Multiple Myeloma (MM) is a clonal disorder of plasma cells. Plasma cells are part of the immune system. There are several types of plasma cells that make antibodies or proteins to protect us from infections. In MM, a specific type of plasma cell becomes cancerous and grows rapidly out of control. These cancerous plasma cells can make antibodies that do not work properly and can damage the kidneys and fail to fight infections.
More than 22,000 people in the United States are diagnosed with MM each year. It affects primarily older patients, with a median age of onset of 72 years. It is rarely seen in patients less than 40 years of age. The cause of MM is not known.
There are a number of treatment options for MM patients. Initial therapy includes chemotherapy and targeted therapy. Chemotherapy works by killing or slowing down the growth of cancerous cells. Targeted therapy works by blocking the growth and spread of cancer cells by disrupting specific parts of the cell cycle. If the disease is controlled with initial treatment and the patient is healthy enough, many patients will then have an autologous transplant.
Peripheral blood stem cells (PBSC) are the preferred blood-forming cells to be used for autologous transplant because of rapid and predictable engraftment. These cells are collected from the patient by a process called apheresis. Once collected the cells are then stored for use after the preparative regimen has been administered. The chemotherapy administered in the preparative regimen is designed to kill as many of the cancerous cells as possible. This therapy also destroys the normal blood forming cells in the bone marrow. To restore the marrow, the patient’s frozen PBSC are thawed and infused into the blood stream. From there, the cells find their way into the bone marrow where they start making healthy white blood cells, red cells and platelets.
Although the autologous transplant can get rid of many of the cancerous plasma cells, the disease almost always returns. When the disease comes back it is called a relapse. Some patients may be given chemotherapy treatment after the autologous transplant to delay the relapse. For some patients, depending upon a variety of factors, the patient my receive a second transplant before the disease relapses. The second transplant may be autologous or an allogeneic transplant.
Allogeneic transplants have been performed for MM. Whether an autologous or allogeneic transplant is right for an individual patient depends on patient age, overall health, and other complications. There are guidelines for when someone should be referred for a transplant consultation.