COVID‐19 Vaccine Failure in Chronic Lymphocytic Leukaemia and Monoclonal B‐Lymphocytosis; Humoral and Cellular Immunity

Prevention and management of infectious complications in patients with chronic lymphocytic leukemia (CLL) treated with BTK and BCL-2 inhibitors, focus on current guidelines

CLL is associated with an increased risk of infectious complications. Treatment with BTK or BCL-2 inhibitors does not seem to increase significantly the risk of opportunistic infections, but the role of combination therapies including BTK and/or BCL-2 inhibitors remains to be established. Various infectious complications can be successfully prevented with appropriate risk management strategies. In this paper we reviewed the international guidelines on prevention and management of infectious complications in patients with CLL treated with BTK or BCL-2 inhibitors. Universal pharmacological anti-herpes, antibacterial or antifungal prophylaxis is not warranted. Reactivation of HBV should be prevented in HBsAg-positive subjects. For HBsAg-negative/HBcAb-positive patients recommendations differ, but in case of combination treatment should follow those for other, particularly anti-CD20, agent. Immunization should be provided preferably before the onset of treatment. Immunoglobulin therapy has favourable impact on morbidity but not mortality in patients with hypogammaglobulinemia and severe or recurrent infections. Lack of high-quality data and heterogeneity of patients or protocols included in the studies might explain differences among the main guidelines. Better data collection is warranted.

Vaccinations in patients with chronic lymphocytic leukemia

Chronic lymphocytic leukemia (CLL) is characterized by immune dysfunction resulting in heightened susceptibility to infections and elevated rates of morbidity and mortality. A key strategy to mitigate infection-related complications has been immunization against common pathogens. However, the immunocompromised status of CLL patients poses challenges in eliciting an adequate humoral and cellular immune response to vaccination. Most CLL-directed therapy disproportionately impairs humoral immunity. Vaccine responsiveness also depends on the phase and type of immune response triggered by immunization. In this review, we discuss the immune dysfunction, vaccine responsiveness, and considerations for optimizing vaccine response in patients with CLL.

Repeated COVID-19 vaccination to maximum antibody response yields very low mortality and hospitalisation rates in patients with CLL and MBL

We analysed COVID-19 infection outcomes of 129/241 chronic lymphocytic leukaemia (CLL) (53.9%) and 22/55 monoclonal B-lymphocytosis (MBL) (40.0%) patients following multiple vaccine doses aiming for maximum measured anti-spike antibody response. Throughout the pandemic to date, there were 8/129 CLL (6.2%) patients hospitalised, with one death (0.8%). No MBL patients were hospitalised or died. CLL patients with COVID-19 had lower anti-spike levels (3778.8 AU/mL) than those without (13 486.8 AU/mL; p = 0.0061). Anti-nucleocapsid antibody was detected in 29.8% within 2 months and 17.5% >6 months. Of COVID-19-infected CLL patients, 47.3% received anti-viral therapy. A multiple vaccine dosing strategy to achieve measured maximum antibody is highly effective in preventing severe COVID-19.

Australia and New Zealand consensus position statement: use of COVID-19 therapeutics in patients with haematological malignancies

Despite widespread vaccination rates, we are living with high transmission rates of SARS-CoV-2. Although overall hospitalisation rates are falling, the risk of serious infection remains high for patients who are immunocompromised because of haematological malignancies. In light of the ongoing pandemic and the development of multiple agents for treatment, representatives from the Haematology Society of Australia and New Zealand and infectious diseases specialists have collaborated on this consensus position statement regarding COVID-19 management in patients with haematological disorders. It is our recommendation that both patients with haematological malignancies and treating specialists be educated regarding the preventive and treatment options available and that patients continue to receive adequate vaccinations, keeping in mind the suboptimal vaccine responses that occur in haematology patients, in particular, those with B-cell malignancies and on B-cell-targeting or depleting therapy. Patients with haematological malignancies should receive treatment for COVID-19 in accordance with the severity of their symptoms, but even mild infections should prompt early treatment with antiviral agents. The issue of de-isolation following COVID-19 infection and optimal time to treatment for haematological malignancies is discussed but remains an area with evolving data. This position statement is to be used in conjunction with advice from infectious disease, respiratory and intensive care specialists, and current guidelines from the National COVID-19 Clinical Evidence Taskforce and the New Zealand Ministry of Health and Cancer Agency Te Aho o Te Kahu COVID-19 Guidelines.

