Enhanced Humoral Immune Response After COVID-19 Vaccination in Elderly Kidney Transplant Recipients on Everolimus Versus Mycophenolate Mofetil-containing Immunosuppressive Regimens

Everolimus Personalized Therapy: Second Consensus Report by the International Association of Therapeutic Drug Monitoring and Clinical Toxicology

ABSTRACT

The Immunosuppressive Drugs Scientific Committee of the International Association of Therapeutic Drug Monitoring and Clinical Toxicology established the second consensus report to guide Therapeutic Drug Monitoring (TDM) of everolimus (EVR) and its optimal use in clinical practice 7 years after the first version was published in 2016. This version provides information focused on new developments that have arisen in the last 7 years. For the general aspects of the pharmacology and TDM of EVR that have retained their relevance, readers can refer to the 2016 document. This edition includes new evidence from the literature, focusing on the topics updated during the last 7 years, including indirect pharmacological effects of EVR on the mammalian target of rapamycin complex 2 with the major mechanism of direct inhibition of the mammalian target of rapamycin complex 1. In addition, various concepts and technical options to monitor EVR concentrations, improve analytical performance, and increase the number of options available for immunochemical analytical methods have been included. Only limited new pharmacogenetic information regarding EVR has emerged; however, pharmacometrics and model-informed precision dosing have been constructed using physiological parameters as covariates, including pharmacogenetic information. In clinical settings, EVR is combined with a decreased dose of calcineurin inhibitors, such as tacrolimus and cyclosporine, instead of mycophenolic acid. The literature and recommendations for specific organ transplantations, such as that of the kidneys, liver, heart, and lungs, as well as for oncology and pediatrics have been updated. EVR TDM for pancreatic and islet transplantation has been added to this edition. The pharmacodynamic monitoring of EVR in organ transplantation has also been updated. These updates and additions, along with the previous version of this consensus document, will be helpful to clinicians and researchers treating patients receiving EVR.

Prevention and treatment strategies for kidney transplant recipients in the context of long-term existence of COVID-19

The sudden outbreak of coronavirus disease 2019 (COVID-19) in early 2020 posed a massive threat to human life and caused an economic upheaval worldwide. Kidney transplant recipients (KTRs) became susceptible to infection during the COVID-19 pandemic owing to their use of immunosuppressants, resulting in increased hospitalization and mortality rates. Although the current epidemic situation is alleviated, the long-term existence of COVID-19 still seriously threatens the life and health of KTRs with low immunity. The Omicron variant, a highly infectious but less-pathogenic strain of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has raised concerns among transplant physicians regarding managing KTRs diagnosed with this variant. However, currently, there are no clear and unified guidelines for caring for KTRs infected with this variant. Therefore, we aimed to summarize the ongoing research on drugs that can treat Omicron variant infections in KTRs and explore the potential of adjusting immunotherapy strategies to enhance their responsiveness to vaccines. Herein, we discuss the situation of KTRs since the emergence of COVID-19 and focus on various prevention and treatment strategies for KTRs since the Omicron variant outbreak. We hope to assist physicians in managing KTRs in the presence of long-term COVID-19 variants.

Impact of immunosuppressive therapy on SARS-CoV-2 mRNA vaccine effectiveness in patients with immune-mediated inflammatory diseases: a Danish nationwide cohort study

OBJECTIVE

Patients receiving immunosuppressives have been excluded from trials for SARS-CoV-2 vaccine efficacy. Investigation of immunosuppressants' impact on effectiveness of vaccines, particularly in patients with immune-mediated inflammatory diseases (IMID), is therefore required.

DESIGN

We performed a nationwide cohort study to assess the risk of COVID-19 infection in vaccinated patients with IMID exposed to immunosuppressives compared with IMID unexposed to immunosuppressives. Exposure to immunosuppressives in the 120 days before receiving the second SARS-CoV-2 mRNA vaccination was assessed. Patients were followed from date of second vaccination and weighted Cox models were used to estimate the risk of infection associated with immunosuppressives. Secondary outcomes included hospitalisation and death associated with a positive SARS-CoV-2 test. Risk of infection by immunosuppressant drug class was also analysed.

