Tissue Engineering for Tracheal Replacement: Strategies and Challenges

The critical feature in trachea replacement is to provide a hollow cylindrical framework that is laterally stable and longitudinally flexible, facilitating cartilage and epithelial tissue formation. Despite advanced techniques and sources of materials used, most inherent challenges are related to the complexity of its anatomy. Limited blood supply leads to insufficient regenerative capacity for cartilage and epithelium. Natural and synthetic scaffolds, different types of cells, and growth factors are part of tissue engineering approaches with varying outcomes. Pre-vascularization remains one of the crucial factors to expedite the regenerative process in tracheal reconstruction. This review discusses the challenges and strategies used in tracheal tissue engineering, focusing on scaffold implantation in clinical and preclinical studies conducted in recent decades.

Erythropoietin or darbepoetin for patients with cancer

BACKGROUND

Anaemia associated with cancer and cancer therapy is an important clinical factor in the treatment of malignant diseases. Therapeutic alternatives are recombinant human erythropoiesis stimulating agents (ESAs) and red blood cell transfusions.

OBJECTIVES

To assess the effects of ESAs to either prevent or treat anaemia in cancer patients.

SEARCH METHODS

This is an update of a Cochrane review first published in 2004. We searched the Central Register of Controlled Trials (CENTRAL), MEDLINE and EMBASE and other databases. Searches were done for the periods 01/1985 to 12/2001 for the first review, 1/2002 to 04/2005 for the first update and to November 2011 for the current update. We also contacted experts in the field and pharmaceutical companies.

SELECTION CRITERIA

Randomised controlled trials on managing anaemia in cancer patients receiving or not receiving anti-cancer therapy that compared the use of ESAs (plus transfusion if needed).

DATA COLLECTION AND ANALYSIS

Several review authors assessed trial quality and extracted data. One review author assessed quality assessment and extracted data, a second review author checked for correctness.

MAIN RESULTS

This update of the systematic review includes a total of 91 trials with 20,102 participants. Use of ESAs significantly reduced the relative risk of red blood cell transfusions (risk ratio (RR) 0.65; 95% confidence interval (CI) 0.62 to 0.68, 70 trials, N = 16,093). On average, participants in the ESAs group received one unit of blood less than the control group (mean difference (MD) -0.98; 95% CI -1.17 to -0.78, 19 trials, N = 4,715). Haematological response was observed more often in participants receiving ESAs (RR 3.93; 95% CI 3.10 to 3.71, 31 trials, N = 6,413). There was suggestive evidence that ESAs may improve Quality of Life (QoL). There was strong evidence that ESAs increase mortality during active study period (hazard ratio (HR) 1.17; 95% CI 1.06 to 1.29, 70 trials, N = 15,935) and some evidence that ESAs decrease overall survival (HR 1.05; 95% CI 1.00 to 1.11, 78 trials, N = 19,003). The risk ratio for thromboembolic complications was increased in patients receiving ESAs compared to controls (RR 1.52, 95% CI 1.34 to 1.74; 57 trials, N = 15,498). ESAs may also increase the risk for hypertension (fixed-effect model: RR 1.30; 95% CI 1.08 to 1.56; random-effects model: RR 1.12; 95% CI 0.94 to 1.33, 31 trials, N = 7,228) and thrombocytopenia/haemorrhage (RR 1.21; 95% CI 1.04 to 1.42; 21 trials, N = 4,507). There was insufficient evidence to support an effect of ESA on tumour response (fixed-effect RR 1.02; 95% CI 0.98 to 1.06, 15 trials, N = 5,012).

AUTHORS' CONCLUSIONS

ESAs reduce the need for red blood cell transfusions but increase the risk for thromboembolic events and deaths. There is suggestive evidence that ESAs may improve QoL. Whether and how ESAs affects tumour control remains uncertain. The increased risk of death and thromboembolic events should be balanced against the potential benefits of ESA treatment taking into account each patient's clinical circumstances and preferences. More data are needed for the effect of these drugs on quality of life and tumour progression. Further research is needed to clarify cellular and molecular mechanisms and pathways of the effects of ESAs on thrombogenesis and their potential effects on tumour growth.

