Neopterin as a prognostic parameter in patients with squamous-cell carcinomas of the oral cavity

Neopterin, the Cell-Mediated Immune Response Biomarker, in Inflammatory Periodontal Diseases: A Narrative Review of a More than Fifty Years Old Biomarker

Neopterin is a biomarker of the activation of cellular immunity. The purpose of this review is to summarise neopterin metabolism, methods of its detection, and its role in inflammation, focusing on periodontal inflammatory diseases. This derivative of guanosine is a non-enzymatic product of 7,8-dihydroneopterin oxidation caused by free radicals which protect activated macrophages from oxidative stress. Various methods, usually based on enzyme-linked immunosorbent essay, high-performance liquid chromatography, or radioimmunoassay were developed for the isolation of neopterin. A wide spectrum of diseases and conditions are known to affect neopterin levels, including cardiovascular, bacterial, viral, and degenerative diseases, as well as malignant tumours. Neopterin levels were found to increase in subjects with periodontitis, especially when the oral fluid and gingival crevicular fluid were evaluated. These findings confirm the role of activated macrophages and cellular immunity in periodontal inflammatory diseases. The gingival crevicular fluid and the oral fluid appear to be the most valuable biologic fluids for the evaluation of neopterin levels in periodontitis. For gingival crevicular fluid, neopterin can be determined as the concentration or the so-called total amount. Nonsurgical periodontal treatment was associated with a decrease in neopterin levels, but an increase was also reported, suggesting the possible role of macrophages in the resolution of the periodontal lesion.

Salivary and serum neopterin and interleukin 6 as biomarkers in patients with oral and oropharyngeal squamous cell carcinoma

Because of an increasing incidence of malignant tumours of the head and neck there is an unmet medical need for early diagnosis of the primary disease or precancerous lesions, and timely detection of recurrence by simple non-invasive tests. The analysis of biomarkers in body fluids may be appropriate for this goal. In this review, we compare the data on utilization of neopterin and interleukin-6 (IL-6) measurements in saliva and plasma/serum of patients with oral and oropharyngeal squamous cell carcinoma, indicating the suitability of using saliva as a diagnostic matrix in head and neck cancers on behalf of close anatomical proximity and a potential to study the tumour microenvironment. Salivary neopterin and IL-6 are potential biomarkers of head and neck cancer suitable not only for early diagnosis, but also for monitoring of treatment results and detection of the disease recurrence.

Neopterin as a biomarker of immune response in cancer patients

With the advent of immunotherapy the topic of biomarkers of immune response is of high interest. Along with the expression of programmed death ligand 1 (PD-L1) or tumor infiltrating lymphocytes (TIL), biomarkers of macrophage activation could be of interest. Neopterin is a biomarker of immune activation increased in different disorders associated with immune activation, including cancer. Neopterin synthesis is induced by interferon-γ that also induces indoleamine 2,3-dioxygenase (IDO), an enzyme catalyzing catabolism of tryptophan to kynurenine. Increased urinary or serum concentrations of neopterin have been associated with poor prognosis across a spectrum of malignant disorders of different primary location. Neopterin concentration in peripheral blood as well as in the tumor microenvironment correlates with phenotypic and functional changes of lymphocytes, indicating immune dysfunction. Increased neopterin concentrations are also accompanied by increased rate of conversion of tryptophan to kynurenine. Increasing neopterin concentrations also accompany side effects of anticancer treatment and could predict subsequent complications. Although almost four decades have elapsed since the discovery of increased neopterin concentrations in cancer patients, the full potential of neopterin as a biomarker in this setting has not been so far realized.

