Monocyte-to-macrophage switch reversibly impaired by Ibrutinib

Evaluation of infectious morbidity due to BTK inhibitors in indolent B-cell lymphomas: latest research findings and systematic analysis

INTRODUCTION

Randomized clinical trials (RCTs) have suggested that BTK inhibitors (BTKis) might increase infectious disease (ID) risk. Systematic analysis of this topic as derived from RCTs and clinical practice is needed.

AREAS COVERED

An extensive Medline, Embase, and Cochrane search of peer-reviewed sources reporting on ID morbidity in patients on BTKis was performed (1 January 2014 - 31 December 2023). Contribution of intrinsic immune defects in indolent B-cell lymphomas to this morbidity was carefully considered.

EXPERT OPINION

Patients with indolent B-cell lymphomas display a wide range of innate and adaptive immune defects. In addition, BTKi use is linked with an increased signal of upper respiratory tract infections (URTIs) and pneumonias, mainly grade 1-2. These agents also increase the risk of rare invasive fungal infections (IFIs), mainly due to Cryptococcus and Aspergillus spp. with a peak within several months after the start of therapy. More than half of these IFIs are fatal. Research suggests a similar ID risk across 1st, 2nd and 3rd generations of BTKis, all causing B-cell dysfunction due to BTK inhibition, along with off-target functional neutrophil/macrophage alterations. Expanding the knowledge base on ID morbidity in patients on BTKis would facilitate timely diagnosis and treatment, and improve clinical outcomes.

Impact of leukemia-associated macrophages on the progression and therapy response of chronic lymphocytic leukemia

The treatment landscape of chronic lymphocytic leukemia (CLL) has advanced remarkably over the past decade. The advent and approval of the BTK inhibitor ibrutinib and BCL-2 inhibitor venetoclax, as well as monoclonal anti-CD20 antibodies rituximab and obinutuzumab, have resulted in deep remissions and substantially improved survival outcomes for patients. However, CLL remains a complex disease with many patients still experiencing relapse and unsatisfactory treatment responses. CLL cells are highly dependent on their pro-leukemic tumor microenvironment (TME), which comprises different cellular and soluble factors. A large body of evidence suggests that CLL-associated macrophages shaped by leukemic cells play a pivotal role in maintaining CLL cell survival. In this review, we summarize the pro-survival interactions between CLL cells and macrophages, as well as the impact of the current first-line treatment agents, including ibrutinib, venetoclax, and CD20 antibodies on leukemia-associated macrophages.

Cryptococcosis Associated With Biologic Therapy: A Narrative Review

Cryptococcus is an opportunistic fungal pathogen that can cause disseminated infection with predominant central nervous system involvement in patients with compromised immunity. Biologics are increasingly used in the treatment of neoplasms and autoimmune/inflammatory conditions and the prevention of transplant rejection, which may affect human defense mechanisms against cryptococcosis. In this review, we comprehensively investigate the association between cryptococcosis and various biologics, highlighting their risks of infection, clinical manifestations, and clinical outcomes. Clinicians should remain vigilant for the risk of cryptococcosis in patients receiving biologics that affect the Th1/macrophage activation pathways, such as tumor necrosis factor α antagonists, Bruton tyrosine kinase inhibitors, fingolimod, JAK/STAT inhibitors (Janus kinase/signal transducer and activator of transcription), and monoclonal antibody against CD52. Other risk factors-such as age, underlying condition, and concurrent immunosuppressants, especially corticosteroids-should also be taken into account during risk stratification.

An updated portrait of monocyte-macrophages in classical Hodgkin lymphoma

Classical Hodgkin lymphoma (cHL) is a unique neoplastic ecosystem characterized by a heterogeneous immune infiltrate surrounding the rare malignant Hodgkin Reed-Sternberg cells. Though less abundant than T-cells, tumor-infiltrating macrophages play a pivotal role in supporting HRS survival through cell-to-cell and paracrine interactions. Traditional immunohistochemistry based upon the M1-M2 dichotomy yielded controversial results about the composition, functional role and prognostic impact of macrophages in cHL. More recent studies exploiting single-cell technologies and image analyses have highlighted the heterogeneity and the peculiar spatial arrangement of the macrophagic infiltrate, with the most immunosuppressive subpopulations lying in close proximity of HRS cells and the most tumor-hostile subsets kept far away from the neoplastic niches. High-throughput analysis of peripheral blood mononuclear cells in cHL patients have also identified a novel, potentially cytotoxic, subpopulation predicting better response to PD-1 blockade. This review examines the phenotypic profile, spatial localization and clinical impact of tumor-infiltrating macrophages and circulating monocytes in cHL, providing an up-do-date portrait of these innate immune cells with possible translational applications.

