It’s something generations of women could only dream about: a cancer vaccine that keeps malignant cells from taking hold in the breast, and stops tumors in their tracks. Announced earlier this week by the Cleveland Clinic, the proposed breast-cancer vaccine contains a small amount of alpha-lactalbumin, a protein that researchers say is present in the majority of breast tumors. The vaccine is intended to create an immune response in your body that should help you beat back breast cancer. But does it work?
Immunologist Vincent Tuohy, PhD., of the Cleveland Clinic’s Lerner Research Institute, is leading the research, which draws on studies from the 1980s that have established a link between breast cancer and alpha-lactalbumin. In one experiment, his team vaccinated young mice with a genetic propensity for breast cancer, then waited eight months to see if tumors developed. They didn’t. When they vaccinated another group of mice with existing tumors, the tumors shrank. By contrast, mice that had an equally high risk for the disease, but received a sham vaccine, saw their cancers blossom.
Tuohy compares the new vaccine to a bouncer who removes an unruly patron from a bar. “It targets this single protein, alpha-lactalbumin, and makes millions of immune cells that recognize it,” he explains. “When your body next encounters the protein, it’s eliminated immediately.”
Alpha-lactalbumin is also present in women who breastfeed. Triggering the immune system to target this protein would ultimately engender a reduction in the production of lactose, making feeding painful and ineffective. For that reason, researchers have focused their efforts on vaccinating women over 40, who are more likely to have finished lactation. But in theory, Tuohy says, high-risk women in their thirties could be vaccinated, too, if their need outweighed these concerns.
Tuohy’s team is currently trying to raise money for a Phase I clinical trial that would evaluate the dosage, safety and optimal immune response of the proposed test vaccine; at the earliest, this work would begin at the end of 2011. It wouldn’t be until 2014, he theorizes, that the vaccine would be tested for effectiveness, most likely on women who have the BRCA-1 gene for breast cancer and a family history of the disease.
Will a vaccine that works on a high-risk mouse work for a healthy woman? Experts wonder. “It’s a great idea,” offers Freya Schnabel, MD, director of breast surgery at New York University’s Langone Medical Center. “But the research is preliminary right now, and it’s not clear how it translates into clinical use. I am concerned about whether this is the right protein to target, and about how well you can pinpoint the moment between the normal sequence of events with this protein and the abnormal development of breast tumors.”
She worries, too, about side effects that might come with stimulating a woman’s immune system into interfering with her own cells. In an attempt to see what might happen, Tuohy vaccinated mice with no breast cancer risk, and found that they experienced no detectable inflammatory changes. He expects women to respond similarly. “I feel confident that we could immunize normal, healthy women without any damage to normal tissue," he says.
Who those women might be is still up in the air. “A significant number of women with breast cancer get it before age 40, but the vaccine might not be appropriate for those individuals,” Schnabel points out. “And for many women, the forties are still child-bearing age, so they may not want the vaccine.” Even if they do get it, it may not do any good: “It can take years for a cell to transform into a malignancy and become a clinically apparent tumor. The forties may be too late.” (Note: The average age of breast cancer diagnosis in the U.S. is 55 to 65.)