Serum neopterin concentrations and tryptophan degradation pattern in patients with late stage larynx carcinoma

As the disease-free 5-year-survival of late stage laryngeal carcinoma patients is extremely low, indoleamine-2,3-dioxygenase-1 (IDO)-induced tryptophan degradation may represent an immune escape mechanism which plays an important role in cancer spreading in advanced stage laryngeal cancers. We examined whether the late stage laryngeal cancer enhances tumor immune evasion by the expression of systemic IDO activities and chronic cellular immune activation. Twenty-two of 42 male laryngeal cancer patients were classified as late stage cancer according to American Joint Committee on Cancer (AJCC) criteria. Their serum neopterin, tryptophan and kynurenine concentrations were compared with 30 cancer-free individuals. IDO activity was approved by correlation between serum neopterin and kynurenine/tryptophan. Late stage cancer patients preoperatively showed a significantly higher IDO activity compared to controls and early stage cancer cases. Six months after tumor removal, late stage cancer patients although having higher serum neopterin concentration compared to early stage patients or controls, they showed a significant decrease in IDO activity and tryptophan consumption. Increased systemic IDO activity may provoke the escape of tumor cells from the immune surveillance of the host. High IDO activity is due to the presence of tumor mass. Persistence of high serum neopterin levels despite tumor removal may indicate poor prognosis.

Salivary neopterin concentrations in patients with cancer of the oral cavity

Tumors of the oral cavity are relatively common malignancies with a poor prognosis. Use of both prognostic and predictive biomarkers in saliva represents one approach to improve the management of patients with these cancers. The aim of the present study was to measure salivary neopterin concentrations before and after surgery in patients with oropharyngeal cancer to assess potential use as a biomarker in clinical practice. Salivary neopterin concentration was determined before and after surgery in 16 patients treated for oropharyngeal cancer and compared with 15 healthy volunteers. Salivary neopterin concentrations were significantly higher in patients before surgery compared to the healthy controls. After the surgery, neopterin concentrations decreased significantly, and concentrations in patients and controls were comparable. A significant correlation was observed between the sum of the Community Periodontal Index of Treatment Needs values and salivary neopterin concentrations. In conclusion, tumor removal results in significant decrease of salivary neopterin concentrations. The use of salivary neopterin in diagnosis is compounded by an association with periodontal disease.

Inhibition of GTP cyclohydrolase reduces cancer pain in mice and enhances analgesic effects of morphine

Noncoding polymorphisms of the GTP cyclohydrolase gene (GCH1) reduce the risk for chronic pain in humans suggesting GCH1 inhibitors as analgesics. We assessed the effects of the GCH1 inhibitor diaminohydroxypyrimidine (DAHP) on nociception and inflammation in a mouse melanoma and a sarcoma cancer pain model, and its co-effects with morphine in terms of analgesic efficacy and respiratory depression. GCH1 inhibition did not reduce the tumor-evoked nociceptive hypersensitivity of the tumor-bearing paw. However, DAHP reduced melanoma- and sarcoma-evoked systemic hyperalgesia as determined by analyzing contralateral paws. GCH1 inhibition increased the inflammatory edema and infiltration with polymorphonuclear leukocytes surrounding the tumor but reduced the tumor-evoked microglia activation in the spinal cord suggesting that an increase of the local immune attack against the tumor may avoid general pain hypersensitivity. When used in combination with morphine at high or low doses, GCH1 inhibition increased and prolonged the analgesic effects of the opioid. It did not, however, increase the respiratory depression caused by morphine. Conversely, the GCH1-product, tetrahydrobiopterin, caused hyperalgesia, antagonized antinociceptive effects of morphine, and aggravated morphine-evoked respiratory depression, the latter mimicked by a cGMP analog suggesting that respiratory effects were partly mediated through the BH4-NO-cGMP pathway. The observed effects of GCH1 inhibition in the tumor model and its enhancement of morphine-evoked antinociception without increase of morphine toxicity suggest that GCH1 inhibitors might be useful as co-therapeutics for opioids in cancer patients.

Serum neopterin as a prognostic indicator in patients with breast carcinoma

Neopterin is a useful indicator of the activation state of the cellular immune system, and an elevated level predicts prognosis in different types of tumors. The aim of this study was to evaluate serum neopterin levels if it is viable predictor for prognosis in breast carcinoma patients. Serum neopterin was investigated in 56 breast carcinoma patients, 16 patients with benign breast lesions and 16 healthy women as controls. Neopterin was measured by ELISA (Enzyme-linked immunosorbent assay). The clinicopathological parameters were determined by reviewing both medical charts and pathological records. All patients had been followed-up until September 2009 or death.The mean serum neopterin concentrations were 8.5 ± 5.2 nmol/L in patients with breast carcinoma, 6.5±3.1 nmol/L in patients with benign breast lesion and 8.1 ± 1.9 nmol/L in healthy volunteers (p>0.05). Elevated neopterin levels were significantly correlated with age, elevated serum CRP level, advanced stage and presence of the distant metastases (p<0.05). Overall survival was significantly shorter in patients with a serum neopterin level >10 nmol/L than patients with neopterin <10 nmol/L level (56 months vs. 76 months, p=0.011). Increased preoperative serum neopterin concentrations are associated with a poor prognosis in patients with breast carcinoma.

