Minimal residual disease after bone marrow transplantation for multiple myeloma: evidence for cure in long-term survivors.

Allogeneic bone marrow transplantation (BMT) can induce long-term complete remission (CR) in patients with multiple myeloma but it is not yet clear whether the disease can be eradicated. We have used immunoglobulin gene fingerprinting, a PCR-based technique, to evaluate minimal residual disease in 5 patients in unmaintained CR 9-60 months after allogeneic BMT. All 5 patients were PCR-positive within the first year after BMT, suggesting that early PCR positivity is common and not predictive of relapse. Three patients were studied at > 1 year post-transplant; one had become PCR-negative at 1 year, a second at 2 years and the third at 4.5 years post-BMT. The ability of the technique to detect clonal evolution was demonstrated by serial studies in a further patient who relapsed post-BMT. The absence of any detectable disease at the molecular level in 3 patients in long-term CR post-transplant suggests that cure of multiple myeloma may be a realistic goal.