T-cell Depleted HSCT Associated with Lower GVHD Rates in ALL
NEW ORLEANS—For adults with acute lymphoblastic leukemia (ALL), ex-vivo T-cell depleted (TCD) allogenic hematopoietic stem cell transplant (HCT) is associated with a lower rate of graft versus host disease (GVHD) than conventional, unmodified allografts, according to a retrospective analysis presented at the 55th American Society of Hematology Annual Meeting and Exposition.
“HCT is an effective treatment modality for patients with ALL with favorable results with either conventional or TCD allografts,” reported Gabriela Hobbs, MD, of Memorial Sloan-Kettering Cancer Center (MSKCC) in New York, NY, and coauthors. “While 3-year OS [overall survival] rates are similar in both groups, TCD effectively reduces the rate of both acute and chronic GVHD.”
Relapse rate was lower after TCD-HCT (19.4% vs. 36.0%; P = 0.05) as well, but Dr. Hobbs cautioned that this finding needs to be confirmed in a prospective study.
The analysis compared outcomes for patients with acute lymphoblastic leukemia (ALL) in first or second complete remission, who received TCD-HCT at MSKCC (n = 52), or conventional grafts at M.D. Anderson Cancer Center in Houston, TX (MDACC; n = 129) between 2000 and 2010. All patients at MSKCC received myeloablative HCT conditioning; at MDACC, 115 of 129 patients received myeloablative HCT conditioning and the remaining 14 received reduced intensity conditioning.
“GVHD prophylaxis consisted of tacrolimus and mini-dose methotrexate, plus antithymocyte globulin for total dose of 4 mg/kg for unrelated donors,” they noted. “A greater percentage of patients in the conventional graft group received transplants from a matched related donor and from bone marrow as a stem cell source. Patients in the TCD group almost exclusively received grafts from peripheral blood.”
TCD and conventional grafts offer similar OS and relapse-free survival, but TCD grafts are associated with lower incidence of grade 2- to 4 acute and chronic GVHD and relapse, the authors found.
“A significant difference in acute GVHD incidence was observed between the TCD and conventional groups, with 100-day cumulative incidence estimates of 17.3% and 40.3%, respectively (P = 0.003),” they reported. “A significant difference was also observed in chronic GVHD rates, with three-year estimates of 13.5% and 34.8% for the TCD and unmodified groups, respectively (P = 0.003).”
The study was the first comparison of TCD versus conventional graft transplantation among patients with ALL, the researchers noted. Previous research has similarly shown that among patients with acute myeloid leukemia, TCD is associated with lower rates of GVHD, with comparable survival and relapse rates as those seen with conventional, unmodified allografts.
“This study adds to the growing body of literature suggesting that TCD is a safe and effective transplantation strategy,” Dr. Hobbs concluded.