Pathogenesis and management of immune dysfunction secondary to B cell haematological malignancies

Malignancies of the B-lymphocyte lineage are among the most diagnosed haematological malignancies in clinical practice. In our community, multiple myeloma (MM) and its precursor condition monoclonal gammopathy of undetermined significance are the commonest, accounting for ~12% of diagnoses, followed by chronic lymphocytic leukaemia (CLL) and its precursor condition monoclonal B lymphocytosis, ~9%. Along with diffuse large B cell lymphoma, follicular lymphoma and marginal zone lymphoma, these conditions comprise around a third of all haematological malignancies diagnosed. Infection remains an important cause of mortality and morbidity in the management of patients with these conditions. This is in part treatment-related but also reflective of disease-related immune dysfunction. Infectious complications account for up to 50% of early mortality in patients with myeloma and up to 50% of all mortality in patients with CLL. A variety of strategies are available to decrease the morbidity and mortality of infectious complications; however, practices vary between countries and often between treating physicians. Treatment options have evolved significantly over the last decade, with the introduction of monoclonal antibodies, small molecule inhibitors, second- and third-generation immunomodulatory agents and CAR-T cell therapy. Much of the data that inform clinical practice in infection management predates current therapeutic approaches. This is in part because of the rapid development of new therapies but also reflective of the long natural history of many of these diseases and the need for prolonged periods of observation. In this article, we review the aspects of disease and treatment that contribute to immune dysfunction in MM, CLL and B-cell non-Hodgkin lymphoma and review the current strategies used to manage immune dysfunction and infection.

Comparison of the blood immune repertoire with clinical features in chronic lymphocytic leukemia patients treated with chemoimmunotherapy or ibrutinib

Chronic lymphocytic leukemia (CLL) is characterized by the accumulation of CD19+ CD5+ clonal B lymphocytes in the blood, bone marrow, and peripheral lymphoid organs. Treatment options for patients range from historical chemoimmunotherapy (CIT) to small molecule inhibitors targeting pro-survival pathways in leukemic B cells, such as the Bruton's tyrosine kinase inhibitor ibrutinib (IBR). Using biobanked blood samples obtained pre-therapy and at standard response evaluation timepoints, we performed an in-depth evaluation of the blood innate and adaptive immune compartments between pentostatin-based CIT and IBR and looked for correlations with clinical sequelae. CD4+ conventional T cells and CD8+ cytotoxic T cells responded similarly to CIT and IBR, although exhaustion status differed. Both treatments dramatically increased the prevalence and functional status of monocyte, dendritic cell, and natural killer cell subsets. As expected, both regimens reduced clonal B cell levels however, we observed no substantial recovery of normal B cells. Although improvements in most immune subsets were observed with CIT and IBR at response evaluation, both patient groups remained susceptible to infections and secondary malignancies during the study.

Immune cell kinetics and antibody response in COVID-19 patients with low-count monoclonal B-cell lymphocytosis

Low-count monoclonal B-cell lymphocytosis (MBLlo ) has been associated with an underlying immunodeficiency and has recently emerged as a new risk factor for severe COVID-19. Here, we investigated the kinetics of immune cell and antibody responses in blood during COVID-19 of MBLlo versus non-MBL patients. For this study, we analyzed the kinetics of immune cells in blood of 336 COVID-19 patients (74 MBLlo and 262 non-MBL), who had not been vaccinated against SARS-CoV-2, over a period of 43 weeks since the onset of infection, using high-sensitivity flow cytometry. Plasma levels of anti-SARS-CoV-2 antibodies were measured in parallel by ELISA. Overall, early after the onset of symptoms, MBLlo COVID-19 patients showed increased neutrophil, monocyte, and particularly, plasma cell (PC) counts, whereas eosinophil, dendritic cell, basophil, and lymphocyte counts were markedly decreased in blood of a variable percentage of samples, and with a tendency toward normal levels from week +5 of infection onward. Compared with non-MBL patients, MBLlo COVID-19 patients presented higher neutrophil counts, together with decreased pre-GC B-cell, dendritic cell, and innate-like T-cell counts. Higher PC levels, together with a delayed PC peak and greater plasma levels of anti-SARS-CoV-2-specific antibodies (at week +2 to week +4) were also observed in MBLlo patients. In summary, MBLlo COVID-19 patients share immune profiles previously described for patients with severe SARS-CoV-2 infection, associated with a delayed but more pronounced PC and antibody humoral response once compared with non-MBL patients.

Antibody response to SARS-CoV-2 vaccines in patients with relapsing multiple sclerosis treated with evobrutinib: A Bruton's tyrosine kinase inhibitor

BACKGROUND

Evobrutinib is an oral, central nervous system (CNS)-penetrant and highly selective covalent Bruton's tyrosine kinase inhibitor under clinical development for patients with relapsing multiple sclerosis (RMS).

