Correlation between FDG/PET, histology, characteristics, and survival in 332 patients with chronic lymphoid leukemia

18F-FDG PET or PET/CT in detecting high-grade transformation of chronic lymphocytic leukaemia and indolent lymphomas: a systematic review and meta-analysis

OBJECTIVES

To evaluate the diagnostic accuracy of 18F-FDG positron emission tomography (PET) or PET/computed tomography (CT) in detecting histological transformation (HT) of indolent lymphomas.

METHODS

A systematic search of articles up to July 2024 was performed in Embase and Medline. Eligible studies included adults with histologically proven indolent lymphoma, 18F-FDG PET or PET/CT as the index test, and sufficient data to assess diagnostic performance. Summary receiver operating characteristic curves were plotted using a bivariate model to estimate diagnostic accuracy with area under the curve (AUC).

RESULTS

Fifteen studies with 1307 participants were included. Ten studies assessed PET ability to detect Richter's transformation, and 5 studies focused on HT in follicular lymphoma and other subtypes. A meta-analysis of the former showed pooled sensitivity of 0.90 (95% CI, 0.84-0.93) and specificity of 0.54 (95% CI, 0.28-0.77) when using a maximum standardized uptake value (SUVmax) threshold of around 5. AUC was 0.89. Pooled sensitivity was 0.74 (95% CI, 0.54-0.87), and specificity was 0.84 (95% CI, 0.67-0.93) when using an SUVmax threshold of around 10. Area under the curve was 0.84. For detecting HT in follicular lymphoma, thresholds were found higher than those for Richter's transformation.

CONCLUSIONS

18F-FDG PET or PET/CT demonstrates good diagnostic accuracy to detect Richter's transformation, best when employing SUVmax ≥ 5. SUVmax thresholds may be limited in discriminating follicular lymphoma from HT, and alternatives should be sought.

ADVANCES IN KNOWLEDGE

If biopsy is feasible, SUVmax ≥ 5 can guide biopsy in patients with clinically suspicious Richter's transformation. If biopsy is infeasible, SUVmax ≥ 10 can better identify HT and guide patient management.

"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.

Guidelines for the diagnosis and treatment of chronic lymphocytic leukemia and small lymphocytic lymphoma from Chronic Lymphocytic Leukemia Spanish Group (GELLC)

INTRODUCTION

Chronic lymphocytic leukemia (CLL) is the most common form of leukemia in adults in Western countries, with a median age at diagnosis of 72 years. This guide, developed by the Spanish Group for Chronic Lymphocytic Leukemia (GELLC), addresses the most relevant aspects of CLL, with the objectives of facilitating and aiding the diagnostic process, establishing therapeutic recommendations for choosing the best treatment for each type of patient, as well as standardizing the management of CLL and ensuring equity across different hospitals in terms of the use of the various available treatment regimens.

METHODOLOGY

The references obtained were classified according to the level of evidence and following the criteria established by the Agency for Health Research and Quality, and the recommendations were classified according to the criteria of the National Comprehensive Cancer Network (NCCN).

DIAGNOSIS

The diagnosis of CLL requires the presence of 5 × 109/l clonal B lymphocytes with the characteristic phenotype (CD19, CD5, CD20, CD23, and kappa or lambda chain restriction) demonstrated by flow cytometry in peripheral blood and maintained for at least 3 months. The presence of cytopenia caused by a typical bone marrow infiltrate establishes the diagnosis of CLL, regardless of the number of circulating lymphocytes or existing lymph node involvement. CLL and small lymphocytic lymphoma (SLL) are the same disease with different presentations, so they should be treated the same way. Current international guidelines recommend FISH with the 4 probes as a mandatory test in clinical practice to guide the prognosis of patients. They also recommend determining the mutational status of the immunoglobulin heavy chain variable region (IGHV) before the first treatment and detecting TP53 mutations before the first and subsequent relapses.

TREATMENT

Treatment should be initiated in symptomatic patients with criteria for active disease according to iwCLL. The first aspect to highlight is the prioritization of targeted therapies over immunochemotherapy. In first-line treatment, for patients with del(17p) and/or TP53 mutation, the best therapeutic option is a second-generation covalent Bruton's tyrosine kinase inhibitor (BTKi) administered indefinitely, while in cases without del(17p) or TP53 mutation with mutated IGHV, time-limited therapy with a combination including a BCL2 inhibitor (BCL2i) should be considered as the first therapeutic option. For patients with unmutated IGHV, both continuous BTKi and finite therapy with BCL2i are valid options that should be individually evaluated considering potential toxicities, drug interactions, patient preference, and logistical aspects. In very frail patients, supportive treatment should be considered. In relapse/refractory patients, prior treatment, the biological risk of CLL, the duration of response (if prior finite treatment), or the reason for stopping BTKi (if prior continuous treatment) should be considered.

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.

BCMA CAR-T induces complete and durable remission in plasmablastic lymphoma synchronous transformation of chronic lymphocytic leukemia: Case report and literature review

Richter transformation is still a serious risk in the era of innovative therapies, despite the fact that targeted therapy with Bruton's tyrosine kinase inhibitor has significantly improved the prognosis for chronic lymphocytic leukemia (CLL). We report a rare case of a 61-year-old male patient's CLL transforming into a synchronous clonal related plasmablastic lymphoma (PBL) after receiving ibrutinib. During COVID-19, the patient stopped taking ibrutinib, which caused the illness to worsen. Histology revealed that PBL was present in the right supraclavicular mass and that CLL had penetrated the bone marrow. Three cycles of CHP (cyclophosphamide, doxorubicin, and prednisone) were administered together with venetoclax and brentuximab vedotin. After receiving BCMA CAR-T cell treatment, the patient was in complete remission. For PBL transformation, a condition with a worse prognosis and few therapy choices, our results suggest the use of BCMA CAR-T and novel target agents.

