Could knee inflammatory synovitis be induced by pembrolizumab?

Pembrolizumab, a selective anti-PD-1 humanized monoclonal antibody, reactivates T cells to fight cancer. Immune-related adverse events such as autoimmune colitis, pneumonitis, hepatitis, nephritis, hypophysitis, and thyroiditis may occur during, or weeks to months after therapy. Pemprolizumab-induced synovitis is rarely reported. With the wide use of immunotherapy to treat cancers, physicians need to be aware of this rare immune-related adverse event and provide immediate treatment to avoid permanent joint damage.