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Introduction: The rapid spread of severe infections mainly due to resistant pathogens, justifies the search for therapies aiming to restore immune functions severely compromised in patients with hematologic malignancies. Areas covered: The present review summarizes the current knowledge on the role of granulocyte transfusions and colony-stimulating factors as treatment strategy for hematologic patients with serious infectious complications. In addition, a survey among 21 hematologic centers, to evaluate the clinical practice for the use of G-CSF originator and biosimilars was performed. Expert commentary: Granulocyte transfusions with a target dose of at least 1.5-3 × 10 8 cells/kg, may be considered as an approach to bridge the gap between marrow suppression and recovery of granulocytes. G-CSF shortens the period of neutropenia, the hospitalization, the use of antibiotics and the rate of febrile neutropenia (FN) in adult and pediatric patients with non-Hodgkin lymphoma, and in adults with acute myeloid leukemia where these advantages nevertheless, did not translate into a clinical benefit. G-CSF biosimilar showed equivalence or non-inferiority to filgrastim. There are no data supporting the use of GM-CSF, eltrombopag and erythropoietin for preventing or treating infectious complications in patients with hematologic disorders.

Patterns of myeloid growth factor (GF) usage and febrile neutropenia (FN) were examined in patients >60 years of age with diffuse large B-cell non-Hodgkin lymphoma (DLBCL) enrolled on CALGB 9793/ECOG-SWOG 4494, receiving initial therapy with cyclophosphamide, doxorubicin, vincristine, prednisone (CHOP) or rituximab + CHOP (R-CHOP). Myeloid GFs were administered to 256/520 (49%) patients. Indications for use were: prevent dose reduction/dose delay (81%, 207/256); treat FN or non-febrile neutropenia (NFN) (19%, 48/256). One or more FN episodes occurred in 41% (212/520) of patients, with FN most often in cycle 1 (38% of episodes). In multivariate analysis, risk factors for FN included age >65 years (odds ratio (OR) = 2.6, 95% CI: [1.4, 4.9]) and anemia (hemoglobin <12 g/dl) (OR =2.2, 95% confidence intervals (CI): [1.4, 3.5]. Myeloid GF use was common in this older DLBCL population receiving CHOP-based therapy, as was FN, especially during cycle one. Risk factors predictive for FN should be used prospectively to identify patients for whom myeloid GFs are best utilized.

Introduction: The administration of myeloid growth factors is the only approved treatment for the prevention of chemotherapy induced neutropenia and febrile neutropenia. However, their specific indications and contraindications and potential side effects limit their application to only a relatively small subset of patients at the highest risk for complications, such as infection., Areas Covered: A computerized systematic literature search was performed through Medline, Google Scholar, Cochrane Library, the Pharmaprojects database and the clinicaltrials.gov website. The shortcomings of the existing treatment approach are reviewed, along with a synopsis of the characteristics of novel agents that protect bone marrow progenitors from the cytotoxic effects of antineoplastic treatment that may be used in the future as a stand-alone preventive strategy or as an adjunct to growth factors., Expert Opinion: There is an abundance of agents undergoing evaluation for the prevention of treatment-induced neutropenia. The appropriate selection of patients, the optimization of the use of existing agents and the increasing competition from biosimilars which likely ensure future decreases in healthcare costs are essential for growth factors to retain their dominant position in this setting.

Fever occurs at high rates in patients with chemotherapy-induced neutropenia and is considered an oncologic emergency. Numerous algorithms have been developed to guide treatment decisions. Prompt care and the initiation of empiric antibiotic therapy are critically important universal aspects of these treatment-decision schemata. Fever may be the only sign of infection, as in patients with cancer who are undergoing chemotherapy, the immune response is attenuated. In the majority of cases, no etiology for neutropenic fever is uncovered; nonetheless, a thorough workup is essential. The workup allows practitioners to risk stratify patients as being at low or high risk for infectious complications so that appropriate care can be administered. Although it is important to note that there are management algorithms to follow, every patient may present and respond differently. We generally start with broad-spectrum monotherapy for Gram-negative bacteria and then consider whether Gram-positive or antifungal coverage is necessary based on the clinical picture, including factors such as duration and degree of neutropenia. It is important for all practitioners to understand how to care for patients with neutropenic fever because it is a common and treatable condition.

The colony-stimulating factors (CSFs) represent the only biological response modifiers used in clinical practice to treat or prevent neutropenia. These pleiotropic cytokines are available in clinical practice as granulocyte CSF (G-CSF), granulocyte-macrophage CSF (GM-CSF) and pegylated G-CSF. Neutropenia and its complications, most importantly febrile neutropenia (FN), remain major and serious side effects of cancer chemotherapy. Several studies and meta-analyses have addressed the clinical applications of CSFs to treat or prevent neutropenia. Guidelines have been developed to foster the appropriate use of CSFs. This article reviews the nature and use of the CSFs, and summarises the critical studies and guidelines. A historical perspective briefly describes the discovery, synthesis and clinical use of CSFs. The major biological and pharmacological characteristics are highlighted. The clinical applications of the CSFs are reviewed, including primary FN prophylaxis, secondary FN prophylaxis, treatment of FN, support of dose-dense chemotherapy regimens, use in leukaemia and myelodysplastic syndromes, utility in stem cell transplantation, and use in elderly and paediatric patients. Finally, clinical efficacy data, as well as the economic impact of the CSFs, are discussed.

