A potential target for the future treatment of malignant pleural effusion: Monocyte chemoattractant protein-1 (MCP-1)

Background and Aim: Malignant pleural effusion (MPE) is a common clinical problem. Management options are mainly pleurodesis and drainage, and have remained unchanged for years. Novel therapies that target the molecules responsible for fluid formation are needed to reduce the need for invasive procedures. The aim of this study is to investigate the potential role of MCP-1 in the development of MPE in patients with metastatic pleural malignancies. Methods: Pleural effusion samples (8-10 ml) were collected from 100 patients who were divided into three groups: Group 1 (MPE, n = 56), Group 2 (benign exudate, n = 27) and Group 3 (transudate, n = 17). The collected effusions were promptly centrifuged at 4°C, and the supernatants were stored at -80°C. MCP-1 levels were determined by ELISA kit (USCN, Wuhan). Results: Median MCP-1 levels were found to be significantly different between the three groups (Group 1: 1303 pg/ml, Group 2: 926 pg/ml, Group 3: 211 pg/ml) (p < 0.001). MCP-1 levels were markedly higher but similar in Group 1 and Group 2, as compared to Group 3. When patients from Group 1 and Group 2 were combined, a positive correlation was observed between pleural fluid MCP-1 and LDH levels (r = 0.38; p = 0.001). Additionally, MCP-1 levels were observed to increase significantly as the volume of pleural fluid increased (p = 0.007). Conclusion: MCP-1 levels were found to be similarly high in both Group 1 (MPE) and Group 2 (Benign exudate), indicating that inflammation accompanying the tumor could play a role in the formation of pleural effusion. This suggests that the development of biological therapies targeting MCP-1 could be a promising approach in the future management of MPE.

Clinical outcomes of chemical pleurodesis using a minocycline

Background:

Pleurodesis is often used to prevent the re-accumulation of a malignant pleural effusion (MPE). Intrapleural urokinase (IPUK) therapy facilitates lung re-expansion for patients with loculated MPE or a trapped lung that allows subsequent pleurodesis. MPE management has been traditionally regarded as a symptomatic treatment. We tried to evaluate their impact on patient survival.

Methods:

There were 314 consecutive patients with symptomatic MPE that underwent minocycline pleurodesis with (n = 109) and without (n = 205) the antecedent IPUK therapy between September 2005 and August 2015, who were recruited for the pleurodesis outcome and survival analysis.

Results:

The rate of successful pleurodesis was similar between the simple pleurodesis group and the IPUK therapy group followed by the pleurodesis group (69.0% versus 70.5%; p = 0.804). The patients who succeeded pleurodesis had a longer survival rate than those who failed in either the simple pleurodesis group (median, 414 versus 100 days; p < 0.001) or the IPUK therapy followed by pleurodesis group (259 versus 102 days; p < 0.001). The survival differences remained when the lung and breast cancer patients were studied separately.

Conclusion:

Successful pleurodesis translated into a better survival rate that promotes performing pleurodesis on lung re-expansion. The apparent shorter survival of the patients with loculated MPE or trapped lung, and those that did not respond to the IPUK therapy, lowered the probability of the survival benefit through the simple physical barrier by the fibrin formation to prevent the tumor spreading. The successfully induced inflammatory response by minocycline is supposed to prohibit the tumor invasion and metastasis. Further studies are warranted to clarify the mechanism and provide opportunities to develop novel therapeutic strategies.

Chemokines in tumor proximal fluids

Chemokines are chemotactic cytokines produced by leukocytes and other types of cells including tumor cells. Their action is determined by the expression of cognate receptors and subsequent signaling in target cells, followed by the modulation of cytoskeletal proteins and the induction of other responses. In tumors, chemokines produced by neoplastic/stroma cells control the leukocyte infiltrate influencing tumor growth and progression. Tumor cells also express functional chemokine receptors responding to chemokine signals, promoting cell survival, proliferation and metastasis formation. Chemokines may be detected in serum of cancer patients, but due to the paracrine nature of these molecules, more significant concentrations are found in the tumor adjacent, non-vascular fluids, collectively called tumor proximal fluids. This review summarizes the expression of CC and CXC chemokines in these fluids, namely in interstitial fluid, pleural, ascitic, and cyst fluids, but also in urine, saliva, cerebrospinal fluid, cervical secretions and bronchoalveolar lavage fluid. Most comparative clinical studies reveal increased chemokine levels in high-grade tumor proximal fluids rather than in low-grade tumors and benign conditions, indicating shorter survival periods. The data confirm peritumoral fluid chemokines as sensitive diagnostic and prognostic markers, as well as offer support for chemokines and their receptors as potential targets for antitumor therapy.

