Impaired response of myelodysplastic marrow progenitors to stimulation with recombinant haemopoietic growth factors

The regulation of haemopoiesis in myelodysplastic syndromes (MDS) was evaluated by measuring and comparing the in vitro response of marrow progenitors from 18 MDS patients to stimulation with recombinant haemopoietic growth factors (HGFs), granulocyte-macrophage colony-stimulating factor (GM-CSF), granulocyte CSF (G-CSF) and interleukin-3 (IL-3). A similar pattern of colony growth was detected with all three HGFs in most MDS patients, exhibiting subnormal growth of GM-CFU and markedly poor to absent growth of BFU-E and CFU-GEMM. A common severe impairment in the growth of all colony types with all three HGFs was observed in five patients, four of whom presented with pancytopenia. The stimulation of MDS marrow progenitors with a five-fold higher than control saturating dose of HGFs induced a significant increase in the frequency of one, two, or all three colony types in cultures of 14 patients, whereas colony numbers in control (n = 8) marrow cell cultures were not significantly changed. All four of the non-responders were pancytopenic and three exhibited markedly impaired colony growth. Supersaturating GM-CSF, G-CSF and IL-3 increased GM-CFU numbers in six, three, and three patients, respectively. The values for BFU-E were three, six, and seven and for CFU-GEMM two, one, and five. The enhancement of MDS marrow colony numbers by supersaturating HGFs which exert their effects directly or via the action of marrow accessory cells, suggests that the progenitor cell growth abnormalities in these disorders may involve a defect in the capacity of accessory and/or progenitor cells to respond to stimulation with specific haemopoietic growth regulators.

Administration of interleukin-6 stimulates multilineage hematopoiesis and accelerates recovery from radiation-induced hematopoietic depression

Hematopoietic depression and subsequent susceptibility to potentially lethal opportunistic infections are well-documented phenomena following radiotherapy. Methods to therapeutically mitigate radiation-induced myelosuppression could offer great clinical value. In vivo studies in our laboratory have demonstrated that interleukin-6 (IL-6) stimulates pluripotent hematopoietic stem cell (CFU-s), granulocyte-macrophage progenitor cell (GM-CFC), and erythroid progenitor cell (CFU-e) proliferation in normal mice. Based on these results, the ability of IL-6 to stimulate hematopoietic regeneration following radiation-induced hematopoietic injury was also evaluated. C3H/HeN female mice were exposed to 6.5 Gy 60Co radiation and subcutaneously administered either saline or IL-6 (1,000 micrograms/kg) on days 1 through 3 or 1 through 6 postexposure. On days 7, 10, 14, 17, and 22, femoral and splenic CFU-s, GM-CFC, and CFU-e contents and peripheral blood white cell, red cell, and platelet counts were determined. Compared with saline treatment, both 3-day and 6-day IL-6 treatments accelerated hematopoietic recovery; 6-day treatment produced the greater effects. For example, compared with normal control values (N), femoral and splenic CFU-s numbers in IL-6-treated mice 17 days postirradiation were 27% N and 136% N versus 2% N and 10% N in saline-treated mice. At the same time, bone marrow and splenic GM-CFC values were 58% N and 473% N versus 6% N and 196% N in saline-treated mice; bone marrow and splenic CFU-e numbers were 91% N and 250% N versus 31% N and 130% N in saline-treated mice; and peripheral blood white cell, red cell, and platelet values were 210% N, 60% N, and 24% N versus 18% N, 39% N, and 7% N in saline-treated mice. These studies demonstrate that therapeutically administered IL-6 can effectively accelerate multilineage hematopoietic recovery following radiation-induced hematopoietic injury.

Chronic neutropenia. A new canine model induced by human granulocyte colony-stimulating factor

Normal dogs were treated with recombinant human granulocyte colony-stimulating factor (rhG-CSF) at 10 micrograms/kg/day for 30 d, which caused an initial neutrophilia, followed by a prolonged period of chronic neutropenia. A control dog treated with recombinant canine G-CSF (rcG-CSF) showed persistent neutrophilia over 3 mo. Serum from dogs during neutropenia contained an antibody to rhG-CSF, which neutralized the stimulatory effects of both rhG-CSF and rcG-CSF on dog marrow neutrophilic progenitor cell growth and on NFS-60 cell proliferation. 4 mo after discontinuation of rhG-CSF, the dogs' neutrophil counts returned to the normal range. Rechallenge with the rhG-CSF re-induced severe neutropenia in 1 wk. Neutropenia was transferred by plasma infusion from a neutropenic dog to a previously normal dog. These data suggest that human rhG-CSF immunizes normal dogs and thereby induces neutralization of endogenous canine G-CSF and neutropenia. This model system should allow more precise definition of the in vivo role of G-CSF.

