AMGEN’s NEUPOGEN (G-CSF) REDUCES FEBRILE NEUTROPENIA EVENTS 44%
AMGEN's NEUPOGEN (G-CSF) REDUCES FEBRILE NEUTROPENIA EVENTS 44% after the first round of chemotherapy in a 126-patient study sponsored by the biotech firm and reported at the American Society of Clinical Oncology annual meeting in Washington on May 21. Of the 50 patients who had finished the six cycles of chemotherapy by April 30, 20 patients randomized to granulocyte colony stimulating factor (G-CSF) experienced no incidences of febrile neutropenia following chemotherapy with a combination of Cytoxan, Adriamycin, and etoposide. Only three patients in the placebo group avoided fever from neutropenia. The interim results of the 14-center, large-scale study in patients receiving chemotherapy for small cell lung cancer were presented by investigator Jeffrey Crawford, MD, Duke University. The 126 patients included in the study represent a little more than half of the target enrollment of 240 patients. Crawford noted that the mean number of days a patient was severely neutropenic (neutrophil count < 500) was 5.6 days in the placebo group versus 2.8 days in the G-CSF group. After six cycles of treatment, 75% of patients randomized to placebo developed febrile neutropenia compared to 45% of patients on GCSF. The total number of days of hospitalization and days on antibiotics were reduced by 40-50% in the drug group, Crawford added. Patients received chemotherapy during days 1-3 of each 21-day treatment cycle and self-administered 230 micrograms/m of G-CSF on days 4-17. Patients measured their own temperatures regularly and were tested for white blood cell counts three times a week. Crawford characterized toxicity as "minimal" with the most common side effect being transient bone pain in about 15% of patients. This side effect lasted for 24-48 hours and was treatable with analgesics, Crawford said. An initial concern in the use of colony stimulating factors had been the potential to stimulate tumor growth, Crawford noted. The initial data, however, shows an overall response rate to chemotherapy of 70-80% in both the placebo and G-CSF groups, which is "at least equivalent to other chemotherapy trials in small cell lung cancers," Crawford said. Asked during a press conference following his presentation whether patient quality of life was significantly improved by G-CSF, Crawford said that his "personal feeling" is that "the large number of patients [on G-CSF] tolerated treatment much better than patients I have dealt with in the past -- their blood counts were recovered within 12 days of chemotherapy which is unusual for patients." The study was designed to look at G-CSF's effect on reducing morbidity in patients with small cell lung cancer and did not look at mortality. Febrile neutropenia, a condition characterized by fever and low white blood cell count, is the most frequent cause of dose reduction or delay of chemotherapy in cancer patients. Crawford noted that several studies of G-CSF use following chemotherapy for other cancers, including lymphoma and breast cancer, are underway. Results from studies with Immunex's Leukine (GM-CSF or granulocyte macrophage colony stimulating factor) in autologous bone marrow transplantation were also presented at the meeting. A 41-patient study conducted by John Nemunaitis, MD, et al., Fred Hutchinson Cancer Center, Seattle, found that GM-CSF reduced the time to a neutrophil count of 1,000/microliter from 27 days to 18 days compared to placebo. The median number of days to achieve neutrophil counts of 100 and 500, however, were not statistically different between the groups. Patients received a regimen of cyclophosphamide and total body irradiation and were administered a two-hour daily infusion of 250 micrograms/m from day zero to 20. Immunex's GM-CSF significantly reduced the incidence of infections by 85% compared to placebo. Six of 19 patients (31%) in the placebo group developed infections compared to one of 22 patients (4.5%) in the GM-CSF group. GM-CSF patients also required 20 days of I.V. antibiotics compared to 24 days in the placebo group. Overall, GM-CSF treated patients were discharged earlier than placebo patients by a mean of 16 days, 27 v. 43 days. No GM-CSF related toxicities were observed. GM-CSF treatment also reduced platelet and red blood cell transfusions. The number of platelet units transfused within 28 days of bone marrow transplant was 82 units in the GM-CSF group compared to 109 units in the placebo group. Patients who received GM-CSF required nine units of red blood cells compared to 16 units for the placebo group. However, relapse and survival were identical in both groups at 80%, Nemunaitis noted. Preliminary data from a 54 patient trial conducted with Schering's GM-CSF in patients with myelodysplasia and aplastic anemia demonstrate a two- to 100-fold increase in neutrophils within two weeks of GM-CSF administration. Study director John Thompson, MD, University of Washington School of Medicine, reported that patients, who self-administered 3.0 micrograms/kg per day subcutaneously for three months, had less bacterial and fungal infections than the placebo group, 12% compared to 20%. A preliminary analysis of the entire 25 center study by Schering confirms that there is a statistically significant reduction in the incidence of severe infection in the GM-CSF group, Thompson said.
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