Pleural fluid osteopontin, vascular endothelial growth factor, and urokinase-type plasminogen activator levels as predictors of pleurodesis outcome and prognosticators in patients with malignant pleural effusion: a prospective cohort study

BACKGROUND

Rapidly growing cancer cells secrete growth-promoting polypeptides and have increased proteolytic activity, contributing to tumor progression and metastasis. Their presentation in malignant pleural effusion (MPE) and their predictive value for the outcome of pleurodesis and survival were studied.

METHODS

Between February 2011 and March 2012, MPE samples were prospectively collected from 61 patients. Twenty-five patients with non-malignant pleural effusion in the same period were included as controls. Pleural fluid osteopontin (OPN), vascular endothelial growth factor (VEGF), and urokinase-type plasminogen activator (uPA) concentrations were measured.

RESULTS

Patients with MPE had higher pleural fluid OPN, VEGF, and uPA concentrations than those with non-malignant pleural effusion, but only differences in VEGF were statistically significant (p = 0.045). Patients with distant metastases had significantly elevated pleural fluid VEGF concentrations than those without (p = 0.004). Pleural fluid OPN, VEGF, and uPA concentrations were positively correlated in most patients. However, there was no significant difference in pleural fluid OPN, VEGF, and uPA concentrations between patients with successful pleurodesis and those without. There was also no significant difference in cancer-specific survival between sub-groups with higher and lower pleural fluid OPN, VEGF, or uPA concentrations. Patients with successful pleurodesis had significantly longer cancer-specific survival than those without (p = 0.015).

CONCLUSIONS

Pleural fluid OPN, VEGF, and uPA concentrations are elevated in MPE but are not satisfactory predictors of pleurodesis outcome or survival. Patients with higher pleural fluid VEGF concentration have higher risk of distant metastasis. Evaluating the benefits of therapy targeting the VEGF pathway in these patients warrants further studies.

EGFR-L858R mutant enhances lung adenocarcinoma cell invasive ability and promotes malignant pleural effusion formation through activation of the CXCL12-CXCR4 pathway

Malignant pleural effusion (MPE) is a common clinical problem in non-small cell lung carcinoma (NSCLC) patients; however, the underlying mechanisms are still largely unknown. Recent studies indicate that the frequency of the L858R mutant form of the epidermal growth factor receptor (EGFR-L858R) is higher in lung adenocarcinoma with MPE than in surgically resected specimens, suggesting that lung adenocarcinoma cells harboring this mutation tend to invade the adjacent pleural cavity. The purpose of this study was to clarify the relationship between the EGFR-L858R mutation and cancer cell invasion ability and to investigate the molecular mechanisms involved in the formation of MPE. We found that expression of EGFR-L858R in lung cancer cells resulted in up-regulation of the CXCR4 in association with increased cancer cell invasive ability and MPE formation. Ectopic expression of EGFR-L858R in lung cancer cells acted through activation of ERK signaling pathways to induce the expression of CXCR4. We also indicated that Inhibition of CXCR4 with small interfering RNA, neutralizing antibody, or receptor antagonist significantly suppressed the EGFR-L858R–dependent cell invasion. These results suggest that targeting the production of CXCR4 and blocking the CXCL12-CXCR4 pathway might be effective strategies for treating NSCLCs harboring a specific type of EGFR mutation.

