Ancestim (r-metHuSCF) Plus Filgrastim for the Mobilization and Collection of Peripheral Blood Progenitor Cells for Autologous Transplant after Failure of Prior Mobilization: The French Experience of Compassionate Use.

Background: Ancestim (r-met human stem cell factor; Amgen Inc, CA, USA) is available in France for compassionate use in patients who have failed prior mobilization or an insufficient number of CD34+ cells for autograft. We retrospectively reviewed data from these patients to evaluate the efficacy of ancestim combined with filgrastim in achieving an adequate stem cell yield.

Patients and methods: Between January 1998 and July 2007, permission for ancestim use was granted by the French health authority and Amgen to 550 patients (pts) at 82 sites (median age 55 yrs (range, 18–74); 50% male). Non-Hodgkin’s lymphoma (NHL) accounted for 50% of pts, multiple myeloma (MM) 28%, chronic lymphocytic leukaemia 6%, Ewing’s sarcoma 4%, neuroblastomas 3%, ovarian carcinoma 1%, osteosarcomas 1%, and other tumours 7%. Of the 508 pts for whom data were available and analysed, 378 had undergone prior mobilization and 117 were considered to have insufficient harvests; mobilization history was unknown for 13 pts. Fifty-eight percent of the pts were treated with ancestim (20 microg/kg/day s.c.) and filgrastim (10 microg/kg/day s.c.) alone for a median of 6 days (range, 2–21), while the other pts received chemotherapy followed by ancestim (20 microg/kg/day s.c.) and filgrastim (5 microg/kg/day s.c.) for a median of 11 days (range, 1–33).

Results: The target threshold of 2x10⁶ CD34+ cells/kg was reached in 198/508 pts (39%) (including 51% of the 144 MM pts and 31% of the 254 NHL pts) after a median of 2 leukaphereses (range, 1–6). 35% of pts with prior mobilization failure and 52% of pts with prior insufficient harvests reached the target of 2 x10⁶ CD34+ cells/kg, with a median number of CD34+ cells harvested of 3.4 x10⁶/kg (range, 0.5–39.5). Of these, 150 pts (76%) proceeded to autologous transplantation. Data on engraftment are available for 137 pts: the median times to reach 0.5 x 10⁹/L neutrophils and 20 x 10⁹/L platelets were 12 days (range, 6–40) and 13 days (range, 0–31), respectively. All pts receiving ancestim were premedicated and treatment was generally well tolerated. Four pts were reported to have experienced severe mast cell-mediated reactions, none of which were life-threatening.

Conclusion: Ancestim plus filgrastim, alone or with chemotherapy, successfully rescued adequate CD34+ cell mobilization and collection in preparation for autologous transplantation in approximately 40% of pts.