Oral combination chemotherapy in conjunction with filgrastim (G-CSF) in the treatment of AIDS-related non-Hodgkin's lymphoma: evaluation of the role of G-CSF; quality-of-life analysis and long-term follow-up

Towards a comprehensive safety understanding of granulocyte-colony stimulating factor biosimilars in treating chemotherapy associated febrile neutropenia: Trends from decades of data

Filgrastim, a biopharmaceutical listed on WHO model list of essential medicines, was approved in USA in 1991 for patients with non-myeloid malignancies associated with severe neutropenia and fever. Several filgrastim biosimilars have now been approved in USA, Europe and elsewhere since 2008, based on the reference product which has lost patent exclusivity; however their immunogenicity and safety is controversial. We conducted a retrospective, post market study between 1991 and May 2018 using VigiBase®. The study included all adverse events with case reports ≥150. Overall, 11,183 adverse drugs reaction reports were identified during observation period; of which 5764; 51.5% reports concerned to Neupogen®, the originator, and rest consists of Leucostim® (N = 680), Zarzio® (N = 622), Grasin® (N = 545), Nivestim® (N = 359) and Tevagrastim® (N = 152) biosimilars. When compared with the originator, Grasin® was associated with higher reporting of pyrexia (11.5% vs 7.9%, ROR 1.52, IC₀₂₅ 1.12), myalgia (37% vs 2.2%, ROR 25.94, IC₀₂₅ 2.11) and back pain (11.3% vs 4%, ROR 3.09, IC₀₂₅ 2.32). Zarzio® was associated with increased reporting of arthralgia (4.5% vs 2.9%, ROR 1.59, IC₀₂₅ 1.25) and neutropenia (11.4% vs 4%, ROR 2.59, IC₀₂₅ 3.07). Bone pain was reported more often with Nivestim® (14.4% vs 8.3%, ROR 1.87, IC₀₂₅ 5.30). Drug ineffectiveness was reported in cases with Zarzio® (35.9%), Nivestim® (19.4%) and Tevagrastim® (42.2%). Authors observed significant differences among originator and biosimilars in particular to efficacy, adverse events reported and time to onset of occurrences. Large epidemiologic studies are needed to further confirm these finding and provide additional insights.

Treatment factors affecting outcomes in HIV-associated non-Hodgkin lymphomas: a pooled analysis of 1546 patients

Limited comparative data exist for the treatment of HIV-associated non-Hodgkin lymphoma. We analyzed pooled individual patient data for 1546 patients from 19 prospective clinical trials to assess treatment-specific factors (type of chemotherapy, rituximab, and concurrent combination antiretroviral [cART] use) and their influence on the outcomes complete response (CR), progression free survival (PFS), and overall survival (OS). In our analysis, rituximab was associated with a higher CR rate (odds ratio [OR] 2.89; P < .001), improved PFS (hazard ratio [HR] 0.50; P < .001), and OS (HR 0.51; P < .0001). Compared with cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP), initial therapy with more dose-intense regimens resulted in better CR rates (ACVBP [doxorubicin, cyclophosphamide, vindesine, bleomycin and prednisolone]: OR 1.70; P < .04), PFS (ACVBP: HR 0.72; P = .049; "intensive regimens": HR 0.35; P < .001) and OS ("intensive regimens": HR 0.54; P < .001). Infusional etoposide, prednisone, infusional vincristine, infusional doxorubicin, and cyclophosphamide (EPOCH) was associated with significantly better OS in diffuse large B-cell lymphoma (HR 0.33; P = .03). Concurrent use of cART was associated with improved CR rates (OR 1.89; P = .005) and trended toward improved OS (HR 0.78; P = .07). These findings provide supporting evidence for current patterns of care where definitive evidence is unavailable.

AIDS-Related Non-Hodgkin's Lymphoma in Sub-Saharan Africa: Current Status and Realities of Therapeutic Approach

Today AIDS-related non-Hodgkin's lymphoma (AR-NHL) is a significant cause of morbidity and mortality in HIV-infected patients the world over, and especially in sub-Saharan Africa. While the overall incidence of AR-NHL since the emergence of combination antiretroviral therapy (cART) era has declined, the occurrence of this disease appears to have stabilized. In regions of the world where access to cART is challenging, the impact on disease incidence is less clear. In the resource-rich environment it is clinically well recognized that it is no longer appropriate to consider AR-NHL as a single disease entity and rather treatment of AIDS lymphoma needs to be tailored to lymphoma subtype. While intensive therapeutic strategies in the resource-rich world are clearly improving outcome, in AIDS epicenters of the world and especially in sub-Saharan Africa there is a paucity of data on treatment and outcomes. In fact, only one prospective study of dose-modified oral chemotherapy and limited retrospective studies with sufficient details provide a window into the natural history and clinical management of this disease. The scarcities and challenges of treatment in this setting provide a backdrop to review the current status and realities of the therapeutic approach to AR-NHL in sub-Saharan Africa. More pragmatic and risk-adapted therapeutic approaches are needed.

