Adaptive immunity and neutralizing antibodies against SARS-CoV-2 variants of concern following vaccination in patients with cancer: The CAPTURE study

Global seroprevalence of neutralizing antibodies against adeno-associated virus serotypes used for human gene therapies

Adeno-associated virus (AAV) vectors are promising gene therapy candidates, but pre-existing anti-AAV neutralizing antibodies (NAbs) pose a significant challenge to successful gene delivery. Knowledge of NAb seroprevalence remains limited and inconsistent. We measured activity of NAbs against six clinically relevant AAV serotypes across 10 countries in adults (n = 502) and children (n = 50) using a highly sensitive transduction inhibition assay. NAb prevalence was generally highest for AAV1 and lowest for AAV5. There was considerable variability across countries and geographical regions. NAb prevalence increased with age and was higher in females, participants of Asian ethnicity, and participants in cancer trials. Co-prevalence was most frequently observed between AAV1 and AAV6 and less frequently between AAV5 and other AAVs. Machine learning analyses revealed a unique clustering of AAVs that differed from previous phylogenetic classifications. These results offer insights into the biological relationships between the immunogenicity of AAVs in humans beyond that observed previously using standard clades, which are based on linear capsid sequences. Our findings may inform improved vector design and facilitate the development of AAV vector-mediated clinical gene therapies.

mRNA-1273 vaccination induces polyfunctional memory CD4 and CD8 T cell responses in patients with solid cancers undergoing immunotherapy or/and chemotherapy

Introduction

Research has confirmed the safety and comparable seroconversion rates following SARS-CoV-2 vaccination in patients with solid cancers. However, the impact of cancer treatment on vaccine-induced T cell responses remains poorly understood.

Methods

In this study, we expand on previous findings within the VOICE trial by evaluating the functional and phenotypic composition of mRNA-1273-induced T cell responses in patients with solid tumors undergoing immunotherapy, chemotherapy, or both, compared to individuals without cancer. We conducted an ELISpot analysis on 386 participants to assess spike-specific T cell responses 28 days after full vaccination. Further in-depth characterization of using flow cytometry was performed on a subset of 63 participants to analyze the functional phenotype and differentiation state of spike-specific T cell responses.

Results

ELISpot analysis showed robust induction of spike-specific T cell responses across all treatment groups, with response rates ranging from 75% to 80%. Flow cytometry analysis revealed a distinctive cytokine production pattern across cohorts, with CD4 T cells producing IFNγ, TNF, and IL-2, and CD8 T cells producing IFNγ, TNF, and CCL4. Variations were observed in the proportion of monofunctional CD4 T cells producing TNF, particularly higher in individuals without cancer and patients treated with chemotherapy alone, while those treated with immunotherapy or chemoimmunotherapy predominantly produced IFNγ. Despite these differences, polyfunctional spike-specific memory CD4 and CD8 T cell responses were comparable across cohorts. Notably, immunotherapy-treated patients exhibited an expansion of spike-specific CD4 T cells with a terminally differentiated effector memory phenotype.

Discussion

These findings demonstrate that systemic treatment in patients with solid tumors does not compromise the quality of polyfunctional mRNA-1273-induced T cell responses. This underscores the importance of COVID-19 vaccination in patients with solid cancers undergoing systemic treatment.

Immunogenicity of COVID-19 vaccines in patients with follicular lymphoma receiving frontline chemoimmunotherapy

Immune responses to primary COVID-19 vaccination were investigated in 58 patients with follicular lymphoma (FL) as part of the PETReA trial of frontline therapy (EudraCT 2016-004010-10). COVID-19 vaccines (BNT162b2 or ChAdOx1) were administered before, during or after cytoreductive treatment comprising rituximab (depletes B cells) and either bendamustine (depletes CD4+ T cells) or cyclophosphamide-based chemotherapy. Blood samples obtained after vaccine doses 1 and 2 (V1, V2) were analysed for antibodies and T cells reactive to the SARS-CoV-2 spike protein using the Abbott Architect and interferon-gamma ELISpot assays respectively. Compared to 149 healthy controls, patients with FL exhibited lower antibody but preserved T-cell responses. Within the FL cohort, multivariable analysis identified low pre-treatment serum IgA levels and V2 administration during induction or maintenance treatment as independent determinants of lower antibody and higher T-cell responses, and bendamustine and high/intermediate FLIPI-2 score as additional determinants of a lower antibody response. Several clinical scenarios were identified where dichotomous immune responses were estimated with >95% confidence based on combinations of predictive variables. In conclusion, the immunogenicity of COVID-19 vaccines in FL patients is influenced by multiple disease- and treatment-related factors, among which B-cell depletion showed differential effects on antibody and T-cell responses.

Immune dysfunction prior to and during vaccination in multiple myeloma: a case study based on COVID-19

Infection is the leading cause of death in multiple myeloma (MM). However, the cellular composition associated with immune dysfunction is not defined. We analyzed immune profiles in the peripheral blood of patients with MM (n = 28) and B-cell chronic lymphoproliferative disorders (n = 53) vs. health care practitioners (n = 96), using multidimensional and computational flow cytometry. MM patients displayed altered distribution of most cell types (41/56, 73%), particularly within the B-cell (17/17) and T-cell (20/30) compartments. Using COVID-19 as a case study, we compared the immune response to vaccination based on 64,304 data points generated from the analysis of 1099 longitudinal samples. MM patients showed limited B-cell expansion linked to lower anti-RBD and anti-S antibody titers after the first two doses and booster. The percentages of B cells and CD4+ T cells in the blood, as well as the absolute counts of B cells and dendritic cells, predicted vaccine immunogenicity at different time points. In contrast with the humoral response, the percentage and antigen-dependent differentiation of SARS-CoV-2-specific CD8+ T cells was not altered in MM patients. Taken together, this study defined the cellular composition associated with immune dysfunction in MM and provided biomarkers such as the B-cell percentage and absolute count to individualize vaccination calendars.

COVID-19 vaccination outcomes in patients with a solid malignancy: Insights from extensive real-world data and propensity score matched analyses

OBJECTIVES

This nationwide, multicentric, retrospective analysis of 1,126,946 COVID-19 cases (March 2020-June 2022) aims to elucidate the impact of COVID-19 vaccination on mortality in patients with a sole solid malignancy.

METHODS

Using data from the national digital medical record repository, outcomes were compared among fully vaccinated and nonvaccinated cohorts, factoring in gender, virus type, age, vaccination status, vaccine type, and cancer type. Logistic regression calculated odds ratios (OR) and their significance.

RESULTS

Among 6,050 patients with both cancer and comorbidities, 1,797 had only solid malignancy. Vaccinated individuals in this group had reduced mortality rates, especially those >63 years (OR 0.169 [95% confidence interval [CI] 0.090-0.317]; P < .001). Lower deaths were observed in non-ICU (OR 0.193 [95% CI 0.097-0.382]; P < .001) and ICU cases (OR 0.224 [95% CI 0.077-0.646]; P = .003), with both vaccine types. No statistically significant benefits were observed against delta and omicron variants. Intrathoracic malignancies (OR 0.376 [95% CI 0.146-0.971]; P = .043) and palliative treatment (OR 0.384 [95% CI 0.192-0.766]; P = .006) showed vaccination benefits. Logistic regression revealed a higher fatal risk in nonvaccinated males >63. Propensity score matching supported these outcomes.

CONCLUSIONS

Patients with sole solid malignancies face elevated COVID-19 mortality risk, particularly without active cytostatic therapy, with advanced disease on palliative treatment, or intrathoracic malignancies.

Response to COVID-19 vaccination in patients on cancer therapy: Analysis in a SARS-CoV-2-naïve population

BACKGROUND

Cancer patients have increased morbidity and mortality from COVID-19, but may respond poorly to vaccination. The Evaluation of COVID-19 Vaccination Efficacy and Rare Events in Solid Tumors (EVEREST) study, comparing seropositivity between cancer patients and healthy controls in a low SARS-CoV-2 community-transmission setting, allows determination of vaccine response with minimal interference from infection.

METHODS

Solid tumor patients from The Canberra Hospital, Canberra, Australia, and healthy controls who received COVID-19 vaccination between March 2021 and January 2022 were included. Blood samples were collected at baseline, pre-second vaccine dose and at 1, 3 (primary endpoint), and 6 months post-second dose. SARS-CoV-2 anti-spike-RBD (S-RBD) and anti-nucleocapsid IgG antibodies were measured.

RESULTS

Ninety-six solid tumor patients and 20 healthy controls were enrolled, with median age 62 years, and 60% were female. Participants received either AZD1222 (65%) or BNT162b2 (35%) COVID-19 vaccines. Seropositivity 3 months post vaccination was 87% (76/87) in patients and 100% (20/20) in controls (p = .12). Seropositivity was observed in 84% of patients on chemotherapy, 80% on immunotherapy, and 96% on targeted therapy (differences not satistically significant). Seropositivity in cancer patients increased from 40% (6/15) after first dose, to 95% (35/37) 1 month after second dose, then dropped to 87% (76/87) 3 months after second dose.

CONCLUSION

Most patients and all controls became seropositive after two vaccine doses. Antibody concentrations and seropositivity showed a decrease between 1 and 3 months post vaccination, highlighting need for booster vaccinations. SARS-CoV-2 infection amplifies S-RBD antibody responses; however, cannot be adequately identified using nucleocapsid serology. This underlines the value of our COVID-naïve population in studying vaccine immunogenicity.

