RWJ-445380

RWJ-445380 is an oral small molecule inhibitor of cathepsin S (CTSS), a cysteine protease involved in antigen presentation and immune system modulation. Cathepsin S is produced by antigen-presenting cells and plays a key role in activating CD4+ T lymphocytes. By inhibiting cathepsin S, RWJ-445380 was developed to modulate immune responses implicated in autoimmune diseases such as rheumatoid arthritis and plaque psoriasis. The drug was initially developed by ALZA Corporation (a Johnson & Johnson company) and later advanced by Johnson & Johnson Pharmaceutical Research & Development. It reached phase 2 clinical trials for both rheumatoid arthritis (as an adjunct to methotrexate therapy) and plaque psoriasis but did not progress further in development[1][2][3][9].