Updates in the Management of Richter Transformation

Richter transformation (RT) is a rare albeit devastating complication of chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL). RT is defined as an aggressive lymphoma, typically diffuse large B-cell lymphoma, in the setting of CLL. A clonal relationship to the preceding CLL clone is detected in the majority of RT cases and confers more aggressive clinicopathologic kinetics, resistance to standard chemoimmunotherapy regimens, and inferior survival. Taken together, these considerations precipitate a significant unmet need for novel therapeutic strategies that improve the outcomes of patients with RT. Through this review, we will explore current data on emerging regimens targeting BTK, BCL-2, CD79, CD20, PI3K, and PD-1-both as single agents and as combination therapies with or without concurrent chemoimmunotherapy. Furthermore, we will review the role of bispecific T-cell engagers, anti-CD19 chimeric antigen receptor T-cell therapies, and hematopoietic stem cell transplantation in RT. To guide therapeutic decision-making, we will outline an algorithmic approach to the management of RT, with particular emphasis on prioritization of clinical trial enrollment and utilization of an ever-evolving array of novel therapies.

Role of Novel Quantitative Imaging Techniques in Hematological Malignancies

Hematological malignancies exhibit a widespread distribution, necessitating evaluation of disease activity over the entire body. In clinical practice, visual analysis and semiquantitative parameters are used to assess 18F-FDGPET/CT imaging, which solely represents measurements of disease activity from limited area and may not adequately reflect global disease assessment. An efficient method for assessing the global disease burden of hematological malignancies is to employ PET/computed tomography based novel quantitative parameters. In this article, we explored novel quantitative parameters on PET/CT imaging for assessing global disease burden and the potential role of artificial intelligence (AI) to determine these parameters in evaluation of hematological malignancies.

Applications of 18F-Fluorodesoxyglucose PET Imaging in Leukemia

The main finding that 18F-FDG PET imaging can reveal in patients with leukemias is the presence of bone marrow (BM) infiltration in both acute or chronic forms. This ability can influence and guide the use of BM biopsy but also assess to therapy response. Additionally 18F-FDG PET imaging has been reported as particularly useful for the diagnosis of leukemias in patients with non specific symptoms. In the case of acute leukemias it revealed also a role for the evaluation of extramedullary forms while in the case of chronic forms a role for the assessment of Richter transformation has been reported.

PET/CT in leukemia: utility and future directions

2-Deoxy-2-[ 18 F]fluoro- d -glucose PET/computed tomography ([ 18 F]FDG PET/CT) has proven to be a sensitive method for the detection and evaluation of hematologic malignancies, especially lymphoma. The increasing incidence and mortality rates of leukemia have raised significant concerns. Through the utilization of whole-body imaging, [ 18 F]FDG PET/CT provides a thorough assessment of the entire bone marrow, complementing the limited insights provided by biopsy samples. In this regard, [ 18 F]FDG PET/CT has the ability to assess diverse types of leukemia The utilization of [ 18 F]FDG PET/CT has been found to be effective in evaluating leukemia spread beyond the bone marrow, tracking disease relapse, identifying Richter's transformation, and assessing the inflammatory activity associated with acute graft versus host disease. However, its role in various clinical scenarios in leukemia remains unacknowledged. Despite their less common use, some novel PET/CT radiotracers are being researched for potential use in specific scenarios in leukemia patients. Therefore, the objectives of this review are to provide a thorough assessment of the current applications of [ 18 F]FDG PET/CT in the staging and monitoring of leukemia patients, as well as the potential for an expanding role of PET/CT in leukemia patients.

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.

Low Cell Bioenergetic Metabolism Characterizes Chronic Lymphocytic Leukemia Patients with Unfavorable Genetic Factors and with a Better Response to BTK Inhibition

Chronic Lymphocytic Leukemia (CLL) is an indolent malignancy characterized by the accumulation of quiescent mature B cells. However, these cells are transcriptionally and translationally active, implicating an active metabolism. The recent literature suggests that CLL cells have an oxidative-type phenotype. Given the role of cell metabolism, which is able to influence the outcome of treatments, in other neoplasms, we aimed to assess its prognostic role in CLL patients by determining the ex vivo bioenergetic metabolic profile of CLL cells, evaluating the correlation with the patient clinical/biological characteristics and the in vivo response to BTK inhibitor treatment. Clustering analysis of primary samples identified two groups, characterized by low (CLL low) or high (CLL high) bioenergetic metabolic rates. Compared to the CLL high, CLL with lower bioenergetic metabolic rates belonged to patients characterized by a statistically significant higher white blood cell count and by unfavorable molecular genetics. More importantly, patients in the CLL low cluster displayed a better and more durable response to the BTK inhibitor ibrutinib, thus defining a bioenergetic metabolic subgroup that can benefit the most from this therapy.

The Diagnostic Performance of 2-[18F]FDG PET/CT in Identifying Richter Transformation in Chronic Lymphocytic Leukemia: An Updated Systematic Review and Bivariate Meta-Analysis

Richter transformation is a rare phenomenon characterized by the transformation of cell chronic lymphocytic leukemia (CLL) into a more aggressive lymphoma variant. The early identification of CLLs with a high risk of RT is fundamental. In this field, 2-deoxy-2-[18F]-fluoro-D-glucose positron emission tomography/computed tomography (2-[18F]FDG PET/CT) has been shown to be a non-invasive and promising tool, but apparently, unclear data seem to be present in the literature. This systematic review and bivariate meta-analysis aimed to investigate the diagnostic performance of 2-[18F]FDG PET/CT and its parameters in predicting RT. Between 2006 and 2024, 15 studies were published on this topic, including 1593 CLL patients. Among semiquantitative variables, SUVmax was the most investigated, and the best threshold derived for detecting RT was five. With this cut-off value, a pooled sensitivity of 86.8% (95% CI: 78.5-93.3), a pooled specificity of 48.1% (95% CI: 27-69.9), a pooled negative predictive value of 90.5% (95% CI: 88.4-92.4), a pooled negative likelihood ratio of 0.35 (95% CI: 0.17-0.70), a pooled positive likelihood ratio of 1.8 (95% CI: 1.3-2.4), and a pooled diagnostic odds ratio of 6.7 (3.5-12.5) were obtained. With a higher cut-off (SUVmax = 10), the specificity increased while the sensitivity reduced. The other metabolic features, like metabolic tumor volume, total lesion glycolysis, and radiomic features, were only marginally investigated with controversial evidence.