SETTING

This study used population-representative data from Danish national health registries in the period from 1 January to 30 November 2021.

RESULTS

Overall, 152 440 patients were followed over 19 341 person years. Immunosuppressants were associated with a significantly increased risk of infection across IMID (HR: 1.4, 95% CI 1.2 to 1.5), in inflammatory bowel disease (IBD) (HR: 1.6, 95% CI 1.4 to 1.9) and arthropathy (HR: 1.3, 95% CI 1.1 to 1.4) but not psoriasis (HR: 1.1, 95% CI 0.9 to 1.4). Immunosuppressants were also associated with an increased risk of hospitalisation across IMID (HR: 1.4, 95% CI 1.1 to 2.0), particularly in IBD (HR: 2.1, 95% CI 1.0 to 4.1). No significantly increased risk of death in immunosuppressant exposed patients was identified. Analyses by immunosuppressant drug class showed increased COVID-19 infection and hospitalisation with anti-tumour necrosis factor (TNF), systemic corticosteroid, and rituximab and other immunosuppressants in vaccinated patients with IMID.

CONCLUSION

Immunosuppressive therapies reduced effectiveness of mRNA SARS-CoV-2 vaccination against infection and hospitalisation in patients with IMID. Anti-TNF, systemic corticosteroids, and rituximab and other immunosuppressants were particularly associated with these risks.

Evaluation of Humoral Response following SARS-CoV-2 mRNA-Based Vaccination in Liver Transplant Recipients Receiving Tailored Immunosuppressive Therapy

Background: The role of tailored immunosuppression (IS) in the development of the humoral response (HR) to SARS-CoV-2 mRNA-based vaccination in liver transplant (LT) recipients is unknown. Methods: This is a single-centre prospective study of patients who underwent LT between January 2015 and December 2021 and who have received three doses of mRNA-based SARS-CoV-2 vaccination. Patients undergoing Tacrolimus-based immunosuppression (TAC-IS) were compared with those undergoing Everolimus-based immunosuppression (EVR-IS). Patients receiving the TAC-EVR combination were divided into two groups based on trough TAC concentrations, i.e., above or below 5 ng/mL. HR (analysed with ECLIA) was assessed at 30 to 135 days after vaccination. The primary outcome was the presence of a positive antibody titre (≥0.8 U/mL). Secondary outcomes were the presence of a highly protective antibody titre (≥142 U/mL), median antibody titre, and incidence of COVID-19. Results: Sixty-one participants were included. Twenty-four (40%) were receiving TAC-IS and thirty-seven (60%) were receiving EVR-IS. At the median follow-up of 116 (range: 89-154) days, there were no significant differences in positive antibody titre (95.8% vs. 94.6%; p = 0.8269), highly-protective antibody titre (83.3% vs. 81.1%; p = 0.8231), median antibody titre (2410 [IQ range 350-2500] vs. 1670 [IQ range 380-2500]; p = 0.9450), and COVID-19 incidence (0% vs. 5.4%; p = 0.5148). High serum creatinine and low estimated glomerular filtration rate were risk factors for a weak or absent HR. Conclusions: Three doses of mRNA-based SARS-CoV-2 vaccination yielded a highly protective HR in LT recipients. The use of TAC or EVR-based IS does not appear to influence HR or antibody titre, while renal disease is a risk factor for a weak or null HR.

Humoral and Cellular Immunity Are Significantly Affected in Renal Transplant Recipients, following Vaccination with BNT162b2

BACKGROUND

Renal transplant recipients (RTRs) tend to mount weaker immune responses to vaccinations, including vaccines against the novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2).