Cancer-related anaemia management in the 21st century

Anaemia has a high prevalence and incidence in patients with cancer receiving chemotherapy and is associated with a range of symptoms, including fatigue, drowsiness, depression, dyspnoea, tachycardia and dizziness. Fatigue, in particular, exerts a considerable impact on patient quality of life, affecting 80-100% of patients receiving chemotherapy and, potentially, delaying treatment. Until recently, red blood cell transfusions were the mainstay of treatment for cancer-related anaemia. While effective in ameliorating symptoms, transfusions are associated with short-lived benefits and a risk of infections and disease transmission. The development of the erythropoiesis-stimulating agent (ESA), recombinant human erythropoietin (rHuEPO), resulted in a 50% reduction in the number of transfusions required in anaemic cancer patients receiving chemotherapy. The subsequently introduced rHuEPO analogue, darbepoetin alfa, stimulates erythropoiesis by the same mechanism as rHuEPO but is associated with a prolonged serum half-life, allowing extended dosing intervals and less frequent administration. With the introduction of a number of ESAs and a growing wealth of data concerning their indications, dosing regimens and safety, European cancer organizations have recently developed guidelines for their effective use in clinical practice.

Cancer-related anemia and recombinant human erythropoietin--an updated overview

For cancer patients, anemia can be a debilitating problem that negatively influences their overall quality of life and worsens their prognosis. The condition is caused either by the cancer itself or by cytotoxic treatment. Anemia is the primary indication for transfusion of red blood cells, but the development of recombinant human erythropoietins (epoetins) provides an alternative to red blood cell transfusions. Treatment with epoetins has been shown to reduce transfusion rates and increase hemoglobin response. There is some evidence that epoetins improve quality of life. It remains unclear, however, whether erythropoietin affects tumor growth and survival, and this area requires further investigation. Data from clinical trials suggest that erythropoietin increases the risk of thromboembolic complications. In the management of anemic patients, physicians should follow closely the dosing recommendations in products' package inserts or the ASCO/American Society of Hematology guidelines. Treatment of patients beyond the correction of anemia, however, has to be regarded as experimental and is potentially harmful, so should only be conducted in clinical trials.

Erythropoietin or darbepoetin for patients with cancer

BACKGROUND

Anaemia associated with cancer and cancer therapy is an important clinical factor in the treatment of malignant diseases. Therapeutic alternatives are recombinant human erythropoietin (Epo), darbepoetin (Darbepo) and red blood cell transfusions.

OBJECTIVES

The aim of this systematic review was to assess the effects of Epo or Darbepo to either prevent or treat anaemia in cancer patients.

SEARCH STRATEGY

We searched the Central Register of Controlled Trials, MEDLINE and EMBASE and other data bases. Searches were done for the periods 01/1985 to 12/2001 for the first review and 1/2002 to 04/2005 for the update. We also contacted experts in the field and pharmaceutical companies.

SELECTION CRITERIA

Randomised controlled trials on managing anaemia in cancer patients that compared the use of Epo/Darbepo (plus transfusion if needed) with observation until red blood cell transfusion was required.

DATA COLLECTION AND ANALYSIS

Several reviewers independently assessed trial quality and extracted data.

MAIN RESULTS

This update of the systematic review included a total of 57 trials with 9,353 patients. Of these, 27 trials with 3,287 adults were also included in the first Cochrane Review. Thirty trials with 6,066 patients were added during the update process. Use of Epo/Darbepo significantly reduced the relative risk of red blood cell transfusions (RR 0.64; 95% CI 0.60 to 0.68, 42 trials, n = 6,510). On average participants in the Epo/Darbepo group received one unit of blood less than the control group (WMD -1.05; 95% CI -1.32 to -0.78, 14 trials, n = 2,353). For participants with baseline haemoglobin below 12 g/dL haematological response was observed more often in participants receiving Epo/Darbepo (RR 3.43; 95% CI 3.07 to 3.84, 22 trials, n = 4,307). There was suggestive evidence that Epo/Darbepo may improve Quality of Life (QoL). The relative risk for thrombo embolic complications was increased in patients receiving Epo/Darbepo compared to controls (RR 1.67, 95% CI 1.35 to 2.06; 35 trials, n = 6,769). Uncertainties remain whether and how Epo/Darbepo effects tumour response (fixed effect RR 1.12; 95% CI 1.01 to 1.23, 13 trials, n = 2,833; random effects: RR 1.09; 95% CI 0.94 to 1.26) or overall survival (unadjusted and adjusted data: HR 1.08; 95% CI 0.99 to 1.18; 42 trials, n = 8,167).

AUTHORS' CONCLUSIONS

There is consistent evidence that administration of Epo/Darbepo reduces the relative risk for blood transfusions and the number of units transfused in cancer patients. For patients with baseline haemoglobin below 12 g/dL (mild anaemia) there is strong evidence that Epo/Darbepo improves haematological response. There is suggestive evidence that Epo/Darbepo may improve QoL. However, there is strong evidence that Epo/Darbepo increases the relative risk for thrombo embolic complications. Whether and how Epo/Darbepo effects tumour response and overall survival remains uncertain.