Effects of recombinant granulocyte colony-stimulating factor treatment on hematopoietic cycles and cellular defects associated with canine cyclic hematopoiesis

Canine cyclic hematopoiesis (CH) is an autosomal recessive disease of gray collie dogs that is characterized by 14-day cycles of neutropenia, monocytosis, thrombocytosis, and reticulocytosis. Platelets from CH dogs have decreased dense-granule serotonin pools and decreased aggregation responses to collagen, platelet-activating factor (PAF), and thrombin. Recombinant granulocyte colony-stimulating factor (rG-CSF) was administered (5 micrograms/kg, b.i.d.) to four CH and six normal dogs to determine if G-CSF therapy corrected qualitative platelet defects in CH dogs. Neutrophil counts increase to greater than 25,000 cells/microliters within 24 h after starting treatment in all dogs. Treatment with G-CSF blocked neutropenic episodes in the CH dogs. Platelet aggregation, and serotonin content and secretion were significantly (p less than 0.05) decreased in the CH dogs both before and during recombinant human (rh) G-CSF treatment compared to normal dogs. Neutrophil myeloperoxidase, a primary granule enzyme, was significantly (p less than 0.05) decreased in CH dogs and was not corrected by rhG-CSF treatment. Administration of rG-CSF to CH dogs eliminated cell cycles but apparently did not correct cellular defects in CH dogs. Identification of primary biochemical defects in cells from CH dogs may be crucial to investigating the biochemical basis for cyclic hematopoiesis.

Survival enhancement and hemopoietic regeneration following radiation exposure: therapeutic approach using glucan and granulocyte colony-stimulating factor

C3H/HeN female mice were exposed to wholebody cobalt-60 radiation and administered soluble glucan (5 mg i.v. at 1 h following exposure), recombinant human granulocyte colony-stimulating factor (G-CSF; 2.5 micrograms/day s.c., days 3-12 following exposure), or both agents. Treatments were evaluated for their ability to enhance hemopoietic regeneration, and to increase survival after radiation-induced myelosuppression. Both glucan and G-CSF enhanced hemopoietic regeneration alone; however, greater effects were observed in mice receiving both agents. For example, on day 17 following a sublethal 6.5-Gy radiation exposure, mice treated with saline, G-CSF, glucan, or both agents, respectively, exhibited 36%, 65%, 50%, and 78% of normal bone marrow cellularity, and 84%, 175%, 152%, and 212% of normal splenic cellularity. At this same time, granulocyte-macrophage colony-forming cell (GM-CFC) values in saline, G-CSF, glucan, or combination-treated mice, respectively, were 9%, 46%, 26%, and 57% of normal bone marrow values, and 57%, 937%, 364%, and 1477% of normal splenic values. Endogenous spleen colony formation was also increased in all treatment groups, with combination-treated mice exhibiting the greatest effects. Likewise, although both glucan and G-CSF alone enhanced survival following an 8-Gy radiation exposure, greatest survival was observed in mice treated with both agents. These studies suggest that glucan, a macrophage activator, can synergize with G-CSF to further accelerate hemopoietic regeneration and increase survival following radiation-induced myelosuppression.

Hemogram changes in lactating dairy cows given human recombinant granulocyte colony stimulating factor (r-MethuG-CSF)

As a prelude to mammary gland challenge experiments, this investigation was implemented to assess the hematologic changes in lactating dairy cattle induced by two dosage regimes of human recombinant colony stimulating factor (Hr-GCSF). This study documents the capability of the human recombinant colony stimulating factor to produce hematologic changes in both a time and dose dependent manner when administered to the adult lactating bovine. A screening dose of 1 microgram/kg of Hr-GCSF administered to three study subjects produced a three- to four-fold increase in peripheral blood mature neutrophil counts (P less than 0.043) by day 12 of the trial. The priming dose treatment group of four lactating cows (3 micrograms/kg of Hr-GCSF) exhibited a three- to five-fold increase in peripheral blood mature neutrophil counts (P less than 0.05) and two- to three-fold increases in white blood cell counts by day 5 of the trial. Hematologic examinations of the control group (n = 4; no Hr-GCSF administration) did not detect significant changes in their neutrophil counts over baseline values. The milk somatic cell counts did not statistically shift over baseline values in any of the control or Hr-GCSF treatment groups. When attempting to alter the course of infectious disease processes, potential applications of colony stimulating factors provide interesting speculations about new therapeutic modalities.

