February 17, 1999. More than 400,000 Americans with
advanced-stage bone cancer may one day find non-sedating relief for
their excruciating bone pain — and possible treatment for their cancer
— in a therapy now being tested in a nationwide clinical trial.
The newly patented nuclear medicine
therapy, based on a compound called tin-117m DTPA, was developed at
the U.S. Department of Energy’s Brookhaven National Laboratory.
"In preliminary clinical trials
involving 47 patients, we showed that it totally or significantly
eased the pain of more than 75 percent of patients, relief that lasted
for up to a year and produced no side effects," said Brookhaven
scientist Suresh Srivastava, co-developer of the therapy.
Srivastava presented those findings
and an outlook for the therapy’s future today at the American College
of Nuclear Physicians’ annual scientific meeting in Hawaii.
He also described the current nationwide
clinical trial, designed to test the compound’s potency in giving
pain relief to patients whose cancer has spread to the bone.
Diatide Inc., a New Hampshire biotechnology
company that has licensed the technology from BNL, is sponsoring and
coordinating the multicenter trial, which will include 100 prostate
cancer patients and 75 patients with other cancers.
Patients are still being accepted at
the participating hospitals, and may call Diatide at 603-621-7574
for more information.
"Based on this promising start,
we’re now investigating whether our approach may actually help shrink
cancer lesions that have spread to the bone, in addition to relieving
the pain they cause," Srivastava said.
New Option for Bone Cancer Pain
Bone cancer is a dreaded secondary result of prostate and breast cancer
and many other cancer, arising when tumor cells spread, or metastasize,
through the bloodstream to the bones. It strikes 60 to 80 percent
of all prostate and breast cancer patients, causing severe pain in
more than 75 percent of patients.
Conventional treatments include strong
sedatives, which decrease quality of life, hormonal treatments, and
radiation therapy that treats only single lesions and requires repeated
Several radio-pharmaceuticals, or short-lived
radioactive drugs, have also been approved by the U.S. Food & Drug
Administration for bone cancer pain.
One of these products, called Metastron,
is being used in the clinical trial of tin-117m DTPA to allow comparison
of the effects of the two drugs.
In the early 1990s, BNL scientists
began developing tin-117m DTPA as a possible addition to the arsenal
of radiopharmaceuticals for bone cancer pain relief. They used the
Lab’s High Flux Beam Reactor research facility to turn regular tin
(tin-117) into its isotope tin-117m, then attached the DTPA (diethylenetriaminepentaacetic
acid), which helps the tin reach the bone without being sidetracked
by interactions with the blood or being taken up into soft tissue.
After initial tests, the researchers
assessed the therapy in animals and then in human patients in the
initial clinical trial. In the initial clinical trial, the Brookhaven
researchers found that the tin-117m targets only the bone, sparing
the marrow and soft tissue, but still delivers a highly localized
dose of electrons to the tumors to ease pain without sedation. Because
it also emits a weak gamma ray, it allowed physicians to use sophisticated
imaging equipment to pinpoint where in the body it had traveled.
Srivastava’s co-inventors are George
Meinken, Harold Atkins and Leonard Mausner. The U.S. patent on this
invention was issued in December 1998 to Brookhaven Science Associates,
which manages and operates BNL under contract with DOE.
The new Diatide clinical trial aims
to give more information about how well tin-117m DTPA works against
bone cancer pain, and to compare it directly with Metastron.
In order to participate in the study,
patients must have no substantial damage to their bone marrow as a
result of their cancer, as well as no bone fractures. They cannot
have had radiation therapy for one month, and cannot have taken Metastron
or other radiopharmaceuticals in the three months before receiving
the tin. Also, they may not have surgery planned.
Prospective patients are screened via
a bone scan that shows physicians the location of their tumors, and
a questionnaire asking them to indicate the areas of their body where
they feel pain. The two are compared to make sure they correlate.
Patients in the trial receive a one-time
intravenous dose of either the tin compound or Metastron, and keep
a daily diary of the effect on their pain for 12 weeks afterward.
They also track their use of narcotic and non-narcotic pain killers
and are examined several times by a physician. Both pain relief and
any toxicity to bone marrow are being gauged.
Patients receiving tin-117m DTPA during
the trial are being given one of three doses, either one of the two
amounts used in the previous BNL studies or a higher dose. Patients
receiving Metastron receive the approved therapeutic dose
. The U.S. Department of Energy’s
Brookhaven National Laboratory creates and operates major facilities
available to university, industrial and government personnel for basic
and applied research in the physical, biomedical and environmental
sciences, and in selected energy technologies. The Laboratory is operated
by Brookhaven Science Associates, a not-for-profit research management
company, under contract with the U.S. Department of Energy.
February 17, 1999
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