Does C1 esterase inhibitor play a role in PASC neurological symptoms? A randomized, double-blind, placebo-controlled, crossover, proof-of-con, 2025

Mij

Senior Member (Voting Rights)
Background: Many patients with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection experience neurologic changes post-infection, which has been hypothesized to be due to dysregulation in the infectious-immune axis that leads to a neuro-immune response. This immune dysfunction has been termed “Alzheimer’s of the Immune System” or AIS and there are several immune factors that may play a key role. These include, among others, complement activation due to low levels of C1-esterase inhibitor (C1-INH) and function, and a decrease in signaling of Toll-like receptor (TLR)-3. We propose that C1-INH replacement may upregulate the immune dysfunction, thereby improving neurological symptoms.

Methods: In this randomized, double-blind, placebo-controlled, crossover, proof-of-concept study, adults experiencing SARS-CoV-2 post-viral fatigue syndrome for >4 weeks post-recovery from coronavirus disease 2019 (COVID-19) infection were randomized 1:1 to two arms: Arm 1 (C1-INH for 8 weeks, then placebo for 8 weeks) or to Arm 2 (placebo for 8 weeks, then C1-INH for 8 weeks). Patients were assessed for adult executive function, abnormal cognitive decline, depression [Beck Depression Inventory-II (BDI-II)], migraine, fatigue [Fatigue Severity Scale (FSS)] and pain (Short-form McGill Pain Questionnaire). Percent change in TLR signaling in response to zymosan was compared with controls at baseline, Week 8 and Week 16. Safety was assessed throughout.

Results: At this interim analysis, 36 patients with SARS-CoV-2 post-viral fatigue syndrome had completed the two 8-week treatment periods. In Arm 1, trends toward improvements from baseline at Week 8 of C1-INH therapy were observed in BDI-II score (−8.7 points), mean FSS score (0.6 points), and mean McGill Pain Questionnaire score (−0.4 points). These improvements were either sustained or worsened at Week 16, following crossover to placebo. The outcomes in Arm 2 were compatible with those in Arm 1. Patients with SARS-CoV-2 post-viral fatigue syndrome had low levels of TLR-related signaling biomarkers compared with healthy controls.

Conclusion: This proof-of-concept study demonstrates sustained dysregulation of the immune system after COVID-19 infection. Improvements in depression, fatigue, and pain were observed with C1-INH treatment in patients with SARS-CoV-2 post-viral fatigue syndrome, indicating C1-INH may be a potential therapeutic target.
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Clinical Trial: RUCONEST

A Randomized, Double Blind, Placebo Controlled, Cross-Over, Proof-of-Concept Study to Evaluate the Benefit of RUCONEST (C1 Esterase Inhibitor [Recombinant]) in Improving Neurological Symptoms in Post-SARS-CoV-2 Infection
 

Funding​

The author(s) declare that financial support was received for the research and/or publication of this article. This study was funded by an educational grant from Pharming Healthcare Inc. The funder had no influence on study design, conduct, manuscript writing, or the decision to submit the manuscript for publication

Ruconest® (Pharming Technologies BV, Leiden, the Netherlands) is a recombinant human C1 esterase inhibitor (rhC1-INH)


I struggle to make much sense of this data. Surely there has to be a better way to present it?

They are planning an open label phase 2 study. Seems like a step backwards.

A step towards finding easier false positives to make bank off of? (Or keep investor money flowing)?
 
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