Long-term follow-up of patients who achieved complete remission after donor leukocyte infusions

Donor leukocyte infusions (DLI) can induce a direct graft-vs-leukemia (GVL) reaction and restore complete remission for patients who relapse after allogeneic bone marrow transplantation (BMT). A critical and unanswered concern is the long-term safety and durability of DLI. To determine remission duration, long-term toxicity, and survival after DLI-induced remissions, we identified 73 patients who achieved complete remission after DLI. Follow-up information was obtained for 66 of the 73 patients, including 39 patients with chronic myelogenous leukemia (CML) and 27 patients with other diseases. Median follow-up for all patients was 32 months; the probability of survival at 1, 2, and 3 years was 83% (95% confidence interval [CI] 74-92), 71% (60-83), and 61% (49-74), respectively. For CML, survival probability at 1, 2, and 3 years was 87% (76-98), 76% (62-90), and 73% (58-88). For other diseases, survival probability at 1 and 2 years is 77% (61-93) and 65% (46-84). Five of 39 patients with CML relapsed, and 11 of 27 patients with other diseases relapsed. Treatment-related toxicity accounted for 10 deaths. Extended follow-up shows that DLI-induced remissions are durable, especially for patients with CML. Late relapses still occur, however, and toxicity remains significant. Continued follow-up will best define the long-term GVL effects of DLI, especially for diseases other than CML.