I
n the race to increase survival
rates for a soft-tissue cancer, one
researcher surges ahead with an
exciting discovery.
When she’s astride her favorite
horse, Brieanna Elmer exudes a
deep sense of joy and exhilaration.
Eyes sparkling, she caresses Apollo’s velvet
nose, listens to the music of his hooves, and
inhales the pungent aroma of stable and
corral. Yet, the 11-year-old has had to put
horseback riding on hold while undergoing
treatment for rhabdomyosarcoma, the
most common type of soft-tissue cancer in
children.
The cancer diagnosis came as a surprise
to Brieanna, who was irritated when her
mom insisted she visit the doctor to check
out mysterious bumps on her neck. “I’m not
sick!” insisted the high-spirited equestrian,
who also loves to hike and fish.
Sure enough, Brieanna’s bloodwork looked
perfect. To be on the safe side, the doctor
prescribed an antibiotic to head off a possible
infection.
But she and her medical team soon
discovered things are not always as they
appear. When the lumps persisted, tests
showed Brieanna had cancer. Originating in
her sinus cavity, the disease had spread to
lymph nodes in her neck and shoulder.
Within a few days of the diagnosis, she and
her parents were on their way to St. Jude
Children’s Research Hospital.
TAKING THE REINS
Meanwhile, in a lab in the Danny Thomas
Research Center at St. Jude, oncologist
and researcher Mark Hatley, MD, PhD, was
having a “eureka” moment.
When it comes to the origins of
rhabdomyosarcoma, he discovered,
appearances can be deceiving.
For decades, scientists worldwide had
assumed rhabdomyosarcoma developed
from immature muscle cells. But Hatley and
his fellow researchers at St. Jude proved
the cancer can originate in the inner surface
of blood vessels tucked into the spaces
between muscle fibers. Identifying the cell
where rhabdomyosarcoma begins may help
scientists improve the diagnosis and develop
new treatment approaches for the disease.
UNBRIDLED ENTHUSIASM
Brieanna and her family say they were
drawn to St. Jude because of its world-class
reputation for both research and clinical care.
“We had to find the best place for her
to receive treatment,” explains her mom,
Amanda.
Brieanna enrolled in a clinical trial
that combines chemotherapy, surgery
and proton beam radiation. St. Jude has
the world’s first proton therapy center
designed solely for children. The hospital
is also home to a cadre of dedicated
experts such as Hatley.
CHANGING HORSES MIDSTREAM
The trail to discovering the origins of
rhabdomyosarcoma has been long and
circuitous. Years ago, Hatley approached
the problem by activating certain proteins
known to play a role in the disease. He
then deleted tumor suppressor genes at
various stages of muscle development.
But the tumors that formed were not the
ones he sought.
“We would never get the cancers we
were looking for,” he says.
Then a researcher at another institution
made an unexpected discovery while
investigating cellular machinery called the
hedgehog pathway. Activating the pathway
caused tumors to form. Hatley and his
colleagues realized that the tumors were
rhabdomyosarcoma.
He has spent the past six years trying
to figure out which cells were giving rise to
those tumors. “We knew it wasn’t muscle,”
he says, “but I always thought it was a type
of metabolic fat called brown fat.”
He ultimately proved his hypothesis
wrong. But in the process, he discovered
the answer that had eluded scientists for
decades: Rhabdomyosarcoma begins in
cells that would normally develop into the
cells that line the inside of blood vessels.
“That could explain why these tumors
occur in places that aren’t skeletal
muscles,” Hatley says. “Every part of the
body has blood vessels.”
GALLOPING AHEAD
In addition to learning the cell of origin
for rhabdomyosarcoma, the research
team found evidence that the disease
process begins before birth. They also
suspect that tumors occurring in different
parts of the body have diverse sources.
By understanding the origins of
rhabdomyosarcoma, Hatley hopes to
uncover new ways to eradicate the disease.
“We’re still using the same therapy that
was used over 40 years ago,” he says. “In
leukemia, we’ve made landmark changes,
pushing survival from 4% to 94%. But for
rhabdomyosarcoma, we’re still sitting at
about 70 percent survival. And for kids
who have the highest-risk disease, the
survival is around 20 percent. We need to
do better.”
Now that researchers have figured out
where rhabdomyosarcoma comes from,
they’re trying to figure out how it happens.
“A pie-in-the-sky idea would be if
we could determine how those early
transformations occur, we could give
them a drug to inhibit that process
in patients with a predisposition to
rhabdomyosarcoma,” Hatley says. “If we
could win the scientific lottery, that’s what
we’d want.”
CHAMPING AT THE BIT
During the past couple of years,
Brieanna has completed many
chemotherapy treatments, followed
by surgery and six weeks of proton
therapy. Her mom says the care has been
exemplary.
“It was surprising to me to realize
that the main concern at St. Jude is to
do what’s best for her—regardless of
what the insurance is going to approve,”
Amanda says. “To me, that’s huge.”
As she finishes her maintenance
chemotherapy, Brieanna spends much
of her time reading books and dreaming
about horseback riding.
An avid reader since age 3, she attained
a high school or higher reading level when
she was in the third grade. She enjoys
books about animals, especially horses.
She also likes to reminisce about her
favorite horse, Apollo.
“He’s a chestnut roan,” she explains.
“He’s brown with itty, bitty little speckles
that are like blue roan colors. He’s really
pretty. I miss him a lot.”
Thanks to St. Jude, Brieanna is
convinced she’ll be back in the saddle
again soon.
Partnerships like the one with the
USAPA, with over $60,000 in donations
in less than three years, help to continue
the groundbreaking research at St. Jude
Children’s Research Hospital. You too can
make a difference in the lives of children
battling cancer, like Brieanna. Dedicate
your next event or tournament to the kids
of St. Jude. Visit stjude.org/yourway to get
started. •
MAY/JUNE 2019 |
MAGAZINE
53