Until three or four years ago, there weren't a lot of treatment choices for lymphoma patients who relapsed or had their cancer transform into a more aggressive form of the disease. Fortunately, these patients have many more options today due to targeted therapies such as Rituxan (rituximab), vaccines, stem cell transplants and the radioimmunotherapies, Zevalin (ibritumomab) and Bexxar (tositumomab).

Bexxar is the topic of today's blog.

Basically, radioimmunotherapies combine a drug with a radioactive substance. Bexxar is composed of the monoclonal antibody tositumomab and the radioisotope Iodine-131, which is attached to the antibody. In lay terms, radiation is usually given externally, but in the case of Bexxar it is given internally, attached to the tositumomab.

Approximately 90 percent of B-cell non-Hodgkin's lymphomas have the CD20 antigen on the surface of the cells. With Bexxar, tositumomab finds and sticks to the CD20 antigen, and the Iodine-131 then gives off radiation and kills the cells.

This differs from Rituxan (which only kills the cells that have the antibody attached), in that it may also kill other cancer cells near the cells to which Bexxar is attached. It's like a drive-by shooting. Anyone close to the target is at risk and can become collateral damage.

Bexxar has been approved for B-cell NHL patients who have already been treated and whose disease did not respond or has returned. It has also been approved for those with transformed disease. It is only given one time (unlike Rituxan, which can be given repeatedly).

The really good news is that results from investigational trials of Bexxar show that complete remissions can be achieved in newly diagnosed patients, as well as in end-stage patients who have exhausted all other options. Bexxar may soon become approved as a frontline treatment for several lymphomas.

As usual, with most drug therapies, Bexxar can be a little scary. Someone I know had Bexxar in the early years (it has been studied for 13 years), but it caused him some sleepless nights thinking before deciding to get it. He was in the hospital when it was administered and he didn't see anyone for two days. His food was given to him by staff dressed like astronauts because at that time they didn't know how high of a radiation contamination risk it was. If no one could even be in his presence, what was his level of contamination!? He was told not to share a bed with anyone or be around others for one to two weeks after his treatment. Scary stuff.

Diane Fallon

Diane's blog can be found at http://blog.healthtalk.com/lymphoma/

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