Quality of life, characteristics and survival of patients with HIV and lymphoma

PURPOSE

We sought to compare the quality of life (QOL), characteristics, and survival of patients with non-Hodgkin lymphoma (NHL) with and without human immunodeficiency virus (HIV) infection.

METHODS

Using the population-based cancer registry for Orange and San Diego Counties, We recruited 50 patients with HIV and systemic NHL (cases) and 50 age, sex and race-matched NHL patients without HIV (controls) diagnosed with NHL during 2002-2006. Patients completed a medical history survey and QOL instrument, the Functional Assessment of Human Immunodeficiency Virus Infection (FAHI) for cases and Functional Assessment of Cancer Therapy-General (FACT G) for controls.

RESULTS

HIV-infected patients had worse overall QOL and survival than uninfected patients. QOL differences were more marked in the areas of functional, physical and social well-being than in the area of emotional well-being. HIV-infected patients had lower income and were less likely to have private insurance and more likely to have diffuse large B cell histology than uninfected patients.

CONCLUSION

HIV-infected NHL patients had worse QOL and survival than uninfected patients, due to a combination of co-morbidity, aggressive histology and lack of social support. However, their emotional well-being was comparable to that of uninfected NHL patients and better than historical norms for the HIV-infected.

Predictors of survival after a diagnosis of non-Hodgkin lymphoma in a resource-limited setting: a retrospective study on the impact of HIV infection and its treatment

OBJECTIVE

We examined factors associated with survival among patients with newly diagnosed non-Hodgkin lymphoma (NHL) in Uganda.

METHODS

Information was abstracted from medical records for all NHL patients >13 years of age at the Uganda Cancer Institute between January 2004 and August 2008. Cox proportional hazard models were used to identify predictors of NHL survival.

RESULTS

One hundred sixty patients with NHL were identified; 51 (31.9%) were known to be HIV positive. Overall, 154 patients had records sufficient for further analysis. The median person-time observed was 104 days (interquartile range 26-222). Median survival after presentation among those whose mortality status was confirmed was 61 days (interquartile range 25-203). HIV-positive patients receiving antiretroviral therapy had survival rates approximating those of HIV-negative persons, but the adjusted hazard of death was significantly elevated among HIV-positive patients not receiving antiretroviral therapy [adjusted hazard ratio (HR) 8.99, P < 0.001] compared with HIV-negative patients. Both B-symptoms (HR 2.08, P = 0.05) and female gender (HR 1.72, P = 0.05) were associated with higher mortality.

CONCLUSIONS

In Uganda, overall survival of NHL patients is poor, and predictors of survival differed from those described in resource-rich regions. HIV is a common comorbidity to NHL, and its lack of treatment was among the strongest predictors of mortality. Strategies are needed for optimal management of HIV-infected individuals with cancer in resource-limited settings.

Implications of the European Organisation for Research And Treatment Of Cancer (EORTC) guidelines on the use of granulocyte colony-stimulating factor (G-CSF) for lymphoma care

Febrile neutropenia (FN) is a potentially life-threatening complication of myelosuppressive chemotherapy. The European Organisation for Research and Treatment of Cancer (EORTC) guidelines recommend use of primary granulocyte colony-stimulating factor (G-CSF) prophylaxis if the overall FN risk to a patient is >or=20%, or if a reduction in chemotherapy dose intensity correlates with a poorer outcome. Many of the regimens used for treatment of lymphoma, including R-CHOP (rituximab combined with cyclophosphamide, doxorubicin, vincristine and prednisolone), are associated with an FN risk of approximately 20% or higher. Individual patient factors that may increase the risk of FN such as advanced age or advanced disease should be taken into account when assessing the need for G-CSF support. Predictive models are being developed to facilitate individual risk assessment. Additional anti-infective prophylaxis may be indicated in some settings. There is now much evidence for the benefits of G-CSF in reducing the incidence of FN and facilitating delivery of chemotherapy, including dose-escalated and dose-dense (interval-reduced) regimens. If given according to guidelines, G-CSF has the potential to reduce FN and related morbidity. Furthermore, by facilitating delivery of planned chemotherapy, use of G-CSF may potentially influence survival in the curative setting. Implementation of the EORTC guidelines will lead to a greater proportion of patients receiving G-CSFs, but the costs involved should be at least partly offset by a reduction in FN and its associated costs, including those of hospitalization.

