Colony stimulating factors (CSF) biosimilars. Progress?

Biosimilars are equivalent drugs for other biotechnological drugs for which patent has expired. These biopharmaceuticals are often looked upon as simple copies of parent drugs whose goal is solely to potentially generate costs savings. The expansion of available drugs is a subject of attention, criticism and quarrels, often related to a lack of product knowledge. These drugs are copies but need scientific development that must meet many strict rules. Many questions arise in connection with the marketing of several biosimilar drugs in the field of hematopoietic growth factors of white and red cells. Many of them should be discussed.

Serum granulocyte colony-stimulating factor kinetics in children receiving intense chemotherapy with or without stem cell support.

In a previous study, we speculated that the early phase of hematopoietic recovery after PBSC transplantation (PBSCT) is rapid because of the increased production of endogenous cytokines by co-transfused monocytes and lymphocytes (Kawano Y, et al. Blood 81:856, 1993). To clarify this point, the serum level of G-CSF was measured using an ELISA, and various other cytokines, including GM-CSF, macrophage-CSF (M-CSF), SCF, IL-6, IFN-gamma, and soluble IL-2 receptor (IL-2R), were tested for comparison in children receiving conventional or high-dose chemotherapy and autologous transplantation with unmanipulated or purified PBSC. Serum G-CSF levels in patients receiving conventional chemotherapy (n = 21) or PBSCT without exogenous G-CSF treatment (n = 19) increased to 1245 +/- 2337 pg/ml and 2741 +/- 2331 pg/ml, respectively. Likewise, the peak level of G-CSF in patients who did not receive G-CSF was statistically equivalent to the trough level in those who did. There was no significant difference in the speed of hematopoietic recovery with or without G-CSF treatment in both the conventional chemotherapy and PBSCT cohorts. In addition, no meaningful change was observed in the kinetics of other tested factors in either conventional therapy or PBSCT settings, regardless of whether the patient did or did not receive G-CSF. Endogenously produced serum peak G-CSF levels after PBSCT with purified CD34+ cells were identical to those after the same procedure with unmanipulated cells. These results confirm that children receiving intense chemotherapy followed by autologous PBSCT produce a high level of G-CSF during the cytopenic period that is not due to the infusion of a large amount of facilitating cells capable of producing G-CSF.

Pharmacokinetic and pharmacodynamic comparisons between human granulocyte colony-stimulating factor purified from human bladder carcinoma cell line 5637 culture medium and recombinant human granulocyte colony-stimulating factor produced in Escherichia coli.

The pharmacokinetics and biological activities of recombinant human granulocyte colony-stimulating factor (hG-CSF) produced in Escherichia coli were compared with those of hG-CSF purified from human bladder carcinoma cell line 5637 culture medium (5637-hG-CSF). Recombinant hG-CSF was biologically active in a bone marrow cell proliferation assay in vitro, with a dose-response curve similar to that of 5637-hG-CSF. The effects of 5637- and recombinant hG-CSF administered via i.v. injection to rats showed similar response patterns of neutrophil counts in peripheral blood. From these results, it is concluded that the O-linked sugar chain of hG-CSF does not contribute to the in vitro and in vivo biological activities. The pharmacokinetics of both forms of hG-CSF in rats were investigated using a sandwich enzyme-linked immunosorbent assay. After i.v. administration, the serum concentration-time curves of 5637- and recombinant hG-CSF declined biexponentially. Total body clearance and steady-state volume of distribution of 5637-hG-CSF were smaller than those for the recombinant form. After s.c. administration, a lower peak serum level, smaller AUC, and lower bioavailability of 5637-hG-CSF were observed compared to recombinant hG-CSF.

Pharmacokinetics and administration of colony-stimulating factors.