OBJECTIVE

To investigate the effect of evobrutinib on immune responses in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccinated patients with RMS from a Phase II trial (NCT02975349).

METHODS

A post hoc analysis of patients with RMS who received evobrutinib 75 mg twice daily and SARS-CoV-2 vaccines during the open-label extension (n = 45) was conducted. Immunoglobulin (Ig)G anti-S1/S2-specific SARS-CoV-2 antibodies were measured using an indirect chemiluminescence immunoassay.

RESULTS

In the vaccinated subgroup, mean/minimum evobrutinib exposure pre-vaccination was 105.2/88.7 weeks. In total, 43 of 45 patients developed/increased S1/S2 IgG antibody levels post-vaccination; one patient's antibody response remained negative post-vaccination and the other had antibody levels above the upper limit of detection, both pre- and post-vaccination. Most patients (n = 36/45), regardless of pre-vaccination serostatus, had a 10-100-fold increase of antibody levels pre- to post-vaccination. Antibody levels post-booster were higher versus post-vaccination.

CONCLUSION

These results suggest evobrutinib, an investigational drug with therapeutic potential for patients with RMS, acts as an immunomodulator, that is, it inhibits aberrant immune cell responses in patients with RMS, while responsiveness to foreign de novo and recall antigens is maintained.

Chronic lymphocytic leukaemia Australasian consensus practice statement

Chronic lymphocytic leukaemia (CLL) is the most common haematological malignancy in Australia and New Zealand (ANZ). Considerable changes to diagnostic and management algorithms have occurred within the last decade. The availability of next-generation sequencing and measurable residual disease assessment by flow cytometry allow for advanced prognostication and response assessments. Novel therapies, including inhibitors of Bruton's tyrosine kinase (BTKi) and B-cell lymphoma 2 (BCL2) inhibitors, have transformed the treatment landscape for both treatment-naïve and relapsed/refractory disease, particularly for patients with high-risk genetic aberrations. Recommendations regarding appropriate supportive management continue to evolve, and special considerations are required for patients with CLL with respect to the global SARS-CoV-2 pandemic. The unique funding and treatment environments in Australasia highlight the need for specific local guidance with respect to the investigation and management of CLL. This consensus practice statement was developed by a broadly representative group of ANZ experts in CLL with endorsement by peak haematology bodies, with a view to providing this standardised guidance.

Induction of neutralizing antibodies in CLL patients after SARS-CoV-2 mRNA vaccination: a monocentric experience

Vaccination represents the best strategy to fight COVID-19 pandemics, especially in immune compromised subjects. In chronic lymphatic leukemia patients, a marked impairment of the immune response to mRNA SARS-CoV-2 vaccine was observed. In this report, we analyzed anti-RBD and neutralizing antibodies in CLL patients after two doses of mRNA SARS CoV 2 vaccine and evaluated the impact of Bruton kinase inhibitory agents. Twenty-seven CLL patients vaccinated with mRNA vaccines against SARS CoV-2 were recruited. Serum IgG, IgM and IgA anti-RBD antibodies and neutralizing antibodies were detected, and antibody avidity was measured. Peripheral blood leukocytes subsets were evaluated by flow cytometry. After two vaccine doses anti-RBD IgG were produced in 11/27 (40.5%) of patients and levels of IgG and IgA anti RBD in CLL patients were sensibly lower than in controls. Neutralizing antibodies were detectable in 12/27 (44.5%) of the patients and their level was lower than that observed in controls. Disease burden and treatment with Bruton kinases inhibitors markedly impaired vaccine induced antibody response. However, in responder patients, antibody avidity was comparable to normal subjects, indicating that the process of clonal selection and affinity maturation takes place as expected. Taken together, these data confirm the impact of disease burden and therapy on production of anti-RBD and neutralizing antibodies and support the current policy of vaccinating CLL patients.

Comparison of humoral and cellular immune responses in hematologic diseases following completed vaccination protocol with BBIBP-CorV, or AZD1222, or BNT162b2 vaccines against SARS-CoV-2

Background

Vaccination has proven the potential to control the COVID-19 pandemic worldwide. Although recent evidence suggests a poor humoral response against SARS-CoV-2 in vaccinated hematological disease (HD) patients, data on vaccination in these patients is limited with the comparison of mRNA-based, vector-based or inactivated virus-based vaccines.

Methods

Forty-nine HD patients and 46 healthy controls (HCs) were enrolled who received two-doses complete vaccination with BNT162b2, or AZD1222, or BBIBP-CorV, respectively. The antibodies reactive to the receptor binding domain of spike protein of SARS-CoV-2 were assayed by Siemens ADVIA Centaur assay. The reactive cellular immunity was assayed by flow cytometry. The PBMCs were reactivated with SARS-CoV-2 antigens and the production of activation-induced markers (TNF-α, IFN-γ, CD40L) was measured in CD4+ or CD8+ T-cells ex vivo.

