Subcutaneous Casirivimab/Imdevimab (Ronapreve™) Injections for Covid-19 Prophylaxis in Kidney Transplant Recipients

Background: Immunosuppressed kidney transplant recipients (KTRs) can show impaired immune responses to COVID-19 vaccines and remain at high risk of developing severe clinical manifestations. Patients who do not adequately respond to vaccination may be offered prophylactic injections of monoclonal anti-SARS-CoV-2 antibodies.Methods: KTRs who failed to show an adequate response to COVID-19 vaccines received subcutaneous injections of casirivimab/imdevimab (Ronapreve™; first dose: 1200 mg) within a pre-exposure prophylaxis framework. Anti-Spike (RBD) IgG titers were quantified longitudinally immediately before the second and third injections.Findings: None of the 168 KTRs who received Ronapreve™ injections in our center was diagnosed with either symptomatic or asymptomatic COVID-19. All of the 142 KTRs who received at least two Ronapreve™ injections showed anti-RBD IgG titers above the protective threshold (i.e., >506 BAU/mL) four weeks after the first injection (median titer: 8817 BAU/mL; interquartile range: 6231.2 to 11028.2 BAU/mL; range: 1624 to >11360 BAU/mL). A total of 78 KTRs received a third injection 4 to 8 weeks after the second and all of them showed anti-RBD IgG titers persistently above the protective threshold. Fourteen KTRs were tested for anti-RBD IgG titers in saliva samples and 12 had positive results. Ronapreve™ injections were well-tolerated.Interpretation: Subcutaneous Ronapreve™ represents a safe and effective approach to confer protection against COVID-19 in KTRs who did not adequately respond to vaccination. Protective anti-RBD IgG titers >506 BAU/mL were observed in all participants and remained persistently elevated for at least 8 weeks after prophylactic injections.Clinical Trial Registration Details: The study was registered at Clinicaltrials.gov (registration number: NCT04828460).Funding Information: The laboratory of S.F.-K. is funded by Strasbourg University Hospital (SeroCoV-HUS; PRI 7782), Programme Hospitalier de Recherche Clinique (PHRC N 2017-HUS no. 6997), the Agence Nationale de la Recherche (ANR-18-CE17-0028), Laboratoire d’Excellence TRANSPLANTEX (ANR-11-LABX-0070_TRANSPLANTEX) and Institut National de la Santé et de la Recherche Médicale (UMR_S 1109).Declaration of Interests: The authors have no conflicts of interest to declare in relation to this manuscript.Ethics Approval Statement: All procedures complied with the Helsinki Declaration and were approved by the local Institutional Review Board (reference number: CE-2021-9).