Tandem transplantation in multiple myeloma

The use of high-dose chemotherapy and autologous stem cell support in the past decade has changed the outlook for patients with multiple myeloma. In newly diagnosed patients, complete remission rates of 25% to 50% can be achieved, with median disease-free and overall survivals exceeding 3 and 5 years, respectively. Despite these results, autologous transplantation has not changed the ultimately fatal outcome of the disease, as there is no substantial evidence of "cure" in most published studies. An additional high-dose chemotherapy course (with tandem transplants) appears to improve progression-free survival, although the effect is not discernible until 3 to 5 years posttransplant. The recent reports of tandem autologous transplant for maximum cytoreduction followed by nonmyeloablative allogeneic transplant for eradication of minimal residual disease appears promising and deserve further investigation. A central issue of tandem transplants, whether they involve autologous or allogeneic transplants, revolves around defining the subsets of patients who will benefit from the procedure. Good-risk patients (defined by normal cytogenetics and low beta-2-microglobulin levels), especially those who achieve a complete or near-complete response after the first transplant, appear to benefit the most from a second cycle. High-risk patients (defined by chromosomal abnormalities usually involving chromosomes 11 and 13 and high beta-2--microglobulin levels) whose median survival after tandem transplant is less than 2 years should be offered novel therapeutic interventions such as tandem "auto/allo" transplants. Until the efficacy and safety of this procedure is fully established, it should be limited to high-risk patients.