Results

The anti-RBD IgG level was the highest upon BNT162b2 vaccination in HDs (1264 BAU/mL) vs. HCs (1325 BAU/mL) among the studied groups. The BBIBP-CorV vaccination in HDs (339.8 BAU/mL ***p < 0.001) and AZD1222 in HDs (669.9 BAU/mL *p < 0.05) resulted in weaker antibody response vs. BNT162b2 in HCs. The response rate of IgG production of HC vs. HD patients above the diagnostic cut-off value was 100% vs. 72% for the mRNA-based BNT162b2 vaccine; 93% vs. 56% for the vector-based AZD1222, or 69% vs. 33% for the inactivated vaccine BBIBP-CorV, respectively. Cases that underwent the anti-CD20 therapy resulted in significantly weaker (**p < 0.01) anti-RBD IgG level (302 BAU/mL) than without CD20 blocking in the HD group (928 BAU/mL). The response rates of CD4+ TNF-α+, CD4+ IFN-γ+, or CD4+ CD40L+ cases were lower in HDs vs. HCs in all vaccine groups. However, the BBIBP-CorV vaccine resulted the highest CD4+ TNF-α and CD4+ IFN-γ+ T-cell mediated immunity in the HD group.

Conclusion

We have demonstrated a significant weaker overall response to vaccines in the immunologically impaired HD population vs. HCs regardless of vaccine type. Although, the humoral immune activity against SARS-CoV-2 can be highly evoked by mRNA-based BNT162b2 vaccination compared to vector-based AZD1222 vaccine, or inactivated virus vaccine BBIBP-CorV, whereas the CD4+ T-cell mediated cellular activity was highest in HDs vaccinated with BBIBP-CorV.

Vaccinations in hematological patients in the era of target therapies: Lesson learnt from SARS-CoV-2

Novel targeting agents for hematologic diseases often exert on- or off-target immunomodulatory effects, possibly impacting on response to anti-SARS-CoV-2 vaccinations and other vaccines. Agents that primarily affect B cells, particularly anti-CD20 monoclonal antibodies (MoAbs), Bruton tyrosine kinase inhibitors, and anti-CD19 chimeric antigen T-cells, have the strongest impact on seroconversion. JAK2, BCL-2 inhibitors and hypomethylating agents may hamper immunity but show a less prominent effect on humoral response to vaccines. Conversely, vaccine efficacy seems not impaired by anti-myeloma agents such as proteasome inhibitors and immunomodulatory agents, although lower seroconversion rates are observed with anti-CD38 and anti-BCMA MoAbs. Complement inhibitors for complement-mediated hematologic diseases and immunosuppressants used in aplastic anemia do not generally affect seroconversion rate, but the extent of the immune response is reduced under steroids or anti-thymocyte globulin. Vaccination is recommended prior to treatment or as far as possible from anti-CD20 MoAb (at least 6 months). No clearcut indications for interrupting continuous treatment emerged, and booster doses significantly improved seroconversion. Cellular immune response appeared preserved in several settings.

Risk of Infections Secondary to the Use of Targeted Therapies in Hematological Malignancies

Concurrent infections in hematological malignancies (HM) are major contributors to adverse clinical outcomes, including prolonged hospitalization and reduced life expectancy. Individuals diagnosed with HM are particularly susceptible to infectious pathogens due to immunosuppression, which can either be inherent to the hematological disorder or induced by specific therapeutic strategies. Over the years, the treatment paradigm for HM has witnessed a tremendous shift, from broad-spectrum treatment approaches to more specific targeted therapies. At present, the therapeutic landscape of HM is constantly evolving due to the advent of novel targeted therapies and the enhanced utilization of these agents for treatment purposes. By initiating unique molecular pathways, these agents hinder the proliferation of malignant cells, consequently affecting innate and adaptive immunity, which increases the risk of infectious complications. Due to the complexity of novel targeted therapies and their associated risks of infection, it often becomes a daunting task for physicians to maintain updated knowledge in their clinical practice. The situation is further aggravated by the fact that most of the initial clinical trials on targeted therapies provide inadequate information to determine the associated risk of infection. In such a scenario, a cumulative body of evidence is paramount in guiding clinicians regarding the infectious complications that can arise following targeted therapies. In this review, I summarize the recent knowledge on infectious complications arising in the context of targeted therapies for HM.

