Does the concurrent use of anthracycline and granulocyte colony-stimulating factor influence the risk of secondary leukaemia in breast cancer women?

Trial Watch-Immunostimulation with cytokines in cancer therapy

During the past decade, great efforts have been dedicated to the development of clinically relevant interventions that would trigger potent (and hence potentially curative) anticancer immune responses. Indeed, developing neoplasms normally establish local and systemic immunosuppressive networks that inhibit tumor-targeting immune effector cells, be them natural or elicited by (immuno)therapy. One possible approach to boost anticancer immunity consists in the (generally systemic) administration of recombinant immunostimulatory cytokines. In a limited number of oncological indications, immunostimulatory cytokines mediate clinical activity as standalone immunotherapeutic interventions. Most often, however, immunostimulatory cytokines are employed as immunological adjuvants, i.e., to unleash the immunogenic potential of other immunotherapeutic agents, like tumor-targeting vaccines and checkpoint blockers. Here, we discuss recent preclinical and clinical advances in the use of some cytokines as immunostimulatory agents in oncological indications.

Trial watch: Immunostimulatory cytokines in cancer therapy

Tumor-targeting immune responses provide a significant contribution to (when they do not entirely account for) the clinical activity of diverse antineoplastic regimens, encompassing not only a large panel of immunotherapeutic strategies but also conventional cytotoxic molecules, targeted anticancer agents and irradiation. In line with this notion, several approaches have been devised to elicit novel or boost existing anticancer immune responses, including the administration of immunomodulatory cytokines. Such a relatively unspecific intervention suffices to mediate clinical effects in (at least a subset of) patients bearing particularly immunogenic tumors, like melanoma and renal cell carcinoma. More often, however, immunostimulatory cytokines are administered to boost the immunogenic potential of other agents, including (but not limited to) immune checkpoint-blocking antibodies, anticancer vaccines, oncolytic viruses and immunogenic chemotherapeutics. Here, we summarize the latest advances in the clinical development of recombinant cytokines as an immunomodulatory intervention for cancer therapy.

Primary prophylactic colony-stimulating factors for the prevention of chemotherapy-induced febrile neutropenia in breast cancer patients

BACKGROUND

High-dose or dose-intensive cytotoxic chemotherapy often causes myelosuppression and severe neutropenia among cancer patients. Severe neutropenia accompanied by fever, named febrile neutropenia (FN), is the most serious manifestation of neutropenia usually requiring hospitalization and intravenous antibiotics. FN and neutropenia can lead to chemotherapy treatment delays or dose reductions, which potentially compromises the effectiveness of cancer treatment and prospects for a cure. Granulocyte-macrophage (GM) and granulocyte colony-stimulating factors (G-CSFs) are administered during chemotherapy in order to prevent or reduce the incidence or the duration of FN and neutropenia.

OBJECTIVES

To assess the effect of prophylactic colony-stimulating factors (CSFs) in reducing the incidence and duration of FN, and all-cause and infection-related mortality during chemotherapy in patients with breast cancer.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE, HEALTHSTAR, International Health Technology Assessment, SOMED, AMED and BIOSIS up to 8 August 2011. We also searched three Chinese databases (VIP, CNKI, CBM), the metaRegister of Controlled Trials, ClinicalTrials.gov, the World Health Organization's International Clinical Trials Registry Platform (WHO ICTRP) and OpenGrey.eu up to August 2011.

SELECTION CRITERIA

Randomized controlled trials (RCTs) comparing CSFs (any dose) with placebo or no treatment in patients with breast cancer at any stage, at risk of developing FN while undergoing any type of chemotherapy.

DATA COLLECTION AND ANALYSIS

We used pooled risk ratios (RR) with 95% confidence intervals (CIs) for binary outcomes. At least two review authors independently extracted data and assessed the risk of bias of the included studies. Trial authors were contacted for further details when information was unclear.

