How receptor tyrosine kinase-like orphan receptor 1 meets its partners in chronic lymphocytic leukemia.

Chronic lymphocytic leukemia (CLL) is the most common leukemia in western societies, recognized by clinical and molecular heterogeneity. Despite the success of targeted therapies, acquired resistance remains a challenge for relapsed and refractory CLL, as a consequence of mutations in the target or the upregulation of other survival pathways leading to the progression of the disease. Research on proteins that can trigger such pathways may define novel therapies for a successful outcome in CLL such as the receptor tyrosine kinase-like orphan receptor 1 (ROR1). ROR1 is a signaling receptor for Wnt5a, with an important role during embryogenesis. The aberrant expression on CLL cells and several types of tumors, is involved in cell proliferation, survival, migration as well as drug resistance. Antibody-based immunotherapies and small-molecule compounds emerged to target ROR1 in preclinical and clinical studies. Efforts have been made to identify new prognostic markers having predictive value to refine and increase the detection and management of CLL. ROR1 can be considered as an attractive target for CLL diagnosis, prognosis, and treatment. It can be clinically effective alone and/or in combination with current approved agents. In this review, we summarize the scientific achievements in targeting ROR1 for CLL diagnosis, prognosis, and treatment.

A 67-Year-Old Man with Chronic Lymphocytic Leukemia (CLL) on Maintenance Therapy with Ibrutinib with Persistent SARS-CoV-2 Infection Unresponsive to Antiviral Treatments.

BACKGROUND SARS-CoV-2 infection can persist in immunocompromised patients with hematological malignancies, despite antiviral treatment. This report is of a 67-year-old man with chronic lymphocytic leukemia (CLL), secondary hypogammaglobulinemia, and thrombocytopenia on maintenance therapy with ibrutinib, with persistent SARS-CoV-2 infection unresponsive to antiviral treatment, including remdesivir, nirmatrelvir/ritonavir (Paxlovid), and tixagevimab/cilgavimab (Evusheld). CASE REPORT The patient was admitted to our hospital 3 times. During his first hospitalization, he was treated with 5-day course of remdesivir and intravenous steroids; however, antigen and molecular nasopharyngeal swabs were persistently positive, and he was discharged home. Due to respiratory worsening, he was rehospitalized, and despite being treated initially with tixagevimab/cilgavimab, and subsequently with a remdesivir course of 5 days, SARS-CoV-2 tests remained persistently positive. During his third hospital stay, our patient was subjected to combined therapy with remdesivir and nirmatrelvir/ritonavir for 5 days, obtaining a significant reduction of viral load at both antigen and molecular testing. As an ultimate attempt to achieve a negative status before discharge, a 10-day course of combined remdesivir and nirmatrelvir/ritonavir was administered, with a temporary reduction of viral load, followed by a sudden increase immediately after the discontinuation of Paxlovid. Due to worsening hematological disease and bacterial over-infections, the patient gradually worsened until death. CONCLUSIONS This is an emblematic case of correlation between persistent SARS-CoV-2 infection and immunosuppression status in hematological hosts. In these patients, the viral load remains high, favoring the evolution of the virus, and the immunodeficiency makes it difficult to identify the appropriate therapeutic approach.

Optimization of In Vitro Th17 Polarization for Adoptive Cell Therapy in Chronic Lymphocytic Leukemia.

Although preclinical investigations have shown notable efficacy in solid tumor models utilizing in vitro-differentiated Th17 cells for adoptive cell therapy (ACT), the potential benefits of this strategy in enhancing ACT efficacy in hematological malignancies, such as chronic lymphocytic leukemia (CLL), remain unexplored. CLL is a B-cell malignancy with a clinical challenge of increased resistance to targeted therapies. T-cell therapies, including chimeric antigen receptor (CAR) T cells, have demonstrated limited success in CLL, which is attributed to CLL-mediated T-cell dysfunction and skewing toward immunosuppressive phenotypes. Herein, we illustrate the feasibility of polarizing CD4+ T cells from the Eµ-TCL1 murine model, the most representative model for human CLL, into Th17 phenotype, employing a protocol of T-cell activation through the inducible co-stimulator (ICOS) alongside a polarizing cytokine mixture. We demonstrate augmented memory properties of in vitro-polarized IL-17-producing T cells, and preliminary in vivo persistence in leukemia-bearing mice. Our findings gain translational relevance through successful viral transduction of Eµ-TCL1 CD4+ T cells with a CD19-targeted CAR construct during in vitro Th17 polarization. Th17 CAR T cells exhibited remarkable persistence upon encountering antigen-expressing target cells. This study represents the first demonstration of the potential of in vitro-differentiated Th17 cells to enhance ACT efficacy in CLL.

