Long-term follow-up results of two stem cell transplantation trials were presented at the 2008 American Society of Hematology (ASH) meeting. The trials were conducted from April 2000 to April 2004 in high risk de novo multiple myeloma patients. De novo multiple myeloma refers to the first occurrence of cancer in the body.

The two trials compared autologous transplantation followed by non-myeloablative allotransplantation (trial IFM99-03) with tandem (double) autologous transplantation (trial IFM99-04).  In the autologous transplantation procedure, a patient's stem cells are collected and stored prior to chemotherapy and later returned to the same patient following treatment to improve the response rate to the treatment. Non-myeloblative allotransplantation is a stem cell transplant from an allogeneic donor (a genetically different person) that employs a less aggressive chemotherapy or radiation treatment to prepare the patient for the transplant. The procedure aims to suppress the patient's immune system to allow engraftment of the donor cells. In order to prevent the immune system from rejecting the transplant, the recipient and the donor must have identical HLA (human leukocyte antigen) genes.

Protocols for both trials consisted of four courses of vincristine, doxorubicin, and dexamethasone (VAD), followed by melphalan and autologous stem cell transplantation (ASCT). The IFM99-03 protocol was followed if a HLA-identical sibling donor was available.  In this trial, ASCT was followed by non-myeloablative allotransplantation. The IFM99-04 protocol was followed when no donor was available. These patients were randomized to receive a second ASCT.

Sixty-five patients participated in the IFM99-03 trial, and 219 participated in the IFM99-04 trial. Event-free survival was examined in all 264 patients at a median follow-up time of 56 months.  Results did not differ significantly between the two trials.  However, overall survival time, or the length of the time that a patient survives, was superior in IFM99-04.  Similar results were found for patients who completed their entire protocol.

The results indicate that, in a subgroup of patients with high-risk de novo multiple myeloma, tandem ASCT is at least equivalent or even superior to ASCT followed by non-myeloablative allotransplantation.

For more information, see abstract 1126 from ASH 2008.