Team Applies Vaccine System to Cancer

Researchers at Harvard Medical School (HMS) have found that a method they developed for vaccinating organisms against harmful foreign cells and viruses could one day help lead to a cancer vaccine.

The Harvard team, led by Assistant Professor of Microbiology and Molecular Genetics Darren E. Higgins, collaborated with cancer researchers at London’s Hammersmith Hospital, who provided them with cells from a model cancer strain they had been using in their own attempts to develop a cancer vaccine.

The London researchers tagged the strain with a particular protein that the human body recognizes as foreign. Coincidentally, Higgins’ vaccination system works on that same protein.

What the latest finding shows, Higgins said, is that the human body, when treated with his vaccination method, reacts the same way to a foreign substance like cancer cells as it does to viruses or bacteria. Now researchers must determine whether the system will work on naturally occurring cancers that aren’t specially tagged.

This potential contribution to the ongoing fight against cancer has drawn the attention of the industry. Already, Higgins has received two patents and several companies have licensed the technology.

While many pathogens can quickly be recognized by the immune system, Higgins’ method deals with those that grow inside the body’s cells, such as viruses and many bacteria.

“The problem with those is since they grow inside human cells they are essentially protected from immune response,” he said.

Higgins’ vaccination system is novel for two reasons.

First, it uses dead E. coli bacteria to deliver the antigen, or disease-causing agent that the body recognizes, to a cell in the immune system known as a macrophage.

Second, Higgins modifies the bacteria to produce a special protein that stimulates the macrophage to produce the desired immune response.

This process amounts to a vaccination system, like childhood immunizations, keeping the body primed to destroy an antigen the next time it is detected.

Traditionally, the most effective vaccines infect patients with a crippled form of the disease they target. Higgins’ method allows for an equally effective vaccine, without the difficulty of engineering a harmless form of the invader.

Higgins had been using ovalbumin as his antigen protein in his research. In their unconnected work, the Hammersmith cancer researchers also had been using ovalbumin as a marker on melanoma cells, which cause a type of skin cancer.

The joint study sought to discover whether systems primed by Higgins’ modified E. coli to wipe out invaders bearing ovalbumin would effectively protect mice from the melanoma strain tagged with that protein.