Allogeneic hematopoetic stem-cell transplantation for patients with relapsed or refractory lymphomas: comparison of high-dose conventional conditioning versus fludarabine-based reduced-intensity regimens.

BACKGROUND: Allogeneic hematopoetic stem-cell transplantation (alloHSCT) has curative potential for poor risk lymphoma patients due to the graft-versus-lymphoma effect. High non-relapse mortality with conventional high-dose conditioning indicates the necessity for less toxic transplant strategies. PATIENTS AND METHODS: Between 1992 and 1999, 25 patients [median age 37 (20-60) years] with relapsed or refractory non-Hodgkin's lymphoma (NHL, n = 20) or Hodgkin's disease (HD, n = 5) received an alloHSCT in our institution. Patients were grafted from HLA matched (17) or mismatched (2) related, or matched unrelated donors (MUD) (6). NHL histological subtypes were lymphoblastic (6), high grade B/T-cell lymphomas (5), follicular (3), mantle cell (2) and CLL, immunocytic, composite lymphoma and panniculitic T-NHL in one patient each. Patients had received a median of four (range three to six) different therapies before alloHSCT, and 10 patients had relapsed after high-dose chemotherapy and autologous (9) or allogeneic (1) HSCT. Remission status prior to allogeneic SCT was CR1 (1), CR2 (1), relapse (11), partial remission (5) or primary refractory induction failure (7). Conventional myeloablative conditioning (cc) regimens contained total body irradiation 12 Gy (5), busulfan 16 mg/kg (7) or BCNU/VP16 (1). Twelve patients received reduced-intensity conditioning (ric) regimens with fludarabine (FLU) plus alkylating agents. Graft-versus-host disease prophylaxis consisted of cyclosporin A +/- prednisone or methotrexate. Six patients also received anti-T-lymphocyte globulin.
RESULTS: Twenty-four patients engrafted. Best response after alloHSCT was complete remission in 16 of all patients [64%: 95% confidence interval (CI) 44% to 84%] and in 16 of 22 evaluable patients (73%: 95% CI 53% to 93%), partial remission in three of 25 (12%), and no change in three of 25 (12%) patients. Early death prevented response evaluation in three of 25 patients. Non-relapse mortality was 54% (95% CI 15% to 78%) in patients after cc and 17% (95% CI 0% to 41%) after FLU-based ric (P = 0.03). Six patients died due to progressive disease or relapse. Four patients with HD died, three in complete remission due to non-relapse mortality and one with progressive disease. Eleven of 25 patients are alive with a median follow up of 618 days (range 383-2815), with an overall survival of 44% (95% CI 23% to 65%) at 1 year for all patients, while eight of 12 (67%: 95% CI 35% to 98%) patients are alive after ric compared with three of 13 (23%; 95% CI 0% to 50%) after cc (P <0.02).
CONCLUSIONS: AlloHSCT induces high rates of complete remission in advanced lymphoma patients, even when the tumor had relapsed after autologous HSCT. It should be considered earlier as part of the therapeutic options in poor risk patients to avoid non-relapse mortality associated with extensive pretreatment. Our novel reduced conditioning regimens show promising results, especially in heavily pretreated patients, and improve survival after allogeneic transplantation.