Complete remission of brain metastases in three patients with stage IV melanoma treated with BOLD and G-CSF

Deciphering molecular mechanisms of metastasis: novel insights into targets and therapeutics

BACKGROUND

The transition of a primary tumour to metastatic progression is driven by dynamic molecular changes, including genetic and epigenetic alterations. The metastatic cascade involves bidirectional interactions among extracellular and intracellular components leading to disintegration of cellular junctions, cytoskeleton reorganization and epithelial to mesenchymal transition. These events promote metastasis by reprogramming the primary cancer cell's molecular framework, enabling them to cause local invasion, anchorage-independent survival, cell death and immune resistance, extravasation and colonization of distant organs. Metastasis follows a site-specific pattern that is still poorly understood at the molecular level. Although various drugs have been tested clinically across different metastatic cancer types, it has remained difficult to develop efficacious therapeutics due to complex molecular layers involved in metastasis as well as experimental limitations.

CONCLUSIONS

In this review, a systemic evaluation of the molecular mechanisms of metastasis is outlined and the potential molecular components and their status as therapeutic targets and the associated pre-clinical and clinical agents available or under investigations are discussed. Integrative methods like pan-cancer data analysis, which can provide clinical insights into both targets and treatment decisions and help in the identification of crucial components driving metastasis such as mutational profiles, gene signatures, associated pathways, site specificities and disease-gene phenotypes, are discussed. A multi-level data integration of the metastasis signatures across multiple primary and metastatic cancer types may facilitate the development of precision medicine and open up new opportunities for future therapies.

Key role for neutrophils in radiation-induced antitumor immune responses: Potentiation with G-CSF

Radiation therapy (RT), a major modality for treating localized tumors, can induce tumor regression outside the radiation field through an abscopal effect that is thought to involve the immune system. Our studies were designed to understand the early immunological effects of RT in the tumor microenvironment using several syngeneic mouse tumor models. We observed that RT induced sterile inflammation with a rapid and transient infiltration of CD11b⁺Gr-1^high+ neutrophils into the tumors. RT-recruited tumor-associated neutrophils (RT-Ns) exhibited an increased production of reactive oxygen species and induced apoptosis of tumor cells. Tumor infiltration of RT-Ns resulted in sterile inflammation and, eventually, the activation of tumor-specific cytotoxic T cells, their recruitment into the tumor site, and tumor regression. Finally, the concurrent administration of granulocyte colony-stimulating factor (G-CSF) enhanced RT-mediated antitumor activity by activating RT-Ns. Our results suggest that the combination of RT and G-CSF should be further evaluated in preclinical and clinical settings.

Administration of granulocyte colony-stimulating factor with radiotherapy promotes tumor growth by stimulating vascularization in tumor-bearing mice

Although granulocyte-colony stimulating factor (G-CSF) is commonly used to support recovery from radiation-induced side-effects, the precise effects of G-CSF on colon cancer under radiotherapy remain poorly understood. In the present study, to investigate the effects of tumor growth following radiotherapy and G-CSF administration in a murine xenograft model of colon cancer, female BALB/c mice were injected with cells of a colon carcinoma cell line (CT26) with irradiation and G-CSF, alone or in combination. Mice received 2 Gy of focal radiation daily for 5 days and intraperitoneal injection of G-CSF (100 µg/kg/day) after irradiation for 7 days. Changes in the levels of myeloperoxidase (MPO), vascular endothelial growth factor (VEGF), matrix metalloproteinase type 9 (MMP-9) and CD31 were assessed in the mouse cancer induced by injection of colon cancer cells. We observed that G-CSF increased the number of circulating neutrophils, but facilitated tumor growth. However, G-CSF treatment did not affect radiation-induced cytotoxicity and cell viability in CT26 cells in vitro. Increased levels of myeloperoxidase, a neutrophil marker and those of vascular endothelial growth factor were observed in tumors with G-CSF supplementation. In addition, we found that increased levels of CD31 and matrix metalloproteinase-9 were correlated with the enhanced tumor growth after G-CSF treatment. Therefore, these data suggest that G-CSF may contribute to tumor growth and decrease the antitumor effect of radiotherapy, possibly by promoting vascularization in cancer lesions.