METHODS

Humoral immunity was assessed using anti-receptor binding domain (RBD) and neutralizing antibodies (NAb) serum levels measured by ELISA, and cellular immunity was assessed using T-, B-, NK, natural killer-like T (NKT)-cell subpopulations, and monocytes measured by flow cytometry, and also specific T-cell immunity, at predefined time points after BNT162b2 vaccination, in 57 adult RTRs.

RESULTS

Administration of three booster doses was necessary to achieve anti-RBD and NAb protective levels in almost all patients (92.98%). Ab production, at several time points, was positively correlated with the corresponding renal function and inversely correlated with hemodialysis vintage (HDV) and treatment with mycophenolic acid (MPA). A gradual rise in several cell subpopulations, including total lymphocytes (p = 0.026), memory B cells (p = 0.028), activated CD4 (p = 0.005), and CD8 cells (p = 0.001), was observed even after the third vaccination dose, while a significant reduction in CD3+PD1+ (p = 0.002), NKT (p = 0.011), and activated NKT cells (p = 0.034) was noted during the same time interval. Moreover, SARS-CoV-2-specific T-cells were present in 41% of the patients who were unable to develop Nabs, and their positivity rates four months after the second dose were in inverse correlation with monocytes (p = 0.045) and NKT cells (p = 0.01).

CONCLUSIONS

SARS-CoV-2-specific T-cell responses preceded the humoral ones, while two booster doses were needed for this group of immunocompromised patients to mount a protective immune response.

The role of interleukin-21 in COVID-19 vaccine-induced B cell-mediated immune responses in patients with kidney disease and kidney transplant recipients

T-cell-mediated help to B cells is required for the development of humoral responses, in which the cytokine interleukin (IL)-21 is key. Here, we studied the mRNA-1273 vaccine-induced SARS-CoV-2-specific memory T-cell IL-21 response, memory B cell response, and immunoglobulin (Ig)G antibody levels in peripheral blood at 28 days after the second vaccination by ELISpot and the fluorescent bead-based multiplex immunoassay, respectively. We included 40 patients with chronic kidney disease (CKD), 34 patients on dialysis, 63 kidney transplant recipients (KTR), and 47 controls. We found that KTR, but not patients with CKD and those receiving dialysis, showed a significantly lower number of SARS-CoV-2-specific IL-21 producing T cells than controls (P < .001). KTR and patients with CKD showed lower numbers of SARS-CoV-2-specific IgG-producing memory B cells when compared with controls (P < .001 and P = .01, respectively). The T-cell IL-21 response was positively associated with the SARS-CoV-2-specific B cell response and the SARS-CoV-2 spike S1-specific IgG antibody levels (both Pearson r = 0.5; P < .001). In addition, SARS-CoV-2-specific B cell responses were shown to be IL-21 dependent. Taken together, we show that IL-21 signaling is important in eliciting robust B cell-mediated immune responses in patients with kidney disease and KTR.

COVID and the Kidney: An Update

Coronavirus disease-2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2, has led to a global pandemic that continues to be responsible for ongoing health issues for people worldwide. Immunocompromised individuals such as kidney transplant recipients and dialysis patients have been and continue to be among the most affected, with poorer outcomes after infection, impaired response to COVID-19 vaccines, and protracted infection. The pandemic also has had a significant impact on patients with underlying chronic kidney disease (CKD), with CKD increasing susceptibility to COVID-19, risk of hospital admission, and mortality. COVID-19 also has been shown to lead to acute kidney injury (AKI) through both direct and indirect mechanisms. The incidence of COVID-19 AKI has been decreasing as the pandemic has evolved, but continues to be associated with adverse patient outcomes correlating with the severity of AKI. There is also increasing evidence examining the longer-term effect of COVID-19 on the kidney demonstrating continued decline in kidney function several months after infection. This review summarizes the current evidence examining the impact of COVID-19 on the kidney, covering both the impact on patients with CKD, including patients receiving kidney replacement therapy, in addition to discussing COVID-19 AKI.

