Effects of granulocyte‐macrophage colony stimulating factor produced in Chinese hamster ovary cells (regramostim), Escherichia coli (molgramostim) and yeast (sargramostim) on priming peripheral blood progenitor cells for use with autologous bone marrow after high‐dose chemotherapy

Abstract: Peripheral blood progenitor cells (PBPCs) were collected without prior association with chemotherapy but after the administration of granulocyte‐macrophage colony‐stimulating factor (GM‐CSF) produced in Chinese hamster ovary cells (CHO‐GM, regramostim), Escherichia coli (E. coli‐GM, molgramostim), or yeast (Yeast‐GM, sargramostim) and used in conjunction with autologous bone marrow after high‐dose chemotherapy in 69 patients with breast cancer or melanoma. The mean peripheral white blood cell (WBC) counts increased by 2.2 to 2.7‐fold after regramostim, 4.5 to 7.3‐fold after molgramostim and 4.3‐fold after sargramostim. All patients underwent three leukaphereses. The mean (± standard error) total nucleated pheresed cells per kg × 10⁸ were 4.15 ± 0.56, 15.10 ± 1.77 and 7.24 ± 1.00 for patients receiving regramostim, molgramostim or sargramostim respectively. The mean (± standard error) granulocyte‐macrophage colony‐forming units per kg × 10⁴ mobilized into the PB were 8.75 ± 3.63, 71.03 ± 17.85, and 65.11 ± 18.74 for patients receiving regramostim, molgramostim, or sargramostim respectively. The total mean (± standard error) CD34+ cells per kg × 10⁷ collected by three leukaphereses were 3.28 ± 1.62, 1.34 ± 0.51 and 2.57 ± 1.93, for patients receiving regramostim, molgramostim or sargramostim respectively. The use of either molgramostim‐ or sargramostim‐primed PBPCs led to complete elimination of absolute leukopenia with a WBC count under 100/mm³ in 64% and 77% of patients treated, respectively. Patients receiving molgramostim‐primed PBPCs required fewer red blood cells transfusions than patients receiving regramostim‐primed PBPCs (p = 0.0062). Our data indicate that PBPCs collected without prior association with chemotherapy but after either molgramostim or sargramostim with autologous bone marrow support and GM‐CSF shorten the hematopoietic recovery after myeloablative chemotherapy in patients with breast cancer or melanoma.