Additional booster doses in patients with chronic lymphocytic leukemia induce humoral and cellular immune responses to SARS-CoV-2 similar to natural infection regardless ongoing treatments: A study by ERIC, the European Research Initiative on CLL

Profound immune dysregulation and impaired response to the SARS-CoV-2 vaccine put patients with chronic lymphocytic leukemia (CLL) at risk of severe COVID-19. We compared humoral memory and T-cell responses after booster dose vaccination or breakthrough infection. (Green) Quantitative determination of anti-Spike specific antibodies. Booster doses increased seroconversion rate and antibody titers in all patient categories, ultimately generating humoral responses similar to those observed in the postinfection cohort. In detail, humoral response with overscale median antibody titers arose in >80% of patients in watch and wait, off-therapy in remission, or under treatment with venetoclax single-agent. Anti-CD20 antibodies and active treatment with BTK inhibitors (BTKi) represent limiting factors of humoral response, still memory mounted in ~40% of cases following booster doses or infection. (Blue) Evaluation of SARS-CoV-2-specific T-cell responses. Number of T-cell functional activation markers documented in each patient. The vast majority of patients, including those seronegative, developed T-cell responses, qualitatively similar between treatment groups or between vaccination alone and infection cases. These data highlight the efficacy of booster doses in eliciting T-cell immunity independently of treatment status and support the use of additional vaccination boosters to stimulate humoral immunity in patients on active CLL-directed treatments.

Targeting antigen-independent proliferation in chronic lymphocytic leukemia through differential kinase inhibition

The clinical success of B-cell receptor (BCR) signaling pathway inhibitors in chronic lymphocytic leukemia (CLL) is attributed to inhibition of adhesion in and migration towards the lymph node. Proliferation of CLL cells is restricted to this protective niche, but the underlying mechanism(s) is/are not known. Treatment with BCR pathway inhibitors results in rapid reductions of total clone size, while CLL cell survival is not affected, which points towards inhibition of proliferation. In vitro, BCR stimulation does not induce proliferation of CLL, but triggering via Toll-like receptor, tumor necrosis factor or cytokine receptors does. Here, we investigated the effects of clinically applied inhibitors that target BCR signaling, in the context of proliferation triggered either via CD40L/IL-21 or after CpG stimulation. CD40L/IL-21-induced proliferation could be inhibited by idelalisib and ibrutinib. We demonstrate this was due to blockade of CD40L-induced ERK-signaling. Targeting JAKs, but not SYK, blocked CD40L/IL-21-induced proliferation. In contrast, PI3K, BTK as well as SYK inhibition prevented CpG-induced proliferation. Knockdown experiments showed that CD40L/IL-21 did not co-opt upstream BCR components such as CD79A, in contrast to CpG-induced proliferation. Our data indicate that currently applied BTK/PI3K inhibitors target antigen-independent proliferation in CLL, and suggest that targeting of JAK and/or SYK might be clinically useful.

Macrophages confer survival signals via CCR1-dependent translational MCL-1 induction in chronic lymphocytic leukemia

Protective interactions with bystander cells in micro-environmental niches, such as lymph nodes (LNs), contribute to survival and therapy resistance of chronic lymphocytic leukemia (CLL) cells. This is caused by a shift in expression of B-cell lymphoma 2 (BCL-2) family members. Pro-survival proteins B-cell lymphoma-extra large (BCL-X_L), BCL-2-related protein A1 (BFL-1) and myeloid leukemia cell differentiation protein 1 (MCL-1) are upregulated by LN-residing T cells through CD40L interaction, presumably via nuclear factor (NF)-κB signaling. Macrophages (Mφs) also reside in the LN, and are assumed to provide important supportive functions for CLL cells. However, if and how Mφs are able to induce survival is incompletely known. We first established that Mφs induced survival because of an exclusive upregulation of MCL-1. Next, we investigated the mechanism underlying MCL-1 induction by Mφs in comparison with CD40L. Genome-wide expression profiling of in vitro Mφ- and CD40L-stimulated CLL cells indicated activation of the phosphoinositide 3-kinase (PI3K)-V-Akt murine thymoma viral oncogene homolog (AKT)-mammalian target of rapamycin (mTOR) pathway, which was confirmed in ex vivo CLL LN material. Inhibition of PI3K-AKT-mTOR signaling abrogated MCL-1 upregulation and survival by Mφs, as well as CD40 stimulation. MCL-1 can be regulated at multiple levels, and we established that AKT leads to increased MCL-1 translation, but does not affect MCL-1 transcription or protein stabilization. Furthermore, among Mφ-secreted factors that could activate AKT, we found that induction of MCL-1 and survival critically depended on C-C motif chemokine receptor-1 (CCR1). In conclusion, this study indicates that two distinct micro-environmental factors, CD40L and Mφs, signal via CCR1 to induce AKT activation resulting in translational stabilization of MCL-1, and hence can contribute to CLL cell survival.

