Unrelated cord blood transplantation may be option for refractory severe aplastic anemia
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Unrelated cord blood transplantation served as a valuable curative option for patients with refractory severe aplastic anemia who had no matched related donors, according to findings from a phase 2 study.
“Outcomes remain poor for severe aplastic anemia patients refractory to first-line immunosuppressive therapy without matched unrelated donors. Recent use of eltrombopag [Promacta, Novartis] shows blood count improvements (40% of cases), but most refractory patients remain unresponsive to eltrombopag and other second-line treatments, exposing them to life-threatening complications,” Regis Peffault de Latour, MD, PhD, professor at Hôpitaux Saint-Louis in Paris, and colleagues wrote. “Moreover, clonal evolution, including paroxysmal nocturnal hemoglobinuria, myelodysplastic syndrome and acute myeloid leukemia may eventually occur.”
Hematopoietic stem cell transplantation using alternative donor sources — such as mismatched unrelated donors, cord blood and haploidentical family donors — may be curative for patients with refractory disease, although complications such as graft rejection, infection and graft-versus-host disease are greater than for transplantations from matched related or unrelated donors.
The researchers performed a nationwide phase 2 study of 26 patients (median age, 16 years) with refractory severe aplastic anemia who had one or two unrelated cord blood units totaling 4x107 frozen nucleated cells/kg available.
Patients received a conditioning regimen of fludarabine, cyclophosphamide, thymoglobulin and a total of 2-Gy of total body irradiation. They also received one injection 150mg/m2 of rituximab (Rituxan; Genentech, Biogen) to prevent Epstein-Barr virus reactivation, and cyclosporine as prophylaxis against graft-versus-host disease.
OS at 1 year served as the study’s primary endpoint. Engraftment, graft-versus-host disease, infections, relapses and causes of death served as secondary outcomes.
Median follow-up was 38.8 months.
Engraftment occurred among 23 patients (88%). The OS rate at 1 year was 88.5% (n = 23), which represented a significant improvement from the 20% expected rate (P < .0001).
The incidence of grade II to grade IV acute GVHD was 45.8%, and the incidence of grade II to grade IV chronic GVHD was 36%.
“Pediatric and young adult severe aplastic anemia patients refractory to first-line immunosuppressive therapy may therefore now be safely considered for cord blood transplantation,” the researchers wrote. – by Andy Polhamus
Disclosures: The authors report no relevant financial disclosures.