Granulocyte colony-stimulating factor (G-CSF) and granulocyte-macrophage colony-stimulating factor (GM-CSF) generally are rapidly eliminated from the blood after intermittent intravenous infusion. Subcutaneous administration of these agents results in lower peak concentrations but is associated with prolonged systemic exposure. Elimination of the factors appears to occur by several mechanisms, including white blood cell receptor-mediated endocytosis, metabolism by proteases, and urinary excretion by glomerular filtration with subsequent reabsorption and catabolism. The pattern and route of elimination are affected by type of factor and dosage, degree of glycosylation, renal function, and number of white blood cell receptors for the particular CSF. Granulocyte CSF and GM-CSF are approved for use in patients with nonmyeloid malignancy who are receiving myelosuppressive chemotherapy, and those undergoing high-dose chemotherapy and bone marrow transplantation, respectively. In these indications, treatment generally is initiated no earlier than 24 hours after chemotherapy and continued beyond the expected chemotherapy-associated neutrophil count nadir. Limited information suggests that subcutaneous administration is more effective than intermittent intravenous infusion. The latter may require the addition of albumin to ensure stability. Storage and handling guidelines include preventing exposure to extreme temperatures and avoiding excessive agitation of the solution.

Cytokines: a new immunotherapy.

Numerous abnormalities in neonatal host-defense mechanisms have been documented over the past decade. Profound disturbances in myeloid progenitor proliferation, bone marrow neutrophil storage pools, a tendency to peripheral neutropenia and significant in vitro abnormalities of mature neutrophil cell effector function all predispose the neonate to a high mortality rate during bacterial sepsis. The recent use of hematopoietic CSFs and other cytokines to enhance host defense mechanisms in the adult has suggested a role for this new form of immunotherapy in the newborn. Several studies over the past 2 years have indicated that a number of these cytokines may in fact enhance neonatal myeloid progenitor proliferation, modulate neonatal bone marrow neutrophil storage and proliferative pools, induce peripheral neutrophilia and protect against the high mortality rate associated with experimental bacterial sepsis to enhance neonatal host defense against overwhelming bacterial infection.

Granulocyte-macrophage colony stimulating factor (GM-CSF) after high-dose melphalan in patients with advanced colon cancer.

Nine patients with progressive, metastatic disease from primary carcinoma of the colon were entered into a phase I/II study using continuous intravenous infusions of granulocyte-macrophage colony-stimulating factor (GM-CSF) and high dose melphalan (120 mg m-2). GM-CSF was given alone to six patients during the first part of the study to determine a dose that would produce a peripheral leucocyte count (WCC) greater than or equal to 50 X 10(9) 1(-1) and was initially given at 3 micrograms kg-1 day-1 and escalated to 10 micrograms kg-1 day-1 after 10 days. The infusion was discontinued when the WCC exceeded 50 X 10(9) 1(-1) and after a gap of one week, melphalan was given over 30 min. GM-CSF was recommenced 8 h later and was continued until the neutrophil count had exceeded 0.5 X 10(9) 1(-1) for greater than 1 week. One patient achieved a WCC greater than 50 X 10(9) 1(-1) with GM-CSF 3 micrograms kg-1 day-1, but the other five who entered this phase of the study required dose escalation to 10 micrograms kg-1. No toxicity attributed to GM-CSF was seen. After melphalan, the median times to severe neutropenia (less than 0.5 X 10(9) 1(-1] and thrombocytopenia (greater than 20 X 10(9) 1(-1] were 6 and 9 days respectively. The median durations of neutropenia and thrombocytopenia were 14 and 10 days respectively. All patients required intensive support with a median duration of inpatient stay of 24 days. There was one treatment related death due to renal failure. One complete and two partial remissions (33% response rate) were seen but these were of short duration (median of 10 weeks). This study demonstrates that GM-CSF given by continuous intravenous infusion produces significant increments of peripheral granulocyte counts at 3 and 10 micrograms kg-1 day-1 and is not associated with any toxicity. The duration of neutropenia and thrombocytopenia induced by high-dose melphalan appears to be reduced by the subsequent administration of GM-CSF to times which are at least as short as have been reported in historical series which have used autologous bone marrow rescue.