T-cells fighting B-cell lymphoproliferative malignancies: the emerging field of CD19 CAR T-cell therapy

CAR T-cells are autologous T-cells transduced with a chimeric antigen receptor (CAR). The CAR contains an antigen recognition part (originating from an antibody), a T-cell receptor transmembrane and cytoplasmic signalling part, and one or more co-stimulatory domains. While CAR T-cells can be directed against any tumour target, most experience thus far has been obtained with targeting of the B-cell antigen CD19 that is expressed by B-cell acute lymphocytic leukaemia, chronic lymphocytic leukaemia and other B-cell lymphomas. The first clinical results are promising, although there are profound differences in response between patients with different haematological malignancies. Treatment-related side effects have been observed that require specific management. This review will explain the mechanism of action, summarise the experience to date and point out future directions for this hopeful new addition to the therapeutic armamentarium in the treatment of lymphoproliferative B-cell malignancies.

Macrophage-mediated chronic lymphocytic leukemia cell survival is independent of APRIL signaling

Survival of chronic lymphocytic leukemia (CLL) cells is mainly driven by interactions within the lymph node (LN) microenvironment with bystander cells such as T cells or cells from the monocytic lineage. Although the survival effect by T cells is largely governed by the TNFR ligand family member CD40L, the exact mechanism of monocyte-derived cell-induced survival is not known. An important role has been attributed to the TNFR ligand, a proliferation-inducing ligand (APRIL), although the exact mechanism remained unclear. Since we detected that APRIL was expressed by CD68+ cells in CLL LN, we addressed its relevance in various aspects of CLL biology, using a novel APRIL overexpressing co-culture system, recombinant APRIL, and APRIL reporter cells. Unexpectedly, we found, that in these various systems, APRIL had no effect on survival of CLL cells, and activation of NF-κB was not enhanced on APRIL stimulation. Moreover, APRIL stity mulation did not affect CLL proliferation, neither as single stimulus nor in combination with known CLL proliferation stimuli. Furthermore, the survival effect conveyed by macrophages to CLL cells was not affected by transmembrane activator and CAML interactor-Fc, an APRIL decoy receptor. We conclude that the direct role ascribed to APRIL in CLL cell survival might be overestimated due to application of supraphysiological levels of recombinant APRIL.

Monoclonal B-cell lymphocytosis: recommendations from the Dutch Working Group on CLL for daily practice

Monoclonal B-cell lymphocytosis (MBL) is defined by the presence of small B-cell clones in asymptomatic individuals. Usually, MBL cells are characterised by a chronic lymphocytic leukaemia (CLL) phenotype ('CLL phenotype MBL'); however, an atypical phenotype ('atypical-CLL phenotype MBL') or non-Hodgkin lymphoma phenotype ('non-CLL phenotype MBL') can be found as well. The prevalence of MBL in the general population with an age over 40 years is 3 to 5%. Subjects with MBL develop CLL requiring treatment at a rate of 1 to 2% per year. At the moment official guidelines with respect to MBL are not available in the Netherlands. On the basis of the available data, we will discuss the definitions of MBL , highlight clinical consequences and offer recommendations for daily practice. Individuals with clinically suspected MBL should undergo a complete evaluation by a haematologist. In case of CLL phenotype MBL , further annual follow-up can take place by the general practitioner. If signs of progression occur patients should be referred to a haematologist.

ERIC recommendations on TP53 mutation analysis in chronic lymphocytic leukemia

Recent evidence suggests that - in addition to 17p deletion - TP53 mutation is an independent prognostic factor in chronic lymphocytic leukemia (CLL). Data from retrospective analyses and prospective clinical trials show that ∼5% of untreated CLL patients with treatment indication have a TP53 mutation in the absence of 17p deletion. These patients have a poor response and reduced progression-free survival and overall survival with standard treatment approaches. These data suggest that TP53 mutation testing warrants integration into current diagnostic work up of patients with CLL. There are a number of assays to detect TP53 mutations, which have respective advantages and shortcomings. Direct Sanger sequencing of exons 4-9 can be recommended as a suitable test to identify TP53 mutations for centers with limited experience with alternative screening methods. Recommendations are provided on standard operating procedures, quality control, reporting and interpretation. Patients with treatment indications should be investigated for TP53 mutations in addition to the work-up recommended by the International workshop on CLL guidelines. Patients with TP53 mutation may be considered for allogeneic stem cell transplantation in first remission. Alemtuzumab-based regimens can yield a substantial proportion of complete responses, although of short duration. Ideally, patients should be treated within clinical trials exploring new therapeutic agents.

