Immunomodulatory effect of ibrutinib: Reducing the barrier against fungal infections

Risk of infectious adverse events of venetoclax therapy for hematologic malignancies: a systematic review and meta-analysis of RCTs

ABSTRACT

Venetoclax is a small molecule inhibitor of BCL-2 used in the treatment of acute myelogenous leukemia (AML) and chronic lymphocytic leukemia (CLL). Recent postmarketing studies of ibrutinib, another small molecule inhibitor, suggested that these agents may predispose to opportunistic infections. We sought to systematically review the randomized controlled trial (RCT) evidence of venetoclax to assess whether it predisposes patients to infectious adverse events (IAEs) and neutropenia. We systematically reviewed RCTs comparing venetoclax therapy with active or placebo controls for patients with hematologic malignancies. Data on IAEs and neutropenia were pooled by Bayesian meta-analysis, and we computed the probability of any increased risk (P[risk ratio (RR) > 1]) of IAEs or neutropenic complications. Seven RCTs were included, comprising 2067 patients. In CLL (n = 1032), there was a low probability of increased risk of high-grade (P[RR > 1] = 71.2%) and fatal IAEs (P[RR > 1] = 64.5%) and high-grade neutropenia (P[RR > 1] = 63.4%). There were insufficient data to perform a meta-analysis of IAEs in AML; however, 1 trial suggested an increased risk of IAEs with venetoclax. Furthermore, in AML (n = 642), venetoclax was associated with a high probability of increased risk of high-grade neutropenia (P[RR > 1] = 94.6%) and febrile neutropenia (P[RR > 1] = 90.6%). Our results suggest that venetoclax has a low probability of increased risk of IAEs or neutropenia in CLL. By contrast, there is likely increased risk of high-grade neutropenia and febrile neutropenia in AML. Importantly, our analyses did not identify any specific IAEs that would benefit from routine antimicrobial prophylaxis or pre-emptive testing.

Patients' preferences for chronic lymphocytic leukemia treatment: The CHOICE study

Chronic lymphocytic leukemia (CLL) therapies differ in efficacy, side effects, route, frequency, and duration of administration. We assessed patient preferences for treatment attributes and evaluated associations with disease stage, treatment line, and socio-demographic characteristics in a cross sectional, observational study conducted at 16 Italian hematology centers. Study visits occurred between February and July 2020; 401 adult patients with CLL (201 Watch and Wait (W&W), 200 treated) participated in a discrete choice experiment (DCE), composed of 8 choices between pairs of treatment profiles with different levels of 5 attributes of currently available CLL treatments (length of response, route and duration of administration, risk of side effects including diarrhea, infections, or organ damage). Health-related quality of life was assessed with the EQ-5D-5L, EORTC QLQ-C30 and QLQ CLL-16. Previously treated patients had longer disease duration (7 vs. 5 years), higher prevalence of serious comorbidities (45.5% vs. 36.2%) and high-risk molecular markers (unmutated IGHV 55.6% vs. 17.1%; TP53 mutation 15.2% vs. 4.0%). Health-related quality of life scores were similar between groups. In the DCE, W&W patients rated "possible occurrence of infections" highest (relative importance [RI] = 36.2%), followed by "treatment and relevant duration" (RI = 28.0%) and "progression-free survival (PFS)" (RI = 16.9%). Previously treated patients rated "treatment and relevant duration" highest (RI = 33.3%), followed by "possible occurrence of infections" (RI = 28.8%), "possible occurrence of organ damage" (RI = 19.4%), and "PFS" (RI = 9.8%). Concern over infection was rated highest overall; unexpectedly PFS was not among the most important criteria in either group, suggesting that the first COVID-19 pandemic wave may have influenced patient preferences and concerns about CLL therapy options.

Severe Fatal Mucormycosis in a Patient with Chronic Lymphocytic Leukaemia Treated with Zanubrutinib: A Case Report and Review of the Literature

Severe mucormycosis is a fatal disease rarely complicating chronic lymphoproliferative disorders. We present a fulminant and fatal case of a 74-year-old Caucasian woman suffering from CLL treated with second-generation BTK inhibitor zanubrutinib. After a first septic episode a month prior, originating from the lung with later systemic involvement by an unidentified agent and treated with large-spectrum antibiotics and fluconazonle, a slow-onset enlarging tender warm and erythematous nodular swollen cutaneous lesion appeared in her lower limbs and spread subsequently to her upper limbs, progressing towards central ulceration with a necrotic core. Suspecting a mycotic dissemination from an unknown agent, a skin punch biopsy was performed, and intraconazole was started. Due to spread of the skin lesions, the patient was hospitalized and intravenous liposomal ampthotericin B was started. Histopathology showed an atypical sporangium-rich mycotic angioinvasion of the small vessels. Only the increase of BDG and GM could corroborate the hypothesis of mycotic infection. However, long-term CLL, immunosuppressive therapies, neutropenia, and prior use of azoles and other antimycotic agents were risk factors for mucormycosis; BTK inhibitor could also be added as another novel risk factor. Despite all therapeutic efforts, the patient died. Post-mortem molecular exams confirmed the diagnosis of disseminated mucormycosis.