COVID-19 vaccination in cancer patients: Immune responses one year after the third dose

Cancer patients (CPs), being immunosuppressed due to the treatment received or to the disease itself, are more susceptible to infections and their potential complications, showing therefore an increased risk of developing severe COVID-19 compared to the general population. We evaluated the immune responses to anti-SARS-CoV-2 vaccination in patients with solid tumors one year after the administration of the third dose and the effect of cancer treatment on vaccine immunogenicity was assessed. Healthy donors (HDs) were enrolled. Binding and neutralizing antibody (Ab) titers were evaluated using chemiluminescence immunoassay (CLIA) and Plaque Reduction Neutralization Test (PRNT) respectively. T-cell response was analyzed using multiparametric flow cytometry. CPs who were administered three vaccine doses showed lower Ab titers than CPs with four doses and HDs. Overall, a lower cell-mediated response was found in CPs, with a predominance of monofunctional T-cells producing TNFα. Lower Ab titers and a weaker T-cell response were observed in CPs without prior SARS-CoV-2 infection when compared to those with a previous infection. While no differences in the humoral response were found comparing immunotherapy and non-immunotherapy patients, a stronger T-cell response in CPs treated with immunotherapy was observed. Our results emphasize the need of booster doses in cancer patients to achieve a level of protection similar to that observed in healthy donors and underlines the importance of considering the treatment received to reach a proper immune response.

Herpes zoster after the third dose of SARS-CoV-2 mRNA-BNT162b2 vaccine in actively treated cancer patients: a prospective study

Several concerns have been raised about a causal relationship between COVID-19 mRNA-based vaccines and the development of herpes zoster (HZ). We performed a prospective analysis of the Vax-On-Third-Profile study to investigate the incidence of HZ after the third dose of mRNA-BNT162b2 (tozinameran) and its correlation with immune responses. Patients who had received a booster dose and had been actively treated for at least 8 weeks were eligible. Serologic assessment was performed before the third dose of tozinameran (timepoint-1) and 4 weeks later (timepoint-2). We also assessed the incidence of SARS-CoV-2 breakthrough infections at predefined time points. The current analysis included 310 patients, of whom 109 (35.2%) and 111 (35.8%) were being treated with targeted therapies and cytotoxic chemotherapy, respectively. All participants received a third dose of tozinameran between September 26 and October 30, 2021. After a mean follow-up of 17.3 (IQR 15.1-18.4) months, HZ occurred in 8 recipients, for a cumulative incidence of 2.6%, and an incidence rate of 0.310 per person-year (95% CI 0.267-0.333). All HZ cases occurred within 30 days of booster dosing (range 5-29 days), with a median time to onset of 15 (IQR 9-22) days. Among the 7 patients (2.2%) who also contracted a SARS-CoV-2 infection, all cases preceded COVID-19 outbreaks. No instances of complicated HZ were reported. In multivariate analysis, impaired T helper and T cytotoxic cell counts independently correlated with HZ occurrence. These findings provide the first evidence that cancer patients on active treatment have a not negligible risk of developing HZ within 30 days after the third dose of tozinameran. The favorable clinical outcome of all observed cases confirms that protective effects of boosters in reducing the risk of severe COVID-19 outweigh the potential risk of HZ occurrence.

Impact of SARS-CoV-2 vaccines and recent chemotherapy on COVID-19 morbidity and mortality in patients with soft tissue sarcoma: an analysis from the OnCovid registry

Background

To date, limited evidence exists on the impact of COVID-19 in patients with soft tissue sarcoma (STS), nor about the impact of SARS-CoV-2 vaccines and recent chemotherapy on COVID-19 morbidity and mortality in this specific population.

Methods

We described COVID-19 morbidity and mortality among patients with STS across 'Omicron' (15 December 2021-31 January 2022), 'Pre-vaccination' (27 February 2020-30 November 2020), and 'Alpha-Delta' phase (01 December 2020-14 December 2021) using OnCovid registry participants (NCT04393974). Case fatality rate at 28 days (CFR28) and COVID-19 severity were also described according to the SARS-CoV-2 vaccination status, while the impact of the receipt of cytotoxic chemotherapy within 4 weeks prior to COVID-19 on clinical outcomes was assessed with Inverse Probability of Treatment Weighting (IPTW) models adjusted for possible confounders.

Results

Out of 3820 patients, 97 patients with STS were included. The median age at COVID-19 diagnosis was 56 years (range: 18-92), with 65 patients (67%) aged < 65 years and most patients had a low comorbidity burden (65, 67.0%). The most frequent primary tumor sites were the abdomen (56.7%) and the gynecological tract (12.4%). In total, 36 (37.1%) patients were on cytotoxic chemotherapy within 4 weeks prior to COVID-19. The overall CFR28 was 25.8%, with 38% oxygen therapy requirement, 34% rate of complications, and 32.3% of hospitalizations due to COVID-19. CFR28 (29.5%, 21.4%, and 12.5%) and all indicators of COVID-19 severity demonstrated a trend toward a numerical improvement across the pandemic phases. Similarly, vaccinated patients demonstrated numerically improved CFR28 (16.7% versus 27.7%) and COVID-19 morbidity compared with unvaccinated patients. Patients who were on chemotherapy experienced comparable CFR28 (19.4% versus 26.0%, p = 0.4803), hospitalizations (50.0% versus 44.4%, p = 0.6883), complication rates (30.6% versus 34.0%, p = 0.7381), and oxygen therapy requirement (28.1% versus 40.0%, p = 0.2755) compared to those who were not on anticancer therapy at COVID-19, findings further confirmed by the IPTW-fitted multivariable analysis.

Conclusion

In this study, we demonstrate an improvement in COVID-19 outcomes in patients with STS over time. Recent exposure to chemotherapy does not impact COVID-19 morbidity and mortality and SARS-CoV-2 vaccination confers protection against adverse outcomes from COVID-19 in this patient population.

mRNA vaccines against SARS-CoV-2 induce divergent antigen-specific T-cell responses in patients with lung cancer

BACKGROUND

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Omicron variant is highly transmissible and evades pre-established immunity. Messenger RNA (mRNA) vaccination against ancestral strain spike protein can induce intact T-cell immunity against the Omicron variant, but efficacy of booster vaccination in patients with late-stage lung cancer on immune-modulating agents including anti-programmed cell death protein 1(PD-1)/programmed death-ligand 1 (PD-L1) has not yet been elucidated.

METHODS

We assessed T-cell responses using a modified activation-induced marker assay, coupled with high-dimension flow cytometry analyses. Peripheral blood mononuclear cells (PBMCs) were stimulated with various viral peptides and antigen-specific T-cell responses were evaluated using flow cytometry.

RESULTS

Booster vaccines induced CD8+ T-cell response against the ancestral SARS-CoV-2 strain and Omicron variant in both non-cancer subjects and patients with lung cancer, but only a marginal induction was detected for CD4+ T cells. Importantly, antigen-specific T cells from patients with lung cancer showed distinct subpopulation dynamics with varying degrees of differentiation compared with non-cancer subjects, with evidence of dysfunction. Notably, female-biased T-cell responses were observed.

CONCLUSION

We conclude that patients with lung cancer on immunotherapy show a substantial qualitative deviation from non-cancer subjects in their T-cell response to mRNA vaccines, highlighting the need for heightened protective measures for patients with cancer to minimize the risk of breakthrough infection with the Omicron and other future variants.

Neutralizing Antibody Response following a Third Dose of the mRNA-1273 Vaccine among Cancer Patients

Cancer patients are at an increased risk of morbidity and mortality from SARS-CoV-2 infection and have a decreased immune response to vaccination. We conducted a study measuring both the neutralizing and total antibodies in cancer patients following a third dose of the mRNA-1273 COVID-19 vaccine. Immune responses were measured with an enzyme-linked immunosorbent assay (ELISA) and neutralization assays. Kruskal-Wallis tests were used to evaluate the association between patient characteristics and neutralization geometric mean titers (GMTs), and paired t-tests were used to compare the GMTs between different timepoints. Spearman correlation coefficients were calculated to determine the correlation between total antibody and neutralization GMTs. Among 238 adults diagnosed with cancer, a third dose of mRNA-1273 resulted in a 37-fold increase in neutralization GMT 28 days post-vaccination and maintained a 14.6-fold increase at 6 months. Patients with solid tumors or lymphoid cancer had the highest and lowest neutralization GMTs, respectively, at both 28 days and 6 months post-dose 3. While total antibody GMTs in lymphoid patients continued to increase, other cancer types showed decreases in titers between 28 days and 6 months post-dose 3. A strong correlation (p < 0.001) was found between total antibody and neutralization GMTs. The third dose of mRNA-1273 was able to elicit a robust neutralizing antibody response in cancer patients, which remained for 6 months after administration. Lymphoid cancer patients can benefit most from this third dose, as it was shown to continue to increase total antibody GMTs 6 months after vaccination.

Immune responses and clinical outcomes following the third dose of SARS-CoV-2 mRNA-BNT162b2 vaccine in advanced breast cancer patients receiving targeted therapies: a prospective study

Purpose

Metastatic breast cancer patients are the most prevalent oncology population with advanced disease facing COVID-19 pandemic. Immune responses after mRNA-based vaccination during treatment with CDK4/6 inhibitors or HER2-directed agents remain unclear. We conducted a prospective analysis to elucidate changes in antibody titers and lymphocyte counts following full course of mRNA-BNT162b2 (tozinameran) vaccination in recipients undergoing these targeted therapies.

