Stem cell transplantation using non-myeloablative conditioning regimen with fludarabine for hematological malignancies

Abstract

Stem cell transplantation (SCT) is a useful treatment for hematological malignancies, but it is limited to younger patients because of its high treatment-related mortality. Fludarabine (Flu), a novel anticancer agent with potent immunosuppressive activity, used as a conditioning regimen (reduced intensity transplantation; RIST), can decrease treatment-related mortality, as recently reported. However, the best drug combination and the best timing for RIST remain unknown. We herein report the SCT outcomes of 36 patients undergoing Flu treatment at our institution since December 2002 and retrospectively analyze the results. RIST conditioning with Flu was well-tolerated. No severe toxicity related conditioning regimens was observed in our patients, even though there were 10 patients with a history of autologous (n=5) or allogeneic stem cell transplantation (n=5). Hematological engraftment was found in 33 patients. The median times for reconstitution of WBCs, RBCs, and platelets were 16 days, 27.5 days and 34 days, respectively. Stable complete donor chimerism after SCT was present in all patients with WBC engraftment, and no patients experienced late rejection. Thirty-two patients were evaluated for acute graft versus host disease (aGVHD). Nine patients had no aGVHD. The incidence of grade I/II and III/IV aGVHD was 78% and 22%, respectively. Skin lesions were the major sites of involvement. Gut involvement was present in 9 patients. All 4 patients with grade IV GVHD had stage four hepatic GVHD. Twenty-two patients were analyzed for chronic GVHD (cGVHD). Twelve patients had no cGVHD, 6 had limited type and 4 had extended type. The overall survival (OS), relapse rate (RR), and non-relapse mortality (NRM) in all patients over 7 years were found to be 41.7%, 20.1%, and 34.6%, respectively. Induction failures were present in 5 cases of AML and 1 case of NHL. Disease progression was the primary cause of death, which occurred in 12 of 21 patients. Six patients died of grade IV GVHD (n=2) or complicated fungal infection contracted during the GVHD treatment (n=4). One patient died of secondary MSD, which originated from donor hematopoietic cells. Two patients died of cerebral bleeding and cardiac rapture, respectively. We found that the patients' state on SCT was the most important factor in long-term survival. The OS of standard risk and high risk patients with hematological malignancies were 75% and 30.3%. We concluded that stem cell transplantation using a non-myeloablative conditioning regimen with Flu was a useful therapeutic approach for patients with hematological malignancies.