A comparison of treatment of canine cyclic hematopoiesis with recombinant human granulocyte-macrophage colony-stimulating factor (GM-CSF), G-CSF interleukin-3, and canine G-CSF

Cyclic hematopoiesis in gray collie dogs is a stem cell disease in which abnormal regulation of cell production in the bone marrow causes cyclic fluctuations of blood cell counts. In vitro studies demonstrated that recombinant human granulocyte-macrophage colony-stimulating factor (GM-CSF), interleukin-3 (IL-3), and granulocyte colony stimulating factor (G-CSF) all stimulated increases in colony formation by canine bone marrow progenitor cells. Based on these results, gray collie dogs were then treated with recombinant human (rh) GM-CSF, IL-3, or G-CSF subcutaneously to test the hypothesis that pharmacologic doses of one of these hematopoietic growth factors could alter cyclic production of cells. When recombinant canine G-CSF became available, it was tested over a range of doses. In vivo rhIL-3 had no effect on the recurrent neutropenia but was associated with eosinophilia, rhGM-CSF caused neutrophilia and eosinophilia but cycling of hematopoiesis persisted. However, rhG-CSF caused neutrophilia, prevented the recurrent neutropenia and, in the two animals not developing antibodies to rhG-CSF, obliterated periodic fluctuation of monocyte, eosinophil, reticulocyte, and platelet counts. Recombinant canine G-CSF increased the nadir neutrophil counts and amplitude of fluctuations at low doses (1 micrograms/kg/d) and eliminated all cycling of cell counts at high doses (5 and 10 micrograms/kg/d). These data suggest significant differences in the actions of these growth factors and imply a critical role for G-CSF in the homeostatic regulation of hematopoiesis.

Recombinant human granulocyte colony-stimulating factor accelerates hematopoietic recovery after DLA-identical littermate marrow transplants in dogs

We studied whether treatment of dogs with recombinant human granulocyte colony-stimulating factor (rhG-CSF), after 920 cGy total body irradiation (TBI) and transplantation of 3.3 +/- 1.0 x 10(8) bone marrow cells per kilogram from a DLA-identical littermate, accelerated hematopoietic recovery and influenced the incidence of subsequent marrow graft failure or graft-versus-host disease (GVHD). Ten animals were treated with 100 micrograms rhG-CSF/kg/d from days 1 through 10 after TBI. Results were compared with those of historical control of 14 dogs not administered rhG-CSF. Neither group of dogs received GVHD prophylaxis. The median time to recovery of 1,000 neutrophils/mm3 was 8 days for dogs administered rhG-CSF compared with 14 days in controls (logrank test: P less than .03). The median time to reach 100 monocytes/mm3 was 17 days in G-CSF-treated dogs compared with 49 days in controls (P less than .002). The median time to attain 500 lymphocytes/mm3 was 15 days versus 31 days, respectively (P less than .01). The median time to reach 20,000 platelets/mm3 was 26 versus 20 days (P = .68). Graft failure occurred in 1 of 10 G-CSF-treated dogs versus 2 of 14 controls (two-tailed Fisher's exact test: P = 1.00). GVHD was seen in 4 of 9 rhG-CSF-treated dogs compared with 1 of 12 controls (P = .12). Two G-CSF-treated dogs died of GVHD versus none of the controls (P = .17). No unusual toxicities were seen in dogs receiving rhG-CSF. In summary, rhG-CSF significantly accelerated recovery of neutrophils, monocytes, and lymphocytes after DLA-identical littermate marrow transplantation without altering platelet recovery. Graft failure was not seen more often than in controls, but there was a trend toward an increased incidence of GVHD.