Treatment of Richter's Transformation with Novel Therapies

PURPOSE OF REVIEW

This review presents recently published clinical trial data and ongoing investigations regarding the treatment of Richter's transformation (RT).

RECENT FINDINGS

Recently, numerous approaches have been investigated for the treatment of RT including: traditional chemoimmunotherapy regimens combined with targeted agents such as BTKi and BCL2i; immunotherapy combined with targeted agents; non-covalent BTKis; bispecific T cell engagers; and CART therapy. In addition, various novel targeted agents are currently being studied for the treatment of RT in phase 1 and 2 clinical trials. Standard of care treatment with chemoimmunotherapy for RT has limited efficacy in achieving durable remissions. Here, we review recent data on the use of combination treatments and targeted agents in RT. Although some progress has been made in the investigation to optimize treatment of RT, further study is needed to evaluate long term outcomes of recently published trials and test efficacy of upcoming novel agents.

Are we closer to a standard of care for Richter's syndrome? Novel treatments on the horizon

INTRODUCTION

The therapeutic landscape for chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL) has significantly evolved over the past decade with dramatically improved outcomes with the introduction of targeted therapies. This unfortunately has not been the case for Richter transformation (RT), the histologic transformation to a more aggressive lymphoma, most typically diffuse large B-cell lymphoma (DLBCL). As such, RT continues to be one of the most challenging complications of CLL/SLL. Historically, RT has a poor response to treatment, with a minority reaching complete remission (CR) and overall survival (OS) being less than a year.

AREAS COVERED

The focus of this review is to discuss the effectiveness of commonly used regimens, and review existing data for emerging regimens being examined in ongoing clinical trials to improve prognosis and outcomes in patients with RT. Despite extensive efforts to optimize therapies for RT, there is still no generalized consensus on either first-line treatment regimens or regimens in the relapsed/refractory setting. RT continues to carry a high mortality rate without durable response to current therapeutic agents.

EXPERT OPINION

Ongoing and future research may identify novel treatment approaches that will eventually improve outcomes for patients with RT. The optimal care for RT patients is a clinical trial, when feasible.

Utility of FDG-PET in predicting the histology of relapsed or refractory lymphoma

ABSTRACT

18F-fluorodeoxyglucose-positron emission tomography (FDG-PET) is a valuable prognostic tool in modern lymphoma care. In this study, we explored the use of quantitative FDG-PET parameters in predicting the histology of suspected relapsed or refractory (R/R) lymphoma. We retrospectively analyzed 290 FDG-PET scans performed for suspected R/R lymphoma. FDG-PET parameters measured were maximum and mean standardized uptake value (SUVMax and SUVMean), total metabolic tumor volume, and total lesion glycolysis (TLG). Receiver operating characteristic curve analysis was used to obtain the optimal thresholds that best discriminate (1) benign vs R/R lymphoma, (2) indolent vs aggressive non-Hodgkin lymphoma (NHL), and (3) aggressive transformation of indolent NHL. We found that although all 4 FDG-PET parameters discriminated R/R lymphoma from benign histology, TLG was the best performing parameter (optimal cut-off ≥245, sensitivity 63%, specificity 86%, positive predictive value [PPV] 97%, negative predictive value [NPV] 30%, area under the curve [AUC] 0.798, and P < .001). SUVMax discriminated aggressive from indolent NHL with modest accuracy (optimal threshold ≥15, sensitivity 46%, specificity 79%, PPV 82%, NPV 38%, AUC 0.638, and P < .001). In patients with a prior diagnosis of indolent NHL, SUVMax was a modest predictor of transformation (optimal cut-off ≥12, sensitivity 71%, specificity 61%, PPV 50%, NPV 78%, AUC 0.676, and P .006). Additionally, SUVMax ≥25 and an increase in SUVMax (ΔSUVMax) from baseline ≥150% were highly specific (96% and 94%, respectively). These FDG-PET thresholds can aid in identification of suspected R/R lymphoma cases with higher likelihood of R/R disease and aggressive transformation of indolent NHL, guiding the necessity and urgency of biopsy.

2-[18F]-FDG PET/CT Semiquantitative and Radiomics Predictive Parameters of Richter's Transformation in CLL Patients

Background and Objectives: Chronic lymphocytic leukemia (CLL) is the most common type of leukemia in developed countries, which can evolve into aggressive lymphoma variants, a process called Richter transformation (RT). The aim of this retrospective study was to analyze the role of 2-deoxy-2-[18F]fluoro-D-glucose positron emission tomography/computed tomography (2-[18F]-FDG PET/CT) and its semiquantitative and radiomics features in detecting RT and evaluate the impact on overall survival (OS). Materials and Methods: One hundred and thirty-seven patients with histologically proven CLL were retrospectively recruited. PET/CT images were qualitatively and semiquantitatively examined by estimating the main metabolic parameters (the maximum standardized uptake value body weight (SUVbw), lean body mass (SUVlbm), body surface area (SUVbsa), lesion-to-blood-pool SUV ratio (L-BP SUV R), lesion-to-liver SUV ratio (L-L SUV R), metabolic tumor volume (MTV), and total lesion glycolysis (TLG) and radiomics first- and second- order variables of the lesion with highest uptake. The role of these parameters in predicting RT and OS was analyzed. Results: One hundred and thirty (95%) PET/CT scans were positive, showing an increased tracer uptake at the site of disease, whereas the remaining 7 (5%) scans were negative. SUVbw, SUVlbm, SUVbsa, L-L SUV ratio, and L-BP SUV ratio were significantly higher in the RT group (p < 0.001 in all cases). Radiomics first- and second-order features were not significantly associated with RT. After a median follow-up of 44 months, 56 patients died; OS was significantly shorter in patients with RT than patients without RT (28 vs. 34 months; p = 0.002). Binet-stage, RT, and L-BP SUV R were shown to be independent prognostic features. Conclusions: Semiquantitative PET/CT parameters such as SUVbw, SUVlbm, SUVbsa, L-L SUV ratio and L-BP SUV ratio may be useful in discriminating patients with a high risk of developing RT, whereas Binet-stage, RT, and L-BP SUV R are also significant in predicting OS.