Mechanisms of cytokine release syndrome and neurotoxicity of CAR T-cell therapy and associated prevention and management strategies

Chimeric antigen receptor (CAR) T-cell therapy has yielded impressive outcomes and transformed treatment algorithms for hematological malignancies. To date, five CAR T-cell products have been approved by the US Food and Drug Administration (FDA). Nevertheless, some significant toxicities pose great challenges to the development of CAR T-cell therapy, most notably cytokine release syndrome (CRS) and immune effector cell-associated neurotoxicity syndrome (ICANS). Understanding the mechanisms underlying these toxicities and establishing prevention and treatment strategies are important. In this review, we summarize the mechanisms underlying CRS and ICANS and provide potential treatment and prevention strategies.

Restoration of the immune function as a complementary strategy to treat Chronic Lymphocytic Leukemia effectively

Chronic Lymphocytic Leukemia (CLL) is a hematological malignancy characterized by uncontrolled proliferation of B-cells and severe immune dysfunction. Chemo(immuno)therapies (CIT) have traditionally aimed to reduce tumor burden without fully understanding their effects on the immune system. As a consequence, CIT are usually associated with higher risk of infections, secondary neoplasms and autoimmune disorders. A better understanding of the biology of the disease has led to the development of therapeutic strategies which not only act against malignant B-cells but also reactivate and enhance the patient's own anti-tumor immune response. Here, we review the current understanding of the underlying interplay between the malignant cells and non-malignant immune cells that may promote tumor survival and proliferation. In addition, we review the available evidence on how different treatment options for CLL including CIT regimens, small molecular inhibitors (i.e, BTK inhibitors, PI3K inhibitors, BCL-2 inhibitors) and T-cell therapies, affect the immune system and their clinical consequences. Finally, we propose that a dual therapeutic approach, acting directly against malignant B-cells and restoring the immune function is clinically relevant and should be considered when developing future strategies to treat patients with CLL.

Multifaceted Immunomodulatory Effects of the BTK Inhibitors Ibrutinib and Acalabrutinib on Different Immune Cell Subsets - Beyond B Lymphocytes

The clinical success of the two BTK inhibitors, ibrutinib and acalabrutinib, represents a major breakthrough in the treatment of chronic lymphocytic leukemia (CLL) and has also revolutionized the treatment options for other B cell malignancies. Increasing evidence indicates that in addition to their direct effects on B lymphocytes, both BTK inhibitors also directly impact the homeostasis, phenotype and function of many other cell subsets of the immune system, which contribute to their high efficacy as well as adverse effects observed in CLL patients. In this review, we attempt to provide an overview on the overlapping and differential effects of ibrutinib and acalabrutinib on specific receptor signaling pathways in different immune cell subsets other than B cells, including T cells, NK cells, monocytes, macrophages, granulocytes, myeloid-derived suppressor cells, dendritic cells, osteoclasts, mast cells and platelets. The shared and distinct effects of ibrutinib versus acalabrutinib are mediated through BTK-dependent and BTK-independent mechanisms, respectively. Such immunomodulatory effects of the two drugs have fueled myriad explorations of their repurposing opportunities for the treatment of a wide variety of other human diseases involving immune dysregulation.

Cryptococcus gattii in Patients with Lymphoid Neoplasms: An Illustration of Evolutive Host-Fungus Interactions

Recent outbreaks of Cryptococcus gattii (CG) infections in North America have sparked renewed interest in the pathogenic potential of CG, and have underscored notable differences with Cryptococcus neoformans in terms of geographic distribution, pathogen virulence, and host susceptibility. While cases of CG are increasingly reported in patients with a wide variety of underlying conditions, only very few have been reported in patients with lymphoid neoplasms. Herein, we report a case of autochthonous CG meningitis in a patient receiving ibrutinib for chronic lymphocytic leukemia in France, and review available data on the clinical epidemiology of CG infections in patients with lymphoid neoplasms. We also summarise recent data on the host responses to CG infection, as well as the potential management pitfalls associated with its treatment in the haematological setting. The clinical epidemiology, clinical presentation, and course of disease during infections caused by CG involve complex interactions between environmental exposure to CG, infecting genotype, pathogen virulence factors, host susceptibility, and host immune responses. Future treatment guidelines should address the challenges associated with the management of antifungal treatments in the onco-haematological setting and the potential drug-drug interactions.

