Stem Cell Transplantation Indicative of Outcome in Multiple Myeloma

Quantity of Cancer Cells in Bone Marrow Following Stem Cell Transplantation Indicative of Outcome in Multiple Myeloma

According to a recent article published in the British Journal of Hematology, the amount of cancer cells detected in the bone marrow following autologous stem cell transplantation is indicative of a patient’s long-term prognosis.

Multiple myeloma is a cancer involving important immune (infection-fighting) cells called plasma cells. Plasma cells aid the body in fighting infection by producing specialized proteins called antibodies that have the ability to target and/or kill foreign cells. In multiple myeloma, cancerous plasma cells produce abnormal and excessive antibodies that do not have the ability to properly fight infection. In addition, the cancerous plasma cells accumulate in the bone marrow, suppressing the normal formation and function of other cells that are necessary for normal production of blood cells and immune functions. The excessive accumulation of cancer cells in the bone marrow ultimately leads to the formation of tumors in the bone and to the breakdown of bone. Standard treatment for multiple myeloma is chemotherapy with or without stem cell transplant.

High-dose therapy (chemotherapy and/or radiation) kills more cancer cells than moderate doses. However, more healthy cells, including stem cells, are also killed due to the high doses, often causing significant side effects. Stem cells are immature blood cells produced in the bone marrow that mature into red blood cells, which carry oxygen to tissues; white blood cells, which fight infection; and platelets, which aid the blood in clotting. Autologous stem cell transplants involve the collection of a patient’s stem cells prior to treatment and re-infusion following high-dose therapy to restore depleted blood cell levels. Long-term outcomes following autologous stem cell transplantation vary between patients and researchers continue to evaluate which patient or disease characteristics may help discern which patients will respond more favorably than others so that treatment considerations may be individualized.

Researchers from Belgium recently conducted a clinical study to determine whether the quantity of myeloma cells found in the bone marrow following autologous stem cell transplantation could help predict progression-free survival following treatment. The researchers used a laboratory test called a quantitative allele-specific oligonucleotide polymerase chain reaction (qASO-PCR) assay to measure the number of cells in bone marrow samples taken from patients following autologous stem cell transplantation. The researchers found that a specific cut-off (0.015% cancer cells in the specimen) significantly determined the duration of progression-free survival in these patients. Patients who were below the cut-off value had an average progression-free survival of approximately 64 months following a transplant, compared to only 16 months for those who had a cut-off value above the specified percentage. This association held true even with evaluation of several different disease or patient variables.

The researchers concluded that the use of qASO-PCR to determine the quantity of myeloma cells in the bone marrow appears to be an independent predictor of a patient’s progression-free survival following an autologous stem cell transplant. Patients who are deemed to have a worse prognosis may benefit from additional or more intensive treatment, while those who are found to have a good prognosis may not benefit from more aggressive therapy. Patients with multiple myeloma who are to undergo an autologous stem cell transplant or who have already been treated with a transplant may wish to speak with their physician about their individual risks and benefits of a qASO-PCR test or the participation in a clinical trial further evaluating novel screening methods.

Reference: Bakkus M, Bouko Y, Samson D, et al. Post-transplantation tumour load in bone marrow, as assessed by quantitative ASO-PCR, is a prognostic parameter in multiple myeloma. British Journal of Hematology. 2004;126:665-674.

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