Anatomic Approach to Common and Uncommon Manifestations of Thoracic Leukemias with Radiologic-Pathologic Correlation

Leukemias are hematopoietic malignancies characterized by the production of abnormal leukocytes in the bone marrow. Clinical manifestations arise from either bone marrow suppression or leukemic organ infiltration. Lymphadenopathy is the most common direct manifestation of intrathoracic leukemia. However, leukemic cells may also infiltrate the lungs, pleura, heart, bones, and soft tissues. Pulmonary complications in patients with leukemia typically include pneumonia, hemorrhage, pulmonary edema, and sequelae of leukemia treatment. However, pulmonary abnormalities can also be related directly to leukemia, including leukemic pulmonary infiltration. The direct, non-treatment-related effects of leukemia on intrathoracic structures will be the focus of this imaging essay. Given the typical anatomic approach for image interpretation, an organ-based depiction of common and less common intrathoracic findings directly caused by leukemic involvement is presented, emphasizing imaging findings with pathologic correlations. Keywords: Leukemia, Pulmonary, Thorax, Soft Tissues/Skin, Hematologic, Bone Marrow © RSNA, 2023.

[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.

Clinical Application of 18F-FDG-PET Quantification in Hematological Malignancies: Emphasizing Multiple Myeloma, Lymphoma and Chronic Lymphocytic Leukemia

Most hematological malignancies display heightened glycolytic activity, leading to their detectability through 18F-FDG-PET imaging. PET quantification enables the extraction of metabolic information from tumors. Among various PET measurements, maximum standardized uptake value (SUVmax), which indicates the highest value of 18F-FDG uptake within the tumor, has emerged as the commonly used parameter in clinical oncology. This is because of SUVmax ease of calculation using most available commercial workstations, as well as its simplicity and independence from observer interpretation. Nonetheless, SUVmax represents the increase in activity within a specific small area, which may not fully capture the overall tumor uptake. Volumetric PET parameters have been identified as a potential solution to overcome certain limitations associated with SUVmax. However, these parameters are influenced by the low spatial resolution of PET when assessing small lesions. Another challenge is the high number of lesions observed in some patients, leading to a time-consuming process for evaluating all focal lesions. Some institutions recently have started advocating for CT-based segmentation as a method for measuring radiotracer uptake in the bone marrow and overall bone of the patients. This review article aims to provide insights into clinical application of PET quantification specifically focusing on 3 major hematologic malignancies: multiple myeloma, lymphoma, and chronic lymphocytic leukemia.

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.

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.

Richter Transformation of Chronic Lymphocytic Leukemia-Are We Making Progress?

PURPOSE OF REVIEW

The treatment paradigm of chronic lymphocytic leukemia (CLL) has dramatically changed with the advent of novel targeted agents over the past decade. Richter transformation (RT), or the development of an aggressive lymphoma from a background of CLL, is a well-recognized complication of CLL and carries significantly poor clinical outcomes. Here, we provide an update on current diagnostics, prognostication, and contemporary treatment of RT.

RECENT FINDINGS

Several genetic, biologic, and laboratory markers have been proposed as candidate risk factors for the development of RT. Although a diagnosis of RT is typically suspected based on clinical and laboratory findings, tissue biopsy is essential for histopathologic confirmation of diagnosis. The standard of care for RT treatment at this time remains chemoimmunotherapy with the goal of proceeding to allogeneic stem cell transplantation in eligible patients. Several newer treatment modalities are being studied for use in the management of RT, including small molecules, immunotherapy, bispecific antibodies, and chimeric antigen receptor T-cell (CAR-T) therapy. The management of patients with RT remains a challenge. Ongoing trials show enormous promise for newer classes of therapy in RT, with the hope being that these agents can synergize, and perhaps supersede, the current standard of care in the near future.

Aggressive chronic lymphocytic leukemia masked by extensive marrow fibrosis

Chronic lymphocytic leukemia (CLL) is one of the most common B-cell leukemias, occurring because of abnormal proliferation of non-functional B-lymphocytes. Progressive disease is commonly complicated by anemia, thrombocytopenia, infections as well as secondary malignancies. Bone marrow fibrosis is infrequently co-occurred along with CLL. Although multiple explanations have been proposed for this association, the etiology remains unclear in most cases. Bone marrow fibrosis occurring as a complication of CLL itself, however, is a rare entity. We present an uncommon case of a patient initially diagnosed with primary myelofibrosis but later revealed to have aggressive CLL leading to bone marrow fibrosis upon re-evaluation. Treatment for CLL resolved the bone marrow fibrosis completely, confirming our suspicion of fibrosis being secondary to CLL. This sheds light on the importance of understanding the etiology of bone marrow fibrosis in patients with CLL owing to its therapeutic implications. The utility of bone marrow biopsy in not only helping understand the etiology of the fibrosis but also providing prognostic information merits reconsideration of performing it in all cases of CLL.

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.

Progression and transformation of chronic lymphocytic leukemia/small lymphocytic lymphoma and B-cell prolymphocytic leukemia: Report from the 2021 SH/EAHP Workshop

OBJECTIVES

Session 3 of the 2021 Workshop of the Society for Hematopathology/European Association for Haematopathology examined progression and transformation of chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL) and B-cell prolymphocytic leukemia (B-PLL).

METHODS

Thirty-one cases were reviewed by the panel. Additional studies such as immunohistochemistry and molecular genetic testing, including whole-exome sequencing and expression profiling, were performed in select cases.

RESULTS

Session 3 included 27 CLL/SLL cases and miscellaneous associated proliferations, 3 cases of B-PLL, and 1 case of small B-cell lymphoma. The criteria for -accelerated CLL/SLL are established for lymph nodes, but extranodal disease can be diagnostically challenging. Richter transformation (RT) is a broad term and includes true transformation from original CLL/SLL clone(s) and clonally unrelated neoplasms. The morphologic, immunophenotypic, and genetic spectrum is diverse with classical and highly unusual examples. T-cell proliferations can also be encountered in CLL/SLL. B-cell prolymphocytic leukemia is a rare, diagnostically challenging disease due to its overlaps with other lymphoid neoplasms.