Mouse models of chronic lymphocytic leukemia and Richter transformation: what we have learnt and what we are missing.

Although the chronic lymphocytic leukemia (CLL) treatment landscape has changed dramatically, unmet clinical needs are emerging, as CLL in many patients does not respond, becomes resistant to treatment, relapses during treatment, or transforms into Richter. In the majority of cases, transformation evolves the original leukemia clone into a diffuse large B-cell lymphoma (DLBCL). Richter transformation (RT) represents a dreadful clinical challenge with limited therapeutic opportunities and scarce preclinical tools. CLL cells are well known to highly depend on survival signals provided by the tumor microenvironment (TME). These signals enhance the frequency of immunosuppressive cells with protumor function, including regulatory CD4+ T cells and tumor-associated macrophages. T cells, on the other hand, exhibit features of exhaustion and profound functional defects. Overall immune dysfunction and immunosuppression are common features of patients with CLL. The interaction between malignant cells and TME cells can occur during different phases of CLL development and transformation. A better understanding of in vivo CLL and RT biology and the availability of adequate mouse models that faithfully recapitulate the progression of CLL and RT within their microenvironments are "conditio sine qua non" to develop successful therapeutic strategies. In this review, we describe the xenograft and genetic-engineered mouse models of CLL and RT, how they helped to elucidate the pathophysiology of the disease progression and transformation, and how they have been and might be instrumental in developing innovative therapeutic approaches to finally eradicate these malignancies.

Defining treatment success in chronic lymphocytic leukemia: exploring surrogate markers, comorbidities, and patient-centered endpoints.

INTRODUCTION: Traditionally, the success of chronic lymphocytic leukemia (CLL) treatment has been primarily assessed based on clinical outcomes, such as disease response, progression-free survival (PFS), and overall survival (OS). However, the evolution of treatment approaches recognizes the importance of a patient-centered perspective that includes factors directly affecting patients' quality of life and overall well-being. AREAS COVERED: Studies addressing the impact of targeted agents on improving either OS or other endpoint surrogates were selected using PubMed and MEDLINE platforms. Our search also included studies that considered patient-centric endpoints such as health-related quality of life and patient-reported outcomes (PROs). EXPERT OPINION: The changing landscape of CLL treatment underscores the importance of continually exploring various endpoints to thoroughly define treatment success. Beyond conventional metrics such as OS and surrogate endpoints, namely, PFS, time to next treatment (TTNT), and measurable residual disease (MRD) assessment, it becomes crucial to integrate enhanced comorbidity evaluations and patient-centered viewpoints into a CLL success roadmap.Subsequent investigations ought to concentrate on enhancing current surrogate endpoints, discerning their contextual significance, and exploring innovative indicators of treatment efficacy and safety. Given the dynamic nature of CLL and the heterogeneity among patient groups, personalized strategies are essential, taking into account individual traits and patient preferences.

Cancer-related Fatigue and the Additive Effect of Treatment in the Context of Lymphoma: An Analysis of the Lymphoma Coalition's 2022 Global Patient Survey.

Cancer-related fatigue (CRF) continues to be a challenging phenomenon that is often under-reported and poorly understood. With etiologies in both disease and treatment manifesting as a symptom and a side effect respectively, CRF is highly incident and presents a significant clinical problem that impacts survivorship. We conducted a survey to ascertain the patient reported incidence of symptoms and side effects for people with lymphoma or chronic lymphocytic leukemia. We found that CRF was enhanced in those who received more intense therapies that coincided with more aggressive lymphoma subtypes. These data illuminate an unmet need among patients with lymphoma and provides an opportunity to further refine treatment regimens to reduce the burden of CRF in this vulnerable population. SIGNIFICANCE: CRF is a highly incident phenomenon in lymphoma that can be ascribed to a combination of causes. We have demonstrated substantial variability across various subtypes of lymphoma and have estimated that nearly half of the reported fatigue comes from treatment. Increased screening for and monitoring of fatigue will yield favorable health-related quality of life that will benefit health technology assessment activities and yield improved outcomes for patients.