Effect of tumor microenvironment on tumor VEGF during anti-VEGF treatment: systems biology predictions

BACKGROUND

Vascular endothelial growth factor (VEGF) is known to be a potent promoter of angiogenesis under both physiological and pathological conditions. Given its role in regulating tumor vascularization, VEGF has been targeted in various cancer treatments, and anti-VEGF therapy has been used clinically for treatment of several types of cancer. Systems biology approaches, particularly computational models, provide insight into the complexity of tumor angiogenesis. These models complement experimental studies and aid in the development of effective therapies targeting angiogenesis.

METHODS

We developed an experiment-based, molecular-detailed compartment model of VEGF kinetics and transport to investigate the distribution of two major VEGF isoforms (VEGF121 and VEGF165) in the body. The model is applied to predict the dynamics of tumor VEGF and, importantly, to gain insight into how tumor VEGF responds to an intravenous injection of an anti-VEGF agent.

RESULTS

The model predicts that free VEGF in the tumor interstitium is seven to 13 times higher than plasma VEGF and is predominantly in the form of VEGF121 (>70%), predictions that are validated by experimental data. The model also predicts that tumor VEGF can increase or decrease with anti-VEGF treatment depending on tumor microenvironment, pointing to the importance of personalized medicine.

CONCLUSIONS

This computational study suggests that the rate of VEGF secretion by tumor cells may serve as a biomarker to predict the patient population that is likely to respond to anti-VEGF treatment. Thus, the model predictions have important clinical relevance and may aid clinicians and clinical researchers seeking interpretation of pharmacokinetic and pharmacodynamic observations and optimization of anti-VEGF therapies.

Interleukin-8 (CXCL8) in tumor associated non-vascular extracellular fluids: its diagnostic and prognostic values. A review

Interleukin-8 (IL-8, CXCL8) was originally discovered as a powerful attractor and activator of polymorphonuclear leukocytes. It was soon recognized that IL-8 also affects proliferation and migration of cancer cells, tumor angiogenesis and metastasis, and that it is expressed in many cancerous cell types. IL-8 protein expression is usually increased in serum of cancer patients, but markedly higher concentrations are found in cancer-associated non-vascular extracellular fluids, such as pleural effusion, ascites and cyst fluid. Elevated concentrations of IL-8 are indicative of malignant processes also in cerebrospinal fluid, urine, saliva, interstitial fluid and cervicovaginal secretions. Higher IL-8 levels are typically found in high-grade peritumoral fluids rather than low-grade tumors and benign conditions, with the exception of inflammatory processes. In line with recent molecular biology investigations, it appears that the local IL-8 production is related to its malignant origin and to tumor progression. Hence, IL-8 in peritumoral fluid is to be taken into consideration while assessing tumor character and monitoring the tumor progression/remission status. Besides, the data here collected justify the attempts to find an IL-8-targeted inhibitory therapy

Diagnostic accuracy of vascular endothelial growth factor for malignant pleural effusion: A meta-analysis

Since the diagnostic accuracy of conventional examinations for malignant pleural effusion (MPE) is limited, a number of studies have investigated the utility of pleural vascular endothelial growth factor (VEGF) in the diagnosis of MPE. The present meta-analysis aimed to determine the overall accuracy of a VEGF test in the diagnosis of MPE. A systematic review of studies published in English was conducted and the data concerning the accuracy of pleural VEGF assays in the diagnosis of MPE were pooled with random effects models. The overall test performance was summarized using receiver operating characteristic curves. Ten studies, based on 1,025 patients, met the inclusion criteria for the meta-analysis and the summary estimates for VEGF in the diagnosis of MPE were: sensitivity 0.75 [95% confidence interval (CI), 0.72-0.79], specificity 0.72 (95% CI, 0.68-0.76), positive likelihood ratio 2.94 (95% CI, 1.97-4.41), negative likelihood ratio 0.38 (95% CI, 0.27-0.51) and diagnostic odds ratio 9.05 (95% CI, 4.60-17.80). The summary receiver operating characteristic curve indicated that the maximum joint sensitivity and specificity was 0.75; the area under the curve was 0.82. Our findings suggest that the determination of pleural VEGF may improve the accuracy of MPE diagnosis, while the results of VEGF assays should be interpreted in parallel with conventional test results and other clinical findings.