Methods

Patients who had received a booster dosing and had been treated for at least 6 months were eligible. Antibody titers against SARS-CoV-2 spike protein were measured at four subsequent time points. Immunophenotyping of circulating lymphocytes was performed before the third dose of tozinameran and four weeks later to quantify the absolute counts of CD3+CD4+ T-helper cells, CD3+CD8+ T-cytotoxic cells, CD19+ B cells, and CD56+CD16+ NK cells. We also assessed the incidence of breakthrough infections and investigated whether immune changes affect time-to-treatment failure (TTF) after booster vaccination.

Results

The current analysis included 69 patients, of whom 38 (55%) and 31 (45%) were being treated with CDK4/6 inhibitors and HER2-targeted therapies, respectively. All participants received a third dose of tozinameran between September 23 and October 7, 2021. Multivariate analysis revealed that CDK4/6 inhibition predicted a significantly impaired humoral response after the booster dose. This detrimental effect was also evident for T-helper cell counts before the third immunization, but it disappeared in the subsequent evaluation. After a median follow-up of 22.3 months, we observed 19 (26%) cases of COVID-19 outbreaks, all experiencing favorable clinical outcomes. Univariate analysis showed a significant association between the onset of SARS-CoV-2 infections and the use of CDK4/6 inhibitors, as well as with an impaired antibody and T-helper cell response. Only the last two covariates remained independent predictors after multivariate testing. Dynamic variations in antibody titers and T-helper cell counts did not affect TTF in multivariate regression analysis.

Conclusions

Our results confirm that the immune response to tozinameran is impaired by CDK4/6 inhibitors, increasing the odds of breakthrough infections despite the third vaccine dose. Current evidence recommends maintaining efforts to provide booster immunizations to the most vulnerable cancer patients, including those with advanced breast cancer undergoing CDK4/6 inhibition.

Omicron related COVID-19 prevention and treatment measures for patients with hematological malignancy and strategies for modifying hematologic treatment regimes

The Omicron variant of SARS-CoV-2 has rapidly become the dominant strain worldwide due to its high transmissibility, although it appears to be less pathogenic than previous strains. However, individuals with hematological malignancy (HM) and COVID-19 remain susceptible to severe infection and mortality, especially those with chronic lymphocytic leukemia (CLL) and those undergoing chimeric antigen receptor T-cell (CAR-T) treatment. Hematologists should thoroughly assess the severity of the patient's hematological disease and the potential risk of SARS-CoV-2 infection before initiating chemotherapy or immunosuppressive treatment. Vaccination and booster doses are strongly recommended and patients with a poor vaccine response may benefit from long-acting COVID-19 neutralizing monoclonal antibodies (such as Evusheld). Early use of small molecule antiviral drugs is recommended for managing mild COVID-19 in HM patients and those with severe immunodeficiency may benefit from SARS-CoV-2 neutralizing monoclonal antibody therapy and high-titer COVID-19 convalescent plasma (CCP). For moderate to severe cases, low-dose glucocorticoids in combination with early antiviral treatment can be administered, with cytokine receptor antagonists or JAK inhibitors added if the condition persists or worsens. In the treatment of hematological malignancies, delaying chemotherapy is preferable for CLL, acute leukemia (AL), and low-risk myelodysplastic syndrome (MDS), but if the disease progresses, appropriate adjustments in dosage and frequency of treatment are required, with the avoidance of anti-CD20 monoclonal antibody, CAR-T and hematopoietic stem cell transplantation (HSCT). Patients with chronic myelocytic leukemia (CML) and myeloproliferative neoplasms (MPNs) can continue current treatment. What's more, non-drug protective measures, the development of new vaccines and antiviral drugs, and monitoring of mutations in immunocompromised populations are particularly important.

Approaches to evaluate the specific immune responses to SARS-CoV-2

The SARS-CoV-2 pandemic has a huge impact on public health and global economy, meaning an enormous scientific, political, and social challenge. Studying how infection or vaccination triggers both cellular and humoral responses is essential to know the grade and length of protection generated in the population. Nowadays, scientists and authorities around the world are increasingly concerned about the arrival of new variants, which have a greater spread, due to the high mutation rate of this virus. The aim of this review is to summarize the different techniques available for the study of the immune responses after exposure or vaccination against SARS-CoV-2, showing their advantages and limitations, and proposing suitable combinations of different techniques to achieve extensive information in these studies. We wish that the information provided here will helps other scientists in their studies of the immune response against SARS-CoV-2 after vaccination with new vaccine candidates or infection with upcoming variants.

COVID-19 Infection despite Previous Vaccination in Cancer Patients and Healthcare Workers: Results from a French Prospective Multicenter Cohort (PAPESCO-19)

In a multicenter prospective cohort of cancer patients (CP; n = 840) and healthcare workers (HCWs; n = 935) vaccinated against COVID-19, we noticed the following: i/after vaccination, 4.4% of HCWs and 5.8% of CP were infected; ii/no characteristic was associated with post-vaccine COVID-19 infections among HCWs; iii/CP who developed infections were younger, more frequently women (NS), more frequently had gastrointestinal, gynecological, or breast cancer and a localized cancer stage; iv/CP vaccinated while receiving chemotherapy or targeted therapy had (NS) more breakthrough infections after vaccination than those vaccinated after these treatments; the opposite was noted with radiotherapy, immunotherapy, or hormonotherapy; v/most COVID-19 infections occurred either during the Alpha wave (11/41 HCW, 20/49 CP), early after the first vaccination campaign started, or during the Omicron wave (21/41 HCW, 20/49 CP), more than 3 months after the second dose; vi/risk of infection was not associated with values of antibody titers; vii/the outcome of these COVID-19 infections after vaccination was not severe in all cases. To conclude, around 5% of our CPs or HCWs developed a COVID-19 infection despite previous vaccination. The outcome of these infections was not severe.

Humoral Responses Elicited by SARS-CoV-2 mRNA Vaccine in People Living with HIV

While mRNA SARS-CoV-2 vaccination elicits strong humoral responses in the general population, humoral responses in people living with HIV (PLWH) remain to be clarified. Here, we conducted a longitudinal study of vaccine immunogenicity elicited after two and three doses of mRNA SARS-CoV-2 vaccine in PLWH stratified by their CD4 count. We measured the capacity of the antibodies elicited by vaccination to bind the Spike glycoprotein of different variants of concern (VOCs). We also evaluated the Fc-mediated effector functions of these antibodies by measuring their ability to eliminate CEM.NKr cells stably expressing SARS-CoV-2 Spikes. Finally, we measured the relative capacity of the antibodies to neutralize authentic SARS-CoV-2 virus after the third dose of mRNA vaccine. We found that after two doses of SARS-CoV-2 mRNA vaccine, PLWH with a CD4 count < 250/mm3 had lower levels of anti-RBD IgG antibodies compared to PLWH with a CD4 count > 250/mm3 (p < 0.05). A third dose increased these levels and importantly, no major differences were observed in their capacity to mediate Fc-effector functions and neutralize authentic SARS-CoV-2. Overall, our work demonstrates the importance of mRNA vaccine boosting in immuno-compromised individuals presenting low levels of CD4.

Effectiveness and safety of COVID-19 vaccines in patients with oncological diseases: State-of-the-art

Although the coronavirus disease 2019 (COVID-19) pandemic was declared to be no longer “a public health emergency of international concern” with its wide range of clinical manifestations and late complications, severe acute respiratory syndrome coronavirus 2 infection proved to be a serious threat, especially to the elderly and patients with comorbidities. Patients with oncologic diseases are vulnerable to severe infection and death. Indeed, patients with oncohematological diseases have a higher risk of severe COVID-19 and impaired post-vaccination immunity. Unfortunately, cancer patients are usually excluded from vaccine trials and investigations of post-vaccinal immune responses and the effectiveness of the vaccines. We aimed to elucidate to what extent patients with cancer are at increased risk of developing severe COVID-19 and what is their overall case fatality rate. We also present the current concept and evidence on the effectiveness and safety of COVID-19 vaccines, including boosters, in oncology patients. In conclusion, despite the considerably higher mortality in the cancer patient group than the general population, countries with high vaccination rates have demonstrated trends toward improved survival of cancer patients early and late in the pandemic.

Longitudinal data on humoral response and neutralizing antibodies against SARS-CoV-2 Omicron BA.1 and subvariants BA.4/5 and BQ.1.1 after COVID-19 vaccination in cancer patients

PURPOSE

The SARS-CoV-2 Omicron variant of concern (VOC) and subvariants like BQ.1.1 demonstrate immune evasive potential. Little is known about the efficacy of booster vaccinations regarding this VOC and subvariants in cancer patients. This study is among the first to provide data on neutralizing antibodies (nAb) against BQ.1.1.

METHODS

Cancer patients at our center were prospectively enrolled between 01/2021 and 02/2022. Medical data and blood samples were collected at enrollment and before and after every SARS-CoV-2 vaccination, at 3 and 6 months.

