Potent new drug reduces cancer
pain and fractures
LOS ANGELES -- Apr.
4, 2001 (Cancer Digest) -- Very low doses of a potent new drug
reduces bone pain and fractures caused by cancers that have spread
to the bone.
Researchers led by
Dr. James Berenson, director of the Multiple Myeloma and Bone
Metastases Program at Cedars-Sinai Medical Center, report their
findings in the April 1st issue of Cancer.
They showed that a
five-minute infusion of zoledronic acid, a member of a new class
of drugs called bisphosphonates, works as effectively as much
higher doses of a similar therapy called pamidronate, which is
given over a two-hour time period.
"Not only was
zoledronic acid effective in much lower doses, but we could give
the drug to patients over a much shorter time period than we
could with pamidronate," Berenson said in a prepared statement.
"This means a more potent and convenient alternative for
patients battling with the debilitating effects of cancers that
have spread to the bone."
Both zoledronic acid
and pamidronate are types of bisphosphonates compounds
that work by slowing the production of cells that destroy bone.
Under normal conditions, cells called osteoclasts remove old
bone, while cells called osteoblasts then begin building new
bone.
When cancer spreads
to bone, the normal balance of the cells is disturbed and the
osteoclasts are more active, causing bone fractures, pain, spinal
cord compression (bone collapsing onto the spine) and hypercalcemia
(an excess of calcium in the blood).
To alleviate these
complications, radiation therapy to the bone is often required,
but radiation causes side effects, such as extreme fatigue and
lower levels of infection fighting white blood cells.
Alternatively, bisphosphonates
cause fewer and less serious side effects, that include flu-like
symptoms and some bone pain and can be given safely to patients
receiving simultaneous chemotherapy or hormone therapy. Thus,
pamidronate and other bisphosphonates have been increasingly
used as safe and effective treatments for the skeletal complications
due to cancers that have spread.
To determine whether
zoledronic acid was as effective as pamidronate in reducing bone
complications, the investigators evaluated 280 patients over
a 10-month period who had bone cancer due to spread of breast
cancer or multiple myeloma, a cancer of the infection fighting
cells in the bone marrow.
In this study, funded
by Novartis, the maker of zoledronic, researchers randomly divided
patients into groups that once a month received one of three
dose levels of zoledronic acid infused over a five-minute period
or, 90 milligrams of pamidronate, infused over a two-hour period.
The investigators determined
that either treatment was effective if the need for radiation
therapy to bone was reduced to less than 30 percent of patients
in each group.
Zoledronic acid at
doses of 2.0 and 4.0 milligrams was as effective as a 90 milligram
dose of pamidronate in reducing the need for radiation to bone.
Of the patients receiving zoledronic acid, 19 percent receiving
2.0 milligrams received radiation to bone, while 21 percent received
radiation in the 4.0 milligram group. Of those patients receiving
pamidronate, 18 percent received radiation to bone.
"We found that
the proportion of patients receiving radiation to bone in the
zoledronic acid group was very comparable to those patients receiving
the much higher dose of pamidronate," said Berenson. "Complications
such as fractures, spinal cord compression - or bone collapsing
onto the spinal cord - and hypercalcemia occurred less frequently
in the patients receiving the higher doses of zoledronic acid."
In addition, the investigators
found that the higher doses of zoledronic acid increased bone
density in the spine by almost 10 percent.
Currently, Berenson
and his team are conducting phase III clinical trials to further
compare the effects of zoledronic acid and pamidronate in bone
metastases.
SOURCE: Cedars-Sinai Medical
Center press release
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