Pharmacokinetics and pharmacodynamics of recombinant human granulocyte-colony stimulating factor after intravenous and subcutaneous administration in the rat.

The pharmacokinetics of recombinant human granulocyte-colony stimulating factor (rhG-CSF) (produced by Kirin Brewery Co., Ltd.) in sera was studied after i.v. and s.c. administration into male Sprague-Dawley rats. Arterial blood samples were taken to determine the rhG-CSF concentrations by measuring its activities using a modified [3H]thymidine assay. After the i.v. dose of 100 micrograms/kg, the half-lives were 25 (alpha) and 102 min (beta). Subcutaneous administration at the 100-micrograms/kg dose resulted in a lower peak serum level but, after 2 hr, rhG-CSF level after the s.c. dose was higher than that of the i.v. dose. The bioavailability of the s.c. dose of 100 micrograms/kg was 78%. The effect of rhG-CSF administration in rats was a specific activity on the neutrophil lineage with increase of neutrophils in peripheral blood. Intravenous and s.c. administration of rhG-CSF had identical effects on the peak neutrophil counts in peripheral blood but, at 24 hr after injection, neutrophil counts after the s.c. dose was greater than that of the i.v. dose. These results indicate the close relationship between pharmacokinetics and pharmacodynamics of rhG-CSF in the rats.

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.

Treatment of chemotherapy-induced neutropenia by subcutaneously administered granulocyte colony-stimulating factor with optimization of dose and duration of therapy.

In patients who have not received extensive prior chemotherapy or radiotherapy, it has been previously demonstrated that granulocyte colony-stimulating factor (G-CSF) abrogated the leukopenia following administration of melphalan (25 mg/m2). This study examined the necessity of a prechemotherapy period of G-CSF administration and the effect of varying the timing and duration of postchemotherapy G-CSF. Initially, patients received 0.3, 1.0, 3.0, and 10 micrograms/kg/d subcutaneously on days 1 to 5 and days 10 to 18. Melphalan was given on day 9. In the next portion of the study melphalan was administered on day 1 and G-CSF, 10 micrograms/kg/d, was administered by subcutaneous infusion on five schedules: (1) days 2 to 13; (2) days 8 to 13; (3) days 2 to 18; (4) days 8 to 18; (5) days -9 to -2 and 2 to 13. G-CSF produced a rapid and sustained elevation in neutrophil levels within 24 hours even when started 8 days after melphalan. This treatment was sufficient to abrogate the neutropenia in patients who had received no prior chemotherapy. It was not necessary to continue G-CSF for more than 7 days. G-CSF did not consistently alter the course of the thrombocytopenia that followed this dose of melphalan. G-CSF was well tolerated, although mild bone pain occurred and was reduced with acetaminophen. One of 22 patients developed cellulitis at an infusion site. We conclude that after melphalan chemotherapy, G-CSF may need to be given for only a short period to prevent chemotherapy-induced neutropenia, and that G-CSF induces a rapid rise in neutrophil levels even when started 8 days after melphalan administration.

Clinical promise of new hematopoietic growth factors: M-CSF, IL-3, IL-6.

Hematopoietic growth factors are reaching maturity in clinical trials. There is a wide spectrum of disorders of bone marrow dysfunction that can be effectively treated by currently available hematopoietic growth factors. Newer growth factors are entering clinical trials. rhM-CSF has a variety of biological activities. It may be useful in hematology/oncology and infectious disease settings. Recombinant human interleukin-3 (rhIL-3) has undergone extensive trials in nonhuman primates that suggest that this hematopoietin is a potent stimulus of bone marrow function following chemotherapy and may be synergistic with other growth factors, such as rhGM-CSF. Other pleotrophic hematopoietic growth factors, such as interleukin-6, are currently being developed and may exert a wide spectrum of activities in disease states.

Evidence for a novel in vivo control mechanism of granulopoiesis: mature cell-related control of a regulatory growth factor.

