A single autologous stem cell transplant is currently considered the standard of care for patients with multiple myeloma. However, there are a number of novel approaches that are being evaluated to try to improve patient outcomes. These are being conducted as clinical trials. These include the following:
- A tandem autologous transplant is an approach that utilizes two autologous transplants. Sufficient stem cells are collected prior to the first transplant. Three to six months after the first transplant, the patient receives a second similar course of high-dose therapy followed by infusion of the other half of the stored stem cells. Preliminary data indicates that tandem transplants result in improved disease control and survival in patients who do not experience either VGPR or CR following first autologous transplant.
- Radiopharmaceuticals (radioactive bone-targeted therapy) are combined with high-dose chemotherapy and autologous stem cell transplant as a means to increase response rates. This approach allows for a two-pronged attack on the myeloma through high-dose chemotherapy plus a radioactive compound that only attacks the bone marrow. There is currently a radiopharmaceutical agent in myeloma clinical trials: Quadramet (samarium Sm-153 lexidronam).
- A “mini” (non-myeloablative) allogeneic transplant involves the use of mild therapy (chemotherapy and/or radiation therapy) to suppress the patient’s immune system to allow for donor stem cells to grow. This dose of chemotherapy does not destroy the bone marrow but does allow for the donor’s blood cells and immune system to grow. After the lowered dose of chemotherapy is administered, the patient receives the donor’s stem cells. Once the allogeneic stem cells grow, the donor’s immune cells attack the myeloma. This is a form of immunotherapy. The risk of this procedure is that the donor’s immune system will “overreact” and attack more than the myeloma cells. This reaction is called “graft-versus-host disease,” which can be very serious and potentially life-threatening.
- Sequential autologous transplant followed by a mini allogeneic transplant. Pilot studies using sequential transplants have shown promise. This involves high-dose chemotherapy with an autologous transplant to destroy the majority of the myeloma cells, followed 2 to 4 months later by an allogeneic mini-transplant to allow the donor’s immune cells to destroy any remaining myeloma cells. As with a single mini allogeneic transplant, there is a risk of graft-versus-host disease, which can be very serious and potentially life-threatening.
- Maintenance therapy is an approach that involves lowered doses of anti-myeloma drugs to maintain longer remission and survival after a transplant. Currently, some of the drugs being evaluated include thalidomide, Revlimid, prednisone, and dexamethasone, alone or in combinations.