (TKIs), which block BcR signaling, have been introduced in therapy with the aim of inhibiting CLL cell clonal expansion and of controlling the disease. Indeed, the impressive results obtained with these compounds provided further proof of the role of BcR in CLL. In this article, the key steps that led to the determination of the role of BcR are reviewed, including the features of the CLL cell repertoire and the fine mechanisms causing BcR engagement and cell signaling. Furthermore, we discuss the biological effects of the engagement, which can lead to cell survival/proliferation or apoptosis depending on certain intrinsic cell characteristics and on signals that the micro-environment can deliver to the leukemic cells. In addition, consideration is given to alternative mechanisms promoting cell proliferation in the absence of BcR signaling, which can explain in part the incomplete effectiveness of TKI therapies. The role of the BcR in determining clonal evolution and disease progression is also described. Finally, we discuss possible models to explain the selection of a special BcR set during leukemogenesis. The BcR may deliver activation signals to the cells, which lead to their uncontrolled growth, with the possible collaboration of other still-undefined events which are capable of deregulating the normal physiological response of B cells to BcR-delivered stimuli.

Uncovering novel mutational signatures by de novo extraction with SigProfilerExtractor

Mutational signature analysis is commonly performed in cancer genomic studies. Here, we present SigProfilerExtractor, an automated tool for de novo extraction of mutational signatures, and benchmark it against another 13 bioinformatics tools by using 34 scenarios encompassing 2,500 simulated signatures found in 60,000 synthetic genomes and 20,000 synthetic exomes. For simulations with 5% noise, reflecting high-quality datasets, SigProfilerExtractor outperforms other approaches by elucidating between 20% and 50% more true-positive signatures while yielding 5-fold less false-positive signatures. Applying SigProfilerExtractor to 4,643 whole-genome- and 19,184 whole-exome-sequenced cancers reveals four novel signatures. Two of the signatures are confirmed in independent cohorts, and one of these signatures is associated with tobacco smoking. In summary, this report provides a reference tool for analysis of mutational signatures, a comprehensive benchmarking of bioinformatics tools for extracting signatures, and several novel mutational signatures, including one putatively attributed to direct tobacco smoking mutagenesis in bladder tissues.

A clinical case of the effective combined use of BCL-2 and PI3K inhibitors in the treatment of a patient with an unfavorable chronic lymphocytic leukemia with transformation into diffuse large B-cell lymphoma (Richter’s syndrome)

Understanding the molecular biological basis of chronic lymphocytic leukemia (CLL) pathogenesis and stratification of patients into risk groups has now led to significant advances in treatment. New targeted drugs with different mechanisms of action (bruton’s tyrosine kinase inhibitors, bCL-2 inhibitors, pI3K inhibitors) have significantly improved the prognosis of high-risk CLL patients. In some CLL cases the nodular tumor component can change to a more aggressive subtype of lymphoma (often diffuse large b-cell) with preservation of the small-cell leukemic component with the CLL phenotype (Richter’s syndrome), usually characterized by rapid progression and poor prognosis. The issue of treatment efficacy in patients with Richter’s syndrome still remains unresolved. The results of new drugs clinical trials are often contradictory and cannot yet be recommended for routine use in clinical practice. The low incidence of Richter’s syndrome, the lack of a unified view of the pathogenesis and therapy approaches make the search for effective drugs an urgent task, so each clinical observation is of undoubted interest.A clinical case of CLL patient with unfavorable molecular cytogenetic risk and transformation into diffuse large b-cell lymphoma (Richter’s syndrome) is presented. The combined use of bCL-2 inhibitors (venetoclax) and pI3K (duvelisib) led to the achievement of partial remission followed by a gradual increase in the positive antitumor effect.