Nirmatrelvir/ritonavir treatment in SARS-CoV-2 positive kidney transplant recipients - a case series with four patients.

BACKGROUND: Despite vaccination coronavirus disease 2019 (COVID-19)-associated mortality caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) remains high in kidney transplant recipients. Nirmatrelvir is a protease inhibitor with activity against SARS-CoV-2. Nirmatrelvir reduces the risk for mortality and hospitalization, which is approved for treating adults at risk for severe disease. Nirmatrelvir is metabolized by the cytochrome P-450 (CYP) 3A4 isozyme CYP3A4 and is therefore co-administered with the irreversible CYP3A4 inhibitor ritonavir, which results in a drug interaction with tacrolimus. A limited number of patients with nirmatrelvir/ritonavir and tacrolimus therapy after kidney transplantation have been reported to date. It has been reported that tacrolimus was paused during the five-day nirmatrelvir/ritonavir therapy and subtherapeutic tacrolimus levels were observed after finishing nirmatrelvir/ritonavir in two patients. Therefore, optimization of tacrolimus dosing is urgently needed in transplant recipients receiving nirmatrelvir/ritonavir treatment. CASE PRESENTATION: Here, we present our first-hand experience with four patients receiving tacrolimus therapy following kidney transplantation and nirmatrelvir/ritonavir therapy due to COVID-19. Tacrolimus was paused during nirmatrelvir/ritonavir therapy in all patients, which resulted in stable therapeutic tacrolimus levels. Tacrolimus was continued directly after finishing nirmatrelvir/ritonavir to avoid subtherapeutic levels in the first patient treated. This patient received his usual tacrolimus maintenance dose, which resulted in toxic levels. Based on this observation, tacrolimus therapy was continued 24 h after finishing nirmatrelvir/ritonavir treatment at a reduced dose in the subsequent patients. In these patients, therapeutic to supratherapeutic tacrolimus levels were observed despite the therapeutic break and dose reduction. DISCUSSION AND CONCLUSIONS: Based on altered CYP3A4 metabolism, tacrolimus levels have to be closely monitored after treatment with nirmatrelvir/ritonavir. Our study suggests that tacrolimus treatment should be paused during nirmatrelvir/ritonavir medication and be continued 24 h after completing nirmatrelvir/ritonavir therapy at a reduced dose and under close monitoring. Based on the limited number of patients in this study, results must be interpreted with caution.

Response to SARS-CoV-2 vaccines in patients receiving B-cell modulating antibodies for renal autoimmune disease.

BACKGROUND: Effective SARS-CoV-2 vaccination in patients receiving treatment with B-cell depleting agents is challenging. Information on vaccination responses in these patients are a valuable tool to develop efficient vaccination regimens. METHODS: In this single-center retrospective observational study, we report the humoral and cellular response in 34 patients receiving anti-CD20 antibody treatment for renal immune disease. RESULTS: After base immunization with SARS-CoV-2-vaccines, 92.0% developed a cellular, 32.4% a humoral response. Humoral immunity correlated with B-cell counts and the timespan between anti-CD20 antibody treatment and vaccination. All patients with > 21/µl B-cells, or > 197 days after treatment showed humoral response. CONCLUSIONS: Adequate timing of SARS-CoV-2-vaccinations after anti-CD20 antibody treatment and CD19 measurements are crucial to generate immunity. Awaiting partial B-cell recovery by postponing regularly scheduled anti-CD20 treatment should be considered in patients with stable immune disease. TRIAL REGISTRATION: This study has been retrospectively registered in the German Clinical Trials Register (DRKS00027049) on 29/10/2021.

Within-host evolution of SARS-CoV-2 in an immunosuppressed COVID-19 patient as a source of immune escape variants.

The origin of SARS-CoV-2 variants of concern remains unclear. Here, we test whether intra-host virus evolution during persistent infections could be a contributing factor by characterizing the long-term SARS-CoV-2 infection dynamics in an immunosuppressed kidney transplant recipient. Applying RT-qPCR and next-generation sequencing (NGS) of sequential respiratory specimens, we identify several mutations in the viral genome late in infection. We demonstrate that a late viral isolate exhibiting genome mutations similar to those found in variants of concern first identified in UK, South Africa, and Brazil, can escape neutralization by COVID-19 antisera. Moreover, infection of susceptible mice with this patient's escape variant elicits protective immunity against re-infection with either the parental virus and the escape variant, as well as high neutralization titers against the alpha and beta SARS-CoV-2 variants, B.1.1.7 and B.1.351, demonstrating a considerable immune control against such variants of concern. Upon lowering immunosuppressive treatment, the patient generated spike-specific neutralizing antibodies and resolved the infection. Our results suggest that immunocompromised patients could be a source for the emergence of potentially harmful SARS-CoV-2 variants.

Comparison of different anticoagulation strategies for renal replacement therapy in critically ill patients with COVID-19: a cohort study.

BACKGROUND: Critically ill coronavirus disease 2019 (COVID-19) patients have a high risk of acute kidney injury (AKI) that requires renal replacement therapy (RRT). A state of hypercoagulability reduces circuit life spans. To maintain circuit patency and therapeutic efficiency, an optimized anticoagulation strategy is needed. This study investigates whether alternative anticoagulation strategies for RRT during COVID-19 are superior to administration of unfractionated heparin (UFH). METHODS: Retrospective cohort study on 71 critically ill COVID-19 patients (≥18 years), admitted to intensive care units at a tertiary health care facility in the southwestern part of Germany between February 26 and May 21, 2020. We collected data on the disease course, AKI, RRT, and thromboembolic events. Four different anticoagulatory regimens were administered. Anticoagulation during continuous veno-venous hemodialysis (CVVHD) was performed with UFH or citrate. Anticoagulation during sustained low-efficiency daily dialysis (SLEDD) was performed with UFH, argatroban, or low molecular weight heparin (LMWH). Primary outcome is the effect of the anticoagulation regimen on mean treatment times of RRT. RESULTS: In patients receiving CVVHD, mean treatment time in the UFH group was 21.3 h (SEM: ±5.6 h), in the citrate group 45.6 h (SEM: ±2.7 h). Citrate anticoagulation significantly prolonged treatment times by 24.4 h (P = .001). In patients receiving SLEDD, mean treatment time with UFH was 8.1 h (SEM: ±1.3 h), with argatroban 8.0 h (SEM: ±0.9 h), and with LMWH 11.8 h (SEM: ±0.5 h). LMWH significantly prolonged treatment times by 3.7 h (P = .008) and 3.8 h (P = .002), respectively. CONCLUSIONS: UFH fails to prevent early clotting events in the dialysis circuit during COVID-19. For patients, who do not require effective systemic anticoagulation, regional citrate dialysis is the most effective strategy. For patients, who require effective systemic anticoagulation, the usage of LMWH results in the longest circuit life spans. The proposed anticoagulatory strategies are safe, can easily be monitored, and allow an individualized treatment.