A Study of CLN-978, a Subcutaneously Administered CD19-directed T Cell Engager, in Subjects With Sjogren's Disease

Inclusion * Diagnosis of SjD at least 24 weeks prior to Screening Visit and meet the 2016 EULAR / ACR Classification Criteria for SjD at Screening. * Have active moderate to severe disease (i.e., ESSDAI ≥5) at Screening. * Laboratory parameters including the following: * Absolute lymphocyte count (ALC) ≥0.5 × 10\^9/L * Peripheral CD19+ B cell count ≥25 cells/µL * Absolute neutrophil count (ANC) ≥1.0 × 10\^9/L * Hemoglobin (Hgb) ≥8 g/dL * Platelet count ≥75 × 10\^9/L * Total bilirubin ≤1.5 × ULN, except patients with confirmed Gilbert's Syndrome * Aspartate aminotransferase (AST) and Alanine aminotransferase (ALT) ≤2.0 × ULN * Estimated glomerular filtration rate (eGFR) based on the CKD-EPI formula ≥30 mL/min/1.73 m2 Exclusion * Concomitant rheumatological autoimmune disease * Considered at high risk for thrombosis * Rapidly progressive glomerulonephritis and/or urine protein/creatinine \>3 mg/mg (339 mg/mmol). * Active, severe central nervous system manifestations of SjD. * History of stroke, seizure, dementia, Parkinson's disease, coordination movement disorder, cerebellar diseases, psychosis, paresis, aphasia, and any other neurologic disorder that the Investigator feels would put the patient at undue risk or confound study results. * Evidence of hepatitis B virus (HBV), hepatitis C virus (HCV), human immunodeficiency virus (HIV), Epstein-Barr virus (EBV), or cytomegalovirus (CMV) infection. * Primary immunodeficiency or history of recurrent infections. * History of splenectomy. * Live or attenuated vaccine within 28 days prior to the Screening Visit or during the Screening Period. * Active, clinically significant bacterial, viral, fungal, mycobacterial, parasitic, or other infection, including severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, within 14 days prior to Day 1. * Active or latent tuberculosis (TB)