Donor Versus No Donor Analysis of Newly Diagnosed Myeloma Patients Included in the HOVON 50/54 Study

The value of allo-SCT in myeloma is disputed. Prospective randomized trials are the gold standard for the evaluation of treatment efficacy; however such a design is difficult to perform in an allo-setting. As the availability of a matched sibling donor is a random process, the presence or absence of a donor can be used as a surrogate for randomization. Patients with an HLA–identical sibling donor, included in the phase-III HOVON50 study, that was designed to assess the effect of thalidomide in induction treatment and as maintenance after high-dose therapy (HDM 200 mg/m2) and auto-SCT could proceed to the Hovon 54 study in which an Allo-SCT after conditioning with low dose TBI only was performed between 2–6 months after HDM. In the first survey performed in a subset of patients that had received at least 1 course of HDM and for whom tissue typing data were already available, 124 could be classified as having a sibling donor and 124 as having no sibling donor. Tissue typing data of another 81 patients are still waited for. Both groups were comparable with regard to age, myeloma stage, and prognostic factors including cytogenetics and ISS stage. 94% of the patients in the no donor group achieved at least a PR (35% CR, 32% VGPR and 26% PR), versus 96% of the patients in the donor group (40% CR, 34% VGPR and 22% PR). After a median follow-up of 38 months after HDM, PFS and OS were also comparable between the two groups. Median PFS was 32 versus 28 months for the donor group and no donor group respectively (P=0.44), while median OS was 61 and 54 months (P=0.14). Among the 98 patients in the donor group who received an allo-SCT non relapse mortality was 10% at 1 year and 13% at 3 years after allo-SCT. This first preliminary analysis showed no improvement of tandem Auto Allo-RIC as part of first line therapy in myeloma as compared Auto-SCT followed by maintenance therapy. A longer follow-up may be needed for definite conclusions. An update of the results including those patients with yet unknown tissue typing status and longer follow up will be presented