Dose-modified oral chemotherapy in the treatment of AIDS-related non-Hodgkin's lymphoma in East Africa

PURPOSE Africa is burdened by the AIDS epidemic and attendant increase in HIV/AIDS-related malignancies. Pragmatic approaches to therapeutic intervention could be of great value. Dose-modified oral chemotherapy for AIDS-related non-Hodgkin's lymphoma is one such approach. PATIENTS AND METHODS The oral regimen consisted of lomustine 50 mg/m(2) on day 1 (cycle 1 only), etoposide 100 mg/m(2) on days 1 to 3, and cyclophosphamide/procarbazine 50 mg/m(2) each on days 22 to 26 at 6-week intervals (one cycle) for two total cycles in HIV-infected patients with biopsy-proven non-Hodgkin's lymphoma. Results Forty-nine patients (21 in Uganda and 28 in Kenya) were treated. The majority of patients were female (59%) and had a poor performance status (63%); 69% of patients had advanced-stage disease; and 18 patients (37%) had access to antiretroviral therapy. In total, 79.5 cycles of therapy were administered. The regimen was well tolerated, had modest effects (decline) on CD4(+) lymphocyte counts (P = .077), and had negligible effects on HIV-1 viral replication. Four febrile neutropenia episodes and three treatment-related deaths (6% mortality rate) occurred. The overall objective response rate was 78% (95% CI, 62% to 88%); median follow-up time was 8.2 months (range, 0.1 to 71 months); median event-free and overall survival times were 7.9 months (95% CI, 3.3 to 13.0 months) and 12.3 months (95% CI, 4.9 to 32.4 months), respectively; and 33% of patients survived 5 years. CONCLUSION Dose-modified oral chemotherapy is efficacious, has comparable outcome to that in the United States in the pre-highly active antiretroviral therapy setting, has an acceptable safety profile, and is pragmatic in sub-Saharan Africa. The international collaboration has been highly successful, and subsequent projects should focus on strategies to optimize combination antiretroviral therapy and chemotherapy and follow-up tissue correlative studies.

Interventions for previously untreated patients with AIDS-associated non-Hodgkin's lymphoma

BACKGROUND

Human immunodeficiency virus (HIV) infection is known to be associated with an increased risk of non-Hodgkin's lymphoma (NHL). The majority of lymphomas (>80%) occurring during immunosuppression are aggressive B-cell in origin and have a high-to-intermediate histology grade. Treatment of NHL is not standardized.

OBJECTIVES

To assess the clinical effectiveness and safety of single agent or combination chemotherapy with or without immunochemotherapy (rituximab) and with or without highly active antiretroviral therapy (HAART) on overall survival (OS) and disease-free survival (DFS) for previously untreated patients with AIDS-related NHL.

SEARCH STRATEGY

The Cochrane Central Register of Controlled Trials (The Cochrane Library Issue 1, 2009), MEDLINE (1966-March 6, 2009), EMBASE (1988-March 6, 2009), LlLACS (1982 to February 17, 2009), Gateway (March 6, 2009), and AIDSearch (2006 -February 2008) were used to identify published, potentially eligible trials. Further, we searched several electronic sources. For additional information see the Cochrane HIV/AIDS Group search strategy.

SELECTION CRITERIA

Randomized controlled trials (RCTs) assessing the effectiveness of systemic treatments for previously untreated AIDS-related NHL. There were no age or language restrictions.

DATA COLLECTION AND ANALYSIS

Authors independently assessed relevant studies for inclusion; four RCTs were selected. No meta-analysis was attempted due to clinical heterogeneity.

MAIN RESULTS

Four RCTs that included 857 patients (number range: 30 to 485) met the inclusion criteria. The studies have a high risk of bias; three RCTs were conducted in the United States and one was a multi-national, multi-centre RCT performed in France and Italy. One of the trials included only men. It was impossible to pool data for any of the outcomes due to the differences in the interventions assessed in these RCTs. Overall survival did not differ significantly between treatment groups. Disease free survival (DFS) was reported in two of the four RCTs, but it was not statistically significant between treatment groups.

