tgAAC94 is a recombinant adeno-associated virus serotype 2 (AAV2) vector genetically engineered to contain the cDNA for a human tumor necrosis factor receptor (TNFR)-immunoglobulin (IgG1) Fc fusion (TNFR:Fc) gene. The DNA sequence of TNFR:Fc in tgAAC94 codes for a protein sequence identical to etanercept (Enbrel®). TNF-alpha has been strongly implicated as a major participant in the inflammatory cascade that leads to joint damage and destruction in diseases such as rheumatoid arthritis (RA), psoriatic arthritis (PsA) and ankylosing spondylitis (AS).