High-dose chemotherapy followed by two procedures for stem-cell transplantation may offer new hope for patients with multiple myeloma, a cancer of the white blood cells with no known cure.
The procedure appears to increase survival and reduce toxicity, compared to treatment with a conventional transplant, according to initial results from Hutch researchers.
Dr. David Maloney of the Clinical Research Division presented preliminary findings earlier this month at the American Society for Hematology meeting in Orlanda, Fla.
The first step in the two-step process is high-dose chemotherapy followed by a transplant using the patient's own stem cells to reduce the disease burden. Typically, patients undergoing high-dose chemotherapy often experience potentially fatal complications.
The second step, one to three months later, is known as a mini-transplant, during which the patient undergoes low-dose radiation followed by an infusion of stem cells from a matched brother or sister. Success relies on cancer-fighting properties of the donated stem cells, the cells that give rise to the blood and immune system.
"Harnessing the power of the donor immune system to eradicate cancer with a lower toxicity is exciting and promising," Maloney said. "The process, called allogeneic immunotherapy, has also been successfully used for the treatment of patients with leukemia, lymphoma and a solid tumor called renal cell cancer."
The study involved 41 patients, ages 39-71, who had advanced-stage multiple myeloma. All patients had undergone chemotherapy to treat their disease. More than a year after treatment, 85 percent of these patients are alive, leading researchers to believe that this two-step treatment option has real potential as a cure. Several patients treated three years ago are now free of disease.
The concept of mini-transplantation was developed at the Hutch by group led by Dr. Rainer Storb, head of Transplantation Biology.
Maloney and colleagues believe that by separating the high-dose conditioning regimen from the immunotherapeutic effect of mini-transplantation, there is a decrease in death from transplant-related complications.
Mini-transplantation establishes an initial tolerance between the donor cells and the patient's own tissues, a phenomenon called "mixed hematopoietic chimerism." Later, the new immune system of the donor replaces the patient's bone marrow. In the process, the donor immune system attacks the malignant myeloma cells, through what is known as a graft-versus-myeloma effect.
Little or no hospitalization
The mini-transplant requires little or no hospitalization. Clinic visits are two to three times a week the first month and once or twice a week for the duration of the recovery period. Treatment-related toxicities are mild to moderate.
The low-dose radiation used in mini-transplants does not cause the usual, severe side effects associated with a high-dose transplant such as nausea, vomiting or diarrhea, and patients do not lose their hair. More significantly, blood counts never drop below levels the body needs to fight infections and stop bleeding.