Preclinical and clinical studies with the hematopoietic colony-stimulating factors and related interleukins

Preclinical immunogenicity testing using anti-drug antibody analysis of GX-G3, Fc-fused recombinant human granulocyte colony-stimulating factor, in rat and monkey models

Human granulocyte colony-stimulating factor (G-CSF, this study used Fc-fused recombinant G-CSF; GX-G3) is an important glycoprotein that stimulates the proliferation of granulocytes and white blood cells. Thus, G-CSF treatment has been considered as a crucial regimen to accelerate recovery from chemotherapy-induced neutropenia in cancer patients suffering from non-myeloid malignancy or acute myeloid leukemia. Despite the therapeutic advantages of G-CSF treatment, an assessment of its immunogenicity must be performed to determine whether the production of anti-G-CSF antibodies causes immune-related disorders. We optimized and validated analytical tools by adopting validation parameters for immunogenicity assessment. Using these validated tools, we analyzed serum samples from rats and monkeys injected subcutaneously with GX-G3 (1, 3 or 10 mg/kg once a week for 4 weeks followed by a 4-week recovery period) to determine immunogenicity response and toxicokinetic parameters with serum concentration of GX-G3. Several rats and monkeys were determined to be positive for anti-GX-G3 antibodies. Moreover, the immunogenicity response of GX-G3 was lower in monkeys than in rats, which was relevant to show less inhibition of toxicokinetic profiles in monkeys, at least 1 mg/kg administrated group, compared to rats. These results suggested the establishment and validation for analyzing anti-GX-G3 antibodies and measurement of serum levels of GX-G3 and anti-GX-G3 antibodies, which was related with toxicokinetic profiles. Taken together, this study provides immunogenicity assessment which is closely implicated with toxicokinetic study of GX-G3 in 4-week repeated administrated toxicological studies.

Study of stem cell homing & self-renewal marker gene profile of ex vivo expanded human CD34+ cells manipulated with a mixture of cytokines & stromal cell-derived factor 1

BACKGROUND & OBJECTIVES

Next generation transplantation medicine aims to develop stimulating cocktail for increased ex vivo expansion of primitive hematopoietic stem and progenitor cells (HSPC). The present study was done to evaluate the cocktail GF (Thrombopoietin + Stem Cell factor + Flt3-ligand) and homing-defining molecule Stromal cell-derived factor 1 (SDF1) for HSPC ex vivo expansion.

METHODS

Peripheral blood stem cell (n=74) harvests were analysed for CD34hiCD45lo HSPC. Immunomagnetically enriched HSPC were cultured for eight days and assessed for increase in HSPC, colony forming potential in vitro and in vivo engrafting potential by analyzing human CD45+ cells. Expression profile of genes for homing and stemness were studied using microarray analysis. Expression of adhesion/homing markers were validated by flow cytometry/ confocal microscopy.

RESULTS

CD34hiCD45lo HSPC expansion cultures with GF+SDF1 demonstrated increased nucleated cells (n=28, P+ cells (n=8, P=0.021) and increased colony forming units (cfu) compared to unstimulated and GF-stimulated HSPC. NOD-SCID mice transplanted with GF+SDF1-HSPC exhibited successful homing/engraftment (n=24, PInterpretation & conclusions: Cocktail of cytokines and SDF1 showed good potential to successfully expand HSPC which exhibited enhanced ability to generate multilineage cells in short-term and long-term repopulation assay. This cocktail-mediated stem cell expansion has potential to obviate the need for longer and large volume apheresis procedure making it convenient for donors.

Porcine granulocyte-colony stimulating factor (G-CSF) delivered via replication-defective adenovirus induces a sustained increase in circulating peripheral blood neutrophils

The use of immunomodulators is a promising area for biotherapeutic, prophylactic, and metaphylactic use to prevent and combat infectious disease. Cytokines, including granulocyte-colony stimulating factor (G-CSF), have been investigated for potential value as biotherapeutic proteins. G-CSF enhances the production and release of neutrophils from bone marrow and is already licensed for use in humans. A limitation of cytokines as immunomodulators is their short half-life which may limit their usefulness as a one-time injectable in production-animal medicine. Here we report that administration of recombinant G-CSF induced a transient neutrophilia in pigs; however, delivery of porcine G-CSF encoded in a replication-defective adenovirus (Ad5) vector significantly increased the neutrophilia pharmacodynamics effect. Pigs given one injection of the Ad5-G-CSF had a neutrophilia that peaked between days 3-11 post-treatment and neutrophil counts remained elevated for more than 2 weeks. Neutrophils from Ad5-G-CSF treated pigs were fully functional based on their ability to release neutrophil extracellular traps and oxidative metabolism after in vitro stimulation. Since acceptable alternatives to the use of antibiotics in food-animal production need to be explored, we provide evidence for G-CSF as a possible candidate for agents in which neutrophils can provide protection.

