BTG3 and synovial sarcoma: CAR-T therapy shows promise for SS, illustrated by a case where anti-CD19 CAR-T induced serologic remission (ANA and anti-Ro-52 negative by day 90) with SS Activity Index (SSDAI)SSDAI dropping from 5 to 2 and normalization of serum cytokines by six months, despite initial grade 2 cytokine release syndrome and grade 1 neurotoxicity; yet clinical data in SS remain scarce, underscoring the need for further research (9).