Therapeutic use of recombinant human G-CSF (rhG-CSF) in a canine model of sublethal and lethal whole-body irradiation

The short biologic half-life of the peripheral neutrophil (PMN) requires an active granulopoietic response to replenish functional PMNs and to maintain a competent host defence in irradiated animals. Recombinant human G-CSF (rhG-CSF) was studied for its ability to modulate haemopoiesis in normal dogs as well as to decrease therapeutically the severity and duration of neutropenia in sublethally and lethally irradiated dogs. For the normal dog, subcutaneous administration of rhG-CSF induced neutrophilia within hours after the first injection; total PMNs continued to increase (with plateau phases) to mean peak values of 1000 per cent of baseline at the end of the treatment period (12-14 days). Bone-marrow-derived granulocyte-macrophage colony-forming cells (GM-CFC) increased significantly during treatment. For a sublethal 200 cGy dose, treatment with rhG-CSF for 14 consecutive days decreased the severity and shortened the duration of neutropenia and thrombocytopenia. The radiation-induced lethality of 60 per cent after a dose of 350 cGy was associated with marrow-derived GM-CFC survival of 1 per cent. Treatment with rhG-CSF markedly reduced the lethality associated with exposure to 350 cGy of radiation to zero. White blood cell (WBC) and platelet recovery kinetics were correlated with degree of marrow damage. The rhG-CSF reduced the severity and duration of neutropenia. Control animals required antibiotic therapy (WBC less than 1000 mm3) for a total of 16 days versus 3 days for rhG-CSF-treated dogs. The duration of thrombocytopenia was reduced, although the severity of depletion was unchanged with treatment. These data indicate that in the lethally irradiated dog, effective cytokine therapy with rhG-CSF will increase survival through the induction of earlier recovery of neutrophils and platelets.

Therapeutic administration of recombinant human granulocyte colony-stimulating factor accelerates hemopoietic regeneration and enhances survival in a murine model of radiation-induced myelosuppression

The primary cause of death after radiation exposure is infection resulting from myelosuppression. Because granulocytes play a critical role in host defense against infection and because granulocyte proliferation and differentiation are enhanced by granulocyte colony-stimulating factor (G-CSF), this agent was evaluated for the ability to accelerate hemopoietic regeneration and to enhance survival in irradiated mice. C3H/HeN mice were irradiated and G-CSF (2.5 micrograms/day, s.c.) or saline was administered on days 3-12, 1-12 or 0-12 post-irradiation. Bone marrow, splenic and peripheral blood cellularity, and bone marrow and splenic granulocyte-macrophage progenitor cell recoveries were evaluated in mice exposed to 6.5 Gy. Mice exposed to 8 Gy were evaluated for multipotent hemopoietic stem cell recovery (using endogenous spleen colony-forming units) and enhanced survival. Results demonstrated that therapeutic G-CSF 1) accelerates hemopoietic regeneration after radiation-induced myelosuppression, 2) enhances survival after potentially lethal irradiation and 3) is most effective when initiated 1 h following exposure.

Recombinant human granulocyte colony-stimulating factor hastens granulocyte recovery after high-dose chemotherapy and autologous bone marrow transplantation in Hodgkin's disease

To determine whether recombinant human granulocyte colony-stimulating factor (rhG-CSF) can accelerate granulocyte recovery after high-dose combination chemotherapy with autologous bone marrow transplantation (ABMT) in patients with Hodgkin's disease, we performed a nonrandomized phase II study using historical controls as a comparison. Eighteen relapsed/refractory Hodgkin's disease patients who received cyclophosphamide at 1.5 g/m2/day (days -6 to -3), carmustine (BCNU) at 300 mg/m2 (day -6), and etoposide (VP-16) at 125 mg/m2 every 12 hours (days -6 to -4), followed by ABMT (day 0) were treated with rhG-CSF at 60 micrograms/kg/day for a maximum of 28 days beginning on day 1. rhG-CSF dosage was gradually diminished and stopped once an adequate granulocyte count was maintained. rhG-CSF significantly accelerated absolute granulocyte count (AGC) compared with historical controls recovery to the 100/microL level (median, 9 days v 13 days; P = .103 x 10(-4), 500/microL level (median, 13 days v 22 days; P = 0.189 x 10(-2), and 1000/microL level (median, 16 days v 30 days levels; P = .125 x 10(-5). Platelet recovery to 50,000/microL was not significantly altered (P = .370). rhG-CSF was well tolerated, bone pain and myalgia being the only side effects noted. rhG-CSF hastens granulocyte recovery after high-dose chemotherapy with ABMT in patients with relapsed/refractory Hodgkin's disease without significant toxicity.