CONCLUSIONS

The workshop highlighted complexity of progression and transformation in CLL/SLL and B-PLL, as well as diagnostic caveats accompanying heterogeneous presentations of RT and other manifestations of disease progression. Molecular genetic studies are pivotal for diagnosis and determination of clonal relationship, and to predict response to treatment and identify resistance to targeted therapy.

Treatment of Richter Transformation of Chronic Lymphocytic Leukemia in the Modern Era

Richter Transformation (RT) refers to the development of an aggressive lymphoma in the setting of chronic lymphocytic leukemia (CLL). While many variants of RT are recognized, diffuse large B-cell lymphoma (RT-DLBCL) is the most common (80%), followed by Hodgkin’s lymphoma (RT-HL, 19%). Diagnosis is based upon histologic evaluation of clinically suspicious lymph nodes. Positron emission tomography (PET) may be used to select the node of interest for biopsy. Although clonality testing is not a prerequisite of RT diagnosis, it has significant implications for survival. Clonally related DLBCL carries the worst prognosis with a median overall survival (OS) of less than one year in the era of combination chemotherapies with or without anti-CD20 antibodies. Prognosis has improved with the use of stem cell transplant and newer agents such as targeted therapy and newer forms of immunotherapy. Consideration of a clinical trial is encouraged. This review describes our current understanding of RT and focuses on treatment of RT-DLBCL, including clinical trials in progress and new therapies in development. We also report an illustrative example of a patient with clonally related DLBCL who survived two years after diagnosis without the use of combination chemotherapy.

Metabolomics: A New Era in the Diagnosis or Prognosis of B-Cell Non-Hodgkin's Lymphoma

A wide range of histological as well as clinical properties are exhibited by B-cell non-Hodgkin's lymphomas. These properties could make the diagnostics process complicated. The diagnosis of lymphomas at an initial stage is essential because early remedial actions taken against destructive subtypes are commonly deliberated as successful and restorative. Therefore, better protective action is needed to improve the condition of those patients who are extensively affected by cancer when diagnosed for the first time. The development of new and efficient methods for early detection of cancer has become crucial nowadays. Biomarkers are urgently needed for diagnosing B-cell non-Hodgkin's lymphoma and assessing the severity of the disease and its prognosis. New possibilities are now open for diagnosing cancer with the help of metabolomics. The study of all the metabolites synthesised in the human body is called "metabolomics." A patient's phenotype is directly linked with metabolomics, which can help in providing some clinically beneficial biomarkers and is applied in the diagnostics of B-cell non-Hodgkin's lymphoma. In cancer research, it can analyse the cancerous metabolome to identify the metabolic biomarkers. This review provides an understanding of B-cell non-Hodgkin's lymphoma metabolism and its applications in medical diagnostics. A description of the workflow based on metabolomics is also provided, along with the benefits and drawbacks of various techniques. The use of predictive metabolic biomarkers for the diagnosis and prognosis of B-cell non-Hodgkin's lymphoma is also explored. Thus, we can say that abnormalities related to metabolic processes can occur in a vast range of B-cell non-Hodgkin's lymphomas. The metabolic biomarkers could only be discovered and identified as innovative therapeutic objects if we explored and researched them. In the near future, the innovations involving metabolomics could prove fruitful for predicting outcomes and bringing out novel remedial approaches.

Patient characteristics that predict Richter's transformation in patients with chronic lymphocytic leukemia treated with ibrutinib

Chronic lymphocytic leukemia (CLL) transformation to aggressive lymphoma, known as Richter's Transformation (RT), has a dismal prognosis. There are limited data evaluating risk of RT in patients treated with ibrutinib. We performed a retrospective analysis to determine prognostic variables associated with development of RT and overall survival (OS) at progression after treatment with ibrutinib. We identified 559 patients with CLL treated with ibrutinib from 2010-2019. After a median follow-up of 44.5 months from ibrutinib start, 179 patients progressed and were included in our analysis. After a median follow-up of 20.8 months from progression, 54 out of 179 patients developed RT. Progression on treatment (hazard ratio [HR] 4.01 [1.60-10.00], p = .003), higher LDH (HR 1.80 for 2-fold increase [1.33-2.43], p = .0001), and lymphadenopathy without lymphocytosis (HR 2.88 [1.15-7.20], p = .02) were independent prognostic variables for the development of RT at progression. Progression with lymphadenopathy without lymphocytosis continued to be an independent prognostic variable of worse OS post-progression. In a subset analysis of 50 patients who obtained a PET-CT at progression, the median SUV_max for patients who would develop RT was 15.2 (n = 30, range: 4.0-46.3) versus those patients who did not develop RT with a SUV_max of 7.7 (n = 20, range: 2.3-27.2) (p = .0030). Median OS from date of RT was 4.0 months, suggesting that prognosis for RT remains poor. A lymph node biopsy to rule out RT should be considered in patients who received ibrutinib who progress on treatment, have an elevated LDH, or progress with lymphadenopathy without lymphocytosis.

Treatment of Richter's syndrome

Richter's syndrome (RS) is an aggressive histologic transformation of chronic lymphocytic leukemia (CLL), most commonly to diffuse large B-cell lymphoma (DLBCL). Outcomes are generally poor, with complete remission (CR) rates of only about 20% and less than 20% long-term survival with chemoimmunotherapy (CIT). RS is biologically heterogeneous, and in 80% of patients with CLL who develop DLBCL, the disease is clonally related to the CLL. Clonally unrelated cases are genetically and immunologically distinct from clonally related DLBCL-RS, have more favorable responses to CIT, and are best treated as de novo DLBCL. Relatively favorable outcomes with CIT are also seen in patients who have never previously received treatment for CLL and who lack TP53 mutation or deletion. For the remaining patients, treatment on a clinical trial is optimal. Fortunately, numerous agents are now in clinical development that show encouraging results. Here we review clinical data for some of the most promising approaches. DLBCL-RS tumor cells frequently express programmed cell death 1 protein (PD-1), and several studies have demonstrated activity for PD-1 inhibitors, especially in combination with ibrutinib. The BCL2 inhibitor venetoclax in combination with R-EPOCH CIT achieved CR in 50% of patients, and a study of venetoclax-R-CHOP is ongoing. The noncovalent Bruton's tyrosine kinase inhibitor pirtobrutinib has achieved responses in approximately two-thirds of heavily pretreated patients and, given its favorable toxicity profile, appears ideally suited to combining with other active agents. Finally, we review available data for bispecific antibodies, antibody-drug conjugates, and chimeric antigen receptor T-cell therapy, which, after revolutionizing the treatment of DLBCL, are now being evaluated in RS.