Characterization of post-vaccination SARS-CoV-2 T cell subtypes in patients with different hematologic malignancies and treatments

Background

To evaluate the benefits of SARS-CoV-2 vaccination in cancer patients it is relevant to understand the adaptive immune response elicited after vaccination. Patients affected by hematologic malignancies are frequently immune-compromised and show a decreased seroconversion rate compared to other cancer patients or controls. Therefore, vaccine-induced cellular immune responses in these patients might have an important protective role and need a detailed evaluation.

Methods

Certain T cell subtypes (CD4, CD8, Tfh, γδT), including cell functionality as indicated by cytokine secretion (IFN, TNF) and expression of activation markers (CD69, CD154) were assessed via multi-parameter flow cytometry in hematologic malignancy patients (N=12) and healthy controls (N=12) after a second SARS-CoV-2 vaccine dose. The PBMC of post-vaccination samples were stimulated with a spike-peptide pool (S-Peptides) of SARS-CoV-2, with CD3/CD28, with a pool of peptides from the cytomegalovirus, Epstein-Barr virus and influenza A virus (CEF-Peptides) or left unstimulated. Furthermore, the concentration of spike-specific antibodies has been analyzed in patients.

Results

Our results indicate that hematologic malignancy patients developed a robust cellular immune response to SARS-CoV-2 vaccination comparable to that of healthy controls, and for certain T cell subtypes even higher. The most reactive T cells to SARS-CoV-2 spike peptides belonged to the CD4 and Tfh cell compartment, being median (IQR), 3.39 (1.41-5.92) and 2.12 (0.55-4.14) as a percentage of IFN- and TNF-producing Tfh cells in patients. In this regard, the immunomodulatory treatment of patients before the vaccination period seems important as it was strongly associated with a higher percentage of activated CD4 and Tfh cells. SARS-CoV-2- and CEF-specific T cell responses significantly correlated with each other. Compared to lymphoma patients, myeloma patients had an increased percentage of SARS-CoV-2-specific Tfh cells. T-SNE analysis revealed higher frequencies of γδT cells in patients compared to controls, especially in myeloma patients. In general, after vaccination, SARS-CoV-2-specific T cells were also detectable in patients without seroconversion.

Conclusion

Hematologic malignancy patients are capable of developing a SARS-CoV-2-specific CD4 and Tfh cellular immune response after vaccination, and certain immunomodulatory therapies in the period before vaccination might increase the antigen-specific immune response. A proper response to recall antigens (e.g., CEF-Peptides) reflects immune cellular functionality and might be predictive for generating a newly induced antigen-specific immune response as is expected after SARS-CoV-2 vaccination.

Cellular and humoral response to the fourth BNT162b2 mRNA COVID-19 vaccine dose in patients with CLL

We assessed the humoral and cellular response to the fourth BNT162b2 mRNA COVID-19 vaccine dose in patients with CLL. A total of 67 patients with CLL and 85 age matched controls tested for serologic response and pseudo-neutralization assay. We also tested the functional T-cell response by interferon gamma (IFNγ) to spike protein in 26 patients. Two weeks after the fourth vaccine antibody serologic response was evident in 37 (55.2%) patients with CLL, 20 /22 (91%) of treatment naïve, and 9/32 (28%) patients with ongoing therapy, compared with 100% serologic response in age matched controls. The antibody titer increased by 10-fold in patients with CLL, however, still 88-folds lower than age matched controls. Predictors of better chances of post fourth vaccination serologic response were previous positive serologies after second, third, and pre-fourth vaccination, neutralizing assay, and treatment naïve patients. T-cell response improved from 42.3% before the fourth vaccine to 84.6% 2 weeks afterwards. During the time period of 3 months after the fourth vaccination, 14 patients (21%) developed COVID-19 infection, all recovered uneventfully. Our data demonstrate that fourth SARS-CoV-2 vaccination improves serologic response in patients with CLL to a lesser extent than healthy controls and induces functional T-cell response.

COVID-19 Vaccination Response and Its Practical Application in Patients With Chronic Lymphocytic Leukemia

