Impact of Human T Cell Lymphotropic Virus Type 1 and 2 Infection on Survival Following Stem Cell Transplantation

Human T cell lymphotropic virus types 1 and 2 (HTLV-1/2) are delta retroviruses. HTLV-1 may lead to complications, including adult T cell leukemia-lymphoma (ATLL) and HTLV-1-associated myelopathy. Immunosuppression may result in progression from an asymptomatic carrier state to ATLL. Data on the safety of stem cell transplantation (SCT) in patients with HTLV-1/2 infection are lacking. The Center for International Blood and Marrow Transplant Research database was queried for patients who tested positive for HTLV infection in the pretransplantation workup and underwent either autologous SCT (autoSCT) or allogeneic SCT (alloSCT). Patients were excluded if they underwent SCT for ATLL. The primary outcome was overall survival (OS) at 3 years and 4 years post-SCT. In those who underwent autoSCT, 54 patients were HTLV-positive and 9836 were HTLV-negative. In those who underwent alloSCT, 105 patients were HTLV-positive and 18,077 were HTLV-negative. No difference in OS was noted between the HTLV-positive and HTLV-negative patients at 3 years post-autoSCT (76% versus 77%; P = .916). Inferior OS (32% versus 46%; P = .017) and nonrelapse mortality (35% versus 27%; P = .030) were observed in HTLV-positive patients at 4 years post-alloSCT. Future work should examine the mechanism by which HTLV-1/2 impact survival in alloSCT recipients.