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.

Chronic lymphocytic leukemia (CLL) cells are provided with essential survival and proliferative signals in the lymph node microenvironment. Here, CLL cells engage in various interactions with bystander cells such as T cells and macrophages. Phenotypically distinct types of tumor infiltrating macrophages can either be tumor supportive (M2) or play a role in tumor immune surveillance (M1). Although recent in vitro findings suggest a protective role for macrophages in CLL, the actual balance between these macrophage subsets in CLL lymphoid tissue is still unclear. Furthermore, the mechanism of recruitment of monocytes towards the CLL lymph node is currently unknown. Both questions are addressed in this paper. Immunofluorescence staining of lymph node samples showed macrophage skewing towards an M2 tumor-promoting phenotype. This polarization likely results from CLL-secreted soluble factors, as both patient serum and CLL-conditioned medium recapitulated the skewing effect. Considering that CLL cell cytokine secretion is affected by adjacent T cells, we next studied CLL-mediated monocyte recruitment in the presence or absence of T-cell signals. While unstimulated CLL cells were inactive, T cell-stimulated CLL cells actively recruited monocytes. This correlated with secretion of various chemokines such as C-C-motif-ligand-2,3,4,5,7,24, C-X-C-motif-ligand-5,10, and Interleukin-10. We also identified CD40L as the responsible T-cell factor that mediated recruitment, and showed that recruitment critically depended on the C-C-motif-chemokine-receptor-2 axis. These studies show that the shaping of a tumor supportive microenvironment depends on cytokinome alterations (including C-C-motif-ligand-2) that occur after interactions between CLL, T cells and monocytes. Therefore, targeted inhibition of CD40L or C-C-motif-chemokine-receptor-2 may be relevant therapeutic options.

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IntroductionLiterature is scarce on the combination treatment of ibrutinib and venetoclax (IV) is scarce in relapsed or refractory chronic lymphocytic leukaemia (RR-CLL). Especially, the possibility of stopping ibrutinib in RR-CLL patients in deep remission is unclear.Methods and analysisIn the HOVON 141/VISION trial, patients with RR-CLL are treated with 12 cycles of IV after a short induction with ibrutinib. Patients reaching undetectable minimal residual disease (uMRD) after 12 cycles of IV are randomised 1:2 to continue ibrutinib or stop treatment. The persistence of uMRD after stopping IV is studied. In addition, in patients who become positive for MRD again after stopping, IV treatment is reinitiated. The efficacy of this approach with regard to progression-free survival 12 months after randomisation is the primary endpoint of the study.Ethics and disseminationThis protocol respects the Helsinki declaration and has been approved by the ethical committee of the Amsterdam Medical Center. Study findings will be disseminated through peer-reviewed papers. All patients who fulfil the inclusion criteria and no-exclusion criteria, and have signed the informed consent form are included in the study.Trial registration numberClinicalTrials.gov Registry (NCT03226301).

