Fixed-dose Pegfilgrastim is Safe and Allows Neutrophil Recovery in Patients with Non-Hodgkin's Lymphoma

Twenty-nine patients with non-Hodgkin's lymphoma received a single subcutaneous injection of 6 mg pegfilgrastim approximately 24 h after the start of CHOP chemotherapy. The safety of pegfilgrastim in this patient population was determined by reports of adverse events. The pharmacokinetics of pegfilgrastim were characterized and the duration of grade 4 neutropenia, time to absolute neutrophil count (ANC) recovery to > or = 2.0 x 10(9)/l, neutrophil nadir, and incidence of febrile neutropenia were determined in the first 21-day chemotherapy cycle. The incidence of grade 4 neutropenia in cycle 1 was 43% with a mean (SD) duration of grade 4 neutropenia value of 1.0 (1.4) day. No apparent relationship between the duration of grade 4 neutropenia and body weight was observed. The median [quartiles] time to ANC recovery was 10 [9, 11] days. The incidence of febrile neutropenia was 11%. No unexpected adverse events were reported and no patient developed antibodies to pegfilgrastim. Serum concentration of pegfilgrastim reached a maximum (median [quartiles]) of 128 [58, 159] ng/ml at approximately 24 h after administration, and was followed by a second smaller peak (median [quartiles]) of 10.6 [3.0, 20.5] ng/ml at the time of the neutrophil nadir. After the second peak, concentration of pegfilgrastim declined linearly with a median terminal half-life of approximately 42 h.

Blinded, randomized, multicenter study to evaluate single administration pegfilgrastim once per cycle versus daily filgrastim as an adjunct to chemotherapy in patients with high-risk stage II or stage III/IV breast cancer

PURPOSE

This multicenter, randomized, double-blind, active-control study was designed to determine whether a single subcutaneous injection of pegfilgrastim (SD/01, sustained-duration filgrastim; 100 microg/kg) is as safe and effective as daily filgrastim (5 microg/kg/d) for reducing neutropenia in patients who received four cycles of myelosuppressive chemotherapy.

PATIENTS AND METHODS

Sixty-two centers enrolled 310 patients who received chemotherapy with docetaxel 75 mg/m(2) and doxorubicin 60 mg/m(2) on day 1 of each cycle for a maximum of four cycles. Patients were randomized to receive on day 2 either a single subcutaneous injection of pegfilgrastim 100 microg/kg per chemotherapy cycle (154 patients) or daily subcutaneous injections of filgrastim 5 microg/kg/d (156 patients). Absolute neutrophil count (ANC), duration of grade 4 neutropenia, and safety parameters were monitored.

RESULTS

One dose of pegfilgrastim per chemotherapy cycle was comparable to daily subcutaneous injections of filgrastim with regard to all efficacy end points, including the duration of severe neutropenia and the depth of ANC nadir in all cycles. Febrile neutropenia across all cycles occurred less often in patients who received pegfilgrastim. The difference in the mean duration of severe neutropenia between the pegfilgrastim and filgrastim treatment groups was less than 1 day. Pegfilgrastim was safe and well tolerated, and it was similar to filgrastim. Adverse event profiles in the pegfilgrastim and filgrastim groups were similar.

CONCLUSION

A single injection of pegfilgrastim 100 microg/kg per cycle was as safe and effective as daily injections of filgrastim 5 microg/kg/d in reducing neutropenia and its complications in patients who received four cycles of doxorubicin 60 mg/m(2) and docetaxel 75 mg/m(2).

Megakaryocyte growth and development factor (MGDF): an Mpl ligand and cytokine that regulates thrombopoiesis

Megakaryocyte growth and development factor (MGDF) is a ligand for the Mpl receptor related to thrombopoietin (TPO). MGDF stimulates megakaryocytopoiesis and thrombopoiesis, and is highly selective to cells bearing the Mpl receptor. Studies done in rodents, nonhuman primates, and humans have confirmed that MGDF can increase platelet counts in normal and chemotherapy- or radiotherapy-treated subjects. Platelet function and physiology remain normal after MGDF administration, with no effect on platelet aggregation. Pegylated recombinant human MGDF (PEG-rHuMGDF) was used clinically with initial success. Cancer patients receiving chemotherapy showed dose-dependent increases in platelet counts and increases in bone marrow megakaryocytes. Clinical development of PEG-rHuMGDF was halted owing to the formation of neutralizing antibodies in some patients and normal volunteers who received the drug. The application of exogenous recombinant Mpl ligands should be explored in the setting of randomized clinical trials and the findings extended to mobilization of CD34+ stem cells, ex vivo expansion techniques, and use in platelet abnormalities.

Systemic effects of pegylated recombinant human megakaryocyte growth and development factor in combination with recombinant murine granulocyte colony-stimulating factor in a murine model of myelosuppression

Megakaryocyte growth and development factor (MGDF) stimulates megakaryopoiesis and thrombopoiesis in vivo. Previous studies indicate that administration of pegylated recombinant human (PEG-rHu) MGDF in combination with recombinant murine granulocyte colony-stimulating factor (rMuG-CSF) prevented lethality and reduced hematotoxicity in carboplatin-treated/irradiated mice, a disease-state animal model of radio-chemotherapy. In the current study we have further characterized the effects of PEG-rHuMGDF in combination with rMuG-CSF with respect to clinical chemistry, hematology variables, and histologic evaluations to determine whether any potential toxicological interaction exists both in normal and myelosuppressed mice. Myelosuppression and subsequent thrombocytopenia in mice was induced with a combination of a single intraperitoneal injection of 1.25 mg carboplatin followed 4 h later with sublethal gamma irradiation exposure of 500 rad. Both normal and carboplatin-treated/irradiated mice were administered daily subcutaneous injections of 50 micrograms/kg PEG-rHuMGDF alone and in combination with 10 micrograms/kg rMuG-CSF for 21 consecutive days. Administration of PEG-rHuMGDF alone or in combination with rMuG-CSF to carboplatin-treated/irradiated mice increased survival 70 and 100%, respectively, and accelerated platelet recovery. Microscopic examination of nonhematopoietic organs showed no evidence of any morphological changes in normal and carboplatin-treated/irradiated animals. In hematopoietic organs clinically significantly increased granulopoiesis and megakaryopoiesis, as well as extramedullary granulopoiesis within the mandibular and mesenteric lymph nodes, were present. The erythroid line was unaffected by cytokine treatment. In normal, non-carboplatin-treated/irradiated mice, platelet counts increased 6 and 12-fold above baseline in the groups administered PEG-rHuMGDF alone or in combination with rMuG-CSF, respectively. The results of this study provide a basis for coadministration of PEG-rHuMGDF with Filgrastim (rHuG-CSF) in the clinical treatment of myelosuppression induced by radiation and chemotherapy.