Breakthrough Covid-19 cases despite tixagevimab and cilgavimab (Evusheld™) prophylaxis in kidney transplant recipients (preprint)

While the combination of casirivimab-imdevimab (Ronapreve Roche Regeneron) has been shown to confer satisfactory protection against the delta variant kidney transplant recipients (KTRs) with COVID-19, it has limited neutralizing activity against the current variants of concern (Omicron BA.1, BA.1.1 and BA.2). In contrast, cilgavimab-tixagevimab combination (Evusheld, Astra Zeneca) retains a partial neutralizing activity against omicron in vitro. We examined whether preexposure prophylaxis with Evusheld can effectively protect kidney transplant recipients (KTRs) against the Omicron variant. Of the 416 KTRs who received intramuscular prophylactic injections of Evusheld (150 mg tixagevimab and 150 mg cilgavimab), 39 (9.4%) developed COVID-19. With the exception of one patient, all KTRs were symptomatic. Hospitalization and admission to an intensive care unit were required for 14 (35.9%) and three patients, respectively. Two KTRs died of COVID-19-related acute respiratory distress syndrome. SARS-CoV-2 sequencing was carried out in 15 cases (BA.1, n = 5; BA.1.1, n = 9; BA.2, n=1). Viral neutralizing activity of the serum against BA.1 variant was negative in the 12 tested patients, suggesting that this prophylaxis strategy provides insufficient protection against this variant of concern. Preexposure prophylaxis with Evusheld does not adequately protect KTRs against Omicron. Further clarification of the optimal dosing can assist in our understanding of how best to harness its protective potential.

Changing of therapeutic trends between the 1st and 2nd wave did not reduce COVID-19 related mortality of renal transplant recipients: a national registry study. (preprint)

SARS-CoV-2 pandemic evolved in two consecutive waves over 2020 (for France: 1st wave from March 1 to July 31; and 2nd wave from August 1 to December 31). Improvements in the management of COVID-19 led to a reduction of mortality rates in hospitalized patients during the second wave. Whether this progress also benefited to kidney transplant recipients (KTR), a population particularly vulnerable to severe COVID-19, remained unclear. In France, 957 KTR were hospitalized for COVID-19 in 2020 and their data were prospectively collected in the French SOT COVID registry. The presentation, management, and outcomes of the 359 KTR diagnosed during the 1st wave were compared to those of the 598 of the 2nd wave. Baseline comorbidities were largely similar between KTR of the 2 waves. Maintenance immunosuppression was reduced in most patients but withdrawal of antimetabolite (73.7% vs 58.4%, p<0.001) or CNI (32.1% vs 16.6%, p<0.001) was less frequent during the 2nd wave. Hydroxychloroquine and azithromycin that were commonly used during the 1st wave (21.7% and 30.9%, respectively) were almost abandoned during the 2nd. In contrast, the use of high dose corticosteroids doubled (19.5% vs. 41.6%, p<0.001). Despite these changing trends in COVID-19 management, 60-day mortality was not statistically different between the 2 waves (25.3% vs. 23.9%; Log Rank, p=0.48). We conclude that changing of therapeutic trends during 2020 did not reduce COVID-19 related mortality in KTR. Our data indirectly support the importance of vaccination and monoclonal neutralizing anti-SARS-CoV-2 antibodies to protect KTR from severe COVID-19.

Antibody response to a fourth mRNA Covid-19 vaccine boost in weak responder kidney transplant recipients (preprint)

The US FDA has recently authorized immunocompromised people to receive a third dose of mRNA Covid-19 vaccine following the two-doses regimen to further boost protection. Unfortunately, a non-negligible proportion of people treated with immunosuppressive drugs either do not respond or show only a weak response after a third boost and should, therefore, still be considered at risk of severe Covid-19. As of June 2021, we were granted the opportunity to offer a fourth vaccine dose to French solid organ transplant recipients who still showed a weak antibody response after the third dose. In this multicenter study, we demonstrate that that the protection conferred by a fourth dose is adequate for the majority of kidney transplant recipients.