Non-Aspergillus invasive mould infections in patients treated with ibrutinib

BACKGROUND

Invasive mould infections (IMIs) are very rare in patients with lymphoid malignancies. However, IMIs, mostly due to Aspergillus species, have been increasingly reported in such patients receiving ibrutinib (IBR). There is paucity of information regarding non-Aspergillus invasive mould infections (NAIMIs) in this setting, OBJECTIVES: To review our recent experience and the published literature on the topic.

PATIENTS/METHODS

We present a case of invasive sinusitis caused by Fusarium in a patient with refractory chronic lymphocytic leukaemia (CLL) who was treated with IBR and review the 12 published cases of NAIMIs during IBR.

RESULTS

Nearly all cases of NAIMIs in the setting of IBR use were encountered in patients with CLL. Mixed fungal infections, brain involvement and late-onset infections were common.

CONCLUSIONS

Although rare, NAIMIs should be considered in patients who receive IBR.

Feasibility and efficacy of CD19-targeted CAR T cells with concurrent ibrutinib for CLL after ibrutinib failure

We previously reported durable responses in relapsed or refractory (R/R) chronic lymphocytic leukemia (CLL) patients treated with CD19-targeted chimeric antigen receptor-engineered (CD19 CAR) T-cell immunotherapy after ibrutinib failure. Because preclinical studies showed that ibrutinib could improve CAR T cell-antitumor efficacy and reduce cytokine release syndrome (CRS), we conducted a pilot study to evaluate the safety and feasibility of administering ibrutinib concurrently with CD19 CAR T-cell immunotherapy. Nineteen CLL patients were included. The median number of prior therapies was 5, and 17 patients (89%) had high-risk cytogenetics (17p deletion and/or complex karyotype). Ibrutinib was scheduled to begin ≥2 weeks before leukapheresis and continue for ≥3 months after CAR T-cell infusion. CD19 CAR T-cell therapy with concurrent ibrutinib was well tolerated; 13 patients (68%) received ibrutinib as planned without dose reduction. The 4-week overall response rate using 2018 International Workshop on CLL (iwCLL) criteria was 83%, and 61% achieved a minimal residual disease (MRD)-negative marrow response by IGH sequencing. In this subset, the 1-year overall survival and progression-free survival (PFS) probabilities were 86% and 59%, respectively. Compared with CLL patients treated with CAR T cells without ibrutinib, CAR T cells with concurrent ibrutinib were associated with lower CRS severity and lower serum concentrations of CRS-associated cytokines, despite equivalent in vivo CAR T-cell expansion. The 1-year PFS probabilities in all evaluable patients were 38% and 50% after CD19 CAR T-cell therapy, with and without concurrent ibrutinib, respectively (P = .91). CD19 CAR T cells with concurrent ibrutinib for R/R CLL were well tolerated, with low CRS severity, and led to high rates of MRD-negative response by IGH sequencing.

Phagocytosis assays with different pH-sensitive fluorescent particles and various readouts

Phagocytosis is a fundamental mechanism of innate immunity and its impairment is associated with severe chronic diseases, for example, chronic obstructive pulmonary disease. Investigating phagocytosis requires flexible tools and assay conditions, such as different fluorescent particle types, detection colors and readouts. We comprehensively evaluated and optimized phagocytosis assays using particles labeled with fluorescent pH-sensitive pHrodo^® dyes, facilitating the specific detection of phagocytosed particles. Beads, bacterial and yeast particles labeled with pHrodo red and green were tested for their uptake by THP-1 cells and primary human macrophages by flow cytometry and high-content imaging. Whereas the latter allowed kinetic phagocytosis measurement, the former demonstrated the feasibility of using cell sorting for periods of up to 6 h, enabling downstream applications such as pooled genetic screens.