Treatment of Post-COVID-19 POTS by inhibiting FcRn: a phase 2 randomized, placebo controlled, double-blind, proof of concept study with efgartigimod

Abstract Background While the underlying pathophysiology is unknown, post–COVID-19 postural orthostatic tachycardia syndrome (POTS) may be related to immune dysfunction and autoimmunity precipitated by SARS-CoV-2 infection. Various autoantibodies, including those targeting G-protein coupled receptors (GPCRs), have been observed in patients with POTS. Binding of these autoantibodies to adrenergic receptors, which are prototypical GPCRs, has been hypothesized to modulate receptor activity, increase sympathetic tone, and cause tachycardia. Moreover, IgG anti-GPCR autoantibodies, acting as partial agonists, are thought to decrease the effect of peripheral vasomotor control, leading to an increased sympathetic response to upright posture that can result in postural tachycardia in the absence of hypotension. Purpose We hypothesize that a reduction in autoantibody levels by efgartigimod, a FcRn-antagonist, will ameliorate the underlying immune-mediated pathogenesis and lead to clinical improvements in patients who developed POTS following COVID-19 infection. We propose a phase II multicenter, randomized, placebo-controlled, double-blind, proof-of-mechanism study initiated to evaluate the safety and efficacy of efgartigimod in adults with post–COVID-19 POTS. Methods Adult patients diagnosed with new-onset of POTS following SARS-CoV-2 infection are eligible for participation in the study. Prior COVID-19 must be confirmed by documentation of historical PCR test, and POTS diagnosis must meet consensus criteria. Study subjects must have moderate to severe autonomic symptoms (COMPASS-31 score ≥ 35 points at screening). Approximately 42 patients will be randomly allocated (2:1) to receive weekly intravenous efgartigimod or placebo for 24 weeks. At the end of the treatment period, participants who complete the study may roll over into an open-label extension (OLE). The co-primary endpoints are change from baseline to week 24 in the COMPASS-31 and Malmo POTS Symptom Score as well as safety and tolerability outcomes. Key secondary endpoints include assessments of disease activity, fatigue, cognitive function, walking capacity and quantitative autonomic testing. Additional exploratory endpoints include intraepidermal small fiber densities (optional), sudomotor innervation (optional) and peripheral blood biomarkers to define histopathological and immune determinants associated with treatment response. Conclusions This phase II study of efgartigimod will evaluate the effect of FcRn inhibition on disease pathology and the potential for therapeutic benefit in patients with post–COVID-19 POTS.