Hematologic effects of recombinant human granulocyte colony-stimulating factor in patients with malignancy

The effect of recombinant human granulocyte colony-stimulating factor (G-CSF) on hematologic parameters was evaluated in a phase I clinical study in 18 patients with advanced malignancy. G-CSF was administered once daily as a 30-minute infusion for 14 days; three patients each were treated at increasing dose levels of 1, 3, 10, 30, and 60 micrograms kg-1 day-1. A transient decrease in neutrophil and monocyte counts was observed immediately after the G-CSF infusion, followed by a dose-dependent increase of up to 15-fold. G-CSF-induced neutrophils exhibited an increased O2- radical production, and serum levels of enzymes related to granulocyte turnover, including lysozyme and elastase, were markedly elevated during therapy. A dose-dependent depression of platelet counts occurred in the second third of the treatment course, followed by a spontaneous recovery despite continuing therapy. G-CSF was well-tolerated; minor to moderate bone pain was the most common side effect. The primary course of the malignant diseases studied was not significantly altered. G-CSF appears to be an appropriate means to selectively increase the number of functionally competent polymorphonuclear phagocytes.

Effect of recombinant human granulocyte colony-stimulating factor on hematopoiesis of normal dogs and on hematopoietic recovery after otherwise lethal total body irradiation

This study was designed to test whether recombinant human G-CSF (rh G-CSF) affects hematopoiesis in normal dogs and, if so, to test the effects of G-CSF in dogs given otherwise lethal total body irradiation (TBI). Rh G-CSF given subcutaneously at 10 or 100 micrograms/kg/d for 14 days to two normal dogs increased peripheral blood neutrophils eight to tenfold and monocytes four to sixfold above controls. Lymphocyte counts remained unchanged at the lower dose and increased threefold at the higher dose of rh G-CSF. No significant changes were observed in eosinophil, platelet, reticulocyte, or hematocrit levels. After 2 weeks of treatment with rh G-CSF, bone marrow displayed myeloid hyperplasia and left-shifted granulocytopoiesis. After discontinuation of rh G-CSF, peripheral leukocyte counts returned to control levels within three days. Five dogs administered 400 cGy TBI at 10 cGy/min from two opposing 60Co sources and no marrow infusion or growth factor, all developed profound pancytopenia and died between 17 and 23 days after TBI with infections secondary to marrow aplasia. Four of five dogs treated within two hours after 400 cGy TBI with 100 micrograms rh G-CSF/kg/d subcutaneously twice a day for 21 days showed complete and sustained endogenous hematopoietic recovery. In contrast, five dogs irradiated with 400 cGy TBI and treated with 100 micrograms rh G-CSF/kg/d starting on day 7 after TBI, all died between days 17 and 20 after TBI with infections secondary to marrow aplasia. Rh G-CSF, if administered shortly after irradiation, can reverse the otherwise lethal myelosuppressive effect of radiation exposure.

Treatment of myelodysplastic syndromes with recombinant human granulocyte colony-stimulating factor. A phase I-II trial

STUDY OBJECTIVE

To determine the hematopoietic effects and toxicity of recombinant human granulocyte colony-stimulating factor (G-CSF) in patients with myelodysplastic syndromes.

DESIGN

The G-CSF was administered by daily subcutaneous injection to outpatients in a phase I-II trial. Dose was escalated every 2 weeks between 0.1 to 3.0 micrograms/kg body weight.d over an 8-week treatment period.

SETTING

Outpatient clinical research center at a university hospital.

PATIENTS

Twelve consecutive patients with myelodysplastic syndromes: two refractory anemia, seven refractory anemia with excess of blasts, three refractory anemia with excess of blasts in transformation.

MEASUREMENTS AND MAIN RESULTS

In 10 of 12 patients, elevations in blood leukocyte counts (2- to 10-fold) and absolute neutrophil counts (5- to 40-fold) were seen over the 8-week treatment period. Five of seven severely neutropenic patients (absolute neutrophil count, less than 0.5 x 10(9)/L) had a rise in count to 1.2 to 16.3 x 10(9)/L. Increased reticulocyte counts occurred in 5 patients, and were associated with decreased transfusion requirements in 2 of 9 erythrocyte transfusion-dependent patients. Treatment with G-CSF enhanced marrow myeloid cell maturation in 9 of 11 evaluable patients. Neutrophil chemotaxis and phagocytosis in vitro were improved or unchanged after treatment in 6 of 8 patients tested. In 11 of 12 patients, there were no substantial changes in platelet, lymphocyte, eosinophil, or monocyte counts. Three responding patients initially had abnormal cytogenetics that persisted after G-CSF therapy, suggesting induced differentiation of the abnormal clone. The therapy was associated with minimal toxicity. None of the patients' conditions converted to acute leukemia during treatment or in short-term follow-up.

