A new cancer vaccine developed at the Center for Genetic and Cellular Therapies is poised to deliver a large blow in the war against cancer.
The vaccine, the result of efforts led by Assistant Research Professor Dr. Smita Nair, makes the body's immune system aware of malignant tumors, enabling patients' own immune systems to fight the cancer.
Professor Eli Gilboa, director of the center, said he is "optimistic" about the future of this vaccine, adding that it is designed to be a general treatment for many types of cancer. "The principles [of this research] will hold for all cancers," he said.
Without the vaccine, tumors produce proteins on their surfaces called antigens, which identify the malignant cells. Special immune cells, called dendritic cells, locate and steal these antigens, causing the dendritic cells to assume the appearance of a tumor cell. Once the dendritic cells take on the appearance of cancerous cells, the body's immune system releases "killer-T" cells that then fight the tumor.
This response mechanism often fails, however, because tumor cells have adapted clever hiding techniques so dendritic cells cannot identify them.
The vaccine works when scientists remove from each individual patient strands of RNA that code for antigens. RNA-the body's instruction manual for building proteins-causes the dendritic cells to produce the antigens normally associated with the tumor. Once the antigens are produced, the body's immune system produces killer-T cells that attack the cancer.
This treatment method effectively eliminates the body's need to find the tumors cells itself, thus solving the problem of tumors hiding from the body. Furthermore, this mechanism is also effective because it relies on RNA to produce the antigens instead of incorporating them on to dendritic cells.
Since it is more difficult to synthesize protein than RNA, the vaccine is easier to make than one based on the antigens themselves.
In addition, by using the patient's tumor RNA to make the proteins, the treatment is individualized. Other treatments have failed because they employed proteins specific to one patient, making them useless in other patients. This new treatment promises to work equally well in all patients.
A press release stated that 15 of 18 samples in a recent study caused an "immediate and sustained" immune response in test tube experiments.
The vaccine is already in the second phase of clinical trial, under the supervision of Dr. H. Kim Lyerly, clinical director of genetics and cell therapy. Phase I, which tests the vaccine for toxicity, has been successful, a press release stated. Lyerly will be producing vaccines for about 100 patients who have breast, lung or colorectal cancers for the second phase of testing. The Food and Drug Administration has also given the green light for Lyerly to start a phase I trial of a version of the vaccine made from colon cancer cells.
Dr. Lisa Denzin, a professor in the Department of Immunology, called the early experiments a "major breakthrough." Because she is unfamiliar with the program's specifics, however, Denzin said she was hesitant to provide further details but added she was optimistic about further human trials.
Gilboa said he could not predict how the vaccine will affect cancer research in general, but he said it was a step forward.
A complete copy of the recent study is available in the April issue of Nature Biotechnology.
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