Most cancer treatment vaccines are customized for a patient and built from a patient’s own
immune or tumor cells. That means they can’t be
mass-produced and are expensive and arduous to
make. (Clinical trials, like Liebert’s, typically cover
the cost of a patient’s treatment.) Provenge, for
example, costs $93,000 and extends a person’s life
by roughly four months on average, according to a
2011 paper in Pharmacy and Therapeutics.
Still, clinical trials of vaccines appeal to people
who have exhausted all other treatments, says
neuro-oncologist Jason Fangusaro at the Ann and
Robert H. Lurie Children’s Hospital of Chicago.
Fangusaro runs a phase I clinical trial of a patient-
derived vaccine for children diagnosed with certain
types of brain and spinal cord tumors. “Many
families are willing to try something new because
their child is in a situation where there’s no cura-
tive option,” he says. “We can’t promise anything
because this is uncharted territory, but the poten-
tial for benefit is something they’re willing to try.”
For Liebert, being treated was a long and complicated
process. Before he received the vaccine, Liebert under-
went a stem cell transplant (SCT), often considered the
standard of care for multiple myeloma. During an SCT,
physicians first harvest stem cells from a patient’s blood
or bone marrow. These cells produce lymphocytes, like
T cells and B cells, that fight infection in the body. They
are soldiers in the immune system’s army. Liebert’s
harvested stem cells were stored while he underwent
treatment with Alkeran (melphalan), a chemotherapy
that suppresses the bone marrow’s ability to make
blood cells. After chemotherapy, Liebert’s harvested
stem cells were returned to his body to boost his
recovery and make new blood cells.
HOW TO MAKE A VACCINE
“Cancer is really, really smart when it comes to
figuring out how to evade the immune system,”
says Gilbert at the NCI. T cells, B cells and other
cancer fighters lurk in the blood around cancerous
growths, but they don’t attack. That’s partly because
tumor cells release proteins into the blood that
effectively blind the immune system.
The challenge lies in finding a way to unmask a
tumor. Gilbert is leading a nationwide clinical trial of
a vaccine for patients with glioblastoma, an aggres-
sive form of brain cancer. Researchers on the trial
are using a vaccine synthesized from each patient’s
tumor. It works, in a way, by revealing the cancer’s
fingerprints to the immune system.
For the multiple myeloma and AML vaccines,
Rosenblatt and Avigan combine a patient’s cancer
cells with harvested dendritic cells. These are the
generals of the immune system; they tell T cells
A DECADE OF PREVENTION
In 2012, cervical cancer killed roughly 266,000 women worldwide, mostly in less-developed countries. According to the U.S. Centers for Disease Control and Prevention
(CDC), more than nine in 10 cases are caused by strains of the human papillomavirus
(HPV), the most prevalent sexually transmitted virus in the world. HPV infection also
causes genital warts and has been linked to many other cancers, including those of
the throat, anus, vulva and rectum.
In 2006, the U.S. Food and Drug Administration (FDA) approved the first vaccine that
can prevent infection by two cancer-causing strains of HPV. The vaccine, Gardasil, is
most effective in people who have not been exposed to HPV. Merck, the manufacturer,
sought fast-track approval from the FDA. As a result, the vaccine was approved only
for adolescent girls, the population believed to benefit the most from it.
Approving a vaccine only for adolescent girls caused a firestorm and political
backlash. Critics questioned the safety of the vaccine, but follow-up data suggest that
people are much more likely to die of cervical cancer than to have an adverse response
to the vaccine. No deaths have been attributed to the vaccine.
Since then, other vaccines have entered the market, some of which can prevent infection by other disease-causing HPV strains. The CDC now recommends that adolescent
boys and girls receive the vaccine before they become sexually active. Data released in
2013 show that infection with cancer-causing HPV strains has decreased by more than
50 percent among girls 14 to 19 in the United States.
However, in the United States only about 63 percent of teenage girls have started
the series—a lower vaccination rate than in many developing countries. In Rwanda,
for example, about 95 percent of teenage girls have received the vaccine through a
government-led effort. —S.O.