IDO-Mediated Tryptophan Degradation in the Pathogenesis of Malignant Tumor Disease

Immune escape is a fundamental trait of cancer in which the Th1-type cytokine interferon- γ (IFN-γ) seems to play a key role. Among other tumoricidal biochemical pathways, IFN-γ induces the tryptophan-degrading enzyme indoleamine 2,3-dioxygenase (IDO) in a variety of cells including macrophages, dendritic cells (DCs) and tumor cells. IDO activity has been shown to reflect the extent and the course in a plethora of malignancies including prostate, colorectal, pancreatic, cervical, endometrial, gastric, lung, bladder, ovarian, esophageal and renal cell carcinomas, glioblastomas, mesotheliomas, and melanomas. Furthermore IDO activity during malignant tumor diseases seems to be part of the tumoricidal immune defense strategy, which in the long run is detrimental to the host, when tryptophan deprivation and production of pro-apoptotic tryptophan catabolites counteract T-cell responsiveness.

Inhibitors of indoleamine-2,3-dioxygenase for cancer therapy: can we see the wood for the trees?

Indoleamine-2,3-dioxygenase (IDO) is an immunosuppressive enzyme capable of inhibiting a destructive maternal T cell response against allogeneic fetuses. Expression of IDO is evident in tumours and is thought to enable escape from immunologically mediated rejection. Consequently, clinical trials using an inhibitor of IDO, 1-methyltryptophan (1MT), have been initiated. However, a review of the current literature indicates that we are far from understanding the biological relevance of IDO expression during tumorigenesis. A better understanding of IDO biology is needed to comprehend the effect of IDO inhibitors and to provide a rationale for their therapeutic application in cancer.

Decreased serum tryptophan concentration predicts poor prognosis in malignant melanoma patients

BACKGROUND

Indoleamine (2,3)-dioxygenase (IDO) catalyses the initial, rate-limiting step in the degradation of the essential amino acid tryptophan. Via tryptophan deprivation, IDO activity suppresses T cell proliferation and differentiation and is thought to be a fundamental immune escape mechanism for tumor cells.

OBJECTIVE AND METHODS

To investigate the potential role of tryptophan degradation as a prognostic marker, serum tryptophan and kynurenine concentrations and the kynurenine-to-tryptophan ratio (kyn/trp) in 87 patients with malignant melanoma were compared to the course of the disease and to concentrations of the immune activation marker neopterin.

RESULTS

Compared to 49 healthy volunteers, the melanoma patients presented with lower tryptophan levels due to accelerated degradation. This was especially true for the subgroups of patients with distant metastases (p = 0.01), though not in patients with lymph node metastases or in patients who had not yet progressed. There existed a positive correlation between kyn/trp and neopterin concentrations (r(s) = 0.587, p <0.001). In patients who died due to dissemination of the tumor, median tryptophan concentrations were significantly decreased (p = 0.006) and kyn/trp (p = 0.03) and neopterin concentrations (p = 0.002) were higher compared to survivors. In addition, lower tryptophan concentrations as well as higher kyn/trp and neopterin concentrations predicted a shorter survival.

CONCLUSION

Decreased serum tryptophan concentrations and elevated serum neopterin levels can be used as predictive markers for the future course in melanoma patients. Moreover, our data support previous speculations that a higher degree of IDO expression could play a crucial role for tumor progression.

Cancer: a single disease with a multitude of manifestions?