Case Report: Management of Acanthamoeba Rhinosinusitis in a Patient with Chronic Lymphocytic Leukemia.

Infections caused by free-living amoebae pose a significant public health threat owing to growing populations of immunocompromised hosts combined with diagnostic delays, treatment difficulties, and high case fatality rates. Nasopharyngeal infections caused by Acanthamoeba are rare and the optimal treatment is not well established. We report a case of Acanthamoeba rhinosinusitis in a patient with chronic lymphocytic leukemia who presented with headaches and chronic rhinosinusitis refractory to multiple courses of antibiotics. A diagnosis of Acanthamoeba rhinosinusitis was established through broad-range polymerase chain reaction testing on sinus tissue. The patient had a favorable response to treatment, which included surgical debridement, cessation of immunosuppressants, and a three-drug regimen consisting of miltefosine, fluconazole, and sulfadiazine.

Multicolour and lineage-specific interphase chromosome Flow-FISH: method development and clinical validation.

Flow cytometry can be applied in the detection of fluorescence in situ hybridisation (FISH) signals to efficiently analyse chromosomal aberrations. However, such interphase chromosome (IC) Flow-FISH protocols are currently limited to detecting a single colour. Furthermore, combining IC Flow-FISH with conventional multicolour flow cytometry is difficult because the DNA-denaturation step in FISH assay also disrupts cellular integrity and protein structures, precluding subsequent antigen-antibody binding and hindering concurrent labeling of surface antigens and FISH signals. We developed a working protocol for concurrent multicolour flow cytometry detection of nuclear IC FISH signals and cell surface markers. The protocol was validated by assaying sex chromosome content of blood cells, which was indicative of chimerism status in patients who had received sex-mismatched allogeneic haematopoietic stem cell transplants (allo-HSCT). The method was also adapted to detect trisomy 12 in chronic lymphocytic leukaemia (CLL) subjects. We first demonstrated the feasibility of this protocol in detecting multiple colours and concurrent nuclear and surface signals with high agreement. In clinical validation experiments, chimerism status was identified in clinical samples (n=56) using the optimised IC Flow-FISH method; the results tightly corresponded to those of conventional slide-based FISH (R2=0.9649 for XX cells and 0.9786 for XY cells). In samples from patients who received sex-mismatched allo-HSCT, individual chimeric statuses in different lineages could be clearly distinguished with high flexibility in gating strategies. Furthermore, in CLL samples with trisomy 12, this method could demonstrate that enriched trisomy 12 FISH signal was present in B cells rather than in T cells. Finally, by performing combined labelling of chromosome 12, X chromosome, and surface markers, we could detect rare residual recipient CLL cells with trisomy 12 after allo-HSCT. This adaptable protocol for multicolour and lineage-specific IC Flow-FISH advances the technique to allow for its potential application in various clinical contexts where conventional FISH assays are currently being utilised.

Eµ-TCL1 adoptive transfer mouse model of chronic lymphocytic leukemia.

Despite being the most common adult leukemia in the western world, Chronic Lymphocytic Leukemia (CLL) remains a life-threatening and incurable disease. Efforts to develop new treatments are highly dependent on the availability of appropriate mouse models for pre-clinical testing. The Eµ-TCL1 mouse model is the most established pre-clinical approach to study CLL pathobiology and response to treatment, backed by numerous studies highlighting its resemblance to the most aggressive form of this malignancy. In contrast to the transgenic Eµ-TCL1 model, employing the adoptive transfer of Eµ-TCL1-derived splenocytes in immunocompetent C57BL/6 mice results in a comparably rapid (e.g., leukemic development within weeks compared to months in the transgenic model) and reliable model mimicking CLL. In this chapter, we would like to provide readers with a thoroughly optimized, detailed, and comprehensive protocol to use the adoptive transfer Eµ-TCL1 model in their research.

Bruton's tyrosine kinase inhibitor-related cardiotoxicity: The quest for predictive biomarkers and improved risk stratification.