Susceptibility to SARS-CoV-2 Infection and Immune Responses to COVID-19 Vaccination Among Recipients of Solid Organ Transplants

Solid organ transplant recipients (SOTRs) are at high risk for infections including SARS-CoV-2, primarily due to use of immunosuppressive therapies that prevent organ rejection. Furthermore, these immunosuppressants are typically associated with suboptimal responses to vaccination. While COVID-19 vaccines have reduced the risk of COVID-19-related morbidity and mortality in SOTRs, breakthrough infection rates and death remain higher in this population compared with immunocompetent individuals. Approaches to enhancing response in SOTRs, such as through administration of additional doses and heterologous vaccination, have resulted in increased seroresponse and antibody levels. In this article, safety and immunogenicity of mRNA COVID-19 vaccines in SOTRs are explored by dose. Key considerations for clinical practice and the current vaccine recommendations for SOTRs are discussed within the context of the dynamic COVID-19 vaccination guideline landscape. A thorough understanding of these topics is essential for determining public health and vaccination strategies to help protect immunocompromised populations, including SOTRs.

Effects of Sirolimus Treatment on Fetal Hemoglobin Production and Response to SARS-CoV-2 Vaccination: A Case Report Study

The β-thalassemias are a group of monogenic hereditary hematological disorders caused by deletions and/or mutations of the β-globin gene, leading to low or absent production of adult hemoglobin (HbA). For β-thalassemia, sirolimus has been under clinical consideration in two trials (NCT03877809 and NCT04247750). A reduced immune response to anti-SARS-CoV-2 vaccination has been reported in organ recipient patients treated with the immunosuppressant sirolimus. Therefore, there was some concern regarding the fact that monotherapy with sirolimus would reduce the antibody response after SARS-CoV-2 vaccination. In the representative clinical case reported in this study, sirolimus treatment induced the expected increase of fetal hemoglobin (HbF) but did not prevent the production of anti-SARS-CoV-2 IgG after vaccination with mRNA-1273 (Moderna). In our opinion, this case report should stimulate further studies on β-thalassemia patients under sirolimus monotherapy in order to confirm the safety (or even the positive effects) of sirolimus with respect to the humoral response to anti-SARS-CoV-2 vaccination. In addition, considering the extensive use of sirolimus for the treatment of other human pathologies (for instance, in organ transplantation, systemic lupus erythematosus, autoimmune cytopenia, and lymphangioleiomyomatosis), this case report study might be of general interest, as large numbers of patients are currently under sirolimus treatment.

Effectiveness, Immunogenicity and Harms of Additional SARS-CoV-2 Vaccine Doses in Kidney Transplant Recipients: A Systematic Review

BACKGROUND

Kidney transplant recipients (KTRs) who have a highly impaired immune response are in need of intensified and safe vaccination strategies to achieve seroconversion and prevent severe disease.

METHODS

We searched the Web of Science Core Collection, the Cochrane COVID-19 Study Register and the WHO COVID-19 global literature on coronavirus disease from January 2020 to 22 July 2022 for prospective studies that assessed immunogenicity and efficacy after three or more SARS-CoV-2 vaccine doses.

RESULTS

In 37 studies on 3429 patients, de novo seroconversion after three and four vaccine doses ranged from 32 to 60% and 25 to 37%. Variant-specific neutralization was 59 to 70% for Delta and 12 to 52% for Omicron. Severe disease after infection was rarely reported but all concerned KTRs lacked immune responses after vaccination. Studies investigating the clinical course of COVID-19 found remarkably higher rates of severe disease than in the general population. Serious adverse events and acute graft rejections were very rare. Substantial heterogeneity between the studies limited their comparability and summary.

CONCLUSION

Additional SARS-CoV-2 vaccine doses are potent and safe in general terms as well as regarding transplant-specific outcomes whilst the Omicron wave remains a significant threat to KTRs without adequate immune responses.

Antibody acquisition after second and third SARS-CoV-2 vaccinations in Japanese kidney transplant patients: a prospective study

BACKGROUND

Kidney transplant patients have lower antibody acquisition after SARS-CoV-2 vaccination. The efficacy of vaccines in Japanese kidney transplant patients with specific characteristics, such as predominant living-donor, ABO-incompatible kidney transplant, and low-dose immunosuppression, requires verification.