Patients with chronic lymphocyticleukemia (CLL) typically have innate/adaptive immune system dysregulation, thus the protective effect of coronavirus disease 2019 (COVID-19) vaccination remains uncertain. This prospective review evaluates vaccination response in these patients, including seropositivity rates by CLL treatment status, type of treatment received, and timing of vaccination. Antibody persistence, predictors of poor vaccine response, and severity of COVID-19 infection in vaccinated patients were also analyzed. Practical advice on the clinical management of patients with CLL is provided. Articles reporting COVID-19 vaccination in patients with CLL, published January 1, 2021-May 1, 2022, were included. Patients with CLL displayed the lowest vaccination responses among hematologic malignancies; however, seropositivity increased with each vaccination. One of the most commonly reported independent risk factors for poor vaccine response was active CLL treatment; others included hypogammaglobulinemia and age >65-70 years. Patients who were treatment-naive, off therapy, in remission, or who had a prior COVID-19 infection displayed the greatest responses. Further data are needed on breakthrough infection rates and a heterologous booster approach in patients with hematologic malignancies. Although vaccine response was poor for patients on active therapy regardless of treatment type, CLL management in the context of COVID-19 should aim to avoid delays in antileukemic treatment, especially with the advent of numerous strategies to mitigate risk of severe COVID-19 such as pre-exposure prophylaxis, and highly effective antivirals and monoclonal antibody therapy upon confirmed infection. Patients with CLL should remain vigilant in retaining standard prevention measures such as masks, social distancing, and hand hygiene.

Coronavirus-Specific Antibody and T Cell Responses Developed after Sputnik V Vaccination in Patients with Chronic Lymphocytic Leukemia

The clinical course of the new coronavirus disease 2019 (COVID-19) has shown that patients with chronic lymphocytic leukemia (CLL) are characterized by a high mortality rate, poor response to standard treatment, and low virus-specific antibody response after recovery and/or vaccination. To date, there are no data on the safety and efficacy of the combined vector vaccine Sputnik V in patients with CLL. Here, we analyzed and compared the magnitudes of the antibody and T cell responses after vaccination with the Sputnik V vaccine among healthy donors and individuals with CLL with different statuses of preexposure to coronavirus. We found that vaccination of the COVID-19-recovered individuals resulted in the boosting of pre-existing immune responses in both healthy donors and CLL patients. However, the COVID-19-naïve CLL patients demonstrated a considerably lower antibody response than the healthy donors, although they developed a robust T cell response. Regardless of the previous infection, the individuals over 70 years old demonstrated a decreased response to vaccination, as did those receiving anti-CD20 therapy. In summary, we showed that Sputnik V, like other vaccines, did not induce a robust antibody response in individuals with CLL; however, it provided for the development of a significant anti-COVID-19 T cell response.

Immunogenicity and risks associated with impaired immune responses following SARS-CoV-2 vaccination and booster in hematologic malignancy patients: an updated meta-analysis

Patients with hematologic malignancies (HM) have demonstrated impaired immune responses following SARS-CoV-2 vaccination. Factors associated with poor immunogenicity remain largely undetermined. A literature search was conducted using PubMed, EMBASE, Cochrane, and medRxiv databases to identify studies that reported humoral or cellular immune responses (CIR) following complete SARS-CoV-2 vaccination. The primary aim was to estimate the seroconversion rate (SR) following complete SARS-CoV-2 vaccination across various subtypes of HM diseases and treatments. The secondary aims were to determine the rates of development of neutralizing antibodies (NAb) and CIR following complete vaccination and SR following booster doses. A total of 170 studies were included for qualitative and quantitative analysis of primary and secondary outcomes. A meta-analysis of 150 studies including 20,922 HM patients revealed a pooled SR following SARS-CoV-2 vaccination of 67.7% (95% confidence interval [CI], 64.8-70.4%; I² = 94%). Meta-regression analysis showed that patients with lymphoid malignancies, but not myeloid malignancies, had lower seroconversion rates than those with solid cancers (R² = 0.52, P < 0.0001). Patients receiving chimeric antigen receptor T-cells (CART), B-cell targeted therapies or JAK inhibitors were associated with poor seroconversion (R² = 0.39, P < 0.0001). The pooled NAb and CIR rates were 52.8% (95% CI; 45.8-59.7%, I² = 87%) and 66.6% (95% CI, 57.1-74.9%; I² = 86%), respectively. Approximately 20.9% (95% CI, 11.4-35.1%, I² = 90%) of HM patients failed to elicit humoral and cellular immunity. Among non-seroconverted patients after primary vaccination, only 40.5% (95% CI, 33.0-48.4%; I² = 87%) mounted seroconversion after the booster. In conclusion, HM patients, especially those with lymphoid malignancies and/or receiving CART, B-cell targeted therapies, or JAK inhibitors, showed poor SR after SARS-CoV-2 vaccination. A minority of patients attained seroconversion after booster vaccination. Strategies to improve immune response in these severely immunosuppressed patients are needed.

