March 5, 2007

C.U. Revolutionizes Cancer Treatment

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In a recently published study, Cornell researchers have identified an antigen-targeting process that has the power to change the future of cancer treatment. In a clinical trial, researchers at the New York-Presbyterian/Weill Cornell Medical Center established that an antibody, referred to as J591, targets a very specific antigen commonly found on prostate tumors as well as on the blood vessels of any type of solid tumor.

The study, published on Feb. 10 in the Journal of Clinical Oncology, confirmed that J591 consistently seeks out only the prostate specific membrane antigen. More importantly, because PSMA is found on non-prostate related tumors, it could be used to damage the blood flow to all kinds of solid tumors.

“PSMA is a misnomer,” said Prof. David M Nanus of Weill Cornell Medical College, a co-researcher in the study. “In reality, it’s expressed on prostate cancer cells more than normal cells, but the blood vessel cells that populate the cancer express it as well, in areas that, normally, antibodies can’t reach.”

Proving that J591 solely targets PSMA is the first step in using it to improve cancer treatment. Because of its specificity, J591 could be used to deliver drugs or radioactive isotopes to the site of the tumor. This could potentially cut off its blood supply and reduce its size, not just halt its growth, as do other drugs currently on the market.

“What represents arguably a step forward is that we have demonstrated for the first time in patients that there is a way to go beyond withdrawing blood supply, to deliver radiation directly to the blood vessels and not just keep them from growing, but actually [kill] them,” said Prof. Neil H. Bander, the Bernard and Josephine Chaus Professor of Oncology at Weill Cornell Medical College, who led the study.

Additionally, the PSMA-targeting process could potentially decrease damage to the patient’s body by localizing treatments like radiation, particularly in cases where the cancer is metastatic, which means that it has spread to other parts of the body.

“The reason to do this is in a disease like prostate cancer, which is metastatic, you can’t radiate the entire body,” said Prof. Stanley J. Goldsmith at Weill Cornell Medical College and another co-researcher in the study.

“If someone has a disseminated disease you might not even see it, but you don’t have to worry about seeing it because the antibody will deliver it to the tumor,” he added.

Goldsmith also pointed out that J591 could be used to “pre-target” tumors by attaching a tracer to the antibody and allowing it to guide doctors to the tumor, making it easier to treat.

Ideally, the antigen-targeting process would be used in conjunction with traditional chemotherapy to more quickly and successfully eliminate cancer growths, which are resilient and hard to eradicate completely, according to the researchers.

“Cancer cells are very virulent,” Nanus said. “They repair themselves even from chemotherapy, and the idea is if you hit them with target radiation, they are not able to repair themselves as quickly.”

The process of proving the safety and effectiveness of J591 treatments on non-prostate cancers and in conjunction with anti-cancer drugs is a slow, albeit necessary one for increasing its accessibility. Currently, the process is available only to participants in clinical trials, and such studies must move slowly to ensure safety. Bander pointed out that safety is a particular issue in this case because there is no animal model for this distinct study.

“Under normal circumstances we could reproduce the cancer in an animal model and test the effects of the process,” Bander said. “In the case of other cancers, such as breast cancer, the blood supply [for the tumor] is derived from the animal’s cells and therefore [J591] won’t be able to recognize and respond to it.”

Although widespread availability is still years away, the discovery of J591’s capabilities represents an advance that could transform the way we combat cancer.

“It’s important that we demonstrate that it could be used for other tumors, which makes it more attractive to a company that could [eventually] manufacture it for the whole country,” Goldsmith said.