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[Efficacy of once-per-cycle administration pegylated recombinant human granulocyte colony-stimulating factor in chemotherapy-induced neutropenia in a phase I trial].

OBJECTIVE
To explore the efficacy of pegylated recombinant human granulocyte colony-stimulating factor (PEG-rhG-CSF) in the prophylaxis of chemotherapy-induced neutropenia.


METHODS
Patients with previously untreated non-small cell lung cancer or breast cancer and with normal bone marrow function were eligible for the trial. In the phase I trial, patients were to treated with two cycles of paclitaxel/carboplatin chemotherapy every 21 days. In cycle 1, if absolute neutrophil count (ANC) dropped below 1.0 x 10(9)/ L with fever and/or ANC dropped below 0.5 x 10(9)/L, rhG-CSF 150 microg/d was administrated until WBC > or = 10 x 10(9)/L or ANC > or = 5.0 x 10(9)/L. In cycle 2, patients were to receive a single injection of PEG-rhG-CSF (30, 60, 100, or 200 microg/kg) 48 hours after chemotherapy. Pharmacodynamic analyses were performed.


RESULTS
All the 16 patients enrolled (4 in each group) were eligible for efficacy evaluation. In cycle 1, 7 patients received rhG-CSF administration because of grade 4 neutropenia, while in cycle 2, there was only 1 episode of grade 4 neutropenia, which were in the 30 microg/kg group. In cycle 1, the mean ANC nadir of 1.37 x 10(9)/L occurred on day 13 in the 9 patients who received no rhG-CSF administration. In cycle 2, the mean ANC nadirs were 0.77 x 10(9)/L, 4.54 x 10(9)/L, 3.00 x 10(9)/L, and 5.56 x 10(9)/L, respectively, in 30, 60, 100, or 200 microg/kg group. The nadirs of the first two groups occurred on day 8 of cycle 2, while those of the other two groups appeared on day 7. After PEG-rhG-CSF administration, two mean ANC peaks were observed. The first one ranging from 20.87 x 10(9)/L to 33.61 x 10(9)/L in the 4 groups appeared on day 3 to day 4. In the 30 microg/ kg group, the mean ANC reached the second peak at 5.03 x 10(9)/L on day 14. The second peaks on day 10 in the other groups were 12.42 x 10(9)/L, 11.59 x 10(9)/L, and 18.92 x 10(9)/L, respectively. Pharmacodynamic analyses showed sustained serum concentrations of PEG-rhG-CSF during the period of neutropenia.


CONCLUSIONS
PEG-rhG-CSF administration may decrease the incidence of grade 4 neutopenia and result in earlier and higher nadir ANCs. PEG-rhG-CSF has a potential of once-per-cycle administration. The ANC and serum concentration of PEG-rhG-CSF are consistent with neutrophil receptor-mediated clearance.