AUTHORS' CONCLUSIONS

We found no evidence that the systemic interventions for untreated patients with AIDS-related NHL provide superior clinical effectiveness for improving OS, DSF, and tumour response rate; however, this conclusion is based on four RCTs with limited sample size and variable quality. More adequately powered RCTs that have low risk of bias are necessary to determine the real benefit or harm of interventions to treat this population. Overall survival (OS), DFS, and quality of life should be included as endpoints.

CNS prophylaxis in lymphoma: Who to target and what therapy to use

The purpose of this article is to review the current data on the risk of CNS relapse in patients with lymphoma and the efficacy of CNS directed prophylactic therapy. CNS relapse occurred in 30-50% of those with Burkitt lymphoma and acute lymphoblastic leukaemia/lymphoma prior to the introduction of intensified regimens that include CNS prophylaxis. Most patients with AIDS-related-lymphoma receive a short course of intrathecal prophylaxis but a re-evaluation of type and targeting of CNS prophylaxis is needed. Patients with diffuse large B-cell lymphoma (DLBCL) have a 5% overall risk of CNS relapse but a high risk sub-population can be identified on the basis of raised LDH and >1 extranodal site, testicular or primary breast involvement. CNS prophylaxis for selected patients with DLBCL may be justified by risk but its benefit is not yet proven. Intravenous methotrexate > or = 3 g/m(2) achieves therapeutic levels in CSF and parenchyma and in combination with intrathecal methotrexate would be a reasonable option for prophylaxis.

Feasibility of withholding antibiotics in selected febrile neutropenic cancer patients

PURPOSE

To investigate the feasibility of withholding antibiotics and early discharge for patients with chemotherapy-induced neutropenia and fever at low risk of bacterial infection by a new risk assessment model.

PATIENTS AND METHODS

Outpatients with febrile neutropenia were allocated to one of three groups by a risk assessment model combining objective clinical parameters and plasma interleukin 8 level. Patients with signs of a bacterial infection and/or abnormal vital signs indicating sepsis were considered high risk. Based on their interleukin-8 level, remaining patients were allocated to low or medium risk for bacterial infection. Medium-risk and high-risk patients received standard antibiotic therapy, whereas low-risk patients did not receive antibiotics and were discharged from hospital after 12 hours of a febrile observation. End points were the feasibility of the treatment protocol.

RESULTS

Of 196 assessable episodes, 76 (39%) were classified as high risk, 84 (43%) as medium risk, and 36 (18%) as low risk. There were no treatment failures in the low-risk group (95% CI, 0% to 10%). Therefore, sensitivity of our risk assessment model was 100% (95% CI, 90% to 100%), the specificity, positive, and negative predictive values were 21%, 13%, and 100%, respectively. Median duration of hospitalization was 3 days in the low-risk group versus 7 days in the medium- and high-risk groups (P < .0001). The incremental costs of the experimental treatment protocol amounted to a saving of 471 (US $572) for every potentially low-risk patient.

CONCLUSION

This risk assessment model appears to identify febrile neutropenic patients at low risk for bacterial infection. Antibiotics can be withheld in well-defined neutropenic patients with fever.

Capacity building for the clinical investigation of AIDS malignancy in East Africa

PURPOSE

To build capacity in the resource-poor setting to support the clinical investigation and treatment of AIDS-related malignancies in a region of the world hardest hit by the AIDS pandemic.

METHODS

An initial MEDLINE database search for international collaborative partnerships dedicated to AIDS malignancies in developing countries failed to identify any leads. This search prompted us to report progress on our collaboration in this aspect of the epidemic. Building on the formal Uganda-Case Western Reserve University (Case) Research Collaboration dating back to 1987, established NIH-supported centers of research excellence at Case, and expanding activities in Kenya, scientific and training initiatives, research capital amongst our institutions are emerging to sustain a international research enterprise focused on AIDS and other viral-related malignancies.

RESULTS

A platform of clinical research trials with pragmatic design has been developed to further enhance clinical care and sustain training initiatives with partners in East Africa and the United States. An oral chemotherapy feasibility trial in AIDS lymphoma is near completion; a second lymphoma trial of byrostatin and vincristine is anticipated and a feasibility trial of indinavir for endemic Kaposi's sarcoma is planned.