Multiple COVID-19 vaccine doses in CLL and MBL improve immune responses with progressive and high seroconversion

Patients with chronic lymphocytic leukemia (CLL) or monoclonal B-lymphocytosis (MBL) have impaired response to COVID-19 vaccination. A total of 258 patients (215 with CLL and 43 with MBL) had antispike antibody levels evaluable for statistical analysis. The overall seroconversion rate in patients with CLL was 94.2% (antispike antibodies ≥50 AU/mL) and 100% in patients with MBL after multiple vaccine doses. After 3 doses (post-D3) in 167 patients with CLL, 73.7% were seropositive, 17.4% had antispike antibody levels between 50 and 999 AU/mL, and 56.3% had antispike antibody levels ≥1000 AU/mL, with a median rise from 144.6 to 1800.7 AU/mL. Of patients who were seronegative post-D2, 39.7% seroconverted post-D3. For those who then remained seronegative after their previous dose, seroconversion occurred in 40.6% post-D4, 46.2% post-D5, 16.7% post-D6, and 0% after D7 or D8. After seroconversion, most had a progressive increase in antispike antibody levels. Neutralization was associated with higher antispike antibody levels, more vaccine doses, and earlier severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants; neutralizing antibody against early clade D614G was detected in 65.3%, against Delta in 52.0%, and against Omicron in 36.5%. SARS-CoV-2-specific T-cell production of interferon γ and interleukin 2 occurred in 73.9% and 60.9%, respectively, of 23 patients tested. After multiple vaccine doses, by multivariate analysis, immunoglobulin M ≥0.53 g/L, immunoglobulin subclass G3 ≥0.22 g/L and absence of current CLL therapy were independent predictors of positive serological responses. Multiple sequential COVID-19 vaccination significantly increased seroconversion and antispike antibody levels in patients with CLL or MBL.

Immune correlates of protection by vaccine against SARS-CoV-2 in patients with chronic lymphocytic leukaemia

In chronic lymphocytic leukaemia (CLL) the efficacy of SARS-CoV-2 vaccination remains unclear as most studies have focused on humoral responses. Here we comprehensively examined humoral and cellular responses to vaccine in CLL patients. Seroconversion was observed in 55.2% of CLL with lower rate and antibody titres in treated patients. T-cell responses were detected in a significant fraction of patients. CD4⁺ and CD8⁺ frequencies were significantly increased independent of serology with higher levels of CD4⁺ cells in patients under a Bruton tyrosine kinase (BTK) or a B-cell lymphoma 2 (BCL-2) inhibitor. Vaccination skewed CD8⁺ cells towards a highly cytotoxic phenotype, more pronounced in seroconverted patients. A high proportion of patients showed spike-specific CD4⁺ and CD8⁺ cells producing interferon gamma (IFNγ) and tumour necrosis factor alpha (TNFα). Patients under a BTK inhibitor showed increased production of IFNγ and TNFα by CD4⁺ cells. Vaccination induced a Th1 polarization reverting the Th2 CLL T-cell profile in the majority of patients with lower IL-4 production in untreated and BTK-inhibitor-treated patients. Such robust T-cell responses may have contributed to remarkable protection against hospitalization and death in a cohort of 540 patients. Combining T-cell metrics with seroprevalence may yield a more accurate measure of population immunity in CLL, providing consequential insights for public health.

Monoclonal B-cell Lymphocytosis - a review of diagnostic criteria, biology, natural history, and clinical management

Since first described almost two decades ago, there has been significant evolution in our definition and understanding of the biology and implications of monoclonal B-cell lymphocytosis (MBL). This review provides an overview of the definition, classification, biology, and natural history of MBL, mainly focused on the dominant CLL-like phenotype form of MBL. The increasingly recognized implications of MBL with respect to immune dysfunction are discussed, particularly in view of the COVID-19 pandemic, along with management recommendations for MBL in the clinic.

B-cell malignancies treated with targeted drugs and SARS-CoV-2 infection: A European Hematology Association Survey (EPICOVIDEHA)

Patients with lymphoproliferative diseases (LPD) are vulnerable to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. Here, we describe and analyze the outcome of 366 adult patients with chronic lymphocytic leukemia (CLL) or non-Hodgkin Lymphoma (NHL) treated with targeted drugs and laboratory-confirmed COVID-19 diagnosed between February 2020 and January 2022. Median follow-up was 70.5 days (IQR 0-609). Most used targeted drugs were Bruton-kinase inhibitors (BKIs) (N= 201, 55%), anti-CD20 other than rituximab (N=61, 16%), BCL2 inhibitors (N=33, 9%) and lenalidomide (N=28, 8%).Only 16.2% of the patients were vaccinated with 2 or more doses of vaccine at the onset of COVID-19. Mortality was 24% (89/366) on day 30 and 36%(134/366) on the last day of follow-up. Age >75 years (p<0.001, HR 1.036), active malignancy (p<0.001, HR 2.215), severe COVID-19 (p=0.017, HR 2.270) and admission to ICU (p<0.001, HR 5.751) were risk factors for mortality at last day of follow up. There was no difference in OS rates in NHL vs CLL patients (p=0.306), nor in patients treated with or without BKIs (p=0.151). Mortality in ICU was 66% (CLL 61%, NHL 76%). Overall mortality rate decreased according to vaccination status, being 39% in unvaccinated patients, 32% and 26% in those having received one or two doses, respectively, and 20% in patients with a booster dose (p=0.245). Overall mortality rate dropped from 41% during the first semester of 2020 to 25% at the last semester of 2021. These results show increased severity and mortality from COVID-19 in LPDs patients treated with targeted drugs.

