Melanoma Unknown Primary Brain Metastasis Treatment with ECHO-7 Oncolytic Virus Rigvir: A Case Report

Abstract

Melanoma is considered an aggressive malignancy with a tendency of forming metastasis in the brain. Less than 10% of all melanoma cases present with unknown primary tumor location. This diagnose is yet to be fully understood, because there are only theoretical assumptions about the nature of the disease. Melanoma brain metastases have many severe side effects and, unfortunately, any disease related to the brain has limited therapeutic options due to the blood-brain barrier. The course of the disease after a treatment course is complicated to predict, and it is difficult to obtain long-lasting remission. In this report, we describe a female patient with unknown primary melanoma brain metastasis treated with the oncolytic ECHO-7 virus Rigvir^® after brain surgery. The patient has been stable, as monitored by magnetic resonance imaging, for more than 3.8 years with ongoing therapy. The median expected overall survival from the time of diagnosis is approximately 5 months. Additional positive effect could have been gained from use of the intranasal administration route, which is considered effective due to the direct anatomical connection between the nasal cavity and the central nervous system. However, further studies are required to fully understand this mode of drug administration.

Keywords: ECHO-7 virus; Rigvir®; blood–brain barrier; intranasal; melanoma brain metastasis; melanoma unknown primary; oncolytic virus.

Figure 1

Contrast-enhanced head and brain magnetic resonance imaging (MRI) scan shows a formation in the craniospinal junction before surgery on 17 March 2014 (A). Contrast-enhanced MRI scan 3 months after surgery shows a minimal, residual caudal part of the tumor on 5 June 2014 (B).

Figure 2

(A) Representative photomicrographs of the melanoma metastasis: epithelioid and spindle cells. Hematoxylin-eosin staining, magnification ×40, scale bar is 50 µm. (B) The tumor cells demonstrated marked nuclear pleomorphism with variation in cell size, shape, and staining and increased mitotic activity. Hematoxylin-eosin staining, magnification ×200, scale bar is 25 µm. (C) MART-1 immunopositivity in the tumor cells. Immunohistochemical staining method, magnification ×200, scale bar is 25 µm. (D) S-100 immunopositivity in the tumor cells. Immunohistochemical staining method, magnification ×200, scale bar is 25 µm.

Figure 3

Contrast-enhanced magnetic resonance imaging scans of the head and brain show residual tissue of the melanoma metastasis without significant changes in structure and size. (A) 11 September 2014, (B) 5 March 2015, (C) 29 September 2015, (D) 29 February 2016, (E) 2 August 2016.