New Molecular Insights, and the Role of Systemic Therapies and Collaboration for Treatment of Epithelioid Hemangioendothelioma (EHE).

OPINION STATEMENT: Epithelioid hemangioendothelioma (EHE) is an ultra-rare, translocated vascular sarcoma. EHE can have different clinical presentations from indolent to rapidly evolving cases, behaving as a high-grade sarcoma. Serosal effusion and systemic symptoms such as fever and severe pain are known as adverse prognostic factors; however, outcome prediction at disease onset remains a major challenge. In spite of its rarity, an international collaborative effort is in place with the support of patient advocates to increase the knowledge of EHE biology, develop new treatment options, and improve patient access to new active medications. Currently, systemic therapies are indicated only for patients suffering from progressive and/or symptomatic disease and in patients with a high risk of organ dysfunction. Standard systemic agents available so far for treatment of sarcomas, and in particular anthracycline-based chemotherapy, have marginal activity in EHE. On this background, EHE patients should be always considered for clinical study when available. The MEK inhibitor trametinib has been recently investigated prospectively in advanced EHE showing some activity, but the publication of the full dataset is still awaited to better interpret the results. Besides, there are data on response to antiangiogenics such as sorafenib and bevacizumab and, from retrospective studies, interferon, thalidomide, and sirolimus. Unfortunately, none of these agents is formally approved for EHE patients and access to treatments varies greatly between countries causing a huge disparity in patient care from one country to another.