Late relapses following reduced intensity allogeneic transplantation in patients with multiple myeloma: a long‐term follow‐up study

Summary We analysed the long‐term outcomes of 60 multiple myeloma patients who underwent reduced intensity allogeneic stem cell transplantation between A ugust 2000 and M arch 2008. Regimens included fludarabine and melphalan conditioning (flu‐mel regimen) for allogeneic haematopoietic cell transplant ( HCT ) or a planned tandem regimen consisting of high‐dose melphalan conditioning for autograft followed by low‐dose total body irradiation conditioning for allogeneic HCT (auto‐allo regimen). Donors included human‐leucocyte‐antigen‐matched siblings ( n  = 55) or matched unrelated donors ( n  = 5). With a median follow‐up of 9·8 years, 7‐year overall survival ( OS ) and progression‐free survival ( PFS ) were 60% and 31%, respectively. By multivariate C ox regression analysis, disease status of complete response ( CR ) or partial response ( PR ) at transplant and the presence of chronic graft‐ versus ‐host disease were significantly associated with improved OS . Only disease status was significantly associated with improved PFS . We noted a surprising number of very late relapses, with six patients (10%) relapsing between 6 and 12 years post‐transplant. Among the six late relapse patients, all were transplanted within 14 months of diagnosis, five had normal karyotypes, and five were in CR / PR . Our data provide additional evidence that, while survival may be extended by reduced intensity allogeneic transplant, ultimately, it may not offer a cure.