Patients with Chronic Lymphocytic Leukemia Have a Very High Risk of Ineffective Response to the BNT162b2 Vaccine

Patients with CLL have high rates of either severe disease or death from COVID-19 and a low response rate after COVID-19 vaccination has been reported. We conducted a single-center study with the main objective to evaluate the immunogenicity of the BNT1162b2 mRNA vaccines in 42 patients affected by CLL with the assessment of antibody response after the second and the third dose. After the second dose of vaccine, 13 patients (30%) showed an antibody response. The presence of hypogammaglobulinemia and the use of steroids or IVIG were the main factors associated with poor response. After the third dose, 5/27 (18%) patients showed an antibody response while in non-responders to the second dose, only 1 patient (4%) showed an elicitation of the immune response by the third dose, with no statistically significant difference. Our data, despite the small size of our cohort, demonstrate that patients with CLL have a low rate of effective response to the BNT162b2 vaccine. However, the effective role of a subsequent dose is still unclear, highlighting the need for alternative methods of immunization in this particularly fragile group of patients.

Current perspectives regarding SARS-CoV-2 vaccination in chronic lymphocytic leukemia

In immunocompetent people, the mRNA vaccines BNT162b2 and mRNA‐1273 have been shown to be safe and effective against coronavirus disease of 2019 (COVID‐19). However, results of cohort studies and meta‐analyses have indicated that the degree of humoral response to SARS‐CoV‐2 vaccines in patients with chronic lymphocytic leukemia (CLL) appears to be lower than that observed in the general population. These inadequate responses are mainly related to the disease itself and to the immunosuppressive effect of therapies administered. In the specific context of CLL, enrolling patients with sub‐optimal vaccine‐response in pivotal vaccine trials could be considered as an appropriate approach to improve response to the COVID‐19 vaccine. These clinical trials should also address the issues of regularity and timing of vaccine booster doses or re‐vaccinations, especially in patients undergoing therapy with pathway‐targeting agents and anti‐CD20 monoclonal antibodies. However, since hypogammaglobulinemia is a serious consequence of CLL, patients who do not have a detectable antibody response should be natural candidates for preventive antibody therapy.

Lack of Induction of RBD-Specific Neutralizing Antibodies despite Repeated Heterologous SARS-CoV-2 Vaccination Leading to Seroconversion and Establishment of T Cell-Specific Memory in a Patient in Remission of Multiple Myeloma

Background: Prophylactic vaccination against infectious diseases may induce a state of long-term protection in the otherwise healthy host. However, the situation is less predictable in immunocompromised patients and may require adjustment of vaccination schedules and/or basic therapy. Methods: A patient in full remission of multiple myeloma since the last three years and on long-term maintenance therapy with pomalidomide, a drug inhibiting angiogenesis and myeloma cell growth, was vaccinated twice with Comirnaty followed by two vaccinations with Vaxzevria. Seroconversion and SARS-CoV-2-specific cellular responses were monitored. Results: No signs of seroconversion or T cellular memory were observed after the first “full immunization” with Comirnaty. Consequently, long-term-maintenance therapy with Pomalidomide was stopped and two additional shots of Vaxzevria were administered after which the patient seroconverted with Spike(S)-protein specific antibody levels reaching 49 BAU/mL, mild S-peptide pool-specific T cell proliferation, effector cytokine production (IL-2, IL-13), and T cellular activation with increased numbers of CD3⁺CD4⁺CD25⁺ T cells as compared to vaccinated and non-vaccinated control subjects. However, despite suspension of immunosuppression and administration of in total four consecutive heterologous SARS-CoV-2 vaccine shots, the patient did not develop neutralizing RBD-specific antibodies. Conclusions: Despite immunomonitoring-based adjustment of vaccination and/or therapy schedules vaccination success, with clear correlates of protection, the development of RBD-specific antibodies could not be achieved in the immunocompromised patient with current SARS-CoV-2 vaccines. Thus, our report emphasizes the need for improved active and passive immunization strategies for SARS-CoV-2 infections.