A phase II double-blind randomized study of the simultaneous administration of recombinant human interleukin-6 and recombinant human granulocyte colony-stimulating factor following paclitaxel and carboplatin chemotherapy in patients with advanced epithelial ovarian cancer

Cytokines for the Treatment of Thrombocytopenia

Multiple cytokines affect the cellular processes that occur during the transition of a hematopoietic stem cell (HSC) to a platelet. Thrombopoietin (TPO) is the physiological regulator of thrombopoiesis. Although a number of cytokines (interleukin [IL]-1, IL-3, and IL-6) were first evaluated for their ability to lessen the degree of thrombocytopenia occurring during a variety of clinical scenarios, their clinical development was abandoned due to their limited effectiveness or excessive toxicity. Clinical results with TPO and a truncated pegylated form of TPO, megakaryocyte growth and development factor (MGDF), were more promising, but the repeated use of MGDF resulted in the development of neutralizing antibodies. This adverse event halted the further clinical development of not only MGDF but also TPO. IL-11 also affects various stages of megakaryocytopoiesis and thrombopoiesis and its use has been shown to shorten the duration of chemotherapy-induced thrombocytopenia, which led to its approval by the US Food and Drug Administration (FDA). A growing number of new non-immunogenic peptides and non-peptide TPO agonists recently have entered clinical trials. These small molecules appear to be effective therapies and have acceptable toxicity, but additional clinical evaluation will be required prior to their approval for clinical use.

Granulocyte colony-stimulating factor (G-CSF) receptor gene expression of ovarian carcinoma does not correlate with G-CSF caused cell proliferation

BACKGROUND

Recombinant human granulocyte colony-stimulating factor (rhG-CSF) is a growth factor commonly used to avoid leukopenia after chemotherapy. Endogenous G-CSF is produced by macrophages and granulocytes that infiltrate tumors. It has been reported that rhG-CSF stimulates the proliferation of several cell lines as well as bladder carcinoma cells. Conversely, in some hematopoietic cell lines such as U-937, WEHI-3B, and K-562 no effect or in some cases a differentiation pattern was found. Moreover, the role of rhG-CSF on the proliferation of solid tumors is not well understood.

METHODS

In this study, 10 ovarian carcinoma biopsies were characterized for the presence of G-CSF and G-CSF receptor by reverse transcription-polymerase chain reaction (RT-PCR) and immunohistochemical analysis. Proliferation was analyzed by ATP viability assays.

RESULTS

Performing RT-PCR, these biopsies and four ovarian carcinoma cell lines were analyzed for endogenous G-CSF production, which was found in some biopsies and in all cell lines. Despite the presence of the G-CSF receptor in all biopsies and cell lines, no proliferation was found after rhG-CSF incubation of the cell lines or the tumor samples for 3 and for 6 days, respectively.

CONCLUSIONS

Summarizing the authors' in vitro studies, rhG-CSF does not affect the proliferation of ovarian carcinoma cells in vitro.

Pharmacologic treatment options in patients with thrombocytopenia

Thrombocytopenia that results from chemotherapy has become an increasingly important issue in the treatment of cancer and remains a difficult clinical problem. The identification of a safe and effective platelet growth factor could significantly improve the management of severe chemotherapy-induced thrombocytopenia. Over the past decade, a number of hematopoietic growth factors with thrombopoietic activity have been identified, including stem-cell factor (c-kit ligand), interleukin (IL)-1, IL-3, IL-6, and IL-11, as well as thrombopoietin (TPO) and its derivatives. Only a few of these agents have shown acceptable tolerability and sufficient ability to stimulate thrombopoiesis to justify testing in randomized clinical trials. Currently, IL-11 is the only cytokine licensed in the United States for treatment of chemotherapy-induced thrombocytopenia. However, its thrombopoietic activity is modest and its use is often associated with unfavorable side effects. Identification of TPO, the c-Mpl ligand, as the primary physiologic regulator of megakaryocyte and platelet development offers important promise for treatment of thrombocytopenia. Preliminary clinical studies of recombinant human TPO (rhTPO), a full-length glycosylated molecule, indicate that it is safe and biologically active in reducing severe chemotherapy-induced thrombocytopenia. In addition to rhTPO, the future may see the development of novel genetically engineered, high-affinity cytokine receptor agonists and c-Mpl ligand mimetic peptides.