Tuesday 1 March 2011
Definition: Tremelimumab is a fully human IgG2 monoclonal antibody produced by Pfizer. Tremelimumab binds to the protein CTLA-4 , which is expressed on the surface of activated T lymphocytes.
Tremelimumab blocks the binding of the antigen-presenting cell ligands B7.1 and B7.2 to CTLA-4, resulting in inhibition of B7-CTLA-4-mediated downregulation of T-cell activation.
Subsequently, B7.1 or B7.2 may interact with another T-cell surface receptor protein, CD28, resulting in a B7-CD28-mediated T-cell activation unopposed by B7-CTLA-4-mediated inhibition.
Tremelimumab is thought to stimulate patients’ immune systems to attack their tumors. It has been shown to induce durable tumor responses in patients with metastatic melanoma in Phase 1 and Phase 2 clinical studies.
On April 2, 2008, Pfizer announced that it has discontinued a Phase III clinical trial for patients with advanced melanoma after the review of interim data showed that the trial would not demonstrate superiority to standard chemotherapy.
Studies for other tumors are planned as of October 2009[update], namely for prostate cancer and bladder cancer.
anti-CTLA-4 / CTLA-4 blockade