What is Newcastle Disease Virus?

by National Cancer Institute

Newcastle disease virus (NDV) is a virus that is of interest because it replicates (makes copies of itself) more quickly in human cancer cells than in most normal human cells and because it can kill these host cells.

NDV can be used to directly kill cancer cells, or it can be given as a cancer vaccine. Cancer vaccines cause the body's natural immune system to seek out and destroy cancer cells.

The results of clinical trials (research studies) of NDV as a cancer treatment have not proved that it works.

The US Food and Drug Administration has not approved NDV as a treatment for cancer.

Questions and Answers About Newcastle Disease Virus

1. What is Newcastle disease virus?

Newcastle disease virus (NDV) is a virus that causes a deadly infection in many kinds of birds. In humans, NDV causes mild flu-like symptoms or conjunctivitis (an infection of the eye that is also called pink eye) and/or laryngitis (an irritation and swelling of the voice box and the area around it).

Like other viruses, NDV infects cells (called host cells) and then uses those cells to replicate (make copies of) itself. Researchers are interested in NDV because it replicates itself more quickly in human cancer cells than in most normal human cells and it can kill the host cells. For these reasons, the virus is being studied as a treatment for cancer.

2. What is the history of the discovery and use of Newcastle disease virus as a complementary or alternative treatment for cancer?

The first report that NDV may be useful as a cancer treatment was published in 1964. For 20 years before this report, NDV was used in a vaccine to prevent Newcastle disease in birds. During that time, it was learned that NDV caused only minor illness in humans. The mild side effects caused by NDV in humans and its ability to replicate up to 10,000 times faster in human cancer cells than in most normal human cells, led researchers to look more closely at NDV as a possible cancer treatment.

3. What is the theory behind the claim that Newcastle disease virus is useful in treating cancer?

There are many strains of NDV, and they may be either lytic or nonlytic for human cells. Lytic strains kill the infected cell by damaging its outer membrane (layer of tissue). Nonlytic strains kill by blocking the basic processes a cell needs to live. Lytic strains of NDV have been studied in humans because they can kill cancer cells directly, but both lytic and nonlytic strains have been used to make vaccines to help the immune system fight cancer.

4. How is Newcastle disease virus administered?

The way NDV is given depends on how the virus is used to target cancer cells. It may be used to directly infect the patient with NDV or to make cancer vaccines. Cancer vaccines made with NDV may improve the body's natural immune response to cancer, causing it to attack and kill more cancer cells than it would if the NDV were not present. Researchers are studying 3 ways of using NDV as a possible cancer treatment:

Infection of the cancer patient with NDV

NDV can be injected directly into the tumor, a muscle, or a vein (intravenous injection), or into the colon. The virus can also be inhaled. As explained in Question 1 1, NDV infects cells and then replicates itself, creating more copies of the virus that can then infect cells throughout the body. This process targets and kills cancer cells by damaging the cells' outer membranes.

Oncolysate vaccine.

Oncolysate vaccines are made using pieces of cancer cell membranes infected with NDV. Oncolysate-based vaccines are injected under or into the skin.

Whole-cell vaccine

Whole-cell vaccines are made using whole tumor cells infected with NDV. The tumor cells used in the vaccine are changed in the laboratory so that they cannot multiply or infect the patient. Whole-cell vaccines with NDV are given only by injection under the skin.

5. Have any preclinical (laboratory or animal) studies been conducted using Newcastle disease virus?

A number of preclinical studies have been done with NDV. Research in a laboratory or using animals is done to find out if a drug, procedure, or treatment is likely to be useful in humans. These preclinical studies are done before any testing in humans is begun. The following has been learned from preclinical studies:

• NDV replicates more quickly in human cancer cells than in any other type of cell.

• Some types of NDV are able to directly kill certain types of cancer cells.

• NDV and NDV-infected cancer cells can cause the immune system to respond in different ways.

A few of these studies used human cells, but most used animal cells. Based on these and other laboratory findings, clinical trials (research studies with people) using NDV were begun.

6. Have any clinical trials (research studies with people) of NDV been conducted?

Clinical trials of NDV have been done but have not proven that NDV is effective as a cancer treatment. Some of the trials reported positive results and some did not. Most of the studies enrolled only small numbers of patients who also received standard treatments. None of the trials published in English were randomized and few were controlled. Randomized clinical trials give the highest level of evidence. In randomized trials, volunteers are assigned randomly (by chance) to one of 2 or more groups that compare different factors related to the treatment. In a controlled clinical trial, one group (called the control group) does not receive the new treatment being studied. The control group is then compared to the groups that receive the new treatment, to see if the new treatment works. Randomized controlled trials, enrolling larger numbers of people, are needed to confirm the results of studies done so far on the use of NDV to treat cancer.

Clinical trials studying the use of NDV as a cancer treatment have been done in the United States, Germany, and Hungary. Below are brief descriptions of these studies.

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