CONCLUSIONS

Treatment with G-CSF administered by subcutaneous injection is well tolerated and effective for improving the neutropenia, and less commonly the transfusion-dependent anemia, over 6 to 8 weeks in patients with myelodysplastic syndromes.

Treatment of cyclic neutropenia with granulocyte colony-stimulating factor

Six patients with cyclic neutropenia were treated with recombinant human granulocyte colony-stimulating factor (G-CSF) for 3 to 15 months. All had a history of recurrent aphthous stomatitis, pharyngitis, lymphadenopathy, fever, and numerous infections during periods of neutropenia. Serial blood-cell counts, findings on bone marrow examination, and signs and symptoms were evaluated before and during the daily administration of G-CSF (3 to 10 micrograms per kilogram of body weight per day), either intravenously or subcutaneously. The kinetics of labeled autologous blood neutrophils and the migration of neutrophils to skin chambers were also measured. Recombinant human G-CSF increased the mean (+/- SEM) neutrophil counts from 717 +/- 171 per microliter to 9814 +/- 2198 per microliter (P = 0.009). In five of the six patients, the cycling of blood-cell counts continued, but the length of the period decreased from 21 to 14 days. The number of days of severe neutropenia was reduced (P = 0.002). Neutrophil turnover increased almost four-fold (P = 0.005), whereas neutrophil migration to a skin chamber was normal. G-CSF therapy reduced the frequency of oropharyngeal inflammation, fever, and infections in these patients. During the first 40 months of treatment, no typical mouth ulcers or bacterial infections occurred; recurrent gingivitis improved. We conclude that G-CSF is effective for the treatment of cyclic neutropenia in humans.

Stimulation of human hematopoietic progenitor cell proliferation and differentiation by recombinant human interleukin 3. Comparison and interactions with recombinant human granulocyte-macrophage and granulocyte colony-stimulating factors

Recombinant human interleukin 3 (IL3) produced in Escherichia coli was purified and its activities examined in cultures of highly enriched human bone marrow progenitor cells. Human IL3 stimulated multipotential (CFU-GEMM) and erythroid (BFU-E) progenitor cells, generating 95% more BFU-E than recombinant human granulocyte-macrophage colony-stimulating factor (GM-CSF). No further enhancement of BFU-E or CFU-GEMM occurred when IL3 and GM-CSF were used in combination. Human IL3 was more effective than GM-CSF in stimulating granulocyte-macrophage colony-forming cells (CFU-GM) in short-term suspension cultures, but did not induce an increase of CFU-GM, BFU-E, or CFU-GEMM above input levels. IL3 was more active on day-14 (d14) than on d7 CFU-GM, similar to GM-CSF, but generated fewer and smaller CFU-GM-derived clones than either GM-CSF or granulocyte CSF (CI-CSF). The simultaneous addition of plateau levels of IL3 and GM-CSF resulted in an infra-additive augmentation of d7 and d14 CFU-GM-derived clones, whereas IL3 and G-CSF enhanced the number and cellularity predominantly of d14 CFU-GM. In liquid cultures, IL3 induced a greater than 100-fold increase in the number of basophil-mast-like cells and eosinophils and allowed maintenance of these cultures for up to 7 weeks. Human GM-CSF was an almost equally potent, stimulus of eosinophil development but had only a marginal effect on basophilic precursors, whereas G-CSF lacked both activities. Therefore, human IL3 is a multilineage hemopoietic growth factor whose activities appear to encompass and extend beyond those of GM-CSF.

Disulfide and secondary structures of recombinant human granulocyte colony stimulating factor

Molecular characteristics and secondary structures of recombinant methionyl human granulocyte colony stimulating factor produced by genetically engineered Escherichia coli are described. Limited radiolabeling of the protein with tritiated iodoacetate and determination of the labeled residue revealed that this recombinant protein contains only one free cysteine at position 17 which is not essential for activity. The free cysteine is inaccessible to modification unless the molecule is unfolded under denaturing conditions. The molecule forms two disulfide bridges which were assigned as Cys(36)-Cys(42) and Cys(64)-Cys(74) based on the results of isolation and characterization of disulfide-containing peptides obtained from a subtilisin digest of the intact protein. CD analyses and secondary structure prediction suggest that the molecule is abundant in alpha-helical structures.

