Immunomodulatory Therapies for COVID-19 in Solid Organ Transplant Recipients

Severe coronavirus disease 2019 (COVID-19) is characterized by the development of a deleterious hyperinflammatory response, in which the pleiotropic cytokine interleukin (IL)-6 plays a pivotal role. The administration of immunomodulatory therapies has been proposed to revert the tissue damage induced by COVID-19-related cytokine release syndrome (CRS). The present review summarizes the biological rationale and available clinical experience with this therapeutic strategy in the specific scenario solid organ transplantation (SOT).

A number of case reports, case series, and non-controlled cohort studies have assessed the efficacy and safety of the anti-IL-6-receptor monoclonal tocilizumab in SOT (namely kidney transplantation) recipients with COVID-19 pneumonia and CRS. Although the heterogeneity in patient management and the lack of a control group limit the interpretation of these results, tocilizumab therapy appears to provide some clinical benefit in post-transplant COVID-19 and to be reasonably safe in terms of bacterial superinfection. A large randomized clinical trial (RCT) has shown survival benefit with adjuvant corticosteroids in non-transplant patients, but supporting evidence is scarce for SOT recipients and confounded by the variable adjustment of baseline immunosuppression. Anecdotal experiences have been reported with the use of the anti-IL-1 agent anakinra and the NLRP3 inflammasome inhibitor colchicine in this population.

Immunomodulation has emerged as a promising option for SOT recipients with COVID-19-related CRS, with available experience mainly restricted to the anti-IL-6 agent tocilizumab. However, the supporting evidence is scarce and of low quality. In the absence of RCT, observational studies including well-matched control groups should be designed in future.