Recombinant human erythropoietin in oncology: current status and further developments

Anaemia effects up to 90% of cancer patients, with more than 60% requiring blood transfusion during or after treatment. With the advent of recombinant human erythropoietins (rHuEPO), an alternative to red blood cell transfusion has become available. So far, three drugs have been approved for the treatment of anaemia in patients with malignancies (epoetin alfa, epoetin beta and darbepoetin alfa). New concepts for the use of erythropoietin in cancer patients include 3- and 4-weekly dosing, as well as loading-dose concepts. Important factors helping to judge the impact of erythropoietin in cancer treatment include pharmacoeconomics and better predictive factors. Lately, the influence of erythropoietin therapy on survival in cancer patients has been discussed very intensively, because conflicting data have emerged. Studies aimed at correcting anaemia in cancer patients had indicated a possible survival advantage of those patients receiving erythropoietin. In contrast, two recent trials aimed at correction of haemoglobin levels beyond anaemia reported a poorer survival of patients receiving erythropoietin. This might grossly be attributed to a higher risk of thrombosis in these patients. The largest systematic review on the use of erythropoietin in cancer patients undergoing treatment indicates a suggestive but not significant survival advantage of erythropoietin-treated patients. In addition, very recent results of a Food and Drug Administration meeting on safety and survival of patients treated with erythropoietin are presented.

Recombinant Human Erythropoietin and Overall Survival in Cancer Patients: Results of a Comprehensive Meta-analysis

BACKGROUND

Anemia associated with cancer and cancer therapy is an important clinical and economic factor in the treatment of malignant diseases.

METHODS

We conducted a systematic literature review to assess the efficacy of erythropoietin to prevent or treat anemia in cancer patients with regard to red blood cell transfusions, hematologic response, adverse events, and overall survival. We searched the Cochrane Library, Medline, EMBASE, and other databases for relevant articles published from January 1985 to December 2001. We included all randomized controlled trials that compared the use of recombinant human erythropoietin (plus transfusion, if needed) with no erythropoietin treatment (plus transfusion, if needed). Relative risks (RRs) and 95% confidence intervals (CIs) were calculated under a fixed-effects model. Clinical and statistical heterogeneity were examined with sensitivity analyses and meta-regression. Statistical tests for effect estimates were two-sided.

RESULTS

We identified 27 trials involving 3287 adult patients. Patients treated with erythropoietin had a lower relative risk of having a blood transfusion than untreated patients (RR = 0.67, 95% CI = 0.62 to 0.73). Erythropoietin-treated patients with baseline hemoglobin levels lower than 10 g/dL were more likely to have a hematologic response than untreated patients (RR = 3.60, 95% CI = 3.07 to 4.23). The relative risk for thromboembolic complications after erythropoietin treatment was not statistically significantly increased (RR = 1.58, 95% CI = 0.94 to 2.66) compared with that of untreated patients. There is suggestive but inconclusive evidence that erythropoietin may improve overall survival (adjusted data: hazard ratio [HR] = 0.81, 95% CI = 0.67 to 0.99; unadjusted data: HR = 0.84, 95% CI = 0.69 to 1.02).

CONCLUSIONS

Erythropoietin treatment may reduce the risk for blood transfusions and improve hematologic response in cancer patients. However, our favorable survival outcome is in contrast to two large (N = 351 and 939) recently published randomized controlled trials in which erythropoietin-treated patients had statistically significantly worse survival than untreated patients. Possible reasons for the disparity with our results include differences in study population and design, higher target hemoglobin levels and higher risk of thromboembolic complications, and concerns that erythropoietin may stimulate tumor growth.

Epoetin Beta

Epoetin beta (NeoRecormon) is a recombinant form of erythropoietin. It increases reticulocyte counts, haemoglobin (Hb) levels and haematocrit. Epoetin beta administered subcutaneously once weekly corrected anaemia and had equivalent efficacy to that of epoetin beta administered three times weekly in patients with haematological malignancies. Subcutaneous epoetin beta reduced transfusion requirements and increased Hb levels versus no treatment in patients with solid tumours and chemotherapy-induced anaemia in nonblind, randomised trials. Anaemia and quality of life were also improved, and blood transfusion requirements were reduced to a significantly greater extent than placebo or no treatment (with supportive blood transfusion) in patients with haematological malignancies. Most patients were receiving chemotherapy. Subcutaneous epoetin beta was well tolerated by patients with cancer; adverse events with the drug occurred with a similar incidence to those with placebo or no treatment (with supportive blood transfusion). Hypertension was relatively uncommon with epoetin beta in clinical trials. Patients with haematological malignancies and a baseline platelet count > or =100 x 10(9)/L, Hb levels of > or =9 g/dL or lower erythropoietin levels have demonstrated better responses to epoetin beta than other patients in clinical trials. However, neither baseline erythropoietin level nor the observed to predicted ratio of erythropoietin levels correlated with the response to epoetin beta in patients with solid tumours and chemotherapy-induced anaemia. A decrease of <1 g/dL or an increase in Hb with epoetin beta during the first chemotherapy cycle indicated a low transfusion need in subsequent cycles in patients with ovarian carcinoma. In general, the efficacy of epoetin beta is not limited by tumour type. Response to the drug occurred irrespective of the nature (platinum- or nonplatinum-based) or presence of chemotherapy treatment in randomised trials.