Predictive factors of response to 3rd dose of COVID-19 mRNA vaccine in kidney transplant recipients (preprint)

Only a minority of kidney transplant recipients (KTRs) develop protective neutralizing titers of anti-receptor binding domain of spike protein (RBD) IgG after two doses of mRNA COVID-19 vaccine. Administration of a third dose of mRNA vaccine to KTRs with sub-optimal response increase anti-RBD IgG titers but with high inter-individual variability. Patients with the higher response rate to the third dose of vaccine can be identified by the presence of low anti-RBD IgG titers and spike-specific CD4+ T cells in their circulation 14 days after the second dose.

Comparison of infected and vaccinated transplant recipients highlights the role of Tfh and neutralizing IgG in COVID-19 protection (preprint)

Transplant recipients, which receive therapeutic immunosuppression to prevent graft rejection, are characterized by high COVID-19-related mortality and defective response to vaccines. Having observed that previous infection by SARS-CoV-2 but not the standard “2 doses” scheme of vaccination, provided complete protection against COVID-19 to transplant recipients, we undertook this translational study to compare the cellular and humoral immune responses of these 2 groups of patients. Neutralizing anti-Receptor Binding Domain (RBD) IgG were identified as the critical immune effectors associated with protection. Generation of anti-RBD IgG was dependent upon spike-specific T follicular helper (Tfh) CD4+ T cells, which acted as limiting checkpoint. Tfh generation was impeded by high dose mycophenolate mofetil in non-responders to vaccine but not in infected patients, suggesting that increasing immunogenicity of vaccine could improve response rate to mRNA vaccine. This theory was validated in two independent prospective cohorts, in which administration of a 3 rd dose of vaccine resulted in the generation of anti-RBD IgG in half of non-responders to 2 doses. One sentence summary The generation of neutralizing IgG, which protects kidney transplant recipients from COVID-19, requires T follicular helper cells.

Justification, safety, and efficacy of a third dose of mRNA vaccine in maintenance hemodialysis patients: a prospective observational study (preprint)

Background Patients on maintenance hemodialysis (MHD) are at high risk of infection with SARS-Cov-2 and death due to COVID-19. This vulnerable population has been prioritized for vaccination, but the level of protection achieved in these immunocompromised patients is unclear. Objectives To evaluate the protection of MHD patients against COVID-19 after 2 doses (2D) of BNT162b2, and the safety and impact on immune responses of a 3 rd dose (3D). Design Prospective observational. Setting, Patients, intervention and measurements REIN national registry was used to compare the severity of 1474 cases of COVID-19 diagnosed in MHD patients after 0, 1 or 2 doses of mRNA vaccine. Anti-spike receptor binding domain (RBD) IgG and interferon gamma-producing CD4+ and CD8+ specific-T cells were measured after 2D and 3D of BNT162b2 in a monocentric cohort of 75 MHD patients. Results Vaccination reduced disease severity but 11% of MHD patients infected after 2D still died. Tolerance to 3D of BNT162b2 was excellent. MHD patients with humoral response similar to healthy volunteers after 2D did not generate more immune effectors after 3D and had more side effects. In contrast, 2/3 of MHD patients with suboptimal response after 2D reached optimal titer of anti-RBD IgG and/or developed spike-specific CD8+ T cells after 3D. Presence of spike-specific CD4+ T cells after 2D was associated with response to 3D in multivariate analysis (OR=4.80 [1.23−21.54]; p=0.029). Limitations Limited number of patients injected with 3D. Conclusion Standard scheme of vaccination provides insufficient protection to some MHD patients. Anti-RBD IgG and specific CD4+ T cells should be measured after 2D. Among patients with suboptimal humoral response, those with specific CD4+ T cells could benefit of a 3 rd dose of vaccine. Registration NCT04881396 Funding Source None