Correction of canine cyclic hematopoiesis with recombinant human granulocyte colony-stimulating factor

Canine cyclic hematopoiesis (CH) is an autosomal recessive disease of gray collie dogs that is characterized by neutropenic episodes at 14-day intervals. The biochemical basis for CH is not known but may involve a regulatory defect of the response to or production of a hematopoietic growth factor. Administration of recombinant human granulocyte colony-stimulating factor (rhG-CSF) to two CH and one normal dog caused a marked leukocytosis (greater than 50,000 WBCs) in all three dogs. The leukocytosis was due largely to a greater than tenfold increase in neutrophils. Less pronounced but significant elevations in monocytes occurred during G-CSF treatment. The elevated WBC count was maintained for more than 20 days in all three dogs, and two predicted neutropenic episodes were prevented in both CH dogs during rhG-CSF treatment. A decline in the WBC count occurred simultaneously in all three dogs during the last five treatment days and was presumably associated with the development of neutralizing antibodies to the heterologous rhG-CSF protein. Bone marrow evaluation indicated that the swings in the myeloid/erythroid progenitor cells that are characteristic of CH were eliminated by rhG-CSF treatment in both CH dogs. These results suggest that the regulatory defect in canine CH can be temporarily alleviated by treatment with rhG-CSF and point to the potential treatment of human cyclic neutropenia with this agent.

Synergistic effect of dolichyl phosphate and human recombinant granulocyte colony-stimulating factor on recovery from neutropenia in mice treated with anti-cancer drugs

Severe hematopoietic injury in mice was induced by using either 5-fluorouracil, adriamycin, mitomycin C, or vinblastine. Daily subcutaneous administration of purified human recombinant granulocyte colony-stimulating factor (rG-CSF; 0.3-10.0 micrograms/day) markedly accelerated recovery from the drug-induced granulocytopenia in a dose-dependent manner, as reported previously. On the other hand, daily intraperitoneal administration of dolichyl phosphate (Dol-P) also enhanced granulopoiesis to accelerate recovery from granulocytopenia, although the effect of Dol-P was relatively moderate as compared with that of rG-CSF. A synergistic recovery of granulopoiesis was observed when Dol-P was administered together with rG-CSF to the mice treated with anti-cancer drugs. Joint use of Dol-P (1 mg/day) and rG-CSF (0.3 micrograms/day) was as effective as a higher dose of rG-CSF (3 micrograms/day). Joint use of Dol-P (1 mg/day) and rG-CSF (3 micrograms/day) was sometimes more effective.

Clinical studies with granulocyte colony stimulating factor (G-CSF) in patients receiving cytotoxic chemotherapy

Bacterially synthesised human granulocyte colony-stimulating factor (G-CSF) was administered to patients with advanced cancer. The immediate effect of G-CSF was a fall in the level of circulating neutrophils followed by a rise after 4 hours that was sustained during G-CSF administration. The rise in neutrophil level was less in patients who had been treated previously with chemotherapy and/or radiotherapy. G-CSF was also administered to patients following melphalan and this resulted in a reduction in the duration of the neutropenia that invariably follows melphalan. G-CSF was well tolerated and did not have to be stopped in any patient.

Recombinant human granulocyte-colony stimulating factor: in vivo effects on myelopoiesis in primates

G-CSF belongs to a family of hematopoietic growth factors, also known as colony stimulating factors. It supports the growth and differentiation of predominantly committed neutrophil precursors and activates the function of peripheral blood neutrophils in vitro. In vivo studies in primates (Cynomolgus monkeys) demonstrated that G-CSF is a potent myeloid growth and differentiation factor causing a dose-dependent increase predominantly in the peripheral blood neutrophils. To assess the effects of G-CSF in chemotherapy induced cytopenias, we administered G-CSF to monkeys that had been treated with cyclophosphamide (60 mg/kg/dx2), or repeated cycles of busulfan (4, 6 or 10 mg/kg/dx3). In both, cyclophosphamide and busulfan induced myelosuppression, G-CSF in doses between 10 and 30 micrograms/kg/d was able to significantly shorten the time of neutropenia. In addition, monkeys were treated with G-CSF (50 or 100 micrograms/kg/d) for one month post autologous bone marrow transplantation following total body irradiation. The time of neutropenia (less than 1,000 neutrophils/mm3) was shorter in the G-CSF treated monkeys (10 days in the 100 micrograms/kg/d treated monkey) compared to two controls (21 days). The post transplant absolute neutrophil count of approximately 30,000/mm3 could be maintained for the entire period of G-CSF exposure.