Artificial intelligence-assisted mapping of proliferation centers allows the distinction of accelerated phase from large cell transformation in chronic lymphocytic leukemia

Chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL) is characterized morphologically by numerous small lymphocytes and pale nodules composed of prolymphocytes and paraimmunoblasts known as proliferation centers (PCs). Patients with CLL can undergo transformation to a more aggressive lymphoma, most often diffuse large B-cell lymphoma (DLBCL), known as Richter transformation (RT). An accelerated phase of CLL (aCLL) also may be observed which correlates with subsequent transformation to DLBCL, and may represent an early stage of transformation. Distinguishing PCs in CLL from aCLL or RT can be diagnostically challenging, particularly in small needle biopsy specimens. Available guidelines pertaining to distinguishing CLL from its' progressive forms are limited, subject to the morphologist's experience and are often not completely helpful in the assessment of scant biopsy specimens. To objectively assess the extent of PCs in aCLL and RT, and enhance diagnostic accuracy, we sought to design an artificial intelligence (AI)-based tool to identify and delineate PCs based on feature analysis of the combined individual nuclear size and intensity, designated here as the heat value. Using the mean heat value from the generated heat value image of all cases, we were able to reliably separate CLL, aCLL and RT with sensitive diagnostic predictive values.

B-cell Receptor Signaling Induced Metabolic Alterations in Chronic Lymphocytic Leukemia Can Be Partially Bypassed by TP53 Abnormalities

It has been unclear what role metabolism is playing in the pathophysiology of chronic lymphocytic leukemia (CLL). One reason is that the study of CLL metabolism is challenging due to the resting nature of circulating CLL cells. Also, it is not clear if any of the genomic aberrations observed in this disease have any impact on metabolism. Here, we demonstrate that CLL cells in proliferation centers exhibit upregulation of several molecules involved in glycolysis and mitochondrial metabolism. Comparison of CXCR4/CD5 intraclonal cell subpopulations showed that these changes are paralleled by increases in the metabolic activity of the CXCR4^lowCD5^high fraction that have recently egressed from the lymph nodes. Notably, anti-IgM stimulation of CLL cells recapitulates many of these metabolic alterations, including increased glucose uptake, increased lactate production, induction of glycolytic enzymes, and increased respiratory reserve. Treatment of CLL cells with inhibitors of B-cell receptor (BCR) signaling blocked these anti-IgM-induced changes in vitro, which was mirrored by decreases in hexokinase 2 expression in CLL cells from ibrutinib-treated patients in vivo. Interestingly, several samples from patients with 17p-deletion manifested increased spontaneous aerobic glycolysis in the unstimulated state suggestive of a BCR-independent metabolic phenotype. We conclude that the proliferative fraction of CLL cells found in lymphoid tissues or the peripheral blood of CLL patients exhibit increased metabolic activity when compared with the bulk CLL-cell population. Although this is due to microenvironmental stimulatory signals such as BCR-engagement in most cases, increases in resting metabolic activity can be observed in cases with 17p-deletion.

Biology and Treatment of Richter Transformation

Richter transformation (RT), defined as the development of an aggressive lymphoma on a background of chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL), represents a clinical unmet need because of its dismal prognosis. An increasing body of knowledge in the field of RT is arising from the recent development of preclinical models depicting the biology underlying this aggressive disease. Consistently, new therapeutic strategies based on a genetic rationale are exploring actionable pathogenic pathways to improve the outcome of patients in this setting. In this review, we summarize the current understandings on RT biology and the available treatment options.

Richter's Transformation

PURPOSE OF REVIEW

Richter's transformation (RT) occurs when chronic (CLL) transforms into an aggressive lymphoma. Despite improvements in the treatment of CLL, prognosis for RT remains poor. Here, we review current literature of RT, with a focus on novel treatment options.

RECENT FINDINGS

Efforts are underway to improve outcomes for patients with RT. While small molecule inhibitors have limited efficacy as monotherapy, recent developments combining them with chemo-immunotherapy show promise. Studies exploring the use of cellular therapies including chimeric antigen receptor T-cells and bispecific antibodies are ongoing. The current treatment paradigm for RT is to enroll these patients on a clinical trial when available, together with consultation for a consolidative allogeneic stem cell transplant. Trials investigating novel combinations and cellular therapy are ongoing. Determining predictive variables of transformation is imperative to design studies that allow for early identification and intervention for patients with RT.

Recurrent Chromosomal Abnormalities in Tissues Involved by Chronic Lymphocytic Leukemia/Small Lymphocytic Lymphoma

OBJECTIVES

Prognostically relevant chromosomal abnormalities in chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL) are routinely identified by fluorescence in situ hybridization (FISH) on peripheral blood or bone marrow specimens. We studied the prevalence of chromosomal abnormalities on extramedullary tissues involved by CLL/SLL and evaluated their association with prominent proliferation centers (PPCs).

METHODS

FISH for recurrent abnormalities in CLL/SLL was performed on formalin-fixed, paraffin-embedded biopsy sections. PPCs were identified on H&E-stained sections. Available FISH results on peripheral blood or bone marrow specimens were also reviewed.

RESULTS

Recurrent FISH abnormalities were detected in 69% of 320 CLL/SLL biopsy specimens studied, including +12 (35%), 13q- (24%), 11q- (15%), 17p- (6%), 6q- (2%), and IGH/BCL2 (0.9%). Forty-three patients had abnormal blood or bone marrow FISH analyses, of whom 7 (16%) had discordant +12 and/or 13q-, and 3 (7%) had discordant 17p- or 11q-. Morphology was positive (17%), negative (78%), or equivocal (6%) for PPCs on 247 evaluable biopsy specimens, a finding not significantly associated with FISH results (P = .7).

CONCLUSIONS

Trisomy 12 is overrepresented in tumoral CLL/SLL involvement, compared with the known predominance of 13q- in blood. Discrepancies between leukemic and tissue FISH findings are occasionally encountered. FISH results do not correlate with the presence of PPCs.

