Ongoing clinical trials explore novel fatigue treatment targets in primary SS, including experimental drugs like Lanraplenib (spleen tyrosine kinase inhibitor), Filgoinib (Janus kinase-1 inhibitor), Tirabrutinib (Bruton’s tyrosine kinase inhibitor), CDZ173 (PI3K inhibitor), and Dazodalibep (CD40L antagonist and Tn3 fusion protein) (Mæland et al., 2021). This evidence concerns the gene CD40LG and synovial sarcoma.