Phase I/II study of recombinant human granulocyte colony-stimulating factor in patients receiving intensive chemotherapy for small cell lung cancer

Twelve patients with advanced small cell carcinoma of the bronchus were treated by continuous infusion of recombinant human granulocyte colony-stimulating factor (rh G-CSF) at the following dose levels: 1 microgram, 5 micrograms, 10 micrograms, 20 micrograms and 40 micrograms/kg/day for 5 days. No toxicities resulted from the treatment and in all 12 patients the number of peripheral neutrophils increased rapidly to a maximum of 100 x 10(9)/l in one patient at 10 micrograms/kg/day. The neutrophils were shown to be functionally normal in tests of their mobility and bactericidal activity. During the Phase II part of the patients were treated using a combination of i.v. Adriamycin, Ifosfamide and Etoposide. The chemotherapy was repeated every 3 weeks. rh G-CSF was given to each patient for 14 days on alternate cycles of chemotherapy and reduced the period of absolute neutropenia considerably (median of 80%), with a return to normal, or above normal, neutrophil counts within 2 weeks after day 1 of chemotherapy. Ten severe infective episodes were observed during the 20 cycles of chemotherapy which did not include rh G-CSF, while only one infective episode occurred in 20 courses when treated with rh G-CSF. These results demonstrate the utility of rh G-CSF in restoring functional neutrophils to patients undergoing intensive chemotherapy.

In vitro and in vivo analysis of the effects of recombinant human granulocyte colony-stimulating factor in patients

Twelve patients with small cell lung cancer were treated with recombinant human granulocyte colony-stimulating factor, rhG-CSF, given by continuous infusion at doses ranging from 1 to 40 micrograms kg-1 day-1. Patients received the rhG-CSF before the start of intensive chemotherapy and after alternate cycles of chemotherapy. Several in vitro assays were performed using peripheral blood neutrophils and marrow progenitor cells collected from patients prior to and after infusion of the growth factor. Peripheral blood neutrophils were tested for mobility and phagocytic activity. In addition, in vitro clonogenic assays of marrow haemopoietic progenitor cells and analysis of bone marrow trephines and aspirates were carried out. We found that rhG-CSF in vivo has at least two main effects: (a) an early fall in peripheral neutrophils, within the first hour, followed by a rapid influx of mature neutrophils into the circulatory pool; (b) stimulation of proliferation and differentiation of neutrophil precursors in the bone marrow. Neutrophils released into the circulation were normal in tests of their mobility and phagocytic activity.

Granulocyte colony-stimulating factor enhances interleukin 3-dependent proliferation of multipotential hemopoietic progenitors

In cultures of spleen cells from normal mice, recombinant human granulocyte colony-stimulating factor (G-CSF) supported the formation of multipotential blast cell colonies. Serial replating of the blast cell colonies in the presence of G-CSF, however, failed to demonstrate any direct effect of G-CSF on murine multipotential progenitors. We therefore examined the effects of G-CSF in combination with murine interleukin 3 on proliferation of murine blast cell colony-forming cells. The time course of total colony formation and multilineage colony formation by spleen cells harvested from mice 4 days after injection of 5-fluorouracil at 150 mg/kg was significantly shortened in cultures containing both factors in contrast with cultures supported by either factor alone. Serial observations of individual multipotential blast cell colonies (mapping) revealed that blast cell colonies emerged at random time intervals in the presence of interleukin 3 or G-CSF. The appearance of blast cell colonies, however, was significantly hastened in cultures containing both factors relative to cultures grown with either factor. In cultures of day-2 post-5-fluorouracil bone marrow cells, G-CSF in concentrations as low as 1 unit/ml revealed synergism with interleukin 3 in supporting the proliferation of multipotential progenitors. This synergistic activity may explain the previous in vivo studies suggesting the effects of G-CSF on apparent multipotential stem cells.