CONCLUSION

Epoetin beta has shown efficacy in the management of cancer-related anaemia in patients with haematological malignancies and of chemotherapy-induced anaemia in patients with solid tumours. Once-weekly administration provides added convenience for patients and may be cost saving, although additional research into the potential pharmacoeconomic benefits of this regimen are required. The drug is well tolerated in patients with cancer and is associated with little injection-site pain when administered subcutaneously. Epoetin beta is an important option in the prevention of chemotherapy-induced anaemia, and a valid and valuable alternative to blood transfusion therapy for the treatment of cancer-related or chemotherapy-induced anaemia.

Clinical and economic impact of epoetins in cancer care

Anaemia develops in most patients undergoing cancer therapy and invariably induces fatigue, which is a major determinant of QOL. Blood transfusions are reserved for patients with severe anaemia, since blood is a scarce resource and provides a short-lived benefit. Epoetins are recombinant proteins capable of alleviating therapy-related anaemia in 40-60% of cancer patients. The number of patients needed to be treated with epoetins to avoid the transfusion of one unit of blood ranges from 2.6 to 5.2; however, the absolute risk reduction depends on patients' characteristics and dose-escalation. The ratio between acquisition costs of epoetins and blood transfusion requirement is very high; thus, many thousands of dollars needs to be spent on epoetins to save 1 blood unit. Despite this, epoetins have been widely adopted by industrialised countries, where cancer patients are about 2% of the total population. The resulting budget impact of epoetins can be calculated at about 10% of the overall direct cost for cancer care, and it is expected to continue growing by about 20% each year, due to the expanding cancer population and the intensification of cancer therapies. The economic burden of epoetins needs to be weighed against the improvement of patients' QOL and society's willingness to pay for a non-life-saving therapy. All published economic evaluations of epoetins invariably report that this supportive therapy is not cost effective. Society should be made aware of the opportunity cost of treatments and should be allowed to elicit preferences for healthcare interventions and prioritisation criteria. In the near future we expect that a wider range of epoetins, drug patent expiry, a more appropriate patient selection criteria and an improved dosage schedule may help increase the efficiency of cancer-related anaemia management.

Recombinant human erythropoietin, epoetin beta, in patients with relapsed lymphoma treated with aggressive sequential salvage chemotherapy--results of a randomized trial

The aim of the study was to investigate the effects of erythropoietin (epoetin beta) on red blood cell (RBC) transfusions, hemoglobin (Hb) levels, and quality of life (QOL) in patients with relapsed lymphoma treated with an aggressive sequential salvage chemotherapy (SSCT) regimen. Sixty patients with early or late relapsed Hodgkin's disease ( n=39) or first relapse of aggressive non-Hodgkin's lymphoma ( n=21) were randomized to receive epoetin beta 10,000 IE subcutaneously three times a week or no epoetin during salvage chemotherapy. Patients in both study arms received two cycles of DHAP (dexamethasone, high-dose cytarabine, cisplatin); patients in partial remission (PR) or complete remission (CR) then received cyclophosphamide, followed by peripheral blood stem cell (PBSC) harvest, methotrexate plus vincristine, and etoposide. The final myeloablative course was BEAM (carmustine, etoposide, cytarabine, and melphalan) followed by autologous stem cell support. The primary endpoint of the study was the number of RBC units needed during SSCT. In addition, Hb levels and QOL were measured. The mean number of RBC units given in the epoetin beta arm was 4.5 compared to 8.3 in the control arm ( P=0.0134). The mean Hb levels during therapy were 10.4 g/dl in the epoetin beta arm and 9.7 g/dl in the control ( P=0.018). From baseline until BEAM therapy QOL (EORTC QLQ C30) and fatigue (MFI) assessment showed little QOL worsening or stable levels in both arms with a steeper increase of fatigue levels in the control group. Patients with relapsed lymphoma undergoing aggressive chemotherapy and stem cell support benefited from epoetin beta therapy, with a decrease of RBC transfusion requirements and lower rise of fatigue levels.