CONCLUSIONS

In the absence of published reports of evolving international partnerships dedicated to AIDS malignancy in resource constrained settings, we feel it important for such progress on similar or related international collaborative pursuits to be published. The success of this effort is realized by the long-term international commitment of the collaborating investigators and institutions to sustain this effort in keeping with ethical and NIH standards for the conduct of research; the provision of formal training of investigators and research personnel on clinical problems our East African partners are faced with in practice and the development of pragmatic clinical trials and therapeutic intervention to facilitate technology transfer and enhance clinical practice.

Posterior segment manifestations of HIV/AIDS

The ocular posterior segment manifestations of AIDS may be divided into four categories: retinal vasculopathy, unusual malignancies, neuro-ophthalmologic abnormalities, and opportunistic infections. Microvasculopathy is the most common manifestation. Opportunistic infections, particularly cytomegalovirus retinitis and progressive outer retinal necrosis, are the most likely to result in visual loss due to infection or subsequent retinal detachment. Diagnosis and treatment are guided by the particular conditions and immune status of the patient.

Oral fludarabine has significant activity in patients with previously untreated chronic lymphocytic leukemia, and leads to increased STAT1 levels in vivo

Fifteen patients with previously untreated chronic lymphocytic leukemia (CLL) were treated with oral fludarabine. Toxicities were mainly hematologic, and the response rate was 80%. To assess the effect of fludarabine on the transcription factor STAT1, blood samples obtained on study entry were treated in vitro with fludarabine for 24 h, and the majority of samples displayed an expected decrease in STAT1. To determine whether similar changes occurred in vivo, we developed a flow cytometric assay to quantitate STAT1 levels. On completion of fludarabine cycle 1, CLL cells showed increased STAT1 in the majority of patients, in contrast to the in vitro findings. This may reflect a survival advantage for cells that express high levels of STAT1. In conclusion, oral fludarabine is highly active and merits further investigation in previously untreated patients with CLL. Larger studies are indicated to determine optimal timing of STAT1 assessment, and if changes in STAT1 represent an in vivo indicator of response to purine analog therapy.

Treatment of human immunodeficiency virus-related lymphoma with haematopoietic stem cell transplantation

The advent of highly active antiretroviral therapy (HAART) and its co-administration with chemotherapy in patients with human immunodeficiency virus (HIV)-related lymphoma has lead to the exploration of potentially curative combination chemotherapy and myeloablative therapy followed by autologous haematopoietic stem cell transplantation (ASCT). Applying the same principles used for patients with HIV-negative aggressive lymphoma, in 1998 we developed a program of high-dose therapy and ASCT at City of Hope for patients with HIV-related lymphoma and Hodgkin's disease. Our studies have primarily included patients with chemosensitive lymphoma in relapse or first remission with poor-risk features at diagnosis. Filgrastim (G-CSF)-primed peripheral blood stem cell mobilization and apheresis have been successful while patients were receiving HAART and chemotherapy. To date, ASCT has been performed in 19 patients with HIV-related lymphoid malignancies, representing the largest single-institution experience reported to date. Most patients received a chemotherapy-based conditioning regimen consisting of high-dose carmustine, etoposide and cyclophosphamide. Early infections, namely bacteremias and neutropenic fever were similar to those observed in the HIV-negative transplant setting. Opportunistic infections were rare and easily treatable. There were three early deaths, two from relapsed lymphoma and one from multi-organ failure in an older patient. The remaining 16 patients are alive and in remission. In summary, ASCT is well tolerated, can result in long-term remissions, and is potentially curative in selected HIV-related lymphoma patients with chemosensitive relapse and high-risk disease in first remission defined by the age-adjusted International Prognostic Index criteria (i.e., two or three of the following: elevated LDH, advanced stage, and poor performance status). Acquisition of resistance to HAART remains as a potential problem for HIV-positive patients who are cured of their lymphoma.

Acquired Immunodeficiency Syndrome–Related Lymphoma in the Era of Highly Active Antiretroviral Therapy

The treatment and outcome of human immunodeficiency virus (HIV) infection altered dramatically in the mid-1990s with the introduction of highly active antiretroviral therapy (HAART). Highly active antiretroviral therapy, where available, has led to a dramatic decline in mortality from HIV and a decrease in the incidence of opportunistic infections and Kaposi sarcoma. This article addresses the effects that HAART has had on acquired immunodeficiency syndrome (AIDS)-related non-Hodgkin's lymphoma (NHL). Metaanalysis of numerous cohort studies confirmed that the incidence of AIDS-related NHL has decreased since the advent of HAART. This decline is most marked for primary cerebral lymphomas and systemic immunoblastic lymphoma but has not been demonstrated for Burkitt lymphoma. In addition to genetic predisposing factors, age, nadir CD4 cell count, and lack of HAART therapy predict the development of NHL. The clinical presentation of AIDS-related NHL has not changed, but several institutions have reported an improvement in survival since the introduction of HAART. Moreover, HAART has been combined safely with systemic chemotherapy in the management of NHL, and this approach results in a more modest decrease in immune function than when chemotherapy is administered alone. This has led to a more aggressive approach to the management of AIDS-related NHL and response rates and overall survival durations that are approaching those seen in stage-matched high-grade lymphomas in the immunocompetent population.