Dose escalation of cytotoxic drugs using haematopoietic growth factors: a randomized trial to determine the magnitude of increase provided by GM-CSF

BACKGROUND

The magnitude of chemotherapy dose escalation made possible by the use of recombinant haematopoietic growth factors has not been quantified in a randomized trial.

PATIENTS AND METHODS

Patients with refractory or relapsing Hodgkin's disease were randomized to receive the Dexa-BEAM regimen with escalating etoposide doses supported by placebo or granulocyte-macrophage colony-stimulating factor (GM-CSF). Using an adaptive sampling method independently in both arms, the etoposide dose was escalated until the maximal tolerated dose for the first cycle was reached.

RESULTS

Thirty patients were randomized to GM-CSF and thirty to placebo. The etoposide dose could be escalated considerably in both treatment arms. Maximal etoposide dose for the first cycle was 1920 mg/m2 for patients receiving GM-CSF and 1160 mg/m2 for patients receiving placebo (P = 0.045 one-sided), corresponding to a 65% higher etoposide dose and a 13% higher dose intensity with GM-CSF. Dose-limiting events were similar in both arms, consisting mainly of prolonged neutropenia and consecutive infections. Treatment efficacy was not different in the two treatment groups.

CONCLUSIONS

While GM-CSF permits a somewhat higher dose escalation than placebo, the increase in dose intensity provided by GM-CSF is small. The use of CSF for interval reduction rather than dose escalation is the more effective strategy for dose intensification.

Growth factors and cord blood stem and progenitor cells

This article reviews recent information on the proliferation kinetics of hematopoietic progenitor cells in patients on clinical trial with growth factors, and the use of umbilical cord blood as a source of transplantable stem and progenitor cells.

Prediction of the role of granulocyte-macrophage colony-stimulating factor in animals and man from in vitro results

The possibility of predicting the clinical effects of cytokines from in vitro data is discussed, using GM-CSF as an example. GM-CSF incubated with bone marrow cells has been shown to induce proliferation and colony formation, predominantly of the colony-forming unit granulocyte and granulocyte-macrophage types. Daily treatment of normal monkeys with GM-CSF resulted in transient neutropenia followed by neutrophilia. After withdrawal of GM-CSF the neutrophil levels returned to baseline. Predictably, GM-CSF administration results in accelerated neutrophil recovery in patients with chemotherapy-induced neutropenia. GM-CSF has also been shown to induce microbial killing by neutrophils and monocytes in vitro. This activity translated into a dose-related protection of GM-CSF-pretreated mice infected with lethal doses of micro-organisms. Interleukin-3 (IL-3) increases the cellularity of the bone marrow and GM-CSF can induce mobilization of bone marrow cells into the peripheral blood. Therefore, it was predicted and subsequently proved that a combination of these cytokines is synergistic, increasing the yields of peripheral blood progenitor cells which could be collected and then retransplanted into patients undergoing myeloablative chemotherapy. Monkeys injected with recombinant human IL-3 and GM-CSF had increased antibody titres to human IL-3 compared with monkeys given IL-3 alone, suggesting a potential use of GM-CSF which was not predicted from its in vitro results, that of vaccine adjuvancy.(ABSTRACT TRUNCATED AT 250 WORDS)

Influence of recombinant human interleukin (IL)-7 on disease progression in mice infected with Friend virus complex

Recombinant human (rhu) IL-7 was evaluated for its influence on disease progression in mice infected with the polycythemia-inducing strain of the Friend virus complex (FVC). DBA/2 mice were injected i.v. with FVC, and then treated s.c. with rhuIL-7. IL-7 significantly prolonged survival time and decreased spleen focus-forming virus (SFFV) levels, expression of SFFV mRNA and SFFV protein production in FVC-infected mice. IL-7 did not appear to directly inactivate SFFV. Although both splenic weight and cellularity in FVC-infected mice treated with IL-7 were higher than those of normal mice, they were respectively 58% and 66% lower than those of the untreated FVC-infected mice. NK-cell activity was substantially lower in FVC-infected mice than in normal mice, while IL-7 restored NK-cell activity to normal levels. IL-6 and IFN-gamma levels were markedly reduced in FVC-infected mice compared to normal mice, but treatment of FVC-infected mice with IL-7 restored these cytokine levels. While the actual mechanisms of these effects are not yet known, the results suggest the potential therapeutic efficacy of IL-7 for certain hematopoietic and viral disorders, possibly mediated through an action on accessory cells and cytokine production.