RESULTS

We analyzed 408 samples from 148 patients (41% female), mainly with solid tumors (85%) on active therapy (92%; 80% chemotherapy). SARS-CoV-2 IgG and nAb titers decreased over time, however, significantly increased following third vaccination (p < 0.0001). NAb (ND50) against Omicron BA.1 was minimal prior and increased significantly after the third vaccination (p < 0.0001). ND50 titers against BQ.1.1 after the third vaccination were significantly lower than against BA.1 and BA.4/5 (p < 0.0001) and undetectable in half of the patients (48%). Factors associated with impaired immune response were hematologic malignancies, B cell depleting therapy and higher age. Choice of vaccine, sex and treatment with chemo-/immunotherapy did not influence antibody response. Patients with breakthrough infections had significantly lower nAb titers after both 6 months (p < 0.001) and the third vaccination (p = 0.018).

CONCLUSION

We present the first data on nAb against BQ.1.1 following the third vaccination in cancer patients. Our results highlight the threat that new emerging SARS-CoV-2 variants pose to cancer patients and support efforts to apply repeated vaccines. Since a considerable number of patients did not display an adequate immune response, continuing to exhibit caution remains reasonable.

SARS-CoV-2 Infection, Vaccination and Risk of Death in People with An Oncological Disease in Northeast Italy

People with a history of cancer have a higher risk of death when infected with SARS-CoV-2. COVID-19 vaccines in cancer patients proved safe and effective, even if efficacy may be lower than in the general population. In this population-based study, we compare the risk of dying of cancer patients diagnosed with COVID-19 in 2021, vaccinated or non-vaccinated against SARS-CoV-2 and residing in Friuli Venezia Giulia or in the province of Reggio Emilia. An amount of 800 deaths occurred among 6583 patients; the risk of death was more than three times higher among unvaccinated compared to vaccinated ones [HR 3.4; 95% CI 2.9-4.1]. The excess risk of death was stronger in those aged 70-79 years [HR 4.6; 95% CI 3.2-6.8], in patients with diagnosis made <1 year [HR 8.5; 95% CI 7.3-10.5] and in all cancer sites, including hematological malignancies. The study results indicate that vaccination against SARS-CoV-2 infection is a necessary tool to be included in the complex of oncological therapies aimed at reducing the risk of death.

COVID-19 Vaccination in Patients With Cancer and Patients Receiving HSCT or CAR-T Therapy: Immune Response, Real-World Effectiveness, and Implications for the Future

Patients with cancer demonstrate an increased vulnerability for infection and severe disease by SARS-CoV-2, the causative agent of COVID-19. Risk factors for severe COVID-19 include comorbidities, uncontrolled disease, and current line of treatment. Although COVID-19 vaccines have afforded some level of protection against infection and severe disease among patients with solid tumors and hematologic malignancies, decreased immunogenicity and real-world effectiveness have been observed among this population compared with healthy individuals. Characterizing and understanding the immune response to increasing doses or differing schedules of COVID-19 vaccines among patients with cancer is important to inform clinical and public health practices. In this article, we review SARS-CoV-2 susceptibility and immune responses to COVID-19 vaccination in patients with solid tumors, hematologic malignancies, and those receiving hematopoietic stem cell transplant or chimeric-antigen receptor T-cell therapy.

Fourth mRNA COVID-19 vaccination in immunocompromised patients with haematological malignancies (COBRA KAI): a cohort study

Background

Patients with haematological malignancies have impaired antibody responses to SARS-CoV-2 vaccination. We aimed to investigate whether a fourth mRNA COVID-19 vaccination improved antibody quantity and quality.

Methods

In this cohort study, conducted at 5 sites in the Netherlands, we compared antibody concentrations 28 days after 4 mRNA vaccinations (3-dose primary series plus 1 booster vaccination) in SARS-CoV-2 naive, immunocompromised patients with haematological malignancies to those obtained by age-matched, healthy individuals who had received the standard primary 2-dose mRNA vaccination schedule followed by a first booster mRNA vaccination. Prior to and 4 weeks after each vaccination, peripheral blood samples and data on demographic parameters and medical history were collected. Concentrations of antibodies that bind spike 1 (S1) and nucleocapsid (N) protein of SARS-CoV-2 were quantified in binding antibody units (BAU) per mL according to the WHO International Standard for COVID-19 serological tests. Seroconversion was defined as an S1 IgG concentration >10 BAU/mL and a previous SARS-CoV-2 infection as N IgG >14.3 BAU/mL. Antibody neutralising activity was tested using lentiviral-based pseudoviruses expressing spike protein of SARS-CoV-2 wild-type (D614G), Omicron BA.1, and Omicron BA.4/5 variants. This study is registered with EudraCT, number 2021-001072-41.

Findings

Between March 24, 2021 and May 4, 2021, 723 patients with haematological diseases were enrolled, of which 414 fulfilled the inclusion criteria for the current analysis. Although S1 IgG concentrations in patients significantly improved after the fourth dose, they remained significantly lower compared to those obtained by 58 age-matched healthy individuals after their first booster (third) vaccination. The rise in neutralising antibody concentration was most prominent in patients with a recovering B cell compartment, although potent responses were also observed in patients with persistent immunodeficiencies. 19% of patients never seroconverted, despite 4 vaccinations. Patients who received their first 2 vaccinations when they were B cell depleted and the third and fourth vaccination during B cell recovery demonstrated similar antibody induction dynamics as patients with normal B cell numbers during the first 2 vaccinations. However, the neutralising capacity of these antibodies was significantly better than that of patients with normal B cell numbers after two vaccinations.

Interpretation

A fourth mRNA COVID-19 vaccination improved S1 IgG concentrations in the majority of patients with a haematological malignancy. Vaccination during B cell depletion may pave the way for better quality of antibody responses after B cell reconstitution.

Funding

The Netherlands Organisation for Health Research and Development and Amsterdam UMC.

Polyfunctional antibodies: a path towards precision vaccines for vulnerable populations

Vaccine efficacy determined within the controlled environment of a clinical trial is usually substantially greater than real-world vaccine effectiveness. Typically, this results from reduced protection of immunologically vulnerable populations, such as children, elderly individuals and people with chronic comorbidities. Consequently, these high-risk groups are frequently recommended tailored immunisation schedules to boost responses. In addition, diverse groups of healthy adults may also be variably protected by the same vaccine regimen. Current population-based vaccination strategies that consider basic clinical parameters offer a glimpse into what may be achievable if more nuanced aspects of the immune response are considered in vaccine design. To date, vaccine development has been largely empirical. However, next-generation approaches require more rational strategies. We foresee a generation of precision vaccines that consider the mechanistic basis of vaccine response variations associated with both immunogenetic and baseline health differences. Recent efforts have highlighted the importance of balanced and diverse extra-neutralising antibody functions for vaccine-induced protection. However, in immunologically vulnerable populations, significant modulation of polyfunctional antibody responses that mediate both neutralisation and effector functions has been observed. Here, we review the current understanding of key genetic and inflammatory modulators of antibody polyfunctionality that affect vaccination outcomes and consider how this knowledge may be harnessed to tailor vaccine design for improved public health.

The Importance of Measuring SARS-CoV-2-Specific T-Cell Responses in an Ongoing Pandemic

Neutralizing antibodies are considered a correlate of protection against SARS-CoV-2 infection and severe COVID-19, although they are not the only contributing factor to immunity: T-cell responses are considered important in protecting against severe COVID-19 and contributing to the success of vaccination effort. T-cell responses after vaccination largely mirror those of natural infection in magnitude and functional capacity, but not in breadth, as T-cells induced by vaccination exclusively target the surface spike glycoprotein. T-cell responses offer a long-lived line of defense and, unlike humoral responses, largely retain reactivity against the SARS-CoV-2 variants. Given the increasingly recognized role of T-cell responses in protection against severe COVID-19, the circulation of SARS-CoV-2 variants, and the potential implementation of novel vaccines, it becomes imperative to continuously monitor T-cell responses. In addition to "classical" T-cell assays requiring the isolation of peripheral blood mononuclear cells, simple whole-blood-based interferon-γ release assays have a potential role in routine T-cell response monitoring. These assays could be particularly useful for immunocompromised people and other clinically vulnerable populations, where interactions between cellular and humoral immunity are complex. As we continue to live alongside COVID-19, the importance of considering immunity as a whole, incorporating both humoral and cellular responses, is crucial.

The presence of senescent peripheral T-cells is negatively correlated to COVID-19 vaccine-induced immunity in cancer patients under 70 years of age

Purpose

Cancer patients are at risk of severe COVID-19 infection, and vaccination is recommended. Nevertheless, we observe a failure of COVID-19 vaccines in this vulnerable population. We hypothesize that senescent peripheral T-cells alter COVID-19 vaccine-induced immunity.

Methods

We performed a monocentric prospective study and enrolled cancer patients and healthy donors before the COVID-19 vaccination. The primary objective was to assess the association of peripheral senescent T-cells (CD28^-CD57⁺KLRG1⁺) with COVID-19 vaccine-induced immunity.

Results

Eighty cancer patients have been included, with serological and specific T-cell responses evaluated before and at 3 months post-vaccination. Age ≥ 70 years was the principal clinical factor negatively influencing the serological (p=0.035) and specific SARS-CoV-2 T-cell responses (p=0.047). The presence of senescent T-cells was correlated to lower serological (p=0.049) and specific T-cell responses (p=0.009). Our results sustained the definition of a specific cut-off for senescence immune phenotype (SIP) (≥ 5% of CD4 and ≥ 39.5% of CD8 T-cells), which was correlated to a lower serological response induced by COVID-19 vaccination for CD4 and CD8 SIP^high (p=0.039 and p=0.049 respectively). While CD4 SIP level had no impact on COVID-19 vaccine efficacy in elderly patients, our results unraveled a possible predictive role for CD4 SIP^high T-cell levels in younger cancer patients.