Introduction Chronic lymphocytic leukemia (CLL) is characterized by a profound immune suppression. In addition, CLL cells evade immune destruction by interacting with cells of the adaptive immune system, resulting in dysfunctional T cells. CD4+ T cells are skewed towards a TH2-profile and the number of regulatory T (Treg) cells, that diminish cellular immune responses, is increased in CLL patients. CD8+ T cells resemble exhausted T cells and have reduced cytotoxic, yet increased cytokine production capacity. The cytotoxic function of NK cells is impaired in CLL patients, but in contrast to CD8+ T cells their cytokine production is also compromised, presumably induced by CLL cells. These data are chiefly obtained from studies on peripheral blood (PB). Although the lymph node (LN) compartment has a central role in the pathobiology of CLL, very little is known about the composition of non-malignant lymphocytes in LN tissue. The Bcl-2 inhibitor venetoclax (Ven) is highly effective in CLL and, especially in combination with anti-CD20 monoclonal antibodies such as obinutuzumab (O), results in high rates of minimal residual disease (MRD) undetectable responses. However, the prospective effects of venetoclax on non-malignant lymphocytes in patient samples remain largely unexplored. Methods PB and LN biopsy specimens were collected at baseline from patients enrolled in the 1st-line FCR-unfit HOVON 139 / GIVE trial. Study treatment consisted of O (cycle 1-2), Ven+O (cycle 3-8) and Ven (cycle 9-14). Immune composition was analyzed by 7-color flow cytometry. Baseline PB samples were compared to paired LN samples. Moreover, PB samples of the first patients that completed 6 cycles of Ven monotherapy (cycle 14) were compared to baseline. Cytokine production and degranulation of T and NK cells was studied after stimulation of PBMCs with PMA/Ionomycin. Results Comparison of LN (n=28) vs PB (n=48) revealed a larger proportion of T cells in LN (13.2% vs 5.1% of the lymphocytes), at the expense of CLL cells, with a skewed CD4:CD8 ratio (5.2 in LN vs 1.8 in PB). Within the CD4+ T cells, significantly higher levels of both follicular T helper cells (15. 7% vs 5.2%) and Tregs (11.5% vs 6.9%) were found in LN (see Table). CD4+ T cells mostly consisted of naïve and memory T cells in both PB and LN. There were fewer CD8+ T cells and especially fewer effector CD8+ T cells in the LN in comparison to PB. CD8+ T cells in LN mostly had a naïve and memory phenotype. An increased percentage of LN-residing CD8+ T cells expressed the exhaustion marker PD-1 as compared to PB CD8+ T cells (30.4% in LN vs 12.4% in PB). We then compared PB baseline samples to PB obtained after cycle 14 (n=11). Ten patients achieved MRD undetectable levels (<10-4, determined by flow cytometry) and 1 patient was MRD intermediate (10-4-10-2). As expected, the treatment regimen led to complete elimination of CD19+ B cells. In contrast, absolute numbers of CD4+ and CD8+ T cells did not change during treatment. Differentiation status of CD4+ and CD8+ T cells remained similar. Interestingly, the proportion and absolute number of Tregs decreased after treatment (6.1% vs 0.9% of CD4+ T cells). After stimulation with PMA/Ionomycin, the percentage of IL-2 producing CD4+ T cells increased after treatment, leading to a higher IL-2:IL-4 ratio, that suggests normalization towards a TH1-profile. Fewer CD8+ T cells expressed PD-1 after treatment. The fraction of CD8+ T cells that produced IFN-γ (69.8% vs 56.2%) and TNF-α (58.4% vs 40.3%) decreased. Degranulation of CD8+ T cells did not change upon treatment. After treatment, the capacity of NK cells to degranulate increased. In addition, a larger proportion of NK cells produced IFN-γ, suggesting recovery of NK cell function after treatment. Conclusion In conclusion, our data strengthen the view that CLL cells reside in an immune suppressive environment in the LN. Moreover, we provide the first evidence that the Ven+O regimen does not harm non-malignant lymphocyte populations other than B cells. Both the improved cytokine production of NK cells and diminished cytokine production of CD8+ T cells may point to normalization of immune function. Collectively, the phenotypical and functional changes observed may reflect the eradication of the immunosuppressive CLL clone by Ven+O and subsequent recovery of the immune microenvironment in CLL patients. Disclosures Eldering: Celgene: Research Funding. Mobasher:F. Hoffmann-La Roche Ltd: Other: Ownership interests non-PLC; Genentech Inc: Employment. Levin:Janssen: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees. Kater:Abbvie: Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Research Funding; Janssen: Membership on an entity's Board of Directors or advisory committees, Research Funding; Acerta: Membership on an entity's Board of Directors or advisory committees, Research Funding; Roche/Genentech: Membership on an entity's Board of Directors or advisory committees, Research Funding.