The Multifaceted Roles Neutrophils Play in the Tumor Microenvironment

Neutrophils are myeloid cells that constitute 50-70 % of all white blood cells in the human circulation. Traditionally, neutrophils are viewed as the first line of defense against infections and as a major component of the inflammatory process. In addition, accumulating evidence suggest that neutrophils may also play a key role in multiple aspects of cancer biology. The possible involvement of neutrophils in cancer prevention and promotion was already suggested more than half a century ago, however, despite being the major component of the immune system, their contribution has often been overshadowed by other immune components such as lymphocytes and macrophages. Neutrophils seem to have conflicting functions in cancer and can be classified into anti-tumor (N1) and pro-tumor (N2) sub-populations. The aim of this review is to discuss the varying nature of neutrophil function in the cancer microenvironment with a specific emphasis on the mechanisms that regulate neutrophil mobilization, recruitment and activation.

Role of the systemic immune system in brain metastasis

Metastatic disease in the central nervous system (CNS) is a cause of increasing mortality amongst cancer patients. As with other types of cancer, cells of the systemic immune system play a range of important roles in the development of metastatic lesions in the CNS, both repressing and promoting tumour growth. Recent advances in immunotherapy have changed the emphasis in cancer treatment away from conventional chemotherapy and radiotherapy for certain tumour types. Despite this, our understanding of systemic immune system involvement in CNS metastases remains poor. The blood-brain barrier prevents the majority of diagnostic and therapeutic agents from crossing into the brain parenchyma until the late stages of metastatic disease. Thus, the development of immunotherapy for CNS pathologies is particularly desirable. This review draws together our current understanding in the relationships between CNS metastases and circulating systemic immune cells. We discuss the roles that circulating systemic immune cells may play in the homing of metastatic cells to the perivascular space, and the pro-metastatic and antagonistic roles that infiltrating systemic immune cells may play at sites of metastasis. This article is part of a Special Issue entitled 'Neuroinflammation in neurodegeneration and neurodysfunction'.

Predictors and survival in patients with melanoma brain metastases

Brain metastases (BM) are one of the most frequent neurological complications of cancers. Melanoma is the third most common tumor to metastasize to the brain with a reported incidence of 10-40 %, and many patients have subclinical BM (>73 %). We computer-searched the clinical records of all our patients registered into a database to identify patients that presented or developed BM. A total of 49 patients with melanoma BM were included in our analysis. General time to brain metastases (TTBM) was 23 months. The nonparametric test between TTBM and the single variables showed an association between TTBM and Breslow thickness (p < 0.0076; Spearman's coefficient-0.411), ulceration (p = 0.0656; Spearman's coefficient-0.287) and positive sentinel lymph node (p < 0.0015; Spearman's coefficient-0.475). Performing multiple regression, positive SLN remained the only, statistically significant, predictive variable (p < 0.01). Regarding the first melanoma site, the axial sites were more likely to develop BM than peripheral ones (p < 0.001). The analysis of brain metastasis survival (BMS) with Kaplan-Meier curves has resulted in a median survival rate of 6 months (range 1-134 months) and was strongly related to response to treatment, number of parenchymal lesions, presence or absence of symptoms. The results of the current analysis revealed clinical and primary tumor characteristics associated with the development of BM, TTBM, and BMS. The SNL was found to be the strongest predictor for BM development.

Metastatic melanoma - a review of current and future drugs

Background:

Melanoma is one of the most aggressive cancers, and it is estimated that 76,250 men and women will be diagnosed with melanoma of the skin in the USA in 2012. Over the last few decades many drugs have been developed but only in 2011 have new drugs demonstrated an impact on survival in metastatic melanoma.

Methods:

A systematic search of literature was conducted, and studies providing data on the effectiveness of current and/or future drugs used in the treatment of metastatic melanoma were selected for review. This review discusses the advantages and limitations of these agents, evaluating past, current and future clinical trials designed to overcome such limitations.