Conclusions

Elderly cancer patients have a poor serological response to vaccination; specific strategies are needed in this population. Also, the presence of a CD4 SIP^high affects the serological response in younger patients and seems to be a potential biomarker of no vaccinal response.

The National COVID Cancer Antibody Survey: a hyper-accelerated study proof of principle for cancer research

The COVID-19 pandemic has led to a range of novel and adaptive research designs. In this perspective, we use our experience coordinating the National COVID Cancer Antibody Survey to demonstrate how a balance between speed and integrity can be achieved within a hyper-accelerated study design. Using the COVID-19 pandemic as an example, we show this approach is necessary in the face of uncertain and evolving situations wherein reliable information is needed in a timely fashion to guide policy. We identify streamlined participant involvement, healthcare systems integration, data architecture and real-world real-time analytics as key areas that differentiate this design from traditional cancer trials, and enable rapid results. Caution needs to be taken to avoid the exclusion of patient subgroups without digital access or literacy. We summarise the merits and defining features of hyper-accelerated cancer studies.

Integration of Cellular and Humoral Immune Responses as an Immunomonitoring Tool for SARS-CoV-2 Vaccination in Healthy and Fragile Subjects

Cellular and humoral immunity are both required for SARS-CoV-2 infection recovery and vaccine efficacy. The factors affecting mRNA vaccination-induced immune responses, in healthy and fragile subjects, are still under investigation. Thus, we monitored the vaccine-induced cellular and humoral immunity in healthy subjects and cancer patients after vaccination to define whether a different antibody titer reflected similar rates of cellular immune responses and if cancer has an impact on vaccination efficacy. We found that higher titers of antibodies were associated with a higher probability of positive cellular immunity and that this greater immune response was correlated with an increased number of vaccination side effects. Moreover, active T-cell immunity after vaccination was associated with reduced antibody decay. The vaccine-induced cellular immunity appeared more likely in healthy subjects rather than in cancer patients. Lastly, after boosting, we observed a cellular immune conversion in 20% of subjects, and a strong correlation between pre- and post-boosting IFN-γ levels, while antibody levels did not display a similar association. Finally, our data suggested that integrating humoral and cellular immune responses could allow the identification of SARS-CoV-2 vaccine responders and that T-cell responses seem more stable over time compared to antibodies, especially in cancer patients.

A Three-Dose mRNA COVID-19 Vaccine Regime Produces Both Suitable Immunogenicity and Satisfactory Efficacy in Patients with Solid Cancers

BACKGROUND

The recommended booster third dose of vaccination against COVID-19 in cancer patients seems reasonable to protect them against a severe disease course. A prospective study was designed to assess the immunogenicity, efficacy, and safety of COVID-19 vaccination in this cohort.

METHODS

Patients with solid malignancies on active treatment were followed up after the primary course and booster third dose of vaccination to assess their anti-SARS-CoV-2 S1 IgG levels, efficacy in the case of SARS-CoV-2 infection, and safety.

RESULTS

Out of 125 patients receiving the primary course of vaccination, 66 patients received a booster third dose of mRNA vaccine, with a 20-fold increase in median anti-SARS-CoV-2 S1 IgG levels compared to Ab levels six months post-primary course of vaccination (p < 0.0001). After the booster third dose, anti-SARS-CoV-2 S1 IgG levels were comparable to healthy controls (p = 0.113). There was a decline in Ab levels 3 (p = 0.0003) and 6 months (p < 0.0001) post-third booster dose. No patients had either a severe disease course or a lethal outcome in the case of SARS-CoV-2 infection after the third booster dose.

CONCLUSION

The third booster vaccination dose against COVID-19 in solid cancer patients triggers substantial immunogenicity and is safe and effective for preventing a severe COVID-19 disease course.

Clinical efficacy of the first two doses of anti-SARS-CoV-2 mRNA vaccines in solid cancer patients

INTRODUCTION

Cancer patients are frail individuals, thus the prevention of SARS-CoV-2 infection is essential. To date, vaccination is the most effective tool to prevent COVID-19. In a previous study, we evaluated the immunogenicity of two doses of mRNA-based vaccines (BNT162b2 or mRNA-1273) in solid cancer patients. We found that seroconversion rate in cancer patients without a previous exposure to SARS-CoV-2 was lower than in healthy controls (66.7% vs. 95%, p = 0.0020). The present study aimed to evaluate the clinical efficacy of the vaccination in the same population.

METHODS

This is a single-institution, prospective observational study. Data were collected through a predefined questionnaire through phone call in the period between the second and third vaccine dose. The primary objective was to describe the clinical efficacy of the vaccination, defined as the percentage of vaccinated subjects who did not develop symptomatic COVID-19 within 6 months after the second dose. The secondary objective was to describe the clinical features of patients who developed COVID-19.

RESULTS

From January to June 2021, 195 cancer patients were enrolled. Considering that 7 (3.59%) patients tested positive for SARS-CoV-2 and 5 developed symptomatic disease, the clinical efficacy of the vaccination was 97.4%. COVID-19 disease in most patients was mild and managed at home; only one hospitalization was recorded and no patient required hospitalization in the intensive care unit.

DISCUSSION

Our study suggests that increasing vaccination coverage, including booster doses, could improve the prevention of infection, hospitalization, serious illness, and death in the frail population of cancer patients.

Limited induction of polyfunctional lung-resident memory T cells against SARS-CoV-2 by mRNA vaccination compared to infection

Resident memory T cells (T_RM) present at the respiratory tract may be essential to enhance early SARS-CoV-2 viral clearance, thus limiting viral infection and disease. While long-term antigen-specific T_RM are detectable beyond 11 months in the lung of convalescent COVID-19 patients, it is unknown if mRNA vaccination encoding for the SARS-CoV-2 S-protein can induce this frontline protection. Here we show that the frequency of CD4⁺ T cells secreting IFNγ in response to S-peptides is variable but overall similar in the lung of mRNA-vaccinated patients compared to convalescent-infected patients. However, in vaccinated patients, lung responses present less frequently a T_RM phenotype compared to convalescent infected individuals and polyfunctional CD107a⁺ IFNγ⁺ T_RM are virtually absent in vaccinated patients. These data indicate that mRNA vaccination induces specific T cell responses to SARS-CoV-2 in the lung parenchyma, although to a limited extend. It remains to be determined whether these vaccine-induced responses contribute to overall COVID-19 control.

Vaccination for seasonal flu, pneumococcal infection, and SARS-CoV-2 in patients with solid tumors: recommendations of the Associazione Italiana di Oncologia Medica (AIOM)

Patients with cancer have a well-known and higher risk of vaccine-preventable diseases (VPDs). VPDs may cause severe complications in this setting due to the immune system impairment, malnutrition and oncological treatments. Despite this evidence, vaccination rates are inadequate. The Italian Association of Medical Oncology (AIOM) has been involved in vaccination awareness since 2014. Based on a careful review of the available data about the immunogenicity, effectiveness and safety of flu, pneumococcal and anti-SARS-CoV-2 vaccines, we report the recommendations of the Associazione Italiana di Oncologia Medica about these vaccinations in adult patients with solid tumors. AIOM recommends comprehensive education on the issue of VPDs. We believe that a multidisciplinary care model may improve the vaccination coverage in immunocompromised patients. Continued surveillance, implementation of preventive practices and future well-designed immunological prospective studies are essential for a better management of our patients with cancer.

Immune Response to SARS-CoV-2 Vaccination in Cancer Patients: A Prospective Study

Introduction Cancer patients on active treatment are at increased risk of developing coronavirus disease 2019 (COVID-19), making effective immunization of the utmost importance. However, the effectiveness of vaccination in this population is still unclear. This study aims to evaluate the response against COVID-19 in a cohort of patients with active cancer under immunosuppressive therapy. Methods This was a prospective, cross-sectional, single-center study that included patients with cancer under immunosuppressive therapy vaccinated against COVID-19 between April and September 2021. Exclusion criteria were: previous known severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, single-dose vaccine or incomplete vaccination scheme. Immunoglobulin G (IgG) anti-SARS-CoV-2 antibody levels were assessed using 35.2 binding antibody units (BAU)/mL as the positive cut-off. Assessments were performed 14-31 days after the first and second dose and three months after the second dose. Results A total of 103 patients were included. The median age was 60 years. Most patients were being treated for gastrointestinal cancer (n=38, 36.9%), breast cancer (n=33, 32%) or head and neck cancer (n=18, 17.5%). At evaluation, 72 patients (69.9%) were being treated with palliative intent. The majority were being treated with chemotherapy (CT) alone (57.3%). At the first assessment, levels of circulating SARS-CoV-2 IgG consistent with seroconversion were present in 49 patients (47.6%). At the time of the second assessment, 91% (n=100) achieved seroconversion. Three months after the second dose, 83% (n=70) maintained levels of circulating SARS-CoV-2 IgG consistent with seroconversion. In this study, no SARS-CoV-2 infection was reported in the study population. Conclusions Our findings suggest that this group of patients had a satisfactory COVID-19 immunization response. Although promising, this study should be replicated on a wider scale in order to validate these findings.