Ibrutinib was the first Bruton's tyrosine kinase (BTK) inhibitor approved for the treatment of patients with chronic lymphocytic leukemia (CLL). While producing durable responses and prolonging survival, roughly 20-25% of patients experience dose limiting side effects, mostly consisting of cardiovascular toxicities like severe hypertension and atrial fibrillation. While clinical predictors of BTK inhibitor-related cardiotoxicity have been proposed and may aid in risk stratification, there is no routine risk model used in clinical practice today to identify patients at highest risk. A recent study investigating genetic predictors of ibrutinib-related cardiotoxicity found that single nucleotide polymorphisms in KCNQ1 and GATA4 were significantly associated with cardiotoxic events. If replicated in larger studies, these biomarkers may improve risk stratification in combination with clinical factors. A clinicogenomic risk model may aid in identifying patients at highest risk of developing BTK inhibitor-related cardiotoxicity in which further risk mitigation strategies may be explored.

[A Case of Small Lymphocytic Lymphoma with -X Transformed Into Diffuse Large B-Cell Lymphoma].

An 80-year-old woman had developed a slight fever and loss of appetite since October 20XX. In November of the same year, the patient visited our hospital. Peripheral blood tests revealed the presence of atypical lymphocytes and a significant increase in sIL-2R. Tests of bone marrow aspiration samples showed the infiltration of small lymphocytes positive for CD19, CD20, CD23, and lambda. Therefore, a diagnosis of small lymphocytic lymphoma(SLL)was made. A complex karyotype including -X and del(13q)was observed in 19/20. Additionally, an enlarged spleen and retroperitoneal tumors were observed. As a result of 3 courses of fludarabine plus rituximab therapy, atypical lymphocytes were no longer observed in the peripheral blood and the enlarged spleen decreased in size. However, the retroperitoneal tumors could not be reduced. Consequently, a needle biopsy from the same area was performed in February 20XX+1, and a diagnosis of diffuse large B-cell lymphoma(DLBCL)was made. Because massive infiltration of CD23-negative lymphocytes was observed in the bone marrow, it was suggested that chronic lymphocytic leukemia(CLL)had transformed into DLBCL. Following 4 courses of CHOP therapy, the retroperitoneal tumors were reduced. In cases where -X is a microclone, the mutation is often age-related. However, in cases of advanced chronogenesis, as occurred in this patient, a correlation with hematopoietic tumors is arguable. Moreover, cases of CLL with -X have been reported to be related to de(l 13q). Our results strongly suggest that -X with del(13q)may be a clonal expansion in CLL/SLL.

Siglec-6 as a therapeutic target for cell migration and adhesion in chronic lymphocytic leukemia.

Siglec-6 is a lectin receptor with restricted expression in the placenta, mast cells and memory B-cells. Although Siglec-6 is expressed in patients with chronic lymphocytic leukemia (CLL), its pathophysiological role has not been elucidated. We describe here a role for Siglec-6 in migration and adhesion of CLL B cells to CLL- bone marrow stromal cells (BMSCs) in vitro and compromised migration to bone marrow and spleen in vivo. Mass spectrometry analysis revealed interaction of Siglec-6 with DOCK8, a guanine nucleotide exchange factor. Stimulation of MEC1-002 CLL cells with a Siglec-6 ligand, sTn, results in Cdc42 activation, WASP protein recruitment and F-actin polymerization, which are all associated with cell migration. Therapeutically, a Siglec-6/CD3-bispecific T-cell-recruiting antibody (T-biAb) improves overall survival in an immunocompetent mouse model and eliminates CLL cells in a patient derived xenograft model. Our findings thus reveal a migratory role for Siglec-6 in CLL, which can be therapeutically targeted using a Siglec-6 specific T-biAb.

The kappa/lambda ratio of surface immunoglobulin light chain as a valuable parameter for MRD assessment in CLL with atypical immunophenotype.