Infectious disease remains an ever-growing health concern worldwide due to increasing antibiotic-resistant microbial strains, immune-compromised populations, international traffic and globalisation, and bioterrorism. There exists an urgent need to develop novel prophylactic and therapeutic strategies. In addition to classic antibiotic therapeutics, immune-modulatory molecules such as cytokines or their inhibitors represent a promising form of antimicrobial therapeutics or immune adjuvant used for the purpose of vaccination. These molecules, in the form of either recombinant protein or transgene, exert their antimicrobial effect by enhancing infectious agent-specific immune activation or memory development, or by dampening undesired inflammatory and immune responses resulting from infection and host defence mechanisms. In the last two decades, a number of cytokine therapy-based experimental and clinical trials have been conducted, and some of these efforts have led to the routine clinical use of cytokines. For instance, although IFNs have been used to treat hepatitis C with great success, many other cytokines are yet to be fully evaluated for their antimicrobial potential. This review discusses the biology and therapeutic potential of selected immune modulatory cytokines and their inhibitors, including granulocyte colony-stimulating factor, granulocyte-macrophage colony-stimulating factor, IFN-gamma, IL-12 and TNF.

The last decade has seen the emergence of immunomodulators as promising therapeutic agents in infectious diseases. A diverse array of recombinant, synthetic and natural immunomodulatory preparations for prophylaxis and treatment of various infections are available today. Some of these substances, such as granulocyte colony-stimulating factor (G-CSF), interferons, imiquimod and bacterial-derived preparations are already licensed for use in patients. Others including IL-12, various chemokines, synthetic cytosine phosphate-guanosine (CpG) oligodeoxynucleotides and glucans are being investigated extensively in clinical and preclinical studies. Immunomodulatory regimens offer an attractive approach as an adjunct modality for control of microbial diseases in the era of antibiotic resistance. Practical application of the advances in molecular biology, bioinformatics, genomic mining and high-throughput peptide synthesis should foster future discovery and development of novel immunomodulators contingent upon scientific evidence rather than dictates of discursive empiricism.

Myelodysplastic syndromes (MDS) are a heterogeneous group of disorders of hematopoiesis involving hyperproliferative and ineffective hematopoiesis associated with morphologic evidence of marrow cell dysplasia resulting in refractory cytopenia(s), and an increased risk of transformation into acute myeloblastic leukemia (AML). The administration of colony-stimulating factor(s) (CSFs) to patients with MDS increased blood neutrophil concentrations, in most patients, and was also expected to be beneficial and to prevent infections. However, the progression to AML during the treatment with CSFs was suspected in some patients. Therefore, extensive in vitro studies were expected to lead to the establishment of criteria for selection of patients who are likely to benefit from CSF's as well as to establish the overall value of the different types of CSFs therapy. For this purpose, in vitro colony assays provide an excellent tool for investigating the biologic characteristics of MDS progenitor cells. However, conditions of the culture must be such that each progenitor can express its full potential for proliferation and differentiation. Because of the above, MDS progenitor cells cannot be used because they carry an impairment in proliferation and differentiation. To address this problem, one needs to know how many cells are being handled and the maximum numbers of colonies and clusters expected. CD34, a stem cell phenotype, is at present one of the best markers of progenitor cells, and can be used for purposes of purification. Using a defined number of CD34+ cells, it was feasible to make direct investigations on MDS progenitor cells. In this review the properties of MDS progenitor cells are described, in association with proliferation and differentiation, with special emphasis on the phenotypic subpopulations of MDS CD34+ cells.

Approved by the FDA in 1991 with indications for acceleration of neutrophil recovery in several clinical settings, CSFs may prove clinically useful in ways beyond hemorestoration. Myeloprotection conferred by GM-CSF may enable higher doses of chemotherapy to be given with only short intervals between cycles. Priming may make resting AML blasts more chemosensitive. Mobilization of peripheral blood stem cells may facilitate and even improve autologous stem cell transplantation.

It has been known for decades that blood neutrophilia occurs after the administration of etiocholanolone, adrenocortical steroids, and endotoxins. Neutrophil leukocytosis in general may be due to several mechanisms such as increased stimulation of the myelopoiesis, increased release from the marrow, a shift from the marginated to the circulating pool (demargination), prolongation in the peripheral half-life, and decreased migration of neutrophils from the blood to the tissue. However, the principal cause of the neutrocytosis for each of the above mentioned agents is increased release of neutrophils from the bone marrow reserves. Since a sufficient reserve capacity is a prerequisite for optimal defenses against infections, the marrow response has been used to estimate the dose of chemotherapy expected to be tolerated without life-threatening neutropenia. However, none of the above "test substances" have gained widespread use due to adverse reactions or undesirable effects on neutrophil function. Recent progress in biotechnology has developed recombinant human (rh) hematopoietic growth factors ready for clinical use. Marrow myelopoiesis is stimulated by granulocyte colony-stimulating factor (rhG-CSF) and granulocyte-macrophage CSF (rhGM-CSF). The immediate effect, however, is mobilization of mature neutrophil granulocytes to the blood. Bone marrow cellularity seems to influence the neutrophil number mobilized during 24 hours by one subcutaneous injection of either rhG-CSF or rhGM-CSF. A recent pilot study has suggested such a "24 hour stimulation test" to predict severe neutropenia following cyclic chemotherapy. This concept is illustrated by two case reports. The "stimulation test" suggests that we may devise strategies to define patient subsets which may benefit from prophylactic growth factor administration during cyclic chemotherapy.

One case has been reported of a patient undergoing allogeneic transplantation with peripheral blood progenitor cells (PBPCs) rather than bone marrow. We now report the first case of a patient who underwent an allogeneic transplant with bone marrow combined with PBPCs.

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.

The cloning of hematopoietic growth factors has allowed their application in clinical medicine. This review deals with clinical studies on GM-CSF and G-CSF in bone marrow insufficiency (primary or secondary to chemotherapy), myelodysplastic syndromes, AIDS and bone marrow transplantation.