As part of phase I/II clinical trials of granulocyte colony-stimulating factor (G-CSF), the pharmacokinetics was studied. To determine the optimal way of abrogating the neutropenia caused by melphalan, patients received G-CSF and melphalan on several schedules. The half-life (t 1/2) of elimination of G-CSF was in the range 1.3 to 4.2 hours and was prolonged at higher doses, suggesting that one clearance mechanism becomes saturated at doses greater than 10 micrograms/kg, When a continuous subcutaneous (SC) infusion was administered for five days, a rapid reduction in serum G-CSF levels occurred during the last two days of the infusion, indicating that an additional clearance mechanism was induced. When a continuous infusion of G-CSF was administered after melphalan, serum G-CSF levels remained constant for a longer period of time but did decrease during the second phase of a biphasic neutrophil response. In another clinical trial, G-CSF was administered after high-dose chemotherapy and autologous bone marrow transplantation (ABMT). In these patients, the G-CSF levels did not decrease while the patients were neutropenic. These results show that increased neutrophil levels are associated with increased clearance of G-CSF. This may be one of the negative feedback mechanisms involved in maintaining neutrophil homeostasis in normal and disease states.

Dose escalation study of recombinant human granulocyte-colony-stimulating factor (KRN8601) in patients with advanced malignancy.

To evaluate the toxicity and efficacy of recombinant human granulocyte-colony-stimulating factor (rh G-CSF) administered with intensive chemotherapy, 39 patients with advanced pulmonary cancers were enrolled in a dose escalation trial of rh G-CSF. Three days after initiation of chemotherapy rh G-CSF was administered i.v. for 14 consecutive days at five dose levels (50-800 micrograms/m2). Absolute neutrophil counts showed a dose-dependent increase with an increasing dose of rh G-CSF and the durations of neutropenia (less than 1000/mm3) shortened significantly at doses of 200, 400, and 800 micrograms/m2 compared to those at 50 micrograms/m2 (P less than 0.01). The duration of neutropenia was shortened significantly at all five dose levels following treatment with rh G-CSF compared to treatment without rh G-CSF (P less than 0.05). Adverse side effects associated with rh G-CSF administration were fever higher than 38 degrees C (21%), chest pain, and low back pain (13%). No intolerable side effects were experienced. It can be concluded that rh G-CSF is effective in shortening the duration of neutropenia following intensive chemotherapy at a dose level of 100 to 200 micrograms/m2 i.v. a 400-micrograms/m2 dose of rh G-CSF is recommended in patients with prior treatment because of the possibility of a lower bone marrow response.

Protective, restorative, and therapeutic properties of recombinant colony-stimulating factors.

Pretreatment of mice with recombinant murine (rM) colony-stimulating factor-granulocyte-macrophage (CSF-gm) or recombinant human (rH) CSF-g provides partial protection from the lethal effects of ionizing radiation or the alkylating agent cyclophosphamide (CTX). In addition, these agents can significantly prolong survival if administered following lethal doses of irradiation or CTX. To induce protective activity, cytokines were injected 20 hours before lethal irradiation or CTX administration. To accelerate recovery from lethal irradiation, the cytokines must be administered shortly following irradiation, and the induction of maximal levels of activity is dependent on chronic administration. In contrast, because of their longer half-lives, accelerated recovery from alkylating agents requires a delay of at least 24 to 48 hours to allow complete clearance of CTX before administration of a CSF. Studies quantitating peripheral blood leukocytes and bone marrow cellularity as well as colony-forming units per culture (CFU-C) frequency and CFU-C per femur revealed a significant correlation between these parameters and the ability to survive lethal irradiation. This is a US government work. There are no restrictions on its use.

Subcutaneous granulocyte-macrophage colony-stimulating factor in patients with myelodysplastic syndrome: toxicity, pharmacokinetics, and hematological effects.