METHODS

We conducted a prospective study to estimate anti-SARS-CoV-2 antibody levels in 105 kidney transplant patients and 57 controls. Blood samples were obtained before vaccination, 1, 3, and 6 months after second vaccination, and 1 month after third vaccination. We investigated antibody acquisition rates, antibody levels, and factors associated with antibody acquisition.

RESULTS

One month after second vaccination, antibody acquisition was 100% in the controls but only 36.7% in the kidney transplant group (P < 0.001). Antibody levels in positive kidney transplant patients were also lower than in the controls (median, 4.9 arbitrary units vs 106.4 arbitrary units, respectively, P < 0.001). Years after kidney transplant (odds ratio 1.107, 95% confidence interval 1.012-1.211), ABO-incompatible kidney transplant (odds ratio 0.316, 95% confidence interval 0.101-0.991) and mycophenolate mofetil use (odds ratio 0.177, 95% confidence interval 0.054-0.570) were significant predictors for antibody acquisition after second vaccination. After third vaccination, antibody positivity in the kidney transplant group increased to 75.3%, and antibody levels in positive patients were 71.7 arbitrary units. No factors were associated with de novo antibody acquisition.

CONCLUSIONS

In Japanese kidney transplant patients, years after kidney transplant, ABO-incompatible kidney transplant and mycophenolate mofetil use were predictors for antibody acquisition after second vaccination. Third vaccination improves antibody status even in patients who were seronegative after the second vaccination.

Comparison of the Immune Response After an Extended Primary Series of COVID-19 Vaccination in Kidney Transplant Recipients Receiving Standard Versus Mycophenolic Acid-sparing Immunosuppressive Regimen

Two doses of coronavirus disease 2019 vaccination provide suboptimal immune response in transplant patients. Mycophenolic acid (MPA) is one of the most important factors that blunts the immune response. We studied the immune response to the extended primary series of 2 doses of AZD1222 and a single dose of BNT162b2 in kidney transplant patients who were on the standard immunosuppressive regimen compared to those on the MPA-sparing regimen.

METHODS

The kidney transplant recipients who were enrolled into the study were divided into 2 groups based on their immunosuppressive regimen. Those on the standard immunosuppressive regimen received tacrolimus (TAC), MPA, and prednisolone (standard group). The patients in the MPA-sparing group received mammalian target of rapamycin inhibitors (mTORi) with low dose TAC plus prednisolone (MPA-sparing group). The vaccination consisted of 2 doses of AZD1222 and a single dose of BNT162b2.

RESULTS

A total of 115 patients completed the study. There were 76 (66.08%) patients in the standard group and 39 (33.91%) patients in the MPA-sparing group. The overall median anti-severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) S antibody level at 4 wk after vaccine completion was 676.64 (interquartile range = 6.02-3644.03) BAU/mL with an 80% seroconversion rate. The MPA-sparing group achieved higher anti-SARS-CoV-2 S antibody level compared to the standard group (3060.69 and 113.91 BAU/mL, P < 0.001). The seroconversion rate of MPA-sparing and standard groups were 97.4% and 71.1%, respectively (P < 0.001). The anti-HLA antibodies did not significantly increase after vaccination.

CONCLUSIONS

The extended primary series of 2 doses of AZD1222 and a single dose of BNT162b2 provided significant humoral immune response. The MPA-sparing regimen with mTORi and low dose TAC had a higher ant-SARS-CoV-2 S antibody level and seroconversion rate compared to the participants in the standard regimen.

