TUESDAY, April 20, 2004 (HealthDayNews) -- Two new studies working at the genetic level may offer breakthroughs in treating cancer patients.
One report focuses on finding genetic markers to predict which patients will have bad side effects from radiation therapy, while the other shows how cloning cows can be used to make antibodies that kill human cancer cells. Both appear in this week's issue of the Proceedings of the National Academy of Sciences.
In the radiation study, lead researcher Dr. Gilbert Chu, a professor of medicine and biochemistry from Stanford University Medical Center, hypothesized that serious side effects to radiation might be caused by an abnormal genetic response to the therapy.
To investigate, Chu's team studied cells from cancer patients who had radiation toxicity during their treatment.
"We were able to find 24 genes that had an abnormal response to radiation therapy," Chu said. These genes could serve as markers that indicate which patients will have a bad reaction to radiation, and which won't.
Of the 14 patients with bad side effects, this method identified nine and missed the other five, Chu said. However, it turned out that two of five patients were receiving experimental radiation treatment that was particularly toxic, he noted.
In another group of 13 cancer patients, Chu's team was able to predict that they wouldn't have bad side effects to radiation, and they didn't. And in another group of patients that included cancer patients and healthy volunteers, the test predicted that none would have bad side effects to radiation.
This genetic test is preliminary and not ready for clinical use, Chu said. However, using this method might identify patients who will react badly to radiation and may play a part in tailoring their treatment.
For example, in cases of prostate and breast cancer where there are choices of treatment, knowing your reaction to radiation therapy ahead of time might help you decide which treatment to choose, Chu said.
Chu believes a similar approach might be used to identify how patients would react to other types of treatment, such as chemotherapy.
"As radiation is increasingly used in preference to other therapeutic methods for treating benign and malignant disease, a rapid and clinically useful method of determining the potential for unacceptable risk may be needed, " said Dr. Jonathan Knisely, an associate professor of radiation medicine from Yale University.
However, for many patients, radiation is the option, "so that the use of such a test may be limited, practically, to those patients who are choosing between radiation and another therapy," he said.
In the antibody report, co-researcher Dr. Mathias Mueller, a professor of animal breeding and genetics from the Veterinary University of Vienna, and his colleagues cloned cows to be used for large-scale production of antitumor drugs, a process known as gene farming.
"We have designed a bispecific antibody to melanoma cells," Mueller said. This antibody can be linked to immune cells, which in turn attack melanoma cells, he explained.
In their experiment, Mueller's team linked the gene for an antibody against human melanoma cells with the gene that activates a cow molecule.
They inserted this gene into embryonic cow cells and generated nine cloned cows. These cows produced large quantities of both bovine antibodies and antibodies against human melanoma.
These purified antibodies from the cows' blood effectively targeted and killed human melanoma cells. In addition, these antibodies did not deteriorate when kept over an extended period.
This method could be an effective therapeutic approach for fighting melanoma, Mueller said. In theory, this approach could be used in fighting other types of cancers, he noted.
Mueller said using cows is a very cheap way to produce these antibodies. "Cows are a living bio-reactor that eat grass or other cheap things, and then produces highly active antibodies."
However, he cautioned this is a very early finding, and it will take several years before these antibodies are ready for use in cancer patients.
Dr. Peter Glazer, a professor of genetics from Yale University, said this study "offers the possibility that biologically made drugs, such as antibodies, could eventually be made more easily, more cheaply and in larger quantities. This could expand the number of such medicines that could be developed, tested and brought to the clinic."