Disseminated fungal infection in a patient receiving zanubrutinib

We report a case of fatal disseminated aspergillosis in the setting of administration of zanubrutinib, a second-generation Bruton's tyrosine kinase inhibitor thought to have a lower rate of immunosuppression-related side effects.

COVID-19 in Adult Patients with Hematological Malignancies-Lessons Learned after Three Years of Pandemic

The COVID-19 pandemic is undoubtedly the most difficult health challenge of the 21st century with more than 600 million laboratory-confirmed SARS-CoV-2 infections and over 6.5 million deaths worldwide. The coronavirus pandemic contributed to rapid development of mRNA vaccines, which, along with new antiviral drugs, have been the subject of extensive research for many decades. Nevertheless, elderly, multi-morbid and immunocompromised patients continue to face a more severe clinical course and a higher risk of death from COVID-19, even now that the risk of COVID-19 in the general population is significantly reduced due to the introduction of global vaccination strategies. In this paper, we present the mechanisms of increased susceptibility to infectious complications and the evolution of the clinical course of COVID-19 in patients with hematological malignancies, taking into account the mutation of the virus and the introduction of vaccines and new antiviral drugs. We also present current recommendations for prophylactic and therapeutic management in patients with hematological malignancies.

Invasive Cutaneous Candidiasis, Autoimmune Hemolytic Anemia and Pancytopenia: A Challenging Scenario for Waldenström Macroglobulinemia in an Elderly Patient

Waldenström macroglobulinemia (WM) is a slowly progressive hematologic malignancy that usually responds rapidly to treatment. Being a lymphoplasmacytoid neoplasm, it is associated with a monoclonal IgM component, which may be associated with multiple manifestations and symptoms. We report the case of a 77-year-old woman diagnosed with WM following the development of severe and sudden pancytopenia associated with a cold agglutinin syndrome. In order to treat the WM and the underlying hemolysis, treatment with rituximab, corticosteroids and cyclophosphamide was started. Despite the improvement in hemolysis parameters, pancytopenia persisted, and we started a second line with ibrutinib. During treatment the patient developed an uncommon invasive fungal infection (IFI) with bone marrow granulomatosis and myelofibrosis. This case shows an unusual clinical course with a poor hematopoietic response to treatment and a large number of intercurrent complications.

Report of consensus panel 2 from the 11th international workshop on Waldenström's macroglobulinemia on the management of relapsed or refractory WM patients

The consensus panel 2 (CP2) of the 11th International Workshop on Waldenström's macroglobulinemia (IWWM-11) has reviewed and incorporated current data to update the recommendations for treatment approaches in patients with relapsed or refractory WM (RRWM). The key recommendations from IWWM-11 CP2 include: (1) Chemoimmunotherapy (CIT) and/or a covalent Bruton tyrosine kinase (cBTKi) strategies are important options; their use should reflect the prior upfront strategy and are subject to their availability. (2) In selecting treatment, biological age, co-morbidities and fitness are important; nature of relapse, disease phenotype and WM-related complications, patient preferences and hematopoietic reserve are also critical factors while the composition of the BM disease and mutational status (MYD88, CXCR4, TP53) should also be noted. (3) The trigger for initiating treatment in RRWM should utilize knowledge of patients' prior disease characteristics to avoid unnecessary delays. (4) Risk factors for cBTKi related toxicities (cardiovascular dysfunction, bleeding risk and concurrent medication) should be addressed when choosing cBTKi. Mutational status (MYD88, CXCR4) may influence the cBTKi efficacy, and the role of TP53 disruptions requires further study) in the event of cBTKi failure dose intensity could be up titrated subject to toxicities. Options after BTKi failure include CIT with a non-cross-reactive regimen to one previously used CIT, addition of anti-CD20 antibody to BTKi, switching to a newer cBTKi or non-covalent BTKi, proteasome inhibitors, BCL-2 inhibitors, and new anti-CD20 combinations are additional options. Clinical trial participation should be encouraged for all patients with RRWM.