Dutch guidelines for diagnosis and treatment of chronic lymphocytic leukaemia 2011

One of the principal responsibilities of the Chronic Lymphocytic Leukaemia (CLL) Working Party of the Dutch/Belgium Haemato-Oncology Foundation for Adults in the Netherlands (HOVON) is to create up-to-date guidelines for CLL . In this article, the revised guidelines for diagnosis and treatment are summarised. Despite recent expansion in treatment options for patients with CLL , the disease remains incurable in most cases and the optimal treatment approach for several subgroups of patients is still unclear. Therefore, it remains highly important to treat patients within clinical studies as much as possible. In this article, the current studies initiated by the HOVON CLL working party are emphasised.

[Severe anaemia caused by Human Parvovirus B19 infection in a patient with autoimmune haemolytic anaemia and a B-cell non-Hodgkin lymphoma]

A 65-year-old man with a 15-year history of 'leukemicised' low-grade lymphocytic B-cell non-Hodgkin lymphoma with a low-titre of IgM kappa paraprotein was admitted with severe anaemia and reticulocytopenia. Treatment with prednisone and chlorambucil had been started two weeks earlier because of a recently diagnosed Coombs-positive haemolytic anaemia. He also received a blood transfusion at that time. During his stay in the hospital, a crista biopsy was performed that revealed no signs of bone marrow suppression but markedly enlarged pro-erythroblasts. Although a serologic test for Human Parvovirus-B19 was negative, PCR showed a sharply increased viral load with more than 1 x 10(11) copies/ml, compatible with a primary parvovirus infection. In retrospect, an earlier transfusion of blood that had not been screened for parvovirus was probably the culprit. Treatment with human immunoglobulin was effective in lowering the viral load and normalising the haemoglobin. This case illustrates that reticulocytopenia in a patient with a haematologic disorder accompanied by a shortened erythrocyte life-span is suggestive for a primary parvovirus infection, especially following a recent transfusion. To prevent transmission of Human Parvovirus B19 via blood transfusion, the Health Council of the Netherlands published a guideline indicating that patients at high risk for a complicated infection with Human Parvovirus B19 should be given 'virus-free' blood products.

Chronic lymphocytic leukemia cells display p53-dependent drug-induced Puma upregulation

We investigated the apoptosis gene expression profile of chronic lymphocytic leukemia (CLL) cells in relation to (1) normal peripheral and tonsillar B-cell subsets, (2) IgV(H) mutation status, and (3) effects of cytotoxic drugs. In accord with their noncycling, antiapoptotic status in vivo, CLL cells displayed high constitutive expression of Bcl-2 and Flip mRNA, while Survivin, Bid and Bik were absent. Paradoxically, along with these antiapoptotic genes CLL cells had high-level expression of proapoptotic BH3-only proteins Bmf and Noxa. Treatment of CLL cells with fludarabine induced only the proapoptotic genes Bax and Puma in a p53-dependent manner. Interestingly, the degree of Puma induction was more pronounced in cells with mutated IgVH genes. Thus, disturbed apoptosis in CLL is the net result of both protective and sensitizing aberrations. This delicate balance can be tipped via induction of Puma in a p53-dependent matter, the level of which may vary between groups of patients with a different tendency for disease progression.

[Chronic lymphocytic leukemia: high time for a risk-adapted approach]

B cell chronic lymphocytic leukaemia (CLL) is the most common leukaemia in the Western world. It is wrongly considered to be an indolent disease: even patients with Binet stage A can have disease-related morbidity, necessitating treatment in about 50% of them, and over 25% of these patients will die of CLL-related causes. It was recently discovered that there are in fact 2 subtypes of CLL: a pre-germinal centre type. Characterised by unmutated genes which code for the variable parts of immunoglobulin chains (IgV), and a post-germinal centre variant, characterised by IgV somatic mutations. This IgV-gene mutational status as well as surface expression of CD38 and characteristic cytogenic abnormalities has recently been shown to be powerful prognostic factors. Furthermore, over the past few years new treatment modalities have been developed including purine analogues, immunotherapy with monoclonal antibodies and stem cell transplantation. Therefore it is time to substitute the present policy used for the vast majority of patients (i.e. an expectant approach, if needs be followed by initial treatment with chlorambucil) with an approach based on the patient's individual risk profile. This should preferably be done within the framework of clinical trials.

