SELECTION AND EXPANSION OF PERIPHERAL-BLOOD CD34(-CELL TRANSPLANTATION FOR BREAST-CANCER() CELLS IN AUTOLOGOUS STEM)

Cytopenia after high-dose chemotherapy and autologous stem cell reinfu sion is a major cause of morbidity. Ex vivo cultured expansion and dif ferentiation of CD34(+) peripheral blood progenitor cells (PBPC) to ne utrophil precursors may shorten the neutropenic period further. We exp lored the use of these ex vivo cultured PBPCs in nine patients with me tastatic breast cancer. All underwent PBPC mobilization with cyclophos phamide, VP-16, and G-CSF. Subsequently, they underwent four to five a pheresis procedures. One apheresis product from each patient was prepa red using the Isolex 300 Magnetic Cell Separation System (Baxter Immun otherapy, Irvine, CA) to obtain CD34(+) cells. These cells were then c ultured in gas permeable bags containing serum-free X-VIVO 10 (BioWhit taker, Walkersville, MD) medium supplemented with 1% human serum album in and 100 ng/mL PIXY321. At day 12 of culture the mean fold expansion was 26x with a range of 6 to 64x. One patient's cells did not expand because of a technical difficulty. The final cell product contained an average of 29.3% CD15(+) neutrophil precursors with a range of 18.5% to 48.1%. The patients underwent high-dose chemotherapy with cyclophos phamide, carboplatin, and thiotepa. On day 0, the cryopreserved PBPCs were reinfused and on day +1 the 12-day cultured cells were washed, re suspended, and reinfused into eight of nine patients. One patient was not infused with cultured cells. The mean number of cultured cells rei nfused was 44.6 x 10(6) cells/kg with a range of 0.8 to 156.6 x 10(6) cells/kg. No toxicity was observed after reinfusion. The eight patient s have recovered absolute neutrophil counts >500/mu L on a median of 8 days (range 8 to 10 days); the median platelet transfusion independen ce occurred on day 10 (range 8 to 12 days) and platelet counts >50,000 /mu L were achieved by day 12 (range 9 to 14) for the seven patients w hose platelet counts could be determined. Expanded CD34(+) selected PB PC can be obtained and safely reinfused into patients. (C) 1996 by The American Society of Hematology.