Bruton tyrosine kinase inhibitors in B-cell lymphoma: beyond the antitumour effect

Targeting B-cell receptor signalling using Bruton tyrosine kinase (BTK) inhibitors (BTKis) has become a highly successful treatment modality for B-cell malignancies, especially for chronic lymphocytic leukaemia. However, long-term administration of BTKis can be complicated by adverse on- and/or off-target effects in particular cell types. BTK is widely expressed in cells of haematopoietic origin, which are pivotal components of the tumour microenvironment. BTKis, thus, show broad immunomodulatory effects on various non-B immune cell subsets by inhibiting specific immune receptors, including T-cell receptor and Toll-like receptors. Furthermore, due to the off-target inhibition of other kinases, such as IL-2-inducible T-cell kinase, epidermal growth factor receptor, and the TEC and SRC family kinases, BTKis have additional distinct effects on T cells, natural killer cells, platelets, cardiomyocytes, and other cell types. Such mechanisms of action might contribute to the exceptionally high clinical efficacy as well as the unique profiles of adverse effects, including infections, bleeding, and atrial fibrillation, observed during BTKi administration. However, the immune defects and related infections caused by BTKis have not received sufficient attention in clinical studies till date. The broad involvement of BTK in immunological pathways provides a rationale to combine BTKis with specific immunotherapies, such as immune checkpoint inhibitor or chimeric antigen receptor-T-cell therapy, for the treatment of relapsed or refractory diseases. This review discusses and summarises the above-mentioned issues as a reference for clinicians and researchers.

Targeted therapies in CLL/SLL and the cumulative incidence of infection: A systematic review and meta-analysis

Background: Patients with chronic lymphocytic leukemia (CLL)/small lymphocytic lymphoma (SLL) are prone to infections.

Aims: Provide a pooled estimate of the cumulative incidence for infections that fulfilled the criteria associated with severe infectious adverse events for grade 3 or higher (including pneumonia, febrile neutropenia and sepsis) in patients who receive targeted therapies.

Methods: We searched PubMed and EMBASE for randomized controlled trials (RCT) that included patients with CLL/SLL who received targeted therapies and performed a random-effects meta-analysis to estimate the cumulative incidence of infections.

Results: Of 2,914 studies screened, we retrieved 31 which evaluated 11,660 patients. The pooled cumulative incidence of infections for patients who received treatment regimens based on a BTK inhibitors was 19.86%. For patients who received treatment based on rituximab and second generation anti-CD20 monoclonal antibodies, the pooled cumulative incidence of infections was 19.85 and 13.46%, respectively. Regarding PI3K inhibitor-based regimens the cumulative incidence of severe infections was 30.89%. BCL-2 inhibitors had a cumulative incidence of infections of 17.49% while lenalidomide and alemtuzumab had an incidence of 13.33 and 45.09%, respectively. The cumulative incidence of pneumonia ranged from 3.01 to 8.45% while febrile neutropenia ranged from 2.68 to 10.80%. Regarding sepsis, the cumulative incidence ranged from 0.9 to 4.48%.

Conclusion: Patients with CLL/SLL who receive targeted therapies may develop severe infections at significant rates that, in addition to disease stage and other complications, depend on the mechanism of action of the used drug. Surveillance for infections and development of effective prophylactic strategies are critical for patients with CLL/SLL who receive targeted therapies.

Systematic Review Registration: [https://systematicreview.gov/], identifier [registration number]

Lenalidomide enhances CD23.CAR T cell therapy in chronic lymphocytic leukemia

Chimeric antigen receptors (CAR)-modified T cells are an emerging therapeutic tool for chronic lymphocytic leukemia (CLL). However, in patients with CLL, well-known T-cell defects and the inhibitory properties of the tumor microenvironment (TME) hinder the efficacy of CAR T cells. We explored a novel approach combining CARs with lenalidomide, an immunomodulatory drug that tempers the immunosuppressive activity of the CLL TME. T cells from patients with CLL were engineered to express a CAR specific for CD23, a promising target antigen. Lenalidomide maintained the in vitro effector functions of CD23.CAR⁺ T cells effector functions in terms of antigen-specific cytotoxicity, cytokine release and proliferation. Overall, lenalidomide preserved functional CAR T-CLL cell immune synapses. In a Rag2^-/-γ_c^-/--based xenograft model of CLL, we demonstrated that, when combined with low-dose lenalidomide, CD23.CAR⁺ T cells efficiently migrated to leukemic sites and delayed disease progression when compared to CD23.CAR⁺ T cells given with rhIL-2. These observations underline the therapeutic potential of this novel CAR-based combination strategy in CLL.

