PERIPHERAL BLOOD STEM CELL AUTOGRAFTING: A NEW THERAPEUTIC OPTION FOR AML?

The last annotation on peripheral blood stem cell (PBSC) transplantation in the treatment of malignant disease proposed that clidical trials should be conducted to investigate the haemopoietic reconstitutive capacity of PBSC (Barr & McBride. 1982). A number of recent reports (Juttner et al. 1985. 1986a. b: Korbling et al. 1986: Reiffers et nl. 1986a: Bell et al, 1986a: Tilly et al, 1986: Castaigne et al. 1986: Kessinger et al. 1986: Stiff et nl. 1986) have now shown that PBSC are capable of haemopoietic reconstitution. These and other unreported cases have been summarized in a comprehensive review by Bell et a1 (1986b). PBSC are usually collected by continuous flow leukapheresis during periods of haemopoietic regeneration in very early remission from acute leukaemia or after chemotherapy in lymphoma .and solid tumours (Richman et al, 1976: Lohrmann et al, 1979). The collections contain higher numbers of myeloid pregenitor cells (CFU-GM)/kg BW than bone marrow (To et al, 1984: Bell at a] , 1986b: Gorin. 1986) and the peripheral blood CFUGM yield appears to be greater following intensive chemotherapy than after less myelosuppressive regimes (Reiffers et al. 1986b). There has been increasing interest in autografting using PBSC collected during very early remission of acute myeloid leukaemia (AML) because cells collected during this period of intense haemopoietic recovery may have low or ‘absent leukaemic contamination and give rise to rapid haemopoietic reconstitution (To et al, 1984: Juttner ef al, 1985). Because early animal (Micklem ef al, 1975: Nothdurft et al, 1977: Abrams et al, 198 1 ) and human (Goldman. 1978: Hershko et al, 19 79: Abrams et al, 1980: Korbling et al, 198 1: McCarthy & Goldman, 1984) studies using PBSC for autografting cast doubt on their haemopoietic reconstitutive capacity, the initial autografts in AML were mostly carried out in patients in relapse. The haemopoietic reconstitutive capacity of PBSC has now been established and the next logical step is to consider PBSC autografting in first remission of AML, in accordance with the current strategy in autologous bone marrow transplantation (Gorin et al, 1986: Cahn et al, 1986: Goldstone et al, 1986: Linch & Burnett, 1986). Several questions need to be answered before PBSC autografting during first remission of AML can be recommended as a new therapeutic option: Can the haemopoietic reconstitutive capacity of PBSC be predicted? Is the rate of haemopoietic recovery faster following PBSC autografting than following bone marrow autografting? Is immune reconstitution more rapid and complete following PBSC autografting than following bone marrow autografting? Are there leukaemic cells among PBSC collected during very early Correspondence: Dr C. A. Juttner. Division of Haematology. Institute of Medical and Veterinary Science, PO Box 14. Rundle Street, Adelaide, South Australia, Australia 5000. remission of AML? PBSC may be relatively deficient in stromal activity (To et al, 1986) but no data are yet available.