Table.

Repurposing of immune-modulating therapies for COVID-19

	Mechanism of action
csDMARDs
Chloroquine or hydroxychloroquine	Interference with ACE2 to block virus invasion; increase of endosomal pH required for virus fusion; mild immune suppression
Glucocorticoids	Suppression of immune and inflammatory responses
Leflunomide	Inhibition of virus replication
Thalidomide	Reduction of inflammatory cell infiltration; reduction of cytokine storm; reduction of lung damage and pulmonary interstitial fibrosis
bDMARDs
Tocilizumab	Blockade of IL-6 receptor and its downstream signalling pathways
Anakinra	Blockade of IL-1 receptor and its downstream signalling pathways
tsDMARDs
Baricitinib	JAK inhibitor; blockade of viral invasion through the inhibition of AAK1; immune suppression
Ruxolitinib	JAK inhibitor; immune suppression
Cell therapy
Stem cells	Suppression of inflammation; proviral silencing
Plasma therapy
Convalescent plasma	Promotion of virus elimination via virus-specific antibodies

AAK1=AP2-associated protein kinase 1. ACE2=angiotensin-converting enzyme 2. bDMARDs=biologic disease-modifying anti-rheumatic drugs. csDMARDs=conventional synthetic disease-modifying anti-rheumatic drugs. IL=interleukin. JAK=Janus kinase. tsDMARDs=targeted synthetic disease-modifying anti-rheumatic drugs.