Oncolytic Virus Therapy

October 24, 2024

This page was reviewed under our medical and editorial policy by Alexis Boling, MSN-RN, CNML, director, nursing, Immune Effector Cell & Gene Therapy Program, City of Hope^® Cancer Center Duarte

Oncolytic virus therapy is a type of immunotherapy treatment that may be used on certain cancers. It is sometimes referred to as oncolytic virotherapy, viral therapy or virotherapy. It is still in the early stages of development, but is a promising tool in the spectrum of treatment options for patients with cancer.

This guide to oncolytic virus therapy is designed to help patients and their families learn more about how this treatment works.

What Is Oncolytic Virus Therapy?

Oncolytic virus therapy is a type of cancer treatment that uses a genetically modified virus to improve the body’s ability to destroy cancer cells, without harming healthy cells. When injected into a tumor, the virus begins to replicate, which breaks open the cancer tumor and destroys it.

Within the United States, only one type of virotherapy is currently approved, and it is for the treatment of advanced melanoma. Called T-VEC or Imlygic^® (talimogene laherparepvec), it is made from a modified version of the herpes simplex virus.

In other countries, virotherapies are already used to treat other cancers, including head and neck tumors. These therapies have the potential to treat many types of cancer, and researchers are continuing to learn more about them.

Clinical trials are ongoing, with this treatment showing the potential to soon treat both triple-negative breast cancer and glioblastoma.

How Are Oncolytic Viruses Administered?

Oncolytic viruses may be administered in several ways, depending on the type of therapy and the type of cancer being treated. The most common way to deliver this therapy is by injection directly into the tumor. This is called intratumoral delivery.

This method provides targeted treatment and limits the virus from reaching healthy areas of the body or being attacked by the immune system before it has a chance to work against cancer. Intratumoral delivery is most often used on tumors near the skin’s surface, such as those caused by melanoma.

Clinical trials are also examining other delivery methods, which vary based on the type of cancer being targeted. These may include injecting the viruses into the abdomen (intraperitoneal), spinal fluid (intrathecal), bloodstream (intravenous) or just under the skin (subcutaneous).

Each type of therapy is administered on different schedules. When used to treat melanoma, for example, T-VEC is given every two weeks.

Researchers are also looking at other dosing regimens, such as a single cycle of therapy within a two-week period. During the cycle, oncolytic virotherapy may be given several times.

How Does Oncolytic Virus Therapy Work?

An oncolytic virus is a type of virus that may live and replicate quickly inside a cancer cell. When the virus is inserted into a cancerous tumor, it infects the cancer’s cells and rapidly makes new virus cells. These burst open the cancer cells, destroying them.

Oncolytic viruses may also be modified to transport genetic material straight to cancer cells. This helps the body produce a protein that aids the patient’s immune system by blocking another protein, TGF-beta. By blocking TGF-beta, the immune system may more successfully identify and destroy cancer cells.

There is much potential for oncolytic virus therapy, which researchers are studying. This treatment may one day be combined with other cancer treatments, including other immunotherapies, such as checkpoint inhibitors.

Risks of Oncolytic Virus Therapy

Like all cancer treatments, oncolytic virus therapy may cause side effects in some patients. These may include:

• Pain or a rash at the injection site
• Flu-like symptoms, including fatigue, fever and chills
• Headaches
• Muscle aches
• Nausea and/or vomiting
• Diarrhea

In some cases, more severe side effects may occur, including:

• Cellulitis, a bacterial skin infection
• Shortness of breath
• Increased heart rate
• Fluid buildup in the chest
• Low blood pressure

Oncolytic Virus Therapy at City of Hope

Researchers at City of Hope are at the forefront of oncolytic virus therapy innovations and clinical trials. Our scientists are constantly evaluating new options and improving the efficacy of existing oncolytic virus therapies to develop more powerful treatments for cancer and other diseases.

Learn more about our oncolytic virus therapy research