Infectious Complications After Unrelated Umbilical Cord Blood Transplantation (UCBT) in Adult Patients with Hematological Malignancies.

Abstract 1142

Poster Board I-164

Unrelated umbilical cord blood is being increasingly used as an alternative stem cell source for allogeneic stem cell transplantation. This retrospective study assessed infectious complications occurring in adult patients after UCBT.

Thrity-one patients received a single (n=4) or double UCBT (n=27) with a median dose of 4.7×10⁷ nucleated cells/kg (range, 2.4-7.7). Patients received either a reduced-intensity conditioning (n=23) or a standard myeloablative regimen (n=8). The cumulative incidence of neutrophil recovery was 90%. Neutrophil recovery was achieved at a median time of 24 (range, 8-60) days after UCBT.

With a median follow up of 10 (range, 3-30) months in surviving patients, the OS was 57% (95%CI, 38-84). At last follow-up, 10 patients have died. Relapse (n=5) and TRM (n=5) were the primary causes of death. In the 5 patients who died from NRM, the causes of death were secondary graft failure (n=1), refractory GVHD (n=2) and infectious-related mortality (n=2; cumulative incidence, 8%). The two patients who died from infectious causes had an EBV-related lymphoproliferative disorder and adenovirus infection respectively. Overall, 7 documented bacteremia were observed in 5 patients, at a median time of 7 (range, 3-277) days after UCBT. The cumulative incidence of first bacteremia was 16% in the whole study population and 21% (n=4/20) when excluding patients with graft failure. Recurrent CMV infection was detected in 6 patients at a median time of 36 (range, 26-89) days. No CMV disease developed after preemptive CMV therapy. The cumulative incidence of recurrent CMV infection was 21%. Of note, 4 of these 6 cases of CMV recurrences were diagnosed in patients with primary graft failure. Therefore, the cumulative incidence was only 11% when focusing on patients without graft failure. EBV reactivation occurred in 6 patients with a median time of 101 (range, 28-438) days after UCBT. Except for one patient who developed a fatal EBV-related lymphoproliferative disorder refractory to Rituximab, all other 5 cases of EBV infections were asymptomatic. Other isolated viruses included: BK-virus with hemorrhagic cystitis (n=6), adenovirus (detected in the blood, n=3), Varicella-Zoster Virus (n=1), Respiratory Syncitial Virus (rhinitis, n=1) and parainfluenzae 3 virus (rhinitis, n=1). Of note, HHV6 was systematically detected in recipient blood samples.

In all, 5 cases of fungal or parasitic infections were documented. Two cases of Toxoplasmosis gondii encephalitis were diagnosed in one patient with a primary graft failure and in another patient with a secondary graft failure (cumulative incidence of parasitic infections, 6%). Three probable pulmonary invasive aspergillosis were also diagnosed, two of which occurred in patients with refractory acute leukemias. The cumulative incidence of invasive fungal infections (IFI) was 10%. None of these fungal or parasitic infections was the primary cause of death. Overall, the cumulative incidence of infectious-related mortality (IRM) was 8%.

In conclusion, this data suggests that UCBT can be performed in adult patients with hematological malignancies with an acceptable incidence of IRM provided a sufficient dose of nucleated cells is infused to the patient.