TRANSPLANTATION OF PERIPHERAL-BLOOD PROGENITOR CELLS FROM HLA-IDENTICAL SIBLING DONORS

Transplantation of peripheral blood progenitor cells (PBPCs) has large ly replaced autologous bone marrow transplantation. The same might occ ur in the allogeneic setting if the favourable initial experience with allogeneic PBPCT is confirmed. We analysed all primary transplants ut ilizing unmodified PBPC from HLA-identical sibling donors reported to the European Group for Flood and Marrow Transplantation (EBMT) for 199 4. 59 patients with a median age of 39 years received myeloablative th erapy for acute myelogenous leukaemia (23 patients), acute lymphoblast ic leukaemia (13), chronic myelogenous leukaemia (nine), lymphoma (sev en), or other diagnoses (seven) mostly of advanced stages followed by transplantation of allogeneic PBPC. Three patients died soon after gra fting, the others showed prompt haemopoietic recovery with median time s to recover an absolute neutrophil count (ANC) above 0.5 and 1.0 x 10 (9)/l of 15 (range 9-27) and 17d (range 10-28) respectively. Time to p latelet recovery above 20 or 50 x 10(9)/l was 16 (range 9-76) and 18d (range 12-100) respectively. 27 patients (46%) developed no or mild ac ute graft-versus-host disease (GVHD). The incidence of moderate (grade II) disease was 27%; 24% of the patients developed severe acute GVHD (grades III or IV). 55% of patients who were alive 90 d after transpla ntation developed chronic GVHD, the probability to develop extensive c hronic GVHD was 32% (95% confidence interval 22-42) with a median foll ow-up of 14 months. Overall and event-free survival (EFS) at 1 year we re 54% (CI 48-60) and 50% (CI 43-57), respectively, the relapse incide nce was 23% (CI 17-29). EFS was 67% (CI 55-79) in patients transplante d for acute leukaemias in first complete remission, chronic myelogenou s leukaemia in first chronic phase, or severe aplastic anaemia. Transp lantation of allogeneic PBPC resulted in prompt and durable engraftmen t. The incidence and severity of acute and chronic GVHD seemed compara ble to that observed after allogeneic BMT. Overall and event-free surv ival in this cohort of patients, most of whom suffered from advanced l eukaemia or lymphoma, is encouraging, suggesting that the high numbers of T lymphocytes and/or natural killer cells contained in a typical P BPC collection product exert a vigorous graft-versus-leukaemia effect. Further evaluation of allogeneic PBPCT is highly desirable.