Results:

To date, there are four drugs approved by the Food and Drug Administration for melanoma (dacarbazine, interleukin-2, ipilimumab and vemurafenib). Despite efforts to develop new drugs, few of them have demonstrated any clinical benefits. Approved in 1975, dacarbazine remains the gold standard in chemotherapy, although ipilimumab and vemurafenib have raised many hopes in the last few years. Combining dacarbazine or other chemotherapy agents with new pharmacological agents may be a new way to achieve better clinical responses in patients with metastatic melanoma.

Discussion:

Advances in the molecular knowledge of melanoma have led to major improvements in the treatment of patients with metastatic melanoma, providing new targets and insights. However, heterogeneity amongst study populations, different approaches to treatment and the different melanoma types and localisations included in the trials makes their comparison difficult. New studies focusing on drugs developed in recent decades are warranted.

Survival over 6 years in a patient with brain metastases from melanoma treated with temozolomide

Cerebral metastases from melanoma are generally associated with a dismal prognosis with survival ranging from 3 to 6 months after treatment. Systemic chemotherapy for these patients has limited effect and evidence for an overall survival benefit from randomised controlled trials is lacking. We report on a 59-year-old patient with a history of malignant melanoma who presented with multiple cerebral metastases after previous surgery and combined whole brain and stereotactic radiotherapy. She has been in sustained remission and in excellent clinical condition after treatment with continued cycles of oral temozolomide for more than 6 years. To our knowledge, similar prolonged survival has been described only once in patients with multiple cerebral metastases from melanoma. This case demonstrates that temozolomide for metastatic central nervous system (CNS) disease in melanoma patients may be highly effective without CNS toxicity.

Polymorphonuclear neutrophils and cancer: intense and sustained neutrophilia as a treatment against solid tumors

Polymorphonuclear neutrophils (PMN) are the most abundant circulating immune cells and represent the first line of immune defense against infection. This review of the biomedical literature of the last 40 years shows that they also have a powerful antitumoral effect under certain circumstances. Typically, the microenvironment surrounding a solid tumor possesses many of the characteristics of chronic inflammation, a condition considered very favorable for tumor growth and spread. However, there are many circumstances that shift the chronic inflammatory state toward an acute inflammatory response around a tumor. This shift seems to convert PMN into very efficient anticancer effector cells. Clinical reports of unexpected antitumoral effects linked to the prolonged use of granulocyte colony-stimulating factor, which stimulates an intense and sustained neutrophilia, suggest that an easy way to fight solid tumors would be to encourage the development of intense peritumoral PMN infiltrates. Specifically designed clinical trials are urgently needed to evaluate the safety and efficacy of such drug-induced neutrophilia in patients with solid tumors. This antitumoral role of neutrophils may provide new avenues for the clinical treatment of cancer.

Tumour cell lines HT-29 and FaDu produce proinflammatory cytokines and activate neutrophils in vitro: possible applications for neutrophil-based antitumour treatment

There is evidence that polymorphonuclear neutrophils (PMNs) can exert severe antineoplastic effects. Cross-talk between tumour cells and endothelial cells (ECs) is necessary for the accumulation of PMN around a tumour. This work reports the ability of two PMN-sensitive, human, permanent cell lines—colorectal adenocarcinoma (HT-29) and pharyngeal squamous-cell carcinoma (FaDu) cells—to act as inflammatory foci. PMNs were cytotoxic to both lines, the adhesion of the PMNs to the tumour cells being important in this effect. The tumour cells released appreciable amounts of IL-8 and GROα, and induced the transmigration of PMN through human microvascular-EC monolayers. Conditioning media associated with both lines induced the adhesion of PMN and the surface expression of ICAM-1 in microvascular-EC. In addition, FaDu-conditioning-medium strongly induced the production of proinflammatory cytokines by microvascular-EC. These results support the idea that tumour cells might normally induce a potent acute inflammatory response, leading to their own destruction.