Richter Transformation in Chronic Lymphocytic Leukemia: Update in the Era of Novel Agents

Richter transformation (RT) is a poorly understood complication of chronic lymphocytic leukemia (CLL) with a dismal prognosis. It is associated with a switch in histopathology and biology, generally with a transformation of the original CLL clone to diffuse large B-cell lymphoma (DLBCL) or less frequently to Hodgkin's variant of Richter transformation (HVRT). It occurs in 2-10% of CLL patients, with an incidence rate of 0.5-1% per year, and may develop in treatment-naïve patients, although it is more common following therapy. In recent years, there has been a deeper understanding of the molecular pathogenesis of RT that involves the inactivation of the TP53 tumor suppressor gene in 50-60% of cases and the activation of aberrations of NOTCH1 and MYC pathways in about 30% of cases. Compared to the preceding CLL, 80% of cases with DLBCL-RT and 30% of HVRT harbor the same IGHV-D-J rearrangements, indicating a clonal evolution of the disease, while the remaining cases represent de novo lymphomas that are clonally unrelated. Despite advances in understanding the molecular variations and the pathogenesis of the disease, there is still no significant improvement in patient outcomes. However, if no clinical trials were designed for patients with RT in the past, now there many studies for these patients that incorporate new drugs and novel combinations that are being explored. In this review, we summarize the new information accumulated on RT with special emphasis on results involving the novel therapy tested for this entity, which represents an unmet clinical need.

Positron emission tomography/computed tomography in the management of Hodgkin and B-cell non-Hodgkin lymphoma: An update

¹⁸ F-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) is now an integral part of lymphoma staging and management. Because of its greater accuracy compared with CT alone, PET/CT is currently routinely performed for staging and for response assessment at the end of treatment in the vast majority of FDG-avid lymphomas and is the cornerstone of response classification for these lymphomas according to the Lugano classification. Interim PET/CT, typically performed after 2 to 4 of 6 to 8 chemotherapy/chemoimmunotherapy cycles with or without radiation, is commonly performed for prognostication and potential treatment escalation or de-escalation early in the course of therapy, a concept known as response-adapted or risk-adapted treatment. Quantitative PET is an area of growing interest. Metrics, such as the standardized uptake value, changes (Δ) in the standardized uptake value, metabolic tumor volume, and total lesion glycolysis, are being investigated as more reproducible and potentially more accurate predictors of response and prognosis. Despite the progress made in standardizing the use of PET/CT in lymphoma, challenges remain, particularly with respect to its limited positive predictive value, emphasizing the need for more specific molecular probes. This review highlights the most relevant applications of PET/CT in Hodgkin and B-cell non-Hodgkin lymphoma, its strengths and limitations, as well as recent efforts at implementing PET/CT-based metrics as promising tools for precision medicine.

Chronic lymphocytic leukaemia and Richter's transformation: multimodal review and new imaging paradigms

Chronic lymphocytic leukaemia (CLL) is the most common leukaemia in adults. It is a malignancy of CD5 B-cells characterised by small, mature-appearing lymphocytes accumulating in the blood, bone marrow, and lymphoid tissues. Richer transformation (RT) is an important adverse complication. Detection of RT is critical to allow initiation of appropriate therapy. CLL staging and response evaluation is complicated and nuanced. From our extensive tertiary centre experience of several hundred CLL cases over the last decade, we detail key computed tomography (CT) and positron-emission tomography (PET) imaging features of the natural history of CLL. The authors present an original imaging-based patient-management paradigm for the investigation of potential RT, which will inform global practice. Potential applications of whole-body diffusion weighted imaging, novel PET radiotracers, minimal residual disease, and ct-DNA are addressed.

Synergistic efficacy of the dual PI3K-δ/γ inhibitor duvelisib with the Bcl-2 inhibitor venetoclax in Richter syndrome PDX models

A small subset of cases of chronic lymphocytic leukemia undergoes transformation to diffuse large B-cell lymphoma, Richter syndrome (RS), which is associated with a poor prognosis. Conventional chemotherapy results in limited responses, underlining the need for novel therapeutic strategies. Here, we investigate the ex vivo and in vivo efficacy of the dual phosphatidylinositol 3-kinase-δ/γ (PI3K-δ/γ) inhibitor duvelisib (Duv) and the Bcl-2 inhibitor venetoclax (Ven) using 4 different RS patient-derived xenograft (PDX) models. Ex vivo exposure of RS cells to Duv, Ven, or their combination results in variable apoptotic responses, in line with the expression levels of target proteins. Although RS1316, IP867/17, and RS9737 cells express PI3K-δ, PI3K-γ, and Bcl-2 and respond to the drugs, RS1050 cells, expressing very low levels of PI3K-γ and lacking Bcl-2, are fully resistant. Moreover, the combination of these drugs is more effective than each agent alone. When tested in vivo, RS1316 and IP867/17 show the best tumor growth inhibition responses, with the Duv/Ven combination leading to complete remission at the end of treatment. The synergistic effect of Duv and Ven relies on the crosstalk between PI3K and apoptotic pathways occurring at the GSK3β level. Indeed, inhibition of PI3K signaling by Duv results in GSK3β activation, leading to ubiquitination and subsequent degradation of both c-Myc and Mcl-1, making RS cells more sensitive to Bcl-2 inhibition by Ven. This work provides, for the first time, a proof of concept of the efficacy of dual targeting of PI3K-δ/γ and Bcl-2 in RS and providing an opening for a Duv/Ven combination for these patients. Clinical studies in aggressive lymphomas, including RS, are under way. This trial was registered at www.clinicaltrials.gov as #NCT03892044.

Hypercalcemia in Small Lymphocytic Lymphoma with an Elevated Parathyroid Hormone-Related Peptide Associated with Early Richter Transformation

Hypercalcemia in malignancy is associated with multiple mechanisms and occurs in up to 20–30% of cancer patients. We report a case of small lymphocytic lymphoma/chronic lymphocytic leukemia (SLL/CLL) associated with hypercalcemia and an elevation in parathyroid hormone-related peptide (PTHrP) in the setting of a Richter transformation. Real-time reverse transcriptase PCR on lymph node biopsy specimens obtained before and after transformation showed an 8-fold increase in PTHrP mRNA levels and about 2-fold decrease in the levels of its cognate receptor PTHR1. The findings of this case suggest that parathyroid hormone-related peptide might be useful in monitoring a specific group of patients with SLL/CLL who develop hypercalcemia during the course of their disease and could suggest an autocrine-like mechanism involving PTHrP in Richter transformation.