Filgrastim in patients with neutropenia: potential effects on quality of life

Treatment- and disease-related neutropenia are associated with a number of negative clinical effects such as febrile neutropenia, documented infection, hospitalisation for infection-related morbidity, infection-related mortality, and decreased ability to administer the planned chemotherapy dose on schedule. Reductions or delays in dosage have the ability to jeopardise the effectiveness of treatment by lowering response rates. Not only are clinical outcomes adversely affected, but these complications can have a negative influence on patient quality of life. Filgrastim is a haematopoietic growth factor that primarily acts to stimulate the proliferation and differentiation of neutrophil progenitor cells. Filgrastim is capable of reducing the incidence and severity of neutropenia and the complications that accompany it in patients with cancer or HIV infection. Although there are few data evaluating the effect of treatment with granulocyte colony-stimulating factor on quality of life, it is assumed that the benefits would be seen through both the reduction of treatment-related complications and the enhanced potential for long-term disease control. A new, longer-acting form of filgrastim is now available that has the potential to simplify the management of neutropenia and further improve patient quality of life by decreasing the number of necessary injections. Additional prospective controlled trials that contain quality-of-life issues as endpoints are needed.

Colony-stimulating factors for the management of neutropenia in cancer patients

Neutropenia and its subsequent infectious complications represent the most common dose-limiting toxicity of cancer chemotherapy. Febrile neutropenia (FN) occurs with common chemotherapy regimens in 25 to 40% of treatment-naive patients, and its severity depends on the dose intensity of the chemotherapy regimen, the patient's prior history of either radiation therapy or use of cytotoxic treatment, and comorbidities. The occurrence of FN often causes subsequent chemotherapy delays or dose reductions. It may also lengthen hospital stay, increase monitoring, diagnostic and treatment costs, and reduce patient quality of life. A decade after their introduction, colony-stimulating factors (CSFs) such as granulocyte colony-stimulating factor (G-CSF) and granulocyte-macrophage colony-stimulating factor (GM-CSF) are now an integral part of the prevention of potentially life-threatening FN; however, only G-CSF has US Food and Drug Administration approval for use in chemotherapy-induced neutropenia. These adjunctive agents accelerate formation of neutrophils from committed progenitors, thereby reducing the duration and severity of neutropenia. Important uses of CSFs in oncology are prevention of FN after chemotherapy, treatment of febrile neutropenic episodes and support following bone marrow transplantation, and collection of CSF-mobilised peripheral blood progenitor cells. G-CSF is used more frequently than GM-CSF for all of these indications because of fewer associated adverse effects. Clinical trials to date have not demonstrated a significant effect on overall survival or disease-free survival, which is most likely to be due to small sample size and lack of power to prove effect. However, they have demonstrated clinical utility in allowing the delivery of planned chemotherapy dose on schedule, an important clinical goal especially in curative tumour settings. The high cost of these agents limits their widespread use. Current American Society of Clinical Oncology guidelines recommend primary prophylaxis, or first cycle use, with CSFs being confined to patients with > or = 40% risk of FN, which may include elderly patients and other high-risk patients. In addition to the risk of FN, primary prophylaxis should also be considered if the patient has risk factors that place them in the Special Circumstances category. These risk factors may include decreased immune function in patients who are already at an increased risk of infection and pre-existing neutropenia due to disease, extensive prior chemotherapy, or previous irradiation to the pelvis or other areas containing large amounts of bone marrow. Future studies are needed to better define the patients most likely to benefit from CSF therapy, both for prophylaxis and as an adjunct to antibiotics for treatment of FN. Other potential uses include combination therapy with stem cell factors and other cytokines to boost progenitor cell development, maintaining dose intensity of salvage therapy in metastatic cancer patients, and application in patients with pneumonia, Crohn's fistulas, diabetic foot infections and a variety of other infectious conditions.