Tumor cells often grow and spread because the body doesn't recognize them as foreign. The vaccines aim to re-educate the immune system to recognize cancer cells as alien invaders that need to be attacked and annihilated.
Both studies were presented here at the annual meeting for the American Association for Cancer Research (AACR).
Vaccine Targets HER2/neu
About 25% of women with breast cancer fall into this category. In the new study, the vaccine reduced their risk of death by 50%.
Importantly, the vaccine worked even better in women who had lower but still elevated levels of HER2/neu, says researcher Linda C. Benavides, MD, of Brooke Army Medical Center in San Diego.
None of the women in this category -- which accounts for about half of breast cancer patients -- died.
If the vaccine pans out in future study, "we'll have an option for the largest subset of breast cancer patients, who really haven't been considered before," Benavides tells WebMD.
She notes that women with high expression of Her2/neu can benefit from targeted therapies, such as Herceptin. But the only options for women with lower expression are conventional chemo, surgery, or radiation, she says.
Breast Cancer Vaccine Cuts Deaths
The study involved 165 women, about one-third of whom had high levels of HER2/neu. The rest had lower or intermediate levels.
All the women had been treated for breast cancer but were disease-free at the time of the study.
Just over half of the women got the vaccine -- one shot every three to four weeks, for a total of six injections.
Immunity was boosted in all the women who got the vaccine. But tests showed that women with low or intermediate HER2/neu levels mounted a stronger immune response than those with high levels. "This was surprising," Benavides says.
By 30 months later, breast cancer came back in similar numbers of women who had high HER2/neu levels, whether or not they got the vaccine. But among those whose disease recurred, those who got the vaccine were 50% less likely to die.
Among women with low or intermediate HER2/neu levels, only about 10% of those who were vaccinated suffered a recurrence, compared with nearly 20% who didn't get the vaccine.
And none of the vaccinated women with recurrent disease died vs. 38% who didn't get the vaccine.
Outgoing AACR President William N. Hait, MD, PhD, of Johnson & Johnson Pharmaceuticals Research and Development, tells WebMD that he's "cautiously optimistic."
"The concept is good. But one would anticipate that women with lower expression of HER2/neu might have a better prognosis. So the question is, did they do better because they had a better prognosis or because of the vaccine?"
Noting that many other attempts to create a vaccine to eradicate cancer have failed, Hait says further study is needed.
Benavides says the vaccine has been licensed to Apthera, which plans a larger study pitting it against a sham vaccine.
Cervical Cancer Vaccine Revs Up Immune System
The cervical cancer vaccine also aims to rev up the immune system to fight cancer, says John Rothman, PhD, vice president of clinical development at Advaxis in North Brunswick, N.J. Advaxis is developing the cervical cancer vaccine, known as Lovaxin C.
The researchers bioengineered a version of the common bacterium listeria to cause it to secrete antigens specific for cervical cancer. When an antigen is introduced into the body, it provokes the immune system to fight it.
Once injected with the modified bacteria, the body launches an all-out immune response, Rothman says. The vaccine "refocuses the immune system to clear the cancer."
One of the big advantages to the approach is that it activates many different components of the immune system, attacking the tumors both immediately and over the long term, he tells WebMD.
Cervical Cancer Vaccine Curbs Tumor Growth
The study included 15 women with progressive, end-stage cervical cancer that had failed all the usual treatments -- chemotherapy, radiotherapy, or surgery.
The vaccine curbed or stopped the growth of tumors in eight of 13 women in whom tumor size was evaluated.
More importantly, there are signs it extends lives, Rothman says.
"Historically, women with end-stage cervical cancer only survive six months. As we talk today, six of the women are still alive [15 months to 18 months after they received the vaccine]," he says.
As for side effects, all the women developed flu-like symptoms, including fever, chills, and nausea. At the two lower doses, the symptoms were easily treated with nonprescription nonsteroidal anti-inflammatory drugs (NSAIDs) and anti-emetics. These are the doses that will be studied further, Rothman says.
The researchers plan studies in women with early cervical cancer as well as in people with head and neck cancer.
"But this approach can be used for breast cancer, prostate cancer, all kinds of cancer," Rothman says. "We know how to construct the vaccine."