The outcome of unrelated donor stem cell transplantation for patients with multiple myeloma.

We performed a retrospective analysis of outcome in 45 patients with multiple myeloma receiving unrelated donor stem cell transplants (UD-SCT) in the UK between 1993 and 2002; 17 received myeloablative conditioning regimens and 28 received reduced intensity conditioning (RIC) protocols. Forty patients received pretransplant CAMPATH serotherapy. Forty-two of 45 patients had detectable disease at transplant, but 33 of 45 were chemoresponsive. Sixty per cent of patients had received a previous autograft. Myeloid engraftment was seen in 95% of recipients and was significantly faster in recipients receiving peripheral blood stem cells (P = 0.07) and RIC (P = 0.001). The incidence of severe (grade 3/4) acute graft versus host disease (aGvHD) was 5% (2/40). The 100-d non-relapse mortality was 18% (5/38) following RIC and 53% (9/17) following myeloablative regimens. Twenty-nine per cent of patients achieved a complete remission, 61% a partial remission, giving a 90% overall response rate. At median follow-up (513 d), overall survival was 40%: 54% in the RIC group (median follow-up: 489 d) and 18% in the myeloablative group (median follow-up: 560 d). In recipients of UD-SCT, RIC protocols that incorporated CAMPATH were associated with faster myeloid engraftment, less severe aGvHD and lower 100-d non-relapse mortality than myeloablative regimens, without a corresponding rise in relapse rate during the period of observation.