Myeloablative allografting for chronic lymphocytic leukemia: evidence for a potent graft-versus-leukemia effect associated with graft-versus-host disease

Summary: In all, 30 patients with CLL proceeded to myeloablative allogeneic BMT using related ( n =20, 67%) or unrelated ( n =10) donors, at the Princess Margaret Hospital (Toronto) ( n =20) or the Leukemia/BMT Program of BC (Vancouver) ( n =10), from 1989 to 2001. Median (range) interval from diagnosis to BMT was 4.8 (0.3–13) years, median number of prior therapies was three and median age 48 years. The preparative regimen included total body irradiation in 15 (50%). In all, 14 of 30 patients (47%) are alive, with median (range) follow up of 4.3 (2.4–10.5) years. All are in complete remission, two following therapy for post-BMT progression. Actuarial overall (OS) and event-free survival (EFS) at 5 years is 39% (OS 48% for related donor and 20% for unrelated donor BMT); cumulative incidence of nonrelapse mortality (NRM) and relapse is 47 and 19%, respectively. Both acute (RR=0.008, P =0.01) and chronic (RR=0.006, P =0.02) Graft-versus-host disease (GVHD) were associated with markedly decreased risk of relapse. Patients receiving grafts from unrelated donors had increased NRM (RR=3.6, P =0.02) and decreased OS (RR of death=3.4, P =0.002). Allogeneic BMT has resulted in long-term EFS in approximately 40% of patients with CLL. There is evidence for a strong graft-versus-leukemia effect associated with acute and chronic GVHD, resulting in near complete protection from relapse.