APPROACH, which attacks the disease at its roots, uses a genetically engineered
vaccine to rev up the patient’s own immune system to destroy cancer
cells. Preliminary results show the tactic is
working. In a study of 17 patients whose cancers had spread beyond the kidney,
the vaccine wiped out tumors in four of them, said the scientists from the
University of Goettingen. There has been no evidence of recurrence for periods
of up to 21 months. And tumors shrank by at least
half in another two patients, they found. While
results of such a small study need to be confirmed in larger, longer trails, the
vaccine nonetheless represents a big step forward, said study author Alexander
Kugler. Fewer than one in 10 patients with advanced kidney cancer typically
respond to conventional drug therapy, he noted.
The work appears in the March issue of Nature Medicine.
American researchers remained cautiously optimistic. “If confirmed,
the results of this study represent an unprecedented advance in the selective
and non-toxic immunotherapy of a disseminated and lethal carcinoma,” said Donald
Kufe of the Dana-Farber Cancer Institute in Boston.
are based on the concept that each tumor cell has on its surface special
proteins — called tumor-associated antigens — that the body recognizes as
foreign and thus can be targeted by the immune system.
While there are several different approaches, the German team created
their vaccine by fusing blood cells called dendritic cells with tumor cells from
the same patient. When the hybrid is injected
back into the body, the immune system recognizes the cells as foreign since they
contain bits of the patient’s tumor and attacks them.
Moreover, the immune system is now charged up and wants to kill any cells
that carry that tumor antigen itself. So like a
police force rounding up criminals, the T cells seek out and destroy other
cancerous cells in the body. In the trial,
patients who kidney cancer disease had spread to the lymph nodes, lungs or bones
were administered the vaccine, with a booster six weeks later. If the patient’s
tumor seemed to be shrinking, additional boosters were given every three
months. One added bonus, the researchers said, is
that unlike chemotherapy or radiation, there were few side effects other than
irritation at the injection site.
OTHER STUDIES At Johns Hopkins in Baltimore, Dr. Donald
Coffey and colleagues tested another type of cancer vaccine on 18 patients with
kidney cancer that had spread throughout the body despite conventional
therapies. All patients had measurable immune
responses, with activation of disease-fighting cells believed to have crucial
anti-tumor activity, reported Dr. Fray Marshall, a cancer specialist.
And one patient, whose tumor continued to grow and spread to
his lungs following conventional surgery, went into remission for seven months,
he said. The therapy is not for everyone; in fact,
its usefulness may be limited to solid tumors such as those seen in kidney,
prostate and pancreatic cancers. Nevertheless,
immune-based cancer vaccines offer a nontoxic approach, Coffey says, “better
than most therapies we can offer these patients