Early lymphocyte recovery as a predictor of outcome, including relapse, after hematopoietic stem cell transplantation.

Background: Despite advances in the treatment of acute leukemia, many patients need to undergo hematopoietic stem cell transplantation. Recent studies show that early lymphocyte recovery may be a predictor of relapse and survival in these patients.

Objective: To analyze the influence of lymphocyte recovery on Days +30 and +100 post-transplant on the occurrence of relapse and survival.

Methods: A descriptive, retrospective study was performed of 137 under 21-year-old patients who we resubmitted to hematopoietic stem cell transplantation for acute leukemia between 1995 and 2008. A lymphocyte count < 0.3 x 10(9)/L on Day +30 post-transplant was considered to be inadequate lymphocyte recovery and counts ≥ 0.3 x 10(9)/L were considered adequate. Lymphocyte recovery was also analyzed on Day +100 with < 0.75 x 10(9)/Land ≤ 0.75 x 10(9)/L being considered inadequate and adequate lymphocyte recovery, respectively.

Results: There was no significant difference in the occurrence of relapse between patients with inadequate and adequate lymphocyte recovery on Day +30 post-transplant. However, the transplant-related mortality was significantly higher in patients with inadequate recovery on Day +30. Patients with inadequate lymphocyte recovery on Day +30 had worse overall survival and relapse-free survival than patients with adequate recovery. There was no significant difference in the occurrence of infections and acute or chronic graft-versus-host disease. Patients with inadequate lymphocyte recovery on Day +100 had worse overall survival and relapse-free survival and a higher cumulative incidence of relapse.

Conclusion: The evaluation of lymphocyte recovery on Day +30 is not a good predictor of relapse after transplant however patients with inadequate lymphocyte recovery had worse overall survival and relapse-free survival. Inadequate lymphocyte recovery on Day +100 is correlated with higher cumulative relapse as well as lower overall survival and relapse-free survival.