BTK Inhibitors Impair Platelet-Mediated Antifungal Activity

In recent years, the introduction of new drugs targeting Bruton’s tyrosine kinase (BTK) has allowed dramatic improvement in the prognosis of patients with chronic lymphocytic leukemia (CLL) and other B-cell neoplasms. Although these small molecules were initially considered less immunosuppressive than chemoimmunotherapy, an increasing number of reports have described the occurrence of unexpected opportunistic fungal infections, in particular invasive aspergillosis (IA). BTK represents a crucial molecule in several signaling pathways depending on different immune receptors. Based on a variety of specific off-target effects on innate immunity, namely on neutrophils, monocytes, pulmonary macrophages, and nurse-like cells, ibrutinib has been proposed as a new host factor for the definition of probable invasive pulmonary mold disease. The role of platelets in the control of fungal growth, through granule-dependent mechanisms, was described in vitro almost two decades ago and is, so far, neglected by experts in the field of clinical management of IA. In the present study, we confirm the antifungal role of platelets, and we show, for the first time, that the exposure to BTK inhibitors impairs several immune functions of platelets in response to Aspergillus fumigatus, i.e., the ability to adhere to conidia, activation (as indicated by reduced expression of P-selectin), and direct killing activity. In conclusion, our experimental data suggest that antiplatelet effects of BTK inhibitors may contribute to an increased risk for IA in CLL patients.

Reactivation of Coccidioides immitis in a Prosthetic Knee after Initiation of Chemotherapy

Coccidioides is an endemic fungus in the Southwestern United States and Central and South America. Coccidioidomycosis primary infections are typically of the lung with an asymptomatic or self-limiting course. Some infections disseminate to other parts of the body and a few can remain latent for many years. Reactivation of latent fungal disease can occur following an insult to the host immune system. Here, we describe a case of a 76-year-old Caucasian male patient who moved from California to Wisconsin with a history of coccidioidomycosis infection of the left knee that reactivated decades later in his prosthetic knee shortly after being initiated on ibrutinib (Imbruvica), a Bruton tyrosine kinase (BTK) inhibitor, for chronic lymphocytic leukemia (CLL)/small lymphocytic lymphoma (SLL). There have been some case reports regarding coccidioidomycosis infections after initiating ibrutinib therapy but none with a 50 year latency period before reactivation. Readers will learn the immunological effects of ibrutinib on the hosts' innate and adaptive immunity and its role in putting the host at risk for invasive fungal infections. We also review the literature and data on treatment regimens and recommendations based on current guidelines.

Bruton's Tyrosine Kinase Inhibitors Impair FcγRIIA-Driven Platelet Responses to Bacteria in Chronic Lymphocytic Leukemia

Bacterial infections are a major cause of morbidity and mortality in chronic lymphocytic leukemia (CLL), and infection risk increases in patients treated with the Bruton’s tyrosine kinase (Btk) inhibitor, ibrutinib. Btk and related kinases (like Tec) are expressed in non-leukemic hematopoietic cells and can be targeted by ibrutinib. In platelets, ibrutinib therapy is associated with bleeding complications mostly due to off-target effects. But the ability of platelets to respond to bacteria in CLL, and the potential impact of ibrutinib on platelet innate immune functions remain unknown. FcγRIIA is a tyrosine kinase-dependent receptor critical for platelet activation in response to IgG-coated pathogens. Crosslinking of this receptor with monoclonal antibodies causes downstream activation of Btk and Tec in platelets, however, this has not been investigated in response to bacteria. We asked whether ibrutinib impacts on FcγRIIA-mediated activation of platelets derived from CLL patients and healthy donors after exposure to Staphylococcus aureus Newman and Escherichia coli RS218. Platelet aggregation, α-granule secretion and integrin αIIbβ3-dependent scavenging of bacteria were detected in CLL platelets but impaired in platelets from ibrutinib-treated patients and in healthy donor-derived platelets exposed to ibrutinib in vitro. While levels of surface FcγRIIA remained unaffected, CLL platelets had reduced expression of integrin αIIbβ3 and GPVI compared to controls regardless of therapy. In respect of intracellular signaling, bacteria induced Btk and Tec phosphorylation in both CLL and control platelets that was inhibited by ibrutinib. To address if Btk is essential for platelet activation in response to bacteria, platelets derived from X-linked agammaglobulinemia patients (lacking functional Btk) were exposed to S. aureus Newman and E. coli RS218, and FcγRIIA-dependent aggregation was observed. Our data suggest that ibrutinib impairment of FcγRIIA-mediated platelet activation by bacteria results from a combination of Btk and Tec inhibition, although off-target effects on additional kinases cannot be discarded. This is potentially relevant to control infection-risk in CLL patients and, thus, future studies should carefully evaluate the effects of CLL therapies, including Btk inhibitors with higher specificity for Btk, on platelet-mediated immune functions.