O-Linked Sialoglycans Modulate the Proteolysis of SARS-CoV-2 Spike and Likely Contribute to the Mutational Trajectory in Variants of Concern

The emergence of a polybasic cleavage motif for the protease furin in SARS-CoV-2 spike has been established as a major factor for human viral transmission. The region N-terminal to that motif is extensively mutated in variants of concern (VOCs). Besides furin, spikes from these variants appear to rely on other proteases for maturation, including TMPRSS2. Glycans near the cleavage site have raised questions about proteolytic processing and the consequences of variant-borne mutations. Here, we identify that sialic acid-containing O-linked glycans on Thr678 of SARS-CoV-2 spike influence furin and TMPRSS2 cleavage and posit O-linked glycosylation as a likely driving force for the emergence of VOC mutations. We provide direct evidence that the glycosyltransferase GalNAc-T1 primes glycosylation at Thr678 in the living cell, an event that is suppressed by mutations in the VOCs Alpha, Delta, and Omicron. We found that the sole incorporation of N-acetylgalactosamine did not impact furin activity in synthetic O-glycopeptides, but the presence of sialic acid reduced the furin rate by up to 65%. Similarly, O-glycosylation with a sialylated trisaccharide had a negative impact on TMPRSS2 cleavage. With a chemistry-centered approach, we substantiate O-glycosylation as a major determinant of spike maturation and propose disruption of O-glycosylation as a substantial driving force for VOC evolution.

Selective suppression of de novo SARS-CoV-2 vaccine antibody responses in patients with cancer on B cell-targeted therapy

We assessed vaccine-induced antibody responses to the SARS-CoV-2 ancestral virus and Omicron variant before and after booster immunization in 57 patients with B cell malignancies. Over one-third of vaccinated patients at the pre-booster time point were seronegative, and these patients were predominantly on active cancer therapies such as anti-CD20 monoclonal antibody. While booster immunization was able to induce detectable antibodies in a small fraction of seronegative patients, the overall booster benefit was disproportionately evident in patients already seropositive and not receiving active therapy. While ancestral virus- and Omicron variant-reactive antibody levels among individual patients were largely concordant, neutralizing antibodies against Omicron tended to be reduced. Interestingly, in all patients, including those unable to generate detectable antibodies against SARS-CoV-2 spike, we observed comparable levels of EBV- and influenza-reactive antibodies, demonstrating that B cell-targeting therapies primarily impair de novo but not preexisting antibody levels. These findings support rationale for vaccination before cancer treatment.

Adverse Hematological Effects of COVID-19 Vaccination and Pathomechanisms of Low Acquired Immunity in Patients with Hematological Malignancies

The SARS-CoV-2 virus and the COVID-19 pandemic have spread across the world and severely impacted patients living with hematological conditions. Immunocompromised patients experience rapidly progressing symptoms following COVID-19 infection and are at high risk of death. In efforts to protect the vulnerable population, vaccination efforts have increased exponentially in the past 2 years. Although COVID-19 vaccination is safe and effective, mild to moderate side effects such as headache, fatigue, and soreness at the injection site have been reported. In addition, there are reports of rare side effects, including anaphylaxis, thrombosis with thrombocytopenia syndrome, Guillain-Barré Syndrome, myocarditis, and pericarditis after vaccination. Further, hematological abnormalities and a very low and transient response in patients with hematological conditions after vaccination raise concerns. The objective of this review is to first briefly discuss the hematological adverse effects associated with COVID-19 infection in general populations followed by critically analyzing the side effects and pathomechanisms of COVID-19 vaccination in immunocompromised patients with hematological and solid malignancies. We reviewed the published literature, with a focus on hematological abnormalities associated with COVID-19 infection followed by the hematological side effects of COVID-19 vaccination, and the mechanisms by which complications can occur. We extend this discussion to include the viability of vaccination efforts within immune-compromised patients. The primary aim is to provide clinicians with critical hematologic information on COVID-19 vaccination so that they can make informed decisions on how to protect their at-risk patients. The secondary goal is to clarify the adverse hematological effects associated with infection and vaccination within the general population to support continued vaccination within this group. There is a clear need to protect patients with hematological conditions from infection and modulate vaccine programs and procedures for these patients.

Determinants of humoral immune response to SARS-CoV-2 vaccines in solid cancer patients: A systematic review and meta-analysis

IMPORTANCE

Solid cancer patients following SARS-CoV-2 vaccination are likely to have a lower seroconversion rate than healthy adults. Seroconversion between those with and without cancer is likely to vary moderately or to be restricted to specific subgroups. Therefore, we sought to conduct a systematic review and meta-analysis to identify risk factors for diminished humoral immune responses in solid cancer patients.

METHODS

MEDLINE, Embase, Web of Science, Cochrane Library, and ClinicalTrials.gov were used to search literature through May 1, 2022. Prospective or retrospective studies comparing responders with non-responders against SARS-CoV-2 spike (S) protein receptor-binding domain (RBD) following COVID-19 vaccination were included. Pooled Odds Ratios (pORs) with 95% CIs for binary variables and differences in means (with SDs) for continuous variables were calculated to determine the pooled effect estimates of risk factors for poor antibody response.

RESULTS

Fifteen studies enrolling 3593 patients were included in the analysis. Seroconversion was seen in 84% of the pooled study population. Male gender, age >65 years, and recent chemotherapy were all factors in a poor immune response. Patients under follow-up, those who received immunotherapy or targeted therapy, were more likely to be seropositive. Cancer subtypes, vaccine types, and timing of antibody testing from the 2nd dose of vaccine did not correlate with seroconversion.

CONCLUSION

Cytotoxic therapy for solid cancer may portend poor immune response following 2 doses of COVID-19 vaccines suggesting a need for booster doses in these patients. Immunotherapy and targeted therapy are likely to be associated with seropositive status, and thus can be considered as an alternative to cytotoxic agents in cases where both therapies are equally efficacious.

The implication of anti-PD-1 therapy in cancer patients for the vaccination against viral and other infectious diseases

The phenomenon of 'T cell exhaustion', a state of T cell dysfunction observed during chronic infections and cancers, has been a major obstacle in mounting appropriate immune responses against infectious agents or tumor antigens. The exhausted T cells are characterized by poor effector functions mainly due to the overexpression of inhibitory receptors such as programmed cell death protein 1 (PD-1), cytotoxic T-lymphocyte-associated protein 4 (CTLA-4), T cell immunoglobulin and mucin-domain containing 3 (TIM3), lymphocyte activation gene 3 (LAG3), and T cell immunoreceptor with immunoglobulin and immunoreceptor tyrosine-based inhibitory motif (ITIM) domain (TIGIT), commonly referred to as immune checkpoint (ICP) molecules. ICP blockade, especially of PD-1 that can potentially reverse T cell exhaustion and thereby re-stimulate the impaired immune system, is widely used in clinics as a promising therapeutic strategy for various cancers and is more recently being investigated in infectious diseases as well. In fact, cancer patients represent a population of immunocompromised individuals who are more susceptible to infections and associated complications, and thus the need for protective vaccinations against these diseases is of prime importance in this category. When it comes to vaccinating anti-PD-1-treated cancer patients against infectious diseases including COVID-19 and influenza, a special focus should be brought on the revived immune cells, which could be dynamically affected by the antigenic stimulation. However, since cancer patients are not generally included in clinical trials for designing vaccines against infectious diseases, the possible interaction between vaccine immune responses and ICP therapy is largely unexplored. Mechanistically, the reversal of T cell exhaustion by ICP in an otherwise immunocompromised population could be beneficial for the vaccine's efficacy, helping the immune system to mount a robust immune response. Nevertheless, patients with cancer undergoing anti-PD-1 blockade are known to experience immune-related adverse effects (irAEs). The risk of increasing the irAEs due to the overstimulation of the immune system during vaccination is a major concern. Therefore, while routine vaccination is indispensable for the protection of cancer patients, the impact of PD-1 blockade on vaccine responses against infectious agents requires careful consideration to avoid undesirable adverse effects that could impair the efficacy of anti-cancer treatment.

Immunogenicity of COVID-19 mRNA vaccines in patients with acute myeloid leukemia and myelodysplastic syndrome

Immunocompromised patients are susceptible to complications from severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). The mRNA vaccines BNT162b2 and mRNA-1273 are effective in immunocompetent adults, but have diminished activity in immunocompromised patients. We measured anti-spike SARS-CoV-2 antibody (anti-S) response, avidity, and surrogate neutralizing antibody activity in COVID-19 vaccinated patients with acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS). Anti-S was induced in 89% of AML and 88% of MDS patients, but median levels were significantly lower than in healthy controls. SARS-CoV-2 antibody avidity and neutralizing activity from AML patients were significantly lower than controls. Antibody avidity was significantly greater in patients after mRNA-1273 versus BNT162b2; there were trends toward higher anti-S levels and greater neutralizing antibody activity after mRNA-1273 vaccination. Patients with AML and MDS are likely to respond to COVID-19 mRNA vaccination, but differences in anti-S levels, avidity, and neutralizing antibody activity may affect clinical outcomes and require further study.

Repeated SARS-CoV-2 vaccination in cancer patients treated with immune checkpoint inhibitors: induction of high-avidity anti-RBD neutralizing antibodies

BACKGROUND

Cancer patients are more vulnerable to COVID-19 and are thus given high priority in vaccination campaigns. In solid cancer patients treated with checkpoint inhibitors, we evaluated the amount of anti-RBD and neutralizing antibodies and antibody avidity after two or three doses of the vaccine.

