Reduced Intensity Bone Marrow Transplantation Offers New Hope for Older Leukemia Patients

City of Hope
Sunday, 1 June 2003

Bone marrow transplantation (BMT) is an effective treatment for leukemia and other life-threatening hematologic diseases, but oncologists have traditionally used it only in younger patients because of its potential toxic side effects. Patients over 60 years of age, who account for the majority of blood cancer cases such as leukemia, lymphoma and multiple myeloma have been unable to take advantage of this potentially life-saving technique.

A new, less toxic form of bone marrow transplantation brings the benefits of this procedure to older patients with hematologic malignancies. Known as "reduced intensity bone marrow transplantation," the procedure reduces side effects by lowering the doses of chemotherapy and radiation typically employed in BMT. At the American Society of Clinical Oncology meeting in Chicago, researchers from City of Hope Cancer Center presented the results of reduced intensity BMT in 23 patients over the age of 60.

"The results thus far are comparable to conventional BMT in younger patients," said Henry Fung, MD, division of Hematology/Bone Marrow Transplantation at City of Hope Cancer Center. "The message is that we are overcoming the age barrier."

With conventional BMT, high doses of radiation and chemotherapy are used to destroy the leukemia patient's bone marrow to eliminate diseased cells and to "make room" for healthy bone marrow from a matched donor. In recent years, according to Dr. Fung, researchers have shown that lower doses of chemo- and radiation therapy that only partially destroy the patient's bone marrow may be sufficient to allow the donor's bone marrow to engraft and thrive.

"The new bone marrow cells generate a healthy immune system that see the remaining cancer cells as 'foreign' and destroys them," said Dr. Fung.

Because it uses lower dosages, reduced intensity BMT has fewer toxic side effects and is more suitable for older patients. In the protocol used at City of Hope, patients were given radiation and chemotherapy doses much lower than the conventional dosage used in transplant regimens. Of the 23 patients treated over the past three years, 13 patients are currently in remission with no evidence of disease progression, although Dr. Fung cautions that it is too early to tell if they have been "cured."

Dr. Fung notes that these statistics are comparable to those of conventional BMT in younger leukemia patients, in which about 50-60 percent of transplantation recipients achieve long-term survival, and about 20 percent die from toxicity of the procedure.

The protocol used at City of Hope incorporated two recent advances in transplantation science which Dr. Fung credits to the success of the new procedure. The first is a new regimen of drugs used to suppress the patient's own immune system to allow the donated blood marrow cells to engraft. The new regimen includes a traditional immunosuppressant—cyclosporine, and a newer drug—Cellcept®.

The researchers also used bone marrow stem cells harvested from the donors' peripheral circulating blood, rather than surgically removed from the donor's bone. In recent years, researchers have found that bone marrow stem cells harvested in this way engraft and generate a new immune system faster than cells removed directly from the bone, an important factor in older patients. Harvesting peripheral stem cells, Dr. Fung added, is also much easier for donors.

For more information, or to contact City of Hope, see their website at: www.cityofhope.org