Biologic response modifiers as antivirals in immunosuppressed hosts

A wide variety of immunomodulators/biologic response modifiers (BRM) have been demonstrated to provide broad spectrum antiviral activity against both RNA and DNA viruses in several animal species. Dramatic decreases in mortality, reduced virus titers in tissues, and reduced histopathology can be produced. The antivirally effective agents include microbially derived materials, polyanions, cytokines, and chemically diverse small molecular weight chemicals. Antiviral efficacy with BRM treatment has been shown in numerous kinds of immunosuppression, emphasizing the potential for BRM treatment in immunocompromised patients. The greatest protective effects are observed with prophylactic or early therapeutic treatment. BRMs act indirectly, most likely by activating cells and/or inducing antiviral mediators early in the course of viral pathogenesis. In general, viral specific immune responses in BRM-treated and infected mice are absent or similar to those in untreated mice. Because BRMs are pleiotropic in their immunomodulatory effects, it has been difficult to establish whether one cell type or mediator is critical for the broad spectrum antiviral activity. Interferon appears to be critical for some small molecular weight synthetic compounds, but does not appear to explain all the antiviral activity of certain large molecular weight polyanions. Whether there is a unified antiviral mechanism among different BRMs remains to be determined.

Immunobiology of hematopoietic colony-stimulating factors: potential application to disease prevention in the bovine

Colony-stimulating factors are a family of glycoproteins instrumental in regulation of hematopoiesis and inflammation. Clinical effects of various colony-stimulating factors have been reported in murine and human hosts. This review summarizes findings from some clinical trial evaluations of macrophage colony-stimulating factor, granulocyte-macrophage colony-stimulating factor, granulocyte colony-stimulating factor, interleukin-1, interleukin-3, interleukin-4, interleukin-5, interleukin-6, and interleukin-7 administration to other species. These factors stimulate clonal expansion of progenitor cells in the bone marrow, induce differentiation of various cell lineages to a mature phenotype, and, in some cases, enhance the effector activities of immune cells. Each colony-stimulating factor has distinct lineages of bone marrow cells upon which they act, although there is some overlap in lineage activity and synergy between colony-stimulating factors. The close relationship in biological activity among different colony-stimulating factors is also reflected at the genomic level at which genes for some hematopoietic growth factors have been mapped to a region of human chromosome 5. Recently, colony-stimulating factor administration to cattle and its potential application to disease control in bovine preventive medicine programs has been investigated. Data from recent hematological, immunological, and intramammary bacterial (Staphylococcus aureus and Klebsiella pneumoniae) challenge studies in dairy cows are reviewed. These studies, with limited numbers of cows, found that rate of new infections, as well as duration and severity of infection, were reduced by pretreatment of cows with granulocyte-colony stimulating factor. The dose-dependent hematological and immunomodulatory effects of granulocyte colony-stimulating factor administration may explain reduced severity and incidence of mastitis in dairy cows given granulocyte colony-stimulating factor.

Anti-tumor effects of recombinant human macrophage colony-stimulating factor, alone or in combination with local irradiation, in mice inoculated with Lewis lung carcinoma cells

Recombinant human (rhu) macrophage colony-stimulating factor (M-CSF) was evaluated for efficacy, either alone or in combination with local X-irradiation (LR), in mice inoculated subcutaneously (s.c.) with Lewis lung carcinoma (LLC) cells. The size of the primary tumor and numbers of lung metastases, 21 days after tumor inoculation and 15 days after the start of treatment, were reduced by 87% in tumor-bearing mice treated with 20 micrograms/dose M-CSF s.c. twice a day for 5 days. LR (800 cGy) to the tumor once a week for 2 weeks had a moderate anti-tumor effect and enhanced the anti-tumor effect of M-CSF. Hematological parameters, including nucleated cellularity in peripheral blood, femoral marrow, spleen and peritoneal exudate, as well as marrow and splenic granulocyte-macrophage progenitor cells, and numbers of splenic Thy 1.2+ cell and peritoneal mast cells, were perturbed in LLC-bearing mice, and were influenced by treatment with M-CSF and LR. Treatment with M-CSF plus LR, but not with either agent alone, was associated with a significant, although slight, enhancement in survival time for LLC-bearing mice. Inability to obtain a better survival-enhancing effect appeared to be related to the limited treatment, since the anti-tumor effects of M-CSF were more notable early on in disease progression and were related to the dose of M-CSF used. The effects of M-CSF were most probably indirect ones on the host immune system. M-CSF, in combination with LR, may be of benefit in the treatment of human tumors that have metastatic potential.