METHODS

Thirty-eight solid cancer patients, 15 untreated hematological patients and 21 healthy subjects were enrolled in the study. Blood was collected before the first dose (T0), 21 days after the second (T2) and in 18 solid cancer patients also 15 days after the third dose of vaccine (T3). IgG, IgM and IgA anti-RBD antibodies were detected by ELISA. Neutralizing antibodies were measured testing the inhibition of RBD binding to ACE2. Antibody avidity was evaluated in 18 patients by a urea avidity ELISA.

RESULTS

IgG anti-RBD antibodies were produced in 65.8% of the cancer patients at T2, and in 60% of hematological patients at levels lower than healthy controls. IgM and IgA anti-RBD antibodies were also produced in 5.3% and 21% cancer patients, respectively. At T3, a significant increase in anti-RBD IgG levels was observed. Neutralizing antibodies were produced in 68.4% of cancer patients as compared with 93% of untreated hematological patients and 100% of controls, at titers lower than in healthy subjects. At T3, neutralizing antibodies and avidity of IgG anti-RBD increased; 6/18 patients negative at T2 developed neutralizing antibodies at T3.

CONCLUSION

The data indicate that in cancer patients mRNA vaccine induces high avidity anti-RBD antibodies and neutralizing antibodies that increase after the third dose. The process of induction and selection of high-affinity antibodies is apparently unaffected by the treatment with anti-PD-1 or anti-PD-L1 antibodies.

Breakthrough SARS-CoV-2 infections among patients with cancer following two and three doses of COVID-19 mRNA vaccines: a retrospective observational study from the COVID-19 and Cancer Consortium

Background

Breakthrough SARS-CoV-2 infections following vaccination against COVID-19 are of international concern. Patients with cancer have been observed to have worse outcomes associated with COVID-19 during the pandemic. We sought to evaluate the clinical characteristics and outcomes of patients with cancer who developed breakthrough SARS-CoV-2 infections after 2 or 3 doses of mRNA vaccines.

Methods

We evaluated the clinical characteristics of patients with cancer who developed breakthrough infections using data from the multi-institutional COVID-19 and Cancer Consortium (CCC19; NCT04354701). Analysis was restricted to patients with laboratory-confirmed SARS-CoV-2 diagnosed in 2021 or 2022, to allow for a contemporary unvaccinated control population; potential differences were evaluated using a multivariable logistic regression model after inverse probability of treatment weighting to adjust for potential baseline confounding variables. Adjusted odds ratios (aOR) and 95% confidence intervals (CI) are reported. The primary endpoint was 30-day mortality, with key secondary endpoints of hospitalization and ICU and/or mechanical ventilation (ICU/MV).

Findings

The analysis included 2486 patients, of which 564 and 385 had received 2 or 3 doses of an mRNA vaccine prior to infection, respectively. Hematologic malignancies and recent receipt of systemic anti-neoplastic therapy were more frequent among vaccinated patients. Vaccination was associated with improved outcomes: in the primary analysis, 2 doses (aOR: 0.62, 95% CI: 0.44-0.88) and 3 doses (aOR: 0.20, 95% CI: 0.11-0.36) were associated with decreased 30-day mortality. There were similar findings for the key secondary endpoints of ICU/MV (aOR: 0.60, 95% CI: 0.45-0.82 and 0.37, 95% CI: 0.24-0.58) and hospitalization (aOR: 0.60, 95% CI: 0.48-0.75 and 0.35, 95% CI: 0.26-0.46) for 2 and 3 doses, respectively. Importantly, Black patients had higher rates of hospitalization (aOR: 1.47, 95% CI: 1.12-1.92), and Hispanic patients presented with higher rates of ICU/MV (aOR: 1.61, 95% CI: 1.06-2.44).

Interpretation

Vaccination against COVID-19, especially with additional doses, is a fundamental strategy in the prevention of adverse outcomes including death, among patients with cancer.

Funding

This study was partly supported by grants from the National Cancer Institute grant number P30 CA068485 to C-YH, YS, SM, JLW; T32-CA236621 and P30-CA046592 to C.R.F; CTSA 2UL1TR001425-05A1 to TMW-D; ACS/FHI Real-World Data Impact Award, P50 MD017341-01, R21 CA242044-01A1, Susan G. Komen Leadership Grant Hunt to MKA. REDCap is developed and supported by Vanderbilt Institute for Clinical and Translational Research grant support (UL1 TR000445 from NCATS/NIH).

Effectiveness and Safety of COVID-19 Vaccination in Patients with Malignant Disease

A novel virus named SARS-CoV-2 has caused a worldwide pandemic, resulting in a disastrous impact to the public health since 2019. The disease is much more lethal among patients with malignant disease. Vaccination plays an important role in the prevention of infection and subsequent severe COVID-19. However, the efficacy and safety of vaccines for cancer patients needs further investigation. Encouragingly, there have been important findings deduced from research so far. In this review, an overview of the immunogenicity, effectiveness, and safeness of COVID-19 vaccines in patients with cancer to date is to be shown. We also highlight important questions to consider and directions that could be followed in future research.

SARS-CoV-2 evolution among patients with immunosuppression in a nosocomial cluster of a Japanese medical center during the Delta (AY.29 sublineage) surge

Background

Previous studies have shown that patients with immunosuppression tend to have longer-lasting SARS-CoV-2 infections and a number of mutations were observed during the infection period. However, these studies were, in general, conducted longitudinally. Mutation evolution among groups of patients with immunosuppression have not been well studied, especially among Asian populations.

Methods

Our study targeted a nosocomial cluster of SARS-CoV-2 infection in a Japanese medical center during Delta surge (AY.29 sublineage), involving ward nurses and inpatients. Whole-genome sequencing analyses were performed to examine mutation changes. Haplotype and minor variant analyses were furtherly performed to detect the mutations on the viral genomes in detail. In addition, sequences of the first wild-type strain hCoV-19/Wuhan/WIV04/2019 and AY.29 wild-type strain hCoV-19/Japan/TKYK15779/2021 were used as references to assess the phylogenetical development of this cluster.

Results

A total of 6 nurses and 14 inpatients were identified as a nosocomial cluster from September 14 through 28, 2021. All were Delta variant (AY.29 sublineage) positive. 92.9% of infected patients (13 out of 14) were either cancer patients and/or receiving immunosuppressive or steroid treatments. Compared to AY.29 wild type, a total of 12 mutations were found in the 20 cases. Haplotype analysis found one index group of eight cases with F274F (N) mutation and 10 other haplotypes with one to three additional mutations. Furthermore, we found that cases with more than three minor variants were all cancer patients under immunosuppressive treatments. The phylogenetical tree analysis, including 20 nosocomial cluster-associated viral genomes, the first wild-type strain and the AY.29 wild-type strain as references, indicated the mutation development of the AY.29 virus in this cluster.

Conclusion

Our study of a nosocomial SARS-CoV-2 cluster highlights mutation acquisition during transmission. More importantly, it provided new evidence emphasizing the need to further improve infection control measures to prevent nosocomial infection among immunosuppressed patients.

SARS-CoV-2-Specific T Cell Responses in Immunocompromised Individuals with Cancer, HIV or Solid Organ Transplants

Adaptive immune responses play an important role in the clinical course of SARS-CoV-2 infection. While evaluations of the virus-specific defense often focus on the humoral response, cellular immunity is crucial for the successful control of infection, with the early development of cytotoxic T cells being linked to efficient viral clearance. Vaccination against SARS-CoV-2 induces both CD4+ and CD8+ T cell responses and permits protection from severe COVID-19, including infection with the currently circulating variants of concern. Nevertheless, in immunocompromised individuals, first data imply significantly impaired SARS-CoV-2-specific immune responses after both natural infection and vaccination. Hence, these high-risk groups require particular consideration, not only in routine clinical practice, but also in the development of future vaccination strategies. In order to assist physicians in the guidance of immunocompromised patients, concerning the management of infection or the benefit of (booster) vaccinations, this review aims to provide a concise overview of the current knowledge about SARS-CoV-2-specific cellular immune responses in the vulnerable cohorts of cancer patients, people living with HIV (PLWH), and solid organ transplant recipients (SOT). Recent findings regarding the virus-specific cellular immunity in these differently immunocompromised populations might influence clinical decision-making in the future.

Observational Study on Antibody Response to COVID-19 Vaccines in PAtients with Gastro-Entero-PanCreatic Cancers and NeuroendocrIne NeoplAsms on Systemic TreatmEnts (VACCINATE)

The coronavirus disease-19 (COVID-19) pandemic dramatically impacted oncological patients' care. Since the introduction of vaccines and the demonstration of their benefit on frail patients, COVID-19 vaccinations were indicated to also be beneficial to oncological population. However, data about the impact of anticancer-treatments and the timing between vaccinations and systemic therapy delivery were not available. We aimed to evaluate potential factors influencing the outcome of the COVID-19 vaccination in cancer patients. We prospectively collected data of patients undergoing the COVID-19 vaccination with gastro-entero-pancreatic and neuroendocrine neoplasms, treated at our institute, between 03/2021 and 12/2021. We enrolled 46 patients, 63.1% males; at the time of data collection, 86.9% had received two-doses of Pfizer-BioNTech and the rest had received the Moderna vaccine. All patients obtained a subsequent immune-response. Chemotherapy seems to determinate a significantly lower antibody response after vaccination compared to the other anti-cancer agents (p = 0.004). No significant effect on immune-response was reported for both vaccinations performed ≤7 vs. >7 days from the last systemic treatment (p = 0.77) and lymphocytes count (p = 0.11). The findings suggest that the optimal timing for COVID-19 vaccination and lymphocytes count are not the issue, but rather that the quality of the subset of lymphocytes before the vaccination determine the efficacy level of immune-response in this population.

