How VBI-1901 works
VBI-1901 is a vaccine against cytomegalovirus, or CMV. It is designed to kill glioblastoma and medulloblastoma tumor cells infected with CMV, as many are.
The immune system already targets cells infected by viruses. VBI-1901’s goal is to boost the immune response to them.
CMV inside tumor cells generate proteins called viral antigens that travel to the cells’ surface. VBI-1901 is designed to coax the body to produce antibodies and white blood cells that can kill tumor cells with these antigens.
The vaccine does not contain live virus. It consists of tiny particles, called envelopes, that contain two kinds of CMV proteins. The particles themselves can’t cause an infection.
The immune system recognizes the CMV-generated proteins as foreign to the body, and mounts a response against them. Because the proteins are on the surface of tumor cells, the immune system eliminates the tumor cells, too.
VBI-1901 also includes a protein called granulocyte-macrophage colony stimulating factor that gives the vaccine more punch. It boosts its ability to trigger an immune response by attracting immune dendritic cells to the site where the vaccine is injected.
The dendritic cells carry the virus’s antigens to the lymph nodes, where immune cells are made. This allows other types of immune cells at the lymph nodes to become acquainted with the antigens, so they can recognize them faster when they encounter them in other parts of the body.
VBI-1901 in clinical trials
VBI-1901 triggers an anti-tumor reaction in white blood cells taken from glioblastoma patients and healthy volunteers, studies have shown. In addition, research has shown that mice as well as monkeys immunized with VBI-1901 produce white blood cells that react specifically with cytomegalovirus antigens.
VDI Vaccines is conducting the first clinical trial of VBI-1901 in patients with the most malignant form of glioblastoma multiforme. The Phase 1/2a trial (NCT03382977) is testing three doses of VBI-1901 in 18 patients with recurrent glioblastoma multiforme.
The study will evaluate the therapy’s safety and patients’ ability to tolerate it. It will also establish an optimal dose of the vaccine for further testing. An extension of the study is expected to include 10 additional patients. All participants will be immunized every four weeks until their tumors worsen.
The company is conducting the trial in New York, where recruitment is already under way, and Falls Church, Virginia, where recruitment has yet to begin.
Glioblastoma is one of the most common and aggressive brain tumors. In the United States alone, 12,000 cases are diagnosed each year. The standard regimen for treating glioblastoma is removing the tumor by surgery, followed by radiation and chemotherapy.
Standard treatment for medulloblastoma also begins with surgical removal of the tumor. Depending on patients’ age and stage of the tumor, many will have radiation and chemotherapy after the surgery. Current treatments have led to patients living longer.
The Meghan Rose Bradley Foundation, a children’s brain cancer advocacy organization, provided a grant for initial research on VBI-1901’s ability to treat medulloblastoma. It involves patient tissue samples.
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