Clinical Trials of the BTK Inhibitors Ibrutinib and Acalabrutinib in Human Diseases Beyond B Cell Malignancies

The BTK inhibitors ibrutinib and acalabrutinib are FDA-approved drugs for the treatment of B cell malignances. Both drugs have demonstrated clinical efficacy and safety profiles superior to chemoimmunotherapy regimens in patients with chronic lymphocytic leukemia. Mounting preclinical and clinical evidence indicates that both ibrutinib and acalabrutinib are versatile and have direct effects on many immune cell subsets as well as other cell types beyond B cells. The versatility and immunomodulatory effects of both drugs have been exploited to expand their therapeutic potential in a wide variety of human diseases. Over 470 clinical trials are currently registered at ClinicalTrials.gov to test the efficacy of ibrutinib or acalabrutinib not only in almost every type of B cell malignancies, but also in hematological malignancies of myeloid cells and T cells, solid tumors, chronic graft versus host disease (cGHVD), autoimmune diseases, allergy and COVID-19 (http:www.clinicaltrials.gov). In this review, we present brief discussions of the clinical trials and relevant key preclinical evidence of ibrutinib and acalabrutinib as monotherapies or as part of combination therapies for the treatment of human diseases beyond B cell malignancies. Adding to the proven efficacy of ibrutinib for cGVHD, preliminary results of clinical trials have shown promising efficacy of ibrutinib or acalabrutinib for certain T cell malignancies, allergies and severe COVID-19. However, both BTK inhibitors have no or limited efficacy for refractory or recurrent solid tumors. These clinical data together with additional pending results from ongoing trials will provide valuable information to guide the design and improvement of future trials, including optimization of combination regimens and dosing sequences as well as better patient stratification and more efficient delivery strategies. Such information will further advance the precise implementation of BTK inhibitors into the clinical toolbox for the treatment of different human diseases.

Severe infections in patients with lymphoproliferative diseases treated with new targeted drugs: A multicentric real-world study

Background

Lymphoid neoplasms treatment has recently been renewed to increase antitumor efficacy and conventional chemotherapies toxicities. Limited data have been published about the infection risk associated with these new drugs, therefore this study analyzes the infectious complications in patients with lymphoproliferative diseases (LPD) treated with monoclonal antibodies (obinutuzumab, ofatumumab, brentuximab, nivolumab, or pembrolizumab), BTK inhibitors (ibrutinib and acalabrutinib), PI3K inhibitors (idelalisib) and BCL2 inhibitors (venetoclax).

Methods

Multicenter retrospective study of 458 LPD patients treated with targeted therapies in real‐life setting, in 18 Spanish institutions, from the time of their commercial availability to August 2020.

Results

Severe infections incidence was 23% during 17‐month median follow‐up; cumulative incidence was higher in the first 3–6 months of targeted drug treatment and then decreased. The most frequent etiology was bacterial (54%). Nine (6%) Invasive fungal infections (IFI) were observed, in its majority in chronic lymphocytic leukemia (CLL) patients treated predominantly with ibrutinib. Significant risk factors for severe infection were: severe lymphopenia (p = 0.009, OR 4.7, range 1.3–1.7), combined targeted treatment vs single agent treatment (p = 0.014 OR 2.2 range 1.1–4.2) and previous rituximab (p = 0.03 OR 1.8, range 1.05–3.3). Infection‐related mortality was 6%. In 22% of patients with severe infections, definitive discontinuation of the targeted drug was observed.

Conclusion

A high proportion of patients presented severe infections during follow‐up, with non‐negligible attributable mortality, but infection incidence is not superior to the one observed during the chemotherapy era. In selected cases with specific risk factors for infection, antimicrobial prophylaxis should be considered.

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.

Keeping a balance in chronic lymphocytic leukemia (CLL) patients taking ibrutinib: ibrutinib-associated adverse events and their management based on drug interactions

INTRODUCTION

Ibrutinib is a highly effective drug for patients with chronic lymphocytic leukemia (CLL), and is well tolerated even by older patients and those unfit to receive conventional immuno-chemotherapy.

AREAS COVERED

The occurrence of adverse events was revealed as a major cause of ibrutinib failure in the real-world. Ibrutinib-induced lymphocytosis carries the risk of an untimely interruption of therapy because it may be misinterpreted as disease progression. In addition, drug interactions can worsen ibrutinib-associated toxicities by increasing the plasma concentration of ibrutinib. In this review, we present a case of major hemorrhage and atrial fibrillation (AF) during ibrutinib use and summarize the adverse events associated with ibrutinib. Furthermore, the practical management of ibrutinib-associated toxicities was covered with reference to a drug interaction mechanism.