In recent years, the significance of detecting minimal/measurable residual disease (MRD) in chronic lymphocytic leukemia (CLL) has increased due to the availability of highly effective therapeutic agents. Flow cytometry provides notable cost-effectiveness and immediacy, with an expected sensitivity level of approximately 10-4. The critical aspect of MRD detection via flow cytometry lies in accurately defining the region containing tumor cells. However, a subset of CLL, known as CLL with atypical immunophenotype, exhibits a distinct cell surface marker expression pattern that can make MRD detection challenging, because these markers often resemble those of normal B cells. To enhance the sensitivity of MRD detection in such atypical cases of CLL, we have capitalized on the observation that cell surface immunoglobulin (sIg) light chains tend to be expressed at a higher level in this subtype. For every four two-dimensional plots of cell surface markers, we used a plot to evaluate the expression of sIg kappa/lambda light chains and identified regions where the kappa/lambda ratio of sIg light chains deviated from a designated threshold within the putative CLL cell region. Using this method, we could detect atypical CLL cells at a level of 10-4. We propose this method as an effective MRD assay.

NOD2 activation enhances macrophage Fcγ receptor function and may increase the efficacy of antibody therapy.

Introduction: Therapeutic antibodies have become a major strategy to treat oncologic diseases. For chronic lymphocytic leukemia, antibodies against CD20 are used to target and elicit cytotoxic responses against malignant B cells. However, efficacy is often compromised due to a suppressive microenvironment that interferes with cellular immune responses. To overcome this suppression, agonists of pattern recognition receptors have been studied which promote direct cytotoxicity or elicit anti-tumoral immune responses. NOD2 is an intracellular pattern recognition receptor that participates in the detection of peptidoglycan, a key component of bacterial cell walls. This detection then mediates the activation of multiple signaling pathways in myeloid cells. Although several NOD2 agonists are being used worldwide, the potential benefit of these agents in the context of antibody therapy has not been explored. Methods: Primary cells from healthy-donor volunteers (PBMCs, monocytes) or CLL patients (monocytes) were treated with versus without the NOD2 agonist L18-MDP, then antibody-mediated responses were assessed. In vivo, the Eµ-TCL1 mouse model of CLL was used to test the effects of L18-MDP treatment alone and in combination with anti-CD20 antibody. Results: Treatment of peripheral blood mononuclear cells with L18-MDP led to activation of monocytes from both healthy donors and CLL patients. In addition, there was an upregulation of activating FcγR in monocytes and a subsequent increase in antibody-mediated phagocytosis. This effect required the NF-κB and p38 signaling pathways. Treatment with L18-MDP plus anti-CD20 antibody in the Eµ-TCL model of CLL led to a significant reduction of CLL load, as well as to phenotypic changes in splenic monocytes and macrophages. Conclusions: Taken together, these results suggest that NOD2 agonists help overturn the suppression of myeloid cells, and may improve the efficacy of antibody therapy for CLL.

Lysosome-Disrupting Agents in Combination with Venetoclax Increase Apoptotic Response in Primary Chronic Lymphocytic Leukemia (CLL) Cells Mediated by Lysosomal Cathepsin D Release and Inhibition of Autophagy.

Venetoclax and obinutuzumab are becoming frontline therapies for chronic lymphocytic leukemia (CLL) patients. Unfortunately, drug resistance still occurs, and the combination could be immunosuppressive. Lysosomes have previously been identified as a target for obinutuzumab cytotoxicity in CLL cells, but the mechanism remains unclear. In addition, studies have shown that lysosomotropic agents can cause synergistic cell death in vitro when combined with the BTK inhibitor, ibrutinib, in primary CLL cells. This indicates that targeting lysosomes could be a treatment strategy for CLL. In this study, we have shown that obinutuzumab induces lysosome membrane permeabilization (LMP) and cathepsin D release in CLL cells. Inhibition of cathepsins reduced obinutuzumab-induced cell death in CLL cells. We further determined that the lysosomotropic agent siramesine in combination with venetoclax increased cell death in primary CLL cells through an increase in reactive oxygen species (ROS) and cathepsin release. Siramesine treatment also induced synergistic cytotoxicity when combined with venetoclax. Microenvironmental factors IL4 and CD40L or incubation with HS-5 stromal cells failed to significantly protect CLL cells from siramesine- and venetoclax-induced apoptosis. We also found that siramesine treatment inhibited autophagy through reduced autolysosomes. Finally, the autophagy inhibitor chloroquine failed to further increase siramesine-induced cell death. Taken together, lysosome-targeting drugs could be an effective strategy in combination with venetoclax to overcome drug resistance in CLL.