The toxicity, pharmacokinetics, and hematologic effects of granulocyte-macrophage colony-stimulating (GM-CSF) were studied in a phase I/II trial of 16 patients with myelodysplastic syndrome (MDS). The GM-CSF was administered subcutaneously (SC) daily so as to achieve prolonged blood levels and to establish an outpatient treatment regimen. Four dose levels were administered for ten days: 0.3 microgram/kg/d (three patients), 1.0 microgram/kg/d (three), 3.0 micrograms/kg/d (four), and 10.0 micrograms/kg/d (six). The most common toxicities were fever and a flu-like syndrome, which were dose-dependent. The maximum-tolerated dose was 10.0 micrograms/kg/d, which induced severe rigors (two patients), fever greater than 40 degrees C (one), severe bronchospasm (one), and WBC 60,000 (one). In one patient, refractory anemia with excess blasts in transformation (RAEB-T) progressed to acute nonlymphocytic leukemia after two doses of GM-CSF, and the patient died of leukemia that did not respond to chemotherapy. After doses of 3.0 and 10.0 micrograms/kg, serum GM-CSF levels peaked at 3.8 to 6.3 hours, and persisted for 14 and 24 hours, respectively. Circulating granulocytes (neutrophils and bands) increased in a dose-dependent manner, as 11 of 13 patients who received greater than or equal to 1.0 microgram/kg/d responded with a two- to 194-fold increase. Although the neutrophils usually returned to pretreatment levels shortly after stopping GM-CSF, two patients continue to exhibit an elevation of neutrophils for 6 months. Dose-related increases in circulating monocytes and eosinophils were also noted. Transient increases in platelet and reticulocyte counts were observed in two and three patients, respectively. Five of the 16 patients later received maintenance GM-CSF at 3 micrograms/kg/d for 2 to 9 weeks. All showed a dramatic increase in neutrophils after 2 weeks. Thereafter, despite continued therapy, the neutrophil count in four patients declined markedly. In conclusion, GM-CSF is well tolerated by the SC route and induces striking, but usually temporary, improvement in the neutropenia of MDS. Larger prospective phase III trials will determine the duration of hematologic responses and the impact on infection, morbidity, and mortality.

Is recombinant human granulocyte colony-stimulating factor (G-CSF) orally available in rats?

Oral availability of recombinant human granulocyte colony-stimulating factor (G-CSF) was investigated in rats by measuring the blood total leucocyte (BTL) counts. Oral test G-CSF solution was prepared with 10% HCO-60 (polyoxyethylated, 60 mumol, castor oil derivative), 1% DK ester (sugar ester) or 10% MYS-40 (polyethyleneglycol monostearate), in which the G-CSF concentration was 500 or 250 micrograms/ml. Each test solution was injected into the duodenum of three rats at the G-CSF dose level of 300 or 600 micrograms/kg, and BTL counts were monitored for 48 h. All of the test G-CSF solution raised the BTL levels within 24 h after injection. In particular, the HCO-60 solution increased the BTL levels over 2 times as compared to the predose level at 600 micrograms/kg dose and the effect was apparently dose-dependent. A short-term study suggested that the effect of G-CSF on the BTL level appeared at the fastest at about 5 h after administration of HCO-60 test solution, 300 micrograms/kg. In view of the pattern of BTL dynamics obtained after i.v. injection of HCO-60 solution at 25 and 50 micrograms/kg, the increase of BTL levels observed after oral administration of the HCO-60 solution is considered to be due to the orally supplied G-CSF.

Effects of bacterially synthesized recombinant human granulocyte-macrophage colony-stimulating factor in patients with advanced malignancy.