Role of human recombinant GM-CSF in the prevention and treatment of leukopenia with special reference to infectious diseases

Recombinant human GM-CSF has been shown to be effective in reversing severe neutropenic states associated with the underlying disease or caused by cytotoxic drugs, and during engraftment after bone marrow transplantation. Preliminary evidence supports the view that restoration of adequate myelopoiesis results in better control of infection. The use of rhGM-CSF in special infectious diseases to activate cell function is currently being studied. Preliminary in vitro and in vivo data allow high expectations for the usefulness of rhGM-CSF in contributing to the control of these diseases.

New therapeutic strategies in the treatment of murine diseases induced by virus and solid tumors: biology and implications for the potential treatment of human leukemia, AIDS, and solid tumors

Understanding the biology and treatment of various cancers (including leukemia) and immunodeficiency disorders is still an ongoing and experimental process. Animal models have been and continue to be important to this process. This review will focus in on work by ourselves and others that have used murine models assessing the effects in vivo of the Friend virus complex (FVC, composed of a spleen focus forming virus and a murine leukemia helper virus) and solid tumors with metastatic potential in order to evaluate new and innovative therapies. These therapies include radiation, hyperthermia, and newly recognized naturally occurring biomolecules termed cytokines. These cytokines include, but are not limited to, the interferons, the tumor necrosis factors, the interleukins, the hematopoietic colony stimulating factors, lactoferrin and E-type prostaglandins. For example, it has been found that lactoferrin, when administered early enough, prolongs the survival of mice injected, but not yet infected, with the FVC. Of even greater potential usefulness is that mice already infected with the FVC can be completely rescued from death by treatment with split low dosage (150 cGy) total body irradiation. Irradiation treatment was associated with restoration of the T helper to T suppressor cell ratio, natural killer cell activity and marrow proliferative responses to the mitogens PHA and con A which were compromised by the FVC. More recent studies in our laboratory have demonstrated the potential of the interleukins and colony stimulating factors to decrease the metastatic potential of the B16 melanoma and the Lewis Lung Carcinoma cell lines. The cytokines can act in greater than additive fashion and combinations of therapies are possible. This review is meant to increase the awareness of these investigative animal models and the new types of combination therapies that can then be used as the basis for future clinical trials evaluating therapeutic efficacy.

Human umbilical cord blood: a clinically useful source of transplantable hematopoietic stem/progenitor cells

This is a review and discussion of studies leading to the first use of human umbilical cord blood, material usually discarded, for the provision of stem/progenitor cells for clinical hematopoietic reconstitution. This prospect arose as a result of extensive studies of the harvesting and cryopreservation of cord blood and of its numerical content of progenitor cells demonstrable in vitro. A male patient with Fanconi anemia (FA) was conditioned with a modified regimen of cyclophosphamide and irradiation that accommodates the abnormally high sensitivity to these agents that is characteristic of FA. Cryopreserved cord blood had been retrieved at birth from a female sibling known from prenatal testing to be unaffected by FA and to be human leukocyte antigen (HLA)-compatible with the prospective sibling recipient. After conditioning and therapeutic infusion of thawed cord blood, successful hematopoietic reconstitution was indicated by the general health of the patient, who had previously required supportive transfusions, by satisfactory hematological criteria and by counts of hematopoietic progenitor cells of various types in the bone marrow. Complete engraftment of the myeloid system with donor cells was evident from cytogenetics, ABO typing, study of DNA polymorphisms, and normal cellular resistance to cytotoxic agents that reveal the fragility of FA cells; the blood contained a residuum of host lymphocytes exhibiting chromosomal damage, but the trend has been towards eliminating these damaged cells. This implies that cord blood from a single individual should provide sufficient reconstituting cells for effective hematopoietic repopulation of an autologous or an HLA-compatible allogeneic recipient.