Prise en charge des patients atteints de métastases cérébrales de mélanome

Insights into the Molecular Mechanisms Mediating Extravasation in Brain Metastasis of Breast Cancer, Melanoma, and Lung Cancer

Brain metastasis is an incurable end-stage of systemic cancer associated with poor prognosis, and its incidence is increasing. Brain metastasis occurs through a multi-step cascade where cancer cells spread from the primary tumor site to the brain. The extravasation of tumor cells through the blood-brain barrier (BBB) is a critical step in brain metastasis. During extravasation, circulating cancer cells roll along the brain endothelium (BE), adhere to it, then induce alterations in the endothelial barrier to transmigrate through the BBB and enter the brain. Rolling and adhesion are generally mediated by selectins and adhesion molecules induced by inflammatory mediators, while alterations in the endothelial barrier are mediated by proteolytic enzymes, including matrix metalloproteinase, and the transmigration step mediated by factors, including chemokines. However, the molecular mechanisms mediating extravasation are not yet fully understood. A better understanding of these mechanisms is essential as it may serve as the basis for the development of therapeutic strategies for the prevention or treatment of brain metastases. In this review, we summarize the molecular events that occur during the extravasation of cancer cells through the blood-brain barrier in three types of cancer most likely to develop brain metastasis: breast cancer, melanoma, and lung cancer. Common molecular mechanisms driving extravasation in these different tumors are discussed.

Burden and Risk Factors of Brain Metastases in Melanoma: A Systematic Literature Review

Melanoma can frequently metastasize to the brain with severe consequences. However, variation of melanoma brain metastases (MBM) development among populations is not well studied, and underlying mechanisms and risk factors for MBM development are not consistently documented. We conducted a systematic literature review (SLR) including a total of 39 articles to evaluate the proportion of melanoma patients who are diagnosed with, or develop, brain metastases, and summarize the risk factors of MBM. The average proportion of MBM was calculated and weighted by the sample size of each study. Meta-analyses were conducted for the selected risk factors using a random-effects model. The proportion of MBM at diagnosis was 33% (975 with MBM out of 2948 patients) among patients with cutaneous melanoma (excluding acral) and 23% (651/2875) among patients with cutaneous mixed with other types of melanoma. The proportion at diagnosis was lower among populations with mucosal (9/96, 9%) or uveal (4/184, 2%) melanoma and among populations outside the United States and Europe. Meta-analysis demonstrated that male vs. female gender and left-sided tumors vs. right-sided were significantly associated with increased risk of melanoma brain metastases. These data may help clinicians to assess an individual patient's risk of developing melanoma brain metastases.

Intracranial Treatment in Melanoma Patients with Brain Metastasis Is Associated with Improved Survival in the Era of Immunotherapy and Anti-BRAF Therapy

Metastatic melanoma patients are at high risk of brain metastases (BM). Although intracranial control is a prognostic factor for survival, impact of local (intracranial) treatment (LT), surgery and/or radiotherapy (stereotactic or whole brain) in the era of novel therapies remains unknown. We evaluated BM incidence in melanoma patients receiving immune checkpoint inhibitors (ICI) or anti-BRAF therapy and identified prognostic factors for overall survival (OS). Clinical data and treatment patterns were retrospectively collected from all patients treated for newly diagnosed locally advanced or metastatic melanoma between May 2014 and December 2017 with available BRAF mutation status and receiving systemic therapy. Prognostic factors for OS were analyzed with univariable and multivariable survival analyses. BMs occurred in 106 of 250 eligible patients (42.4%), 64 of whom received LT. Median OS in patients with BM was 7.8 months (95% CI [5.4-10.4]). In multivariable analyses, LT was significantly correlated with improved OS (HR 0.21, p < 0.01). Median OS was 17.3 months (95% CI [8.3-22.3]) versus 3.6 months (95% CI [1.4-4.8]) in patients with or without LT. LT correlates with improved OS in melanoma patients with BM in the era of ICI and anti-BRAF therapy. The use of LT should be addressed at diagnosis of BM while introducing systemic treatment.

Systemic Therapies for Melanoma Brain Metastases: A Primer for Radiologists

OBJECTIVE

The purpose of this article is to provide a primer for radiologists outlining the modern systemic therapies used in melanoma brain metastases, including tyrosine kinase inhibitors and immune checkpoint inhibitors. The role of radiologic treatment response evaluation will be discussed from the standpoint of both modern systemic therapies and more traditional treatments.

CONCLUSION

Understanding the role of systemic treatments in melanoma brain metastases is critical for oncologic imaging interpretation in this unique patient population.