EXPERT OPINION

Clinicians should examine the prescribed drugs prior to ibrutinib initiation and carefully monitor toxicities while taking ibrutinib. A reduced dose of ibrutinib with the concurrent use of CYP3A inhibitors such as antifungal agents could be an attractive strategy to reduce toxicities and may confer financial benefits. Reducing unexpected toxicities is as significant as achieving treatment response in the era of life-long therapy with ibrutinib in patients with CLL.

BTK Inhibitors in Chronic Lymphocytic Leukemia: Biological Activity and Immune Effects

Bruton´s tyrosine kinase (BTK) inhibitor (BTKi)s block the B-cell receptor (BCR) signaling cascade by binding to the BTK enzyme preventing the proliferation and survival of malignant and normal B cells. During the past decade, the clinical use of BTKis for the treatment of B-cell malignancies has exponentially grown, changing the treatment landscape for chronic lymphocytic leukemia (CLL) in particular. At present, three different covalent BTKis, ibrutinib, acalabrutinib and zanubrutinib, are FDA-approved and many new inhibitors are under development. Despite having remarkable selectivity for BTK, the first-in-class BTKi ibrutinib can also bind, with various affinities, to other kinases. The combined inhibition of BTK (“on-target” effect) and other kinases (“off-target” effect) can have additive or synergistic anti-tumor effects but also induce undesired side effects which might be treatment-limiting. Such “off-target” effects are expected to be more limited for second-generation BTKis. Moreover, the blockade of BCR signaling also indirectly affects the tumor microenvironment in CLL. Treatment with BTKis potentially impacts on both innate and adaptive immunity. Whether this affects infection susceptibility and vaccination efficacy requires further investigation. Here, we summarize the available knowledge on the impact of BTKis on the immune system and discuss the possible clinical implications. Indeed, a deeper knowledge on this topic could guide clinicians in the management and prevention of infections in patients with CLL treated with BTKis.

Efficacy and Safety of Ibrutinib in Central Nervous System Lymphoma: A PRISMA-Compliant Single-Arm Meta-Analysis

Background

Central nervous system lymphoma (CNSL) is an aggressive lymphoma. Studies investigating primary CNSL determined that the Bruton tyrosine kinase (BTK) played an important role in pathogenesis. Ibrutinib, an oral BTK inhibitor, is a new treatment strategy for CNSL. The purpose of this meta-analysis was to clarify the effectiveness and safety of ibrutinib in the treatment of CNSL.

Methods

A systematic search of PubMed, Embase, Cochrane library, Wanfang Data Knowledge Service Platform, and China National Knowledge Infrastructure databases was conducted through to 31 October 2019. Studies involving patients with CNSL who received ibrutinib that reported the overall response (OR), complete remission (CR), and partial response (PR) were included. The random-effects or fixed-effects model with double arcsine transformation was used for the pooled rates and 95% confidence intervals (CI) were determined for all outcomes.

Results

Eight studies including 162 patients were identified and included in the meta-analysis. The pooled OR rate after treatment with ibrutinib was 69% (95% CI, 61-79%, I² = 47.57%, p = 0.06), while the pooled CR and PR was 52% (95% CI, 35-68%, I² = 74.95%, p = 0.00) and 17% (95% CI, 7-30%, I² = 67.85%, p = 0.00), respectively. Among PCNSL patients, including new diagnoses PCNSL and R/R PCNSL, the pooled OR rate was 72% (95% CI, 63-80%, I² = 49.20%, p = 0.06) while the pooled CR and PR rates were 53% (95% CI, 33-73%, I² = 75.04%, p = 0.00) and 22% (95% CI, 14-30%, I² = 46.30%, p = 0.07), respectively. Common adverse events above grade 3 included cytopenia and infections.

Conclusions

The ibrutinib-containing therapy was well tolerated and offered incremental benefit to patients with CNSL. However, randomized-controlled studies that directly compare efficacy and adverse events of ibrutinib are still needed.

Systematic Review Registration

https://www.crd.york.ac.uk/prospero/, identifier CRD42020218974.

