We have all been watching the news lately regarding the
terrifying Ebola virus. We have seen the great suffering and death that it has
caused in Africa, and we have watched helplessly as the disease has crossed the
borders from one country to the next. We have even seen it vault the ocean,
respecting no boundaries, political or physical, to come to America. We have
all felt that sense of insecurity and dread as we have asked, “Why have we not
developed a vaccine? We have eradicated smallpox, polio is almost gone, and one
hardly hears of mumps, measles and rubella anymore-all thanks to vaccination.
We have known of Ebola since the 1970s. Why then has no one developed a
vaccine?” An effective vaccine could allow us to forever close our borders, and
the borders of all nations, to this intolerable threat.
My purpose today, however, is not to discuss Ebola. Rather
is it to highlight another threat; an internal threat. The disease I wish to
speak of is cancer. Cancer is not an infection. Instead, cancer happens when
cells from our own body begin to grow and divide out of control. First they
form a tumor. But like Ebola, malignant cells also respect no borders, and they
chew through surrounding normal tissues (a process called invasion), and
individual cells break off to form new tumors elsewhere in the body (a process
called metastasis). These growing lesions disrupt the function of vital organs,
eventually leading to death. Advances in surgery, drug therapy and radiation
have steadily reduced death rates for most cancers. Nonetheless, the disease
remains a major health problem, and the radical surgeries, harsh chemotherapies
and daunting radiation treatments make cancer one of the few remaining diseases
where the therapies are feared almost more than the malady itself. Cancer
survivors can never be completely free from the concern their ordeal will
return. If only there were a vaccine for cancer!
Fortunately, scientists are not neglecting the vaccine
approach to protect us from cancer. One physician-scientist in particular, Dr.
Brian Czerniecki of the University of Pennsylvania, has had remarkable success
with an early form of breast cancer called ductal carcinoma in situ, or DCIS. A
large proportion of breast cancers produce a protein called HER-2, and this is
the target of Dr. Czerniecki’s vaccine. The vaccine is provided to the cancer
patient once a week for four to six weeks after which the remaining tumor is
surgically removed. After treating more than 80 patients since 2004, it was
found that one out of five of those vaccinated had “complete responses”, i.e.
no remaining tumor was found at the time of surgery. What’s more, Dr.
Czerniecki can detect long-lived immune responses in the patients up to several
years after vaccination. This alone suggests the possibility of long-term
protection, but even stronger evidence is that none of the patients who have
had complete responses to the vaccine have ever experienced a recurrent breast
cancer! When compared to other experimental cancer vaccines being tested, this
approach appears to induce much higher response rates as well as longer-lasting
immunity. Although the initial focus is on breast cancer, it is likely that Dr.
Czerniecki’s basic platform can be adapted to other carcinomas including
colorectal, prostate, some lung cancers, and others.
Dr. Czerniecki also made another surprising discovery during
the course of his vaccine study. He found that healthy individuals with no
history of breast cancer had relatively high proportions of T cells (a type of
white blood cell of the immune system) that could specifically recognize and
react to the HER-2 tumor target. Interestingly, when he examined the blood from
unvaccinated DCIS patients, as well as those who had progressed to invasive breast
cancer, and then to metastatic breast cancer, he observed a progressive loss of
HER-2-recognizing T cells. By the time the tumors became invasive, there were
almost no anti-HER-2 T cells at all! It was as though the growing tumor,
through some as-yet unknown means, was disabling or eliminating the very cells
of the immune system that could protect us from cancer, through their ability
to recognize and kill tumor cells that produce HER-2 vaccine target.
Interestingly, however, Dr. Czerniecki found that his
vaccine could restore the numbers of HER-2-reactive T cells to levels near that
of individual who had never had cancer. This “immuno-restoration TM” may prove
key to long-term protection from future malignancies.
These are exciting times for the development of vaccines
against cancer, and more work needs to be done before we reach our goal. It is
imperative that Dr. Czerniecki’s work be continued so that a safe and effective
anti-cancer vaccine can be a reality. Only then can we forever close our
borders to deadly cancers.
Gary K.
Koski, Ph.D.
Associate
Professor of Biological Sciences
Kent State
University