The relationships of critical nutrients such as plant phenolics, vitamins, minerals and lipids are considered with respect to the incidence of a variety of cancers, and analyzed in terms of how these nutrient deficiencies alter immune function, DNA integrity and cell proliferation. With a significant correlation found between cancer and these nutrient deficiencies, the hypothesis is presented here that nutrition could provide a unifying perception of cancer and recast it as a single disease. This further suggests that a coordinated administration of specific, critical nutrients to cancer patients could lead to the reversal of the disease. It is also proposed that the concurrent presence of a variety of nutritional deficiencies in cancer patients requires a multilevel, systemic approach to this disease as opposed to the single active therapeutic agent approach that is the cornerstone of contemporary research and pharmacology.

Clinical implications of biomarkers in head and neck cancer

The term biomarker refers to a host of biologic factors found within a tumor or other clinical specimen that can be used to assess the tumor in some way. Biomarkers have many potential clinical applications. Before they are used in actual clinical settings, however, they must be carefully validated. The literature contains many reports of this ongoing work related to head and neck squamous cell carcinoma. Candidate biomarkers for this disease include the p53 gene and its protein; microsatellite regions throughout the genome; human papillomavirus; proteins involved in cellular proliferation, apoptosis, angiogenesis, and intracellular adhesion; epithelial growth factor receptor; and various measures of immune response to cancer. The best new evidence for the validity of each of these candidates is critiqued in this review.

Neopterin: a prognostic variable in operations for lung cancer

BACKGROUND

We studied the prognostic value of preoperatively measured neopterin to predict survival of lung cancer patients. Neopterin is produced and secreted by interferon-gamma-stimulated monocytic cells. High urinary neopterin concentrations are found in patients with viral infections, allograft rejection episodes, and some malignant diseases. In various tumor types high urinary neopterin concentrations are associated with a worse prognosis.

METHODS

Preoperative neopterin levels of 110 patients (29 women, 81 men) with lung cancer including 7 patients with small cell lung cancer were measured and related to the time of survival after operation. Patients with clinically suspected stage IIIB lung cancer were not operated and therefore not enrolled in this study. Infectious diseases were not apparent at the time of preoperative urine sampling. Median postoperative follow-up period was 17.4 months.

RESULTS

In a univariate analysis, patients with a preoperative neopterin concentration of more than 212 micromol/mol creatinine (4th quartile) were determined to have a significantly lower survival probability. In a multivariate analysis, a neopterin concentration of more than 212 micromol/mol creatinine (p < 0.01) and T-stage status (p < 0.005) were determined to be significantly predictive variables for worse survival prognosis.

CONCLUSIONS

Preoperative neopterin proved to be a reliable prognostic factor for survival. Immunology may provide an accurate assessment of tumor aggression and its clinical behavior. In this sense, neopterin can serve as an immunologically based estimation of malignant outgrowth. In patients who are operable by clinical tumor stage but have a high risk for operation, elevated preoperative neopterin may help in the decision for a nonoperative treatment.

Neopterin Is an Independent Prognostic Variable in Females with Breast Cancer

Background: Neopterin, produced by human monocytes/macrophages upon stimulation by interferon-γ, is a sensitive marker for monitoring Th1-cell immune response in humans. In malignant diseases, the frequency of increases in neopterin in the serum and urine of patients depends on tumor stage and type.

Methods: In a retrospective study comprising 129 females with breast cancer, urinary neopterin/creatinine ratios were measured at the time of diagnosis. Tumor characteristics were determined concomitantly.

Results: Urinary neopterin was increased in 18% of the patients. It did not correlate with tumor size or lymph node status, but it was influenced by the presence of distant metastases (P &lt;0.05) and by tumor differentiation (P = 0.01). When product-limit estimates were calculated after follow-up for up to 13 years (median follow-up, 56 months), the presence of distant metastases (P &lt;0.001), neopterin (P &lt;0.001), tumor size (P = 0.001), and lymph node status (P &lt;0.01) were significant predictors of survival. By multivariate analysis, a combination of the variables presence of distant metastases (P &lt;0.001), neopterin (P &lt;0.01), and lymph node status (P &lt;0.05) was found to jointly predict survival. In lymph node-negative patients without distant metastases, the relative risk of death associated with increased neopterin concentrations was 2.5 compared with patients with neopterin concentrations within the reference interval.

Conclusion: Urinary neopterin provides additional prognostic information in patients with breast cancer.