Please Tell Me About Monoclonal Antibodies and OKT3
&127; OKT3 is a drug sometimes used for "acute" organ rejection - meaning rejection that occurs suddenly and threatens to destroy a new organ very quickly. It may also be used to prevent rejection during the first 10 to 14 days after surgery in patients who have serious side effects with other immunosuppressive drugs.
OKT3 is made of a specially engineered monoclonal antibody that can target certain cells and stop their attack. It is an antibody to the T3 antigen of human T cells - those cells that directly attack a new organ. OKT3 prevents or reverses graft rejection by blocking the T cells and stopping their work. It has been available for general use since 1986. Reversal of rejection occurs in about 95 percent of patients given the drug. The major problem has been with side effects.
When side effects occur, they typically are seen within a few hours after the first dose. With the first or second doses, you may have flu-like symptoms, headaches, chills and fever, and nausea, diarrhea, and breathing problems. To reduce the side effects, patients may be given an antihistamine to reduce the allergic reaction, Tylenol¨ to prevent fever, and steroids such as Solu-Medrol¨ or Solu-Cortef¨ to diminish the allergic response. These are given 30 to 60 minutes before the OKT3.
OKT3 is usually given once a day in a very fast intravenous dose. It usually must be given in a hospital for the first three or four days and always requires close medical supervision. Interestingly, your body can form antibodies against OKT3. Therefore, blood tests are done during treatment to watch for signs of antibodies. In addition, you may need to have some extra blood tests before the drug can be used again - to assure the treatment will work.
Laboratory studies are underway to design new monoclonal antibodies that will block the side effects of OKT3. In addition, a whole new series of monoclonal antibodies are being looked at for use in organ transplant, including OKT4A, AntiTACac, T10B9.A-3A, and 33B3.1.