Umbilical Cord Blood Transplantation in Hematologic Diseases in Patients Over 15 Years Old: Long-term Experience at the Pontificia Universidad Catolica de Chile

Most patients who require a sibling stem cell transplantation do not have a matched donor. In our experience, only 1/3 patients have a matched unrelated donor (MUD); therefore, the majority of the patients will require umbilical cord blood (UCB). Patients treated for hematologic diseases with UCB transplants were included. UCB selection and conditioning regimens were performed according to the Minnesota group. Graft-versus-host disease (GVHD) prophylaxis, infection prevention, and patient care were performed according to institutional guidelines. We analyzed patients and graft demography, neutrophil and platelet recovery, chimerism kinetics, GVHD incidence, overall (OS), progression-free survival (PFS) and transplant-related mortality (TRM). We included 29 patients with a median age of 34.8 years (range 15-55). Eighteen were male and the median weight was 72.6 kg (range 54-100). Nineteen patients had acute leukemia. Myeloablative (MA) conditioning was used in 27 patients. Seventeen received double UCB (DUCB) grafts. Median total nucleated cell (10(7)/kg) was 4.2 (range 3.9-4.9) and 4.4 (range 2.8-6.3) for single UCB (SUCB) and DUCB transplants, respectively. Median time for neutrophil engraftment was 24.7 (range 14-43) and 25.8 days (range 14-52) after SUCB and DUCB transplants, respectively. Median time for platelet engraftment was 147 (range 30-516) and 81 days (range 37-200) after SUCB and DUCB transplants, respectively. All the patients receiving MA conditioning had >95% chimerism shortly after transplant. Cumulative incidence of grades II-IV and III-IV acute GVHD was 41% and 20%, respectively. Localized chronic GVHD was seen in 14% of the patients. Median follow-up was 16.7 months (range 1-63). Five-year OS and PFS were 38% and 39%, respectively. One-year TRM was 42%. UCB transplantation is associated with potential cure of hematologic malignancies and our results are similar to other series. Studies are needed to decrease mortality and improve immune reconstitution.