COVID-19: Simulation Study of Tocilizumab and Siltuximab Interventions
in the Context of Acute Respiratory Distress Syndrome
Abstract
Aim: To assess the potential of interleukin-6 (IL-6) signaling blockade
in the lung to treat SARS-CoV-2 infection via model-based simulation by
exploring soluble IL-6 receptor (sIL-6R) sequestration by tocilizumab
(TCZ) and IL-6 sequestration by siltuximab (SIL). Methods: Literature
values of IL-6, the IL-6 antagonist SIL, sIL-6R, the IL-6R antagonist
TCZ, and their respective binding constants were used to develop a model
to predict the impact of treatment on IL-6 signaling. Models were used
to generate simulated bronchoalveolar lavage (BAL) concentrations for
normal subjects, subjects at risk of developing acute respiratory
distress syndrome (ARDS), and subjects with ARDS were simulated under
four conditions: without treatment, treatment with TCZ, treatment with
SIL, and treatment with TCZ + SIL. Results: With TCZ intervention, IL-6
levels are unaffected and sIL-6R is reduced somewhat below the Normal
case. IL-6:sIL-6R complex only slightly decreased relative to the
no-intervention case. With SIL intervention, sIL-6R levels are
unaffected and IL-6 is greatly reduced below the Normal case.
IL-6:sIL-6R complex is greatly decreased relative to the no-intervention
case. With TCZ + SIL intervention, IL-6 and sIL-6R levels are reduced
below the Normal case and achieve suppression equivalent to monotherapy
results for their respective targets. IL-6:sIL-6R complex reduction is
predicted to be greater than monotherapy. This reflects sequestration of
both components of the complex and the nonlinear binding equilibrium.
Conclusion: Co-administration of both IL-6 and IL-6R sequestering
products such as SIL and TCZ may be necessary to effectively treat
COVID-19 patients who have or are at risk of developing ARDS.