Benefits of Switching Mycophenolic Acid to Sirolimus on Serological Response after a SARS-CoV-2 Booster Dose among Kidney Transplant Recipients: A Pilot Study

Kidney transplant recipients (KTRs) have a suboptimal immune response to COVID-19 vaccination due to the effects of immunosuppression, mostly mycophenolic acid (MPA). This study investigated the benefits of switching from the standard immunosuppressive regimen (tacrolimus (TAC), MPA, and prednisolone) to a regimen of mammalian target of rapamycin inhibitor (mTORi), TAC and prednisolone two weeks pre- and two weeks post-BNT162b2 booster vaccination. A single-center, opened-label pilot study was conducted in KTRs, who received two doses of ChAdOx-1 and a single dose of BNT162b2. The participants were randomly assigned to continue the standard regimen (control group, n = 14) or switched to a sirolimus (an mTORi), TAC, and prednisolone (switching group, n = 14) regimen two weeks before and two weeks after receiving a booster dose of BNT162b2. The anti-SARS-CoV-2 S antibody level after vaccination in the switching group was significantly greater than the control group (4051.0 [IQR 3142.0-6466.0] BAU/mL vs. 2081.0 [IQR 1077.0-3960.0] BAU/mL, respectively; p = 0.01). One participant who was initially seronegative in the control group remained seronegative after the booster dose. These findings suggest humoral immune response benefits of switching the standard immunosuppressive regimen to the regimen of mTORi, TAC, and prednisolone in KTRs during vaccination.

Factors Associated With COVID-19 Vaccine Response in Transplant Recipients: A Systematic Review and Meta-analysis

BACKGROUND

The rapid development and universal access to vaccines represent a milestone in combating the coronavirus disease 2019 (COVID-19) pandemic. However, there are major concerns about vaccine response in immunocompromised populations in particular transplant recipients. In the present study, we aim to comprehensively assess the humoral response to COVID-19 vaccination in both orthotopic organ transplant and allogeneic hematopoietic stem cell transplant recipients.

METHODS

We performed a systematic review and meta-analysis of 96 studies that met inclusion criteria.

RESULTS

The pooled rates of seroconversion were 49% (95% confidence interval [CI], 43%-55%) in transplant recipients and 99% (95% CI, 99%-99%) in healthy controls after the second dose of vaccine. The pooled rate was 56% (95% CI, 49%-63%) in transplant recipients after the third dose. Immunosuppressive medication is the most prominent risk factor associated with seroconversion failure, but different immunosuppressive regimens are associated with differential outcomes in this respect. Calcineurin inhibitors, steroids, or mycophenolate mofetil/mycophenolic acid are associated with an increased risk of seroconversion failure, whereas azathioprine or mammalian target of rapamycin inhibitors do not. Advanced age, short interval from receiving the vaccine to the time of transplantation, or comorbidities confers a higher risk for seroconversion failure.

CONCLUSIONS

Transplant recipients compared with the general population have much lower rates of seroconversion upon receiving COVID-19 vaccines. Immunosuppressants are the most prominent factors associated with seroconversion, although different types may have differential effects.

Immune response to third SARS-CoV-2 vaccination in seronegative kidney transplant recipients: Possible improvement by mycophenolate mofetil reduction

Modification of vaccination strategies is necessary to improve the immune response to SARS-CoV-2 vaccination in kidney transplant recipients (KTRs). This multicenter observational study analyzed the effects of the third SARS-CoV-2 vaccination in previously seronegative KTRs with the focus on temporary mycophenolate mofetil (MMF) dose reduction within propensity matched KTRs. 56 out of 174 (32%) previously seronegative KTRs became seropositive after the third vaccination with only three KTRs developing neutralizing antibodies against the omicron variant. Multivariate logistic regression revealed that initial antibody levels, graft function, time after transplantation and MMF trough levels had an influence on seroconversion (P < .05). After controlling for confounders, the effect of MMF dose reduction before the third vaccination was calculated using propensity score matching. KTRs with a dose reduction of ≥33% showed a significant decrease in MMF trough levels to 1.8 (1.2-2.5) μg/ml and were more likely to seroconvert than matched controls (P = .02). Therefore, a MMF dose reduction of 33% or more before vaccination is a promising approach to improve success of SARS-CoV-2 vaccination in KTRs.