A preliminary clinical study performed at the Dana-Farber Cancer Institute of Harvard Medical School (HMS) found that a new antibody therapy may enhance the effectiveness of cancer vaccines, according to a statement released earlier this month.

The new treatment is based on the ability of an antibody, MDX-CTLA4, to block a protein that normally restrains the immune system from attacking cancer cells.

The combination of the antibody with a particular cancer vaccine “resulted in especially potent immune attack on tumors,” according to results of the study released earlier this month.

This finding was first proved in mice by James Allison of the University of California, Berkeley.

The researchers at Dana-Farber worked with nine cancer patients—seven with metastatic melanoma (skin cancer) and two with metastatic ovarian cancer, all of whom had received cancer vaccines prior to the study. Researchers gave the patients a single-injection of the antibody.

Phase I of this clinical trial was performed to establish the safety of the treatment.

After following the patients for several years, researchers found best results in those who had been previously treated with a vaccine that uses their own cells to help produce the molecule GM-CSF (granulocyte-macrophage-colony-stimulating factor).

In the five patients who had received this vaccine, the researchers found signs of increased cell death in the presence of tumor-fighting immune cells—suggesting the antibody treatment had enhanced the effects of the vaccine.

These results were absent in the four antibody-treated patients who had received alternate vaccines in the past.

“The study suggests that this antibody expands the memory of the immune system,” said lead author of the study F. Stephen Hodi ’88, an instructor of medicine at HMS, arguing the treatment gives the body an additional resource to fight cancer.

While the antibody did not appear to cause severe side-effects in patients, some of the melanoma patients developed mild rashes. But this is a positive sign, says Allison, explaining that the rashes indicate that the melanoma is being attacked well, and that tumor cells are being killed.

“The new study offers the first evidence that the technique has promise in human patients, although much more study will be needed to demonstrate that this is the case,” HMS co-researcher Glenn Dranoff said in a press release.

Hodi says follow up studies with the GM-CSF vaccine are currently being performed on patients with lung cancer, melanoma, ovarian cancer and leukemia.