Revisiting Richter transformation in the era of novel CLL agents

Richter transformation (RT) is the development of aggressive lymphoma - most frequently diffuse large B-cell lymphoma (DLBCL) and rarely Hodgkin lymphoma (HL) - arising on the background of chronic lymphocytic leukaemia (CLL). Despite recent advances in CLL treatment, RT also develops in patients on novel agents, usually occurring as an early event. RT incidence is lower in CLL patients treated with novel agents in the front line compared to relapsed/refractory cases, with a higher incidence in patients with TP53 disruption. The genetic heterogeneity and complexity are higher in RT-DLBCL than CLL; the genetics of RT-HL are largely unknown. In addition to TP53, aberrations in CDKN2A, MYC, and NOTCH1 are common in RT-DLBCL; however, no distinct RT-specific genetic aberration is recognised yet. RT-DLBCL on ibrutinib is frequently associated with BTK and PLCG2 mutations. Here, we update on genetic analysis, diagnostics and treatment options in RT in the era of novel agents.

The Role of 2-[18F]-FDG PET/CT in Detecting Richter Transformation in Chronic Lymphocytic Leukemia: A Systematic Review

Richter transformation (RT) is a condition wherein B cell chronic lymphocytic leukemia (CLL) transforms into a more aggressive lymphoma variant. The incidence and the significance of RT detected by 2-[18F]-FDG PET/CT is a clinical challenge and it is not widely investigated in the literature. The aim of this systematic review was to analyze published data about the potential role of 2-[18F]-FDG PET/CT in detecting RT. A comprehensive computer literature search of the PubMed/MEDLINE, Embase and Cochrane library databases was conducted up to December 2020. Thirteen studies (1336 patients with CLL) were selected. The maximum standardized uptake value (SUVmax) was the most common metabolic parameter used to detect RT. An SUVmax of 5 had an average overall sensitivity of 87% (range: 71–96%), an average overall specificity of 49% (range: 4–80%), an average positive predictive value of 41% (range: 16–53%) and an average negative predictive value of 84% (range: 33–97%). Other metabolic variables were only marginally investigated, with promising results. 2-[18F]-FDG PET/CT imaging may play an important role in the detection of RT in CLL, based on the high metabolic activity of the nodal lesions that transformed into aggressive lymphomas. 2-[18F]-FDG PET/CT has high negative predictive value for evaluating RT.

Richter Syndrome

PURPOSE OF REVIEW

Richter syndrome (RS) is an uncommon but aggressive evolution of chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL). RS is an unmet clinical need in the field of CLL. Recent advances in understanding the biology of this condition provide the rationale for testing new therapeutic concepts in order to improve the outcome of patients developing RS, which is so far poor. In this review, we summarize disease characteristics and available therapeutic options for RS.

RECENT FINDINGS

Current regimens with novel agents in monotherapy have shown little impact on survival. Nevertheless, the better reported outcome for RS has been achieved with the combination of chemo-immunotherapy with a novel agent, confirming the synergistic effect of the approaches. Still, the frailty of this population may impose a less toxic management leaving most patients with no reasonable therapeutic option. Treatment options for RS need to be further expanded. Preclinical models in current development may allow to explore actionable pathways and identify new drug targeted combinations.

Non-Hodgkin Lymphoma Metabolism

Non-Hodgkin lymphomas (NHLs) are a heterogeneous group of lymphoid neoplasms with different biological characteristics. About 90% of all lymphomas in the United States originate from B lymphocytes, while the remaining originate from T cells [1]. The treatment of NHLs depends on the neoplastic histology and stage of the tumor, which will indicate whether radiotherapy, chemotherapy, or a combination is the best suitable treatment [2]. The American Cancer Society describes the staging of lymphoma as follows: Stage I is lymphoma in a single node or area. Stage II is when that lymphoma has spread to another node or organ tissue. Stage III is when it has spread to lymph nodes on two sides of the diaphragm. Stage IV is when cancer has significantly spread to organs outside the lymph system. Radiation therapy is the traditional therapeutic route for localized follicular and mucosa-associated lymphomas. Chemotherapy is utilized for the treatment of large-cell lymphomas and high-grade lymphomas [2]. However, the treatment of indolent lymphomas remains problematic as the patients often have metastasis, for which no standard approach exists [2].

Prognostic Significance of PET/CT in Patients with Chronic Lymphocytic Leukemia (CLL) Treated with Frontline Chemoimmunotherapy

The role of positron emission tomography/computed tomography (PET/CT) in identifying Richter Syndrome (RS) is well established, while its impact on the survival of patients with chronic lymphocytic leukemia (CLL) has been less explored. The clinical characteristics and PET/CT data of 40 patients with a biopsy-proven CLL who required frontline chemoimmunotherapy, FCR (fludarabine, cyclophosphamide, rituximab) in 20 patients, BR (bendamustine, rituximab) in 20, were retrospectively analyzed. Standardized uptake volume (SUVmax) values ≥ 5 were observed more frequently in patients with deletion 11q (p = 0.006) and biopsies characterized by a rate of Ki67 positive cells ≥ 30% (p = 0.02). In the multivariate analysis, the presence of large and confluent PCs emerged as the only factor with a negative impact on progression-free survival (PFS), and overall survival (OS). Deletion 11q also revealed a significant and independent effect on PFS. SUVmax values ≥ 5 showed no statistical impact on PFS while in multivariate analysis, they revealed a significant adverse impact on OS (median survival probability not reached vs. 56 months; p = 0.002). Moreover, patients with higher SUVmax values more frequently developed Richter Syndrome (p = 0.015). Our results show that higher SUVmax values identify CLL patients with a pronounced rate of proliferating cells in the lymph-node compartment, inferior survival, and an increased risk of developing RS.