A rash, diarrhea, and poor liver function are signs that transplant doctors know well. They mean that their leukemia patient may be getting into trouble following a procedure called stem cell transplantation. This complication is known as graft versus host disease or GVHD.

Standard drugs work to prevent the rejection of the stem cells 40% of the time, but doctors are searching for ways to help those who do not benefit from these drugs. A new study reported in the journal Blood (Vol. 98, No. 7: 2052-2058) found that a method using monoclonal antibodies to treat GVHD improved survival.

Many blood cancers, such as leukemia, are being treated with stem cell transplantation. These cells are separated from the blood and then transfused into the leukemia patient after he or she has received large doses of chemotherapy and sometimes radiation.

After a few days, the stem cells begin to grow in the patient's marrow and form new cells. But unless the donor was an identical twin, these new cells see the patient as a foreign tissue. By one to three months, they begin to react against their host, the patient. This leads to acute GVHD, which can kill the patient if it is severe.

Over the years, doctors have developed many ways of preventing and treating severe GVHD. All transplant patients receive drugs to suppress their immune systems to block this reaction.

Sometimes, these don't work and patients will develop signs of acute GVHD. Then the patients are given drugs such as steroids. This is successful about 40% percent of the time.

In this study, doctors representing the major transplantation centers in the US treated 59 patients with acute GVHD. Steroid treatment did not work, and for most it was life threatening.

Patients were treated with a monoclonal antibody called ABX-CBL. An antibody is a protein in the blood that is part of the immune system and helps fight infection. A monoclonal antibody is an antibody made in the lab. These man-made proteins are designed to attack certain immune system cells. And these cells, called T-lymphocytes, are responsible for GVHD.

About 40% of the patients in this study improved. This proved to be life-saving because most of the patients who did not respond died, while over half the patients who got better survived.

The monoclonal antibody drug is a small step toward improving patient survival. It has some serious side effects, including severe muscle pain. Also, after a little over a year, most of the patients had died, though not all of acute GVHD.

Experts in stem cell transplantation say there are other drugs and treatments that are available for patients with acute GVHD that may be as good. All are being tested and it is not known which of these treatments is best.

And, according to another report in the same issue of Blood, it appears that using younger stem cell donors reduces the risk of GVHD.

The problem of acute GVHD has increased because the major source of the stem cells has become unrelated donors. Matched unrelated donors stem cells are linked to more GVHD than are matched sibling stem cells.

Transplant doctors prefer to use a sibling for stem cell transplant, but most people do not have a sibling that matches them completely. Because of this, unrelated donors from our national registry are used.

But experts warn that GVHD is not all bad. In the past, doctors tried to eliminate GVHD by removing the donor T lymphocytes just before the transplant. This was successful and reduced the GVHD.

Without GVHD, often the leukemia would come back. It turns out that a little GVHD is helpful, because the T lymphocytes also react against any stray leukemia cells that might have survived the chemotherapy.