MAIN RESULTS

We included eight RCTs involving 2156 participants with different stages of breast cancer and chemotherapy regimens. The trials were carried out between 1995 and 2008 and judged as being at least at moderate risk of bias. The strength of the evidence was weak for the majority of outcomes, which was mostly because of the small numbers of evaluable patients, varying definitions, as well as unclear measurements of the trials' outcomes and uncertain influences of supportive treatments on them. In most trials, the chemotherapy regimens had a risk of FN that was below the threshold at which current guidelines recommend routine primary prophylaxis with CSFs. Using CSFs significantly reduced the proportion of patients with FN (RR 0.27; 95% CI 0.11 to 0.70; number needed to treat for an additional beneficial outcome (NNTB) 12) but there was substantial heterogeneity which can be explained by possible differential effects of G-CSFs and GM-CSFs and different definitions of FN. A significant reduction in early mortality was observed in CSF-treated patients compared to placebo or no treatment (RR 0.32; 95% CI 0.13 to 0.77; NNTB 79). This finding was based on 23 fatal events in 2143 patients; wherein 19 of these 23 events occurred in one study and 17 events were attributed to progression of the disease by the study authors. For infection-related mortality, there were no significant differences between CSF and control groups (RR 0.14; 95% CI 0.02 to 1.29). In CSF-treated patients, the risk for hospitalization was significantly reduced (RR 0.14; 95% CI 0.06 to 0.30; NNTB 13), as well as the use of intravenous antibiotics (RR 0.35; 95% CI 0.22 to 0.55; NNTB 18). The risks of severe neutropenia, infection or not maintaining the scheduled dose of chemotherapy did not differ between CSF-treated and control groups. CSFs frequently led to bone pain (RR 5.88; 95% CI 2.54 to 13.60; number needed to treat for an additional harmful outcome (NNTH) 3) and injection-site reactions (RR 3.59; 95% CI 2.33 to 5.53; NNTH 3).

AUTHORS' CONCLUSIONS

In patients with breast cancer receiving chemotherapy, CSFs have shown evidence of benefit in the prevention of FN. There is evidence, though less reliable, of a decrease of all-cause mortality during chemotherapy and a reduced need for hospital care. No reliable evidence was found for a reduction of infection-related mortality, a higher dose intensity of chemotherapy with CSFs or diminished rates of severe neutropenia and infections. The majority of adverse events reported from CSF use were bone pain and injection-site reactions but no conclusions could be drawn regarding late-term side effects.

Granulocyte colony-stimulating factor administration: adverse events

Recombinant human granulocyte colony-stimulating factor (G-CSF) has been in clinical use for approximately 2 decades. In healthy donors, it has been used to mobilize peripheral blood progenitor cells for hematopoietic stem cell transplantation and granulocytes for apheresis collection. In patients, it has been used to decrease the duration of neutropenia after chemotherapy and to offset the neutropenia due to myelodysplasia, acquired immunodeficiency syndrome, and genetic disorders of granulocyte production. As the number of uses of G-CSF in clinical practice grows, more side effects of this generally safe pharmaceutical agent are being recognized. Our objective in this article is to provide an in-depth review of the reported adverse events associated with the use of G-CSF.

Acute myeloid leukemia or myelodysplastic syndrome following use of granulocyte colony-stimulating factors during breast cancer adjuvant chemotherapy

BACKGROUND

Recently, increasing numbers of women receiving adjuvant chemotherapy for breast cancer have also received granulocyte colony-stimulating factors (G-CSFs) or granulocyte-macrophage colony-stimulating factors (GM-CSFs). Although these growth factors support chemotherapy, their long-term safety has not been evaluated. We studied the association between G-CSF use and incidence of leukemia in a population-based sample of breast cancer patients.

METHODS

Among women aged 65 years or older in the Surveillance, Epidemiology, and End Results-Medicare database who were diagnosed with stages I-III breast cancer from January 1, 1991, to December 31, 1999, we identified those who received G-CSF or GM-CSF concurrently with chemotherapy. We used Cox proportional hazards models to estimate hazard ratios for the association of treatment with G-CSF or GM-CSF and subsequent (through December 31, 2003) diagnosis of acute myeloid leukemia (AML) or myelodysplastic syndrome (MDS). All statistical tests were two-sided.

RESULTS

Of 5510 women treated with chemotherapy, 906 (16%) received G-CSF or GM-CSF therapy, and 64 (1.16%) were subsequently diagnosed with either MDS or AML before a cancer recurrence. Use of G-CSF and GM-CSF was associated with more recent diagnosis, younger age, urban residence, fewer comorbidities, receipt of radiation therapy, positive lymph nodes, and cyclophosphamide treatment. Of the 906 patients who were treated with G-CSF, 16 (1.77%) developed AML or MDS; of the 4604 patients not treated with G-CSF, 48 (1.04%) developed AML or MDS. The hazard rate ratio for AML or MDS among those treated with G-CSF or GM-CSF compared with those who were not was 2.14 (95% confidence interval [CI] = 1.12 to 4.08). AML or MDS developed within 48 months of breast cancer diagnosis in 1.8% of patients who received G-CSF or GM-CSF but only in 0.7% of patients who did not (hazard ratio = 2.59, 95% CI = 1.30 to 5.15).

CONCLUSIONS

The use of G-CSF was associated with a doubling in the risk of subsequent AML or MDS among the population that we studied, although the absolute risk remained low. Even if this association is confirmed, the benefits of G-CSF may still outweigh the risks. Meanwhile, however, G-CSF use should not be assumed to be risk free.