Clonal cytogenetic changes and myeloma relapse after reduced intensity conditioning allogeneic transplantation.

To identify a correlation between metaphase cytogenetics and relapse after reduced intensity conditioning (RIC) allotransplant for patients with multiple myeloma, data on 60 patients (median age 52) who received grafts from a sibling (n = 49) or unrelated donor (n = 11) were analyzed. Fifty-three patients (88%) showed chromosomal abnormalities (CA) before the allotransplant, including 42 with abnormalities involving 13q (CA13). Twenty-two patients (41%) relapsed post-allotransplant at a median of 165 days. Of these, 11 patients showed abnormal cytogenetics at the time of post-allotransplant relapse at a median of 167 days. Of 54 patients who developed graft-versus-host disease, relapse occurred in 19 of 48 patients (43%) with CA present before RCI allotransplant, versus 1 of 6 without CA (17%) (P = 0.06). Loss of CA before RIC allotransplant and disease status > PR after RIC allotransplant were significantly associated with a lower risk of post-allotransplant relapse with cytogenetic abnormalities; 5.2 vs 36%, and 18 vs 53%, (both P < 0.05), respectively. The current data suggests that myeloma associated with persistent clonal cytogenetic abnormalities is an entity which most likely escapes the effects of a graft versus myeloma activity, maybe because of acquisition of resistance to immunologic manipulations.