Prognostic Impact and Risk Factors of Infections in Patients with Chronic Lymphocytic Leukemia Treated with Ibrutinib

Ibrutinib represents extraordinary progress in the treatment of chronic lymphocytic leukemia (CLL). However, treatment-related adverse events limit the benefit of this agent. This observational, multicenter study focused on the incidence, risk factors, and prognostic impact of infections in 494 patients with CLL treated with an ibrutinib-based treatment. Ibrutinib was given to 89 (18%) previously untreated patients (combined with rituximab, 24) and 405 (82%) relapsed/refractory patients. Pneumonia (PN), grade ≥3 non-opportunistic infections (NOI), and opportunistic infections (OI) were recorded in 32% of patients with an overall incidence rate per 100 person-year of 15.3% (PN, 10%; NOI, 3.3%; OI, 2%). Infections were the reason for the permanent discontinuation of ibrutinib in 9% of patients. Patients who experienced pneumonia or a severe infection showed a significantly inferior survival than those who were infection-free (p < 0.0001). A scoring system based on the three factors associated with a significant and independent impact on infections-PN or severe infection in the year before starting ibrutinib, chronic obstructive pulmonary disease, ≥2 prior treatments-identified patients with a two- to threefold increase in the rate of infections. In conclusion, the results of this study highlight the adverse impact of infectious events on the outcomes of CLL patients treated with ibrutinib.

[Relevance of liposomal amphotericin B in the treatment of invasive fungal infections in patients with hematologic malignancies]

Liposomal amphotericin B (L-AmB) has been a key cornerstone for the management of invasive fungal infections (IFI) caused by a wide array of molds and yeasts during the last three decades. Multiple studies performed over this period have generated a large body of evidence on its efficacy and safety, becoming the main antifungal agent in the management of IFI in patients with hematologic malignancies in several not mutually exclusive clinical settings. First, L-AmB is the most commonly used antifungal agent in patients undergoing intensive chemotherapy for acute leukemia and high-risk myelodysplastic syndrome, as well as in hematopoietic stem cell transplant recipients. Additionally, due to the administration of newer targeted therapies (such as monoclonal antibodies or small molecule inhibitors), opportunistic mold infections are increasingly being reported in patients with hematologic malignancies usually considered low-risk for IFI. These agents usually have a high drug-drug interaction potential, being triazoles, commonly used for antifungal prophylaxis, included. Finally, patients developing breakthrough IFI because of either subtherapeutic concentrations of antifungal prophylactic drugs in blood or selection of resistant strains, require broad spectrum antifungal therapy, usually with an antifungal of a different class. In both situations, L-AmB remains as the best option for early antifungal therapy.

Invasive fungal disease and the immunocompromised host including allogeneic hematopoietic cell transplant recipients: Improved understanding and new strategic approach with sargramostim

In hosts with damaged or impaired immune systems such as those undergoing hematopoietic cell transplant (HCT) or intensive chemotherapy, breakthrough fungal infections can be fatal. Risk factors for breakthrough infections include severe neutropenia, use of corticosteroids, extended use of broad-spectrum antibiotics, and intensive care unit admission. An individual's cumulative state of immunosuppression directly contributes to the likelihood of experiencing increased infection risk. Incidence of invasive fungal infection (IFI) after HCT may be up to 5-8%. Early intervention may improve IFI outcomes, although many infections are resistant to standard therapies (voriconazole, caspofungin, micafungin, amphotericin B, posaconazole or itraconazole, as single agents or in combination). We review herein several contributing factors that may contribute to the net state of immunosuppression in recipients of HCT. We also review a new approach for IFI utilizing adjunctive therapy with sargramostim, a yeast-derived recombinant human granulocyte-macrophage colony-stimulating factor (rhu GM-CSF).

The Right Dose: From Phase I to Clinical Practice

To realize the full potential of promising new anticancer drugs, it is of paramount importance to administer them at the right dose. The aim of this educational article is to provide several opportunities to optimize anticancer drug dosing, focusing on oral targeted therapies. First, therapeutic drug monitoring can optimize exposure in individual patients, if the optimal concentration is known. This approach is of particular interest in regard to oral kinase inhibitors with high interindividual pharmacokinetic variability. If exposure is related to response, then therapeutic drug monitoring is potentially feasible, although the clinical utility of this approach has not yet been established. Other approaches to reduce variability include administration of more frequent, smaller doses and administration under optimal prandial conditions. However, for many drugs, the labeled dose has not been demonstrated to be the optimal dose; for such agents, the vast majority of patients may be receiving excessive doses, which results in excessive toxicity. Furthermore, administration of lower off-label doses may reduce both medical and financial toxicity. These strategies should be applied from registration studies to clinical practice, with the goal of better optimizing anticancer treatment.