Three doses of BNT162b2 COVID-19 mRNA vaccine establish long-lasting CD8+ T cell immunity in CLL and MDS patients

Patients with hematological malignancies are prioritized for COVID-19 vaccine due to their high risk for severe SARS-CoV-2 infection-related disease and mortality. To understand T cell immunity, its long-term persistence, and its correlation with antibody response, we evaluated the BNT162b2 COVID-19 mRNA vaccine-specific immune response in chronic lymphocytic leukemia (CLL) and myeloid dysplastic syndrome (MDS) patients. Longitudinal analysis of CD8⁺ T cells using DNA-barcoded peptide-MHC multimers covering the full SARS-CoV-2 Spike-protein (415 peptides) showed vaccine-specific T cell activation and persistence of memory T cells up to six months post-vaccination. Surprisingly, a higher frequency of vaccine-induced antigen-specific CD8⁺ T cells was observed in the patient group compared to a healthy donor group. Furthermore, and importantly, immunization with the second booster dose significantly increased the frequency of antigen-specific CD8⁺ T cells as well as the total number of T cell specificities. Altogether 59 BNT162b2 mRNA vaccine-derived immunogenic responses were identified, of which 23 established long-term CD8⁺ T cell memory response with a strong immunodominance for NYNYLYRLF (HLA-A24:02) and YLQPRTFLL (HLA-A02:01) epitopes. In summary, we mapped the vaccine-induced antigen-specific CD8⁺ T cells and showed a booster-specific activation and enrichment of memory T cells that could be important for long-term disease protection in this patient group.

Potent high-avidity neutralizing antibodies and T cell responses after COVID-19 vaccination in individuals with B cell lymphoma and multiple myeloma

Individuals with hematologic malignancies are at increased risk for severe coronavirus disease 2019 (COVID-19), yet profound analyses of COVID-19 vaccine-induced immunity are scarce. Here we present an observational study with expanded methodological analysis of a longitudinal, primarily BNT162b2 mRNA-vaccinated cohort of 60 infection-naive individuals with B cell lymphomas and multiple myeloma. We show that many of these individuals, despite markedly lower anti-spike IgG titers, rapidly develop potent infection neutralization capacities against several severe acute respiratory syndrome coronavirus 2 variants of concern (VoCs). The observed increased neutralization capacity per anti-spike antibody unit was paralleled by an early step increase in antibody avidity between the second and third vaccination. All individuals with hematologic malignancies, including those depleted of B cells and individuals with multiple myeloma, exhibited a robust T cell response to peptides derived from the spike protein of VoCs Delta and Omicron (BA.1). Consistently, breakthrough infections were mainly of mild to moderate severity. We conclude that COVID-19 vaccination can induce broad antiviral immunity including ultrapotent neutralizing antibodies with high avidity in different hematologic malignancies.

Add fuel to the fire: Inflammation and immune response in lung cancer combined with COVID-19

The corona virus disease 2019 (COVID-19) global pandemic has had an unprecedented and persistent impact on oncological practice, especially for patients with lung cancer, who are more vulnerable to the virus than the normal population. Indeed, the onset, progression, and prognosis of the two diseases may in some cases influence each other, and inflammation is an important link between them. The original chronic inflammatory environment of lung cancer patients may increase the risk of infection with COVID-19 and exacerbate secondary damage. Meanwhile, the acute inflammation caused by COVID-19 may induce tumour progression or cause immune activation. In this article, from the perspective of the immune microenvironment, the pathophysiological changes in the lungs and whole body of these special patients will be summarised and analysed to explore the possible immunological storm, immunosuppression, and immune escape phenomenon caused by chronic inflammation complicated by acute inflammation. The effects of COVID-19 on immune cells, inflammatory factors, chemokines, and related target proteins in the immune microenvironment of tumours are also discussed, as well as the potential role of the COVID-19 vaccine and immune checkpoint inhibitors in this setting. Finally, we provide recommendations for the treatment of lung cancer combined with COVID-19 in this special group.

Immunogenicity assessment of elder hepatocellular carcinoma patients after inactivated whole-virion SARS-CoV-2 vaccination

BACKGROUND

Research on immunogenicity after 3rd SARS-CoV-2 vaccine in elder hepatocellular carcinoma (HCC) was limited. This study aimed to investigate the efficacy and influencing factors of inactivated SARS-CoV-2 vaccine in elder HCC.

RESEARCH DESIGN AND METHODS

We assessed total antibodies, anti-RBD IgG, and neutralizing antibodies (NAb) toward SARS-CoV-2 wild type (WT) as well as BA.4/5 in 304 uninfected HCC, 147 matched healthy control (HC), and 53 SARS-CoV-2 infected HCC, all aged over 60 years. The levels of antibodies were compared in the period 7-90, 91-180, and >180 days after 2nd or 3rd vaccination, respectively.

RESULTS

HCC had lower seropositivity than HC after 2nd dose (total antibodies, 64% vs. 92%, P < 0.0001; anti-RBD IgG, 50% vs. 77%, P < 0.0001). But 3rd dose can efficaciously close the gap (total antibodies, 96% vs. 100%, P = 0.1212; anti-RBD IgG: 87% vs. 87%, P > 0.9999). Booster effect of 3rd dose can persist >180 days in HCC (2nd vs. 3rd: total antibodies, 0.60 vs. 3.20, P < 0.0001; anti-RBD IgG, 13.86 vs. 68.85, P < 0.0001; WT NAb, 11.70 vs. 22.47, P < 0.0001). Vaccinated HCC had more evident humoral responses than unvaccinated ones after infection (total antibodies: 3.85 vs. 3.20, P < 0.0001; anti-RBD IgG: 910.92 vs. 68.85, P < 0.0001; WT NAb: 96.09 vs. 22.47, P < 0.0001; BA.4/5 NAb: 86.53 vs. 5.59, P < 0.0001).

CONCLUSIONS

Our findings highlight the booster effect and protective role of 3rd dose. Our results could provide a theoretical foundation for informing decisions regarding SARS-CoV-2 vaccination in elder HCC.

Impact of the COVID-19 pandemic on the diagnosis and treatment of onco-hematologic patients: a discussion paper

We do not know the precise figure for solid organ tumors diagnosed each year in Spain and it is therefore difficult to calculate whether there has been a decrease in cancer diagnoses as a consequence of the pandemic. Some indirect data suggest that the pandemic has worsened the stage at which some non-hematological neoplasms are diagnosed. Despite the lack of robust evidence, oncology patients seem more likely to have a poor outcome when they contract COVID-19. The antibody response to infection in cancer patients will be fundamentally conditioned by the type of neoplasia present, the treatment received and the time of its administration. In patients with hematological malignancies, the incidence of infection is probably similar or lower than in the general population, due to the better protective measures adopted by the patients and their environment. The severity and mortality of COVID-19 in patients with hematologic malignancies is clearly higher than the general population. Since the immune response to vaccination in hematologic patients is generally worse than in comparable populations, alternative methods of prevention must be established in these patients, as well as actions for earlier diagnosis and treatment. Campaigns for the early diagnosis of malignant neoplasms must be urgently resumed, post-COVID manifestations should be monitored, collaboration with patient associations is indisputable and it is urgent to draw the right conclusions to improve our preparedness to fight against possible future catastrophes.

Immune Response and Effects of COVID-19 Vaccination in Patients with Lung Cancer-COVID Lung Vaccine Study

Lung cancer patients represent a subgroup of special vulnerability in whom the SARS-CoV-2 infection could attain higher rates of morbidity and mortality. Therefore, those patients were recommended to receive SARS-CoV-2 vaccines once they were approved. However, little was known at that time regarding the degree of immunity developed after vaccination or vaccine-related adverse events, and more uncertainty involved the real need for a third dose. We sought to evaluate the immune response developed after vaccination, as well as the safety and efficacy of SARS-CoV-2 vaccines in a cohort of patients with lung cancer. Patients were identified through the Oncology/Hematology Outpatient Vaccination Program. Anti-Spike IgG was measured before any vaccine and at 3-6-, 6-9- and 12-15-month time points after the 2nd dose. Detailed clinical data were also collected. In total, 126 patients with lung cancer participated and received at least one dose of the SARS-CoV-2 vaccine. At 3-6 months after 2nd dose, 99.1% of baseline seronegative patients seroconverted and anti-Spike IgG titers went from a median value of 9.45 to 720 UI/mL. At the 6-9-month time point, titers raised to a median value of 924 UI/mL, and at 12-15 months, after the boost dose, they reached a median value of 3064 UI/mL. Adverse events to the vaccine were mild, and no SARS- CoV-2 infection-related deaths were recorded. In this lung cancer cohort, COVID-19 vaccines were safe and effective irrespective of the systemic anticancer therapy. Most of the patients developed anti-Spike IgG after the second dose, and these titers were maintained over time with low infection and reinfection rates with a mild clinical course.

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.