[Thrombotic microangiopathy: thrombocytopenia and hemolytic anemia]

Thrombotic microangiopathy is an acute and severe syndrome characterised by a combination of thrombocytopenia, haemolytic anaemia with a negative direct antiglobulin test, and fragmentocytes in the blood smear. The condition can be idiopathic but can also be caused by various underlying diseases. The main causes are thrombotic thrombocytopenic purpura and haemolytic uraemic syndrome. By measuring the von Willebrand factor cleaving protease activity, it now appears possible to distinguish between the different causes of thrombotic microangiopathy, although the sensitivity and specificity of this measurement still need to be clarified. In patients with haemolytic uraemic syndrome without preceding diarrhoea, one should search for infectious foci outside the gastrointestinal tract, using a polymerase-chain reaction to detect the two different verotoxin genes where necessary. Plasmapheresis treatment has reduced the fatality rate amongst patients with thrombotic thrombocytopenic purpura from 90% to 10-25%. Since patients benefit most from rapid institution of treatment, yet the diagnostics currently take several days, the recommendation in case of doubt regarding the original diagnosis is to apply initial plasma exchange therapy to all patients with thrombotic microangiopathy.

Low adjusted-dose acenocoumarol therapy in sickle cell disease: a pilot study

Vasoocclusion is a continuous process in sickle cell disease (SCD) and accumulates to significant end organ damage, mostly irrespective of the occurrence of manifest acute vasoocclusive events. As there are indications that reversing the hypercoagulable state may be of clinical benefit in sickle cell patients, we performed a randomized, double blind, placebo-controlled, cross-over pilot study to assess the efficacy and safety of low-adjusted dose acenocoumarol therapy (International Normalized Ratio: 1.6-2.0) in SCD. Treatment consisted of either acenocoumarol or placebo for 14 weeks, after which treatment was discontinued for a period of five weeks. Then, patients initially on acenocoumarol received placebo (and vice versa) for 14 weeks. Therapy efficacy was assessed by comparing the frequency of vasoocclusive complications, the occurrence of bleeding, and clotting activation between acenocoumarol and placebo treatment of each individual patient. Twenty-two patients (14 homozygous [HbSS] and 8 double heterozygous sickle-C [HbSC]; aged 20-59 years) completed the entire study. Acenocoumarol treatment did not result in a significant reduction of acute vasoocclusive events (three painful crises during acenocoumarol, five painful crises during placebo). There was a marked reduction of the hypercoagulable state (depicted by a decrease in plasma levels of prothrombin F1.2 fragments [P = 0.002], thrombin-antithrombin complexes [P = 0.003], and D-dimer fragments [P = 0.001]) without the occurrence of major bleeding. Even though no clinical benefit (pertaining to the frequency of painful crises) was detected in this pilot study, the value of low adjusted-dose acenocoumarol for preventing specific events (such as strokes) and as a long-term treatment of sickle cell patients should be subject of further study.

Toxin-mediated haemolytic uraemic syndrome without diarrhoea

A 52-year-old previously healthy man was admitted to the hospital with haematuria, painful micturition and fever. Laboratory investigation showed the presence of a haemolytic uraemic syndrome (HUS), characterized by haemolysis, renal insufficiency and mental disturbances. A urinary tract infection caused by a verotoxin-producing E. coli other than O157:H7 was diagnosed. Treatment of this infection resulted in his complete recovery from the illness. Both the search for a focus outside the gastrointestinal tract and the search for verotoxin genes by specific polymerase chain reaction can be crucial in a patient with HUS without preceding diarrhoea.

[Quality of life in children with sickle cell disease in Amsterdam area]

OBJECTIVE

To determine the differences in quality of life between children with sickle cell disease and healthy immigrant children.

DESIGN

Descriptive, comparative.

METHOD

The quality of life of children with sickle cell disease between 5 and 15 years old being treated in the Emma Children's Hospital AMC in Amsterdam, the Netherlands, was assessed by using a questionnaire for parents (TNO-AZL Children's Quality of Life Questionnaire (TACQOL) parent form) if the child was between 5 and 11 years old and a questionnaire for children (TACQOL child form) if the child was between 8 and 15 years old. The study period was April-October 1998. The questionnaires were completed by 45 (parents of) patients. The results were compared with a healthy reference group of immigrant children. Statistical analysis was performed using the Student t-Test.

RESULTS

Children with sickle cell disease as well as their parents scored significantly lower on the items general physical, motor and independent daily functioning and on occurrence of negative emotions. No significance was observed for the items cognitive functioning and school performance nor for social functioning or occurrence of positive emotions.

CONCLUSION

In children, sickle cell disease leads to compromised physical and possibly also psychological wellbeing, as well as the experience of decreased independence in daily functioning, but not to compromised cognitive or social aspects of the quality of life.