Managing toxicities of Bruton tyrosine kinase inhibitors

Inhibition of Bruton's tyrosine kinase (BTK) has revolutionized the treatment landscape for patients with chronic lymphocytic leukemia (CLL). By targeting this critical kinase in proximal B-cell receptor signaling, BTK inhibitors (BTKis) impair cell proliferation, migration, and activation of NF-κB. Clinically, because indefinite inhibition is a mainstay of therapy, there is an extended period of exposure in which adverse effects can develop. Given the impressive efficacy and activity of BTKis in the treatment of patients with CLL, appropriate management of treatment-emergent adverse events (AEs) is of paramount importance. Here we review the BTKi landscape and present the available toxicity and safety data for each agent. The long-term toxicity profile of ibrutinib, a first-in-class inhibitor, is well characterized and includes a clinically significant incidence of cardiac arrhythmias, bleeding, infection, diarrhea, arthralgias, and hypertension. Acalabrutinib, the initial second-generation BTKi to earn approval from the US Food and Drug Administration, demonstrates improved kinase selectivity for BTK, with commonly observed adverse reactions including infection, headache, and diarrhea. Mediated by both on-target inhibition of BTK and variable off-target inhibition of other kinases including interleukin-2-inducible T-cell kinase (ITK), tyrosine-protein kinase (TEC), and endothelial growth factor receptor (EGFR), the toxicity profile of BTKis is closely linked to their pattern of kinase binding. Other emerging BTKis include second-generation agents with variable degrees of kinase selectivity and third-generation agents that exhibit reversible noncovalent binding to BTK. We also highlight critical considerations for the prevention and monitoring of AEs and offer practical management strategies for treatment-emergent toxicities.

BTK Inhibition Impairs the Innate Response Against Fungal Infection in Patients With Chronic Lymphocytic Leukemia

Infections represent a cause of morbidity and mortality in patients affected by chronic lymphocytic leukemia (CLL). Introduction of new drugs in CLL clinical practice has showed impressive efficacy, in particular those targeting BTK. Among the consistent clinical data, an increasing number of reports describing the occurrence of unexpected opportunistic fungal infections has been reported during treatment with ibrutinib in the first 6 months of treatment. The reason underlying manifestations of invasive fungal infections in patients treated with ibrutinib is still under investigation. Our study aimed to understand the impact of BTK inhibition on immune response to fungal infection mediated by macrophages and CD14+ monocytic population obtained from CLL patients. Exposure to ibrutinib and acalabrutinib reduced signaling pathways activated by Aspergillus fumigatus determining an exacerbation of an immunosuppressive signature, a reduction of phagocytosis and a significant deficit in the secretion of inflammatory cytokines either in macrophages and monocytes isolated from CLL patients and healthy donors. These effects lead to a failure in completely counteracting conidia germination. In addition we investigated the biological effects of ibrutinib on monocyte counterpart in patients who were undergoing therapy. A significant impairment in cytokine secretion and a deficit of phagocytosis in circulating monocytes were detected after 3 months of treatment. Thus, our results uncover modifications in the innate response in CLL patients induced by ibrutinib that may impair the immunological response to fungal infection.

KEYPOINTS

•BTK inhibition affects a productive immune response of CLL-associated macrophages (NLC) during Aspergillus fumigatus infection.•Reduction of TNF-α secretion and phagocytosis are detected in monocytes isolated from CLL patients during ibrutinib therapy.

COVID-19 severity and mortality in patients with chronic lymphocytic leukemia: a joint study by ERIC, the European Research Initiative on CLL, and CLL Campus

Chronic lymphocytic leukemia (CLL) is a disease of the elderly, characterized by immunodeficiency. Hence, patients with CLL might be considered more susceptible to severe complications from COVID-19. We undertook this retrospective international multicenter study to characterize the course of COVID-19 in patients with CLL and identify potential predictors of outcome. Of 190 patients with CLL and confirmed COVID-19 diagnosed between 28/03/2020 and 22/05/2020, 151 (79%) presented with severe COVID-19 (need of oxygen and/or intensive care admission). Severe COVID-19 was associated with more advanced age (≥65 years) (odds ratio 3.72 [95% CI 1.79–7.71]). Only 60 patients (39.7%) with severe COVID-19 were receiving or had recent (≤12 months) treatment for CLL at the time of COVID-19 versus 30/39 (76.9%) patients with mild disease. Hospitalization rate for severe COVID-19 was lower (p < 0.05) for patients on ibrutinib versus those on other regimens or off treatment. Of 151 patients with severe disease, 55 (36.4%) succumbed versus only 1/38 (2.6%) with mild disease; age and comorbidities did not impact on mortality. In CLL, (1) COVID-19 severity increases with age; (2) antileukemic treatment (particularly BTK inhibitors) appears to exert a protective effect; (3) age and comorbidities did not impact on mortality, alluding to a relevant role of CLL and immunodeficiency.

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.