STUDY OBJECTIVE: To define the clinical and hematologic effects of subcutaneously administered bacterially synthesized recombinant human granulocyte-macrophage colony-stimulating factor (rhGM-CSF). DESIGN: Single arm nonrandomized dose escalation study. PATIENTS: Twenty-one patients with advanced malignancy who were not receiving concurrent myelosuppressive therapy. INTERVENTIONS: Subcutaneous administration of rhGM-CSF by once-daily injection to groups of two to four patients at doses of 0.3 to 30 micrograms/kg body weight.d for 10 consecutive days. Some patients received a second 10-day period of daily rhGM-CSF treatment after a 10-day nontreatment interval followed by alternate-day treatment. Clinical status and hematologic values were monitored frequently. MEASUREMENTS AND MAIN RESULTS: All doses of rhGM-CSF caused an immediate transient fall of 84% to 99% in circulating neutrophils, eosinophils, and monocytes. Continued daily dosing caused a leukocytosis of up to 10-fold with increases in numbers of circulating neutrophils, eosinophils, monocytes, and lymphocytes. There appeared to be a plateau in the increase in neutrophils in the dose range 3 to 15 micrograms/kg.d. Marrow aspirates showed increased proportions of promyelocytes and myelocytes. Alternate-day injection of 15 micrograms/kg maintained a leukocytosis. At doses up to 15 micrograms/kg.d, rhGM-CSF was well tolerated but adverse effects included bone pains, myalgias, rashes, and liver dysfunction. At doses exceeding 15 micrograms/kg.d, pericarditis was a dose-limiting toxicity. Idiopathic thrombocytopenic purpura was reactivated by rhGM-CSF in one patient. CONCLUSIONS: Bacterially synthesized rhGM-CSF induces a leukocytosis in the dose range of 3 to 15 micrograms/kg.d. These doses are appropriate for phase II studies.

Hematopoietic responses in patients with advanced malignancy treated with recombinant human granulocyte-macrophage colony-stimulating factor.

The in vivo effect of yeast-derived recombinant human granulocyte-macrophage colony-stimulating factor (rh GM-CSF) was investigated in 30 patients with advanced malignancy in a phase Ib trial. Patients were treated at four different dose levels (120 to 1,000 micrograms/m2/d) by either daily intravenous (IV) bolus injection or 24-hour continuous infusion. Administration of rh GM-CSF resulted in a broad spectrum of dose- and schedule-dependent hematopoietic effects. Sustained infusion of rh GM-CSF elicited a maximum 17-fold average peak increase of the total WBC count with mainly neutrophils, eosinophils, and monocytes accounting for this rise, and increases in bone marrow cellularity with a shift to immature myeloid elements. Elevation of lymphocytes, platelets, and reticulocytes was not induced. Within five days after discontinuation of treatment the leukocytosis had disappeared. Adverse reactions encountered with rh GM-CSF seen in 65% of the patients studied were never life-threatening and always rapidly reversible. They included mild myalgias, facial flushing, low-grade fever, headache, bone discomfort, nausea, dyspnea, and transient decline of platelet counts. These results suggest that rh GM-CSF can be safely administered at the doses and schedules used and that it can induce in vivo some of the biological effects reported in in vitro studies. Although no objective antitumour responses have been seen, the ability of rh GM-CSF to increase number and function of leukocytes in vivo may prevent neutropenia and infections when GM-CSF is added to cytotoxic cancer therapy.

Tissue distribution of murine hemopoietic growth factor mRNA production.

We have studied the tissue distribution of interleukin (IL) and hemopoietic colony-stimulating factor (CSF) transcripts in mice by S1-nuclease protection analysis. Accumulation of several of these mRNAs in response to intravenous injection of lipopolysaccharide (LPS) appears to occur in a tissue-specific fashion. IL-1 alpha transcripts accumulate in spleen and lung; IL-6 transcripts accumulate in kidney, heart, and spleen; granulocyte-macrophage-CSF transcripts accumulate in lung and heart; and granulocyte-CSF transcripts accumulate in heart. Three distinct patterns of in vivo mRNA accumulation were detected: 1) silent--interleukins 2-5 showed no transcripts in either LPS-treated or untreated animals; 2) induced--IL-1 alpha, IL-6, granulocyte-macrophage (GM)-CSF, and G-CSF transcripts were increased in abundance in LPS-injected mice; and 3) constitutive--M-CSF transcripts were found in similar amounts in both untreated and treated mice and were present in all tissues examined.