New cancer drug carries high hopes of oncologists
Trials underway for Oasmia Pharmaceutical's Paccal Vet
February 17, 2009 (published)
Veterinarians always welcome new cancer drugs to fight the No. 1 killer of dogs and other companion animals.
Soon, they might have a new weapon in their armamentarium. Clinical
trials are underway in the United States for Paccal Vet, a paclitaxel
(Taxol) analogue that could become the nation’s first
government-approved drug for treating canine mast cell tumors.
The research is creating a buzz among oncologists in veterinary medicine.
“I want this drug," said Lisa Barber, an assistant professor of
oncology at Tufts University’s Cummings School of Veterinary Medicine.
"We were frustrated with the drugs that we had to treat cancers in
dogs. All the stuff we use is for humans. It is important to have
medications for dogs.”
Roughly a year ago, a Swedish pharmaceutical company contacted Barber
to evaluate the potentially groundbreaking chemotherapeutic treatment
in dogs in the United States. By November, a large-scale clinical trial
for Paccal Vet was launched in multiple veterinary centers to treat
dogs with high-grade mast cell tumors, a severe form of the most common
type of skin cancer in dogs.
Two clinical trials completed in Europe for Sweden’s Oasmia
Pharmaceutical’s product have shown encouraging results, insiders say.
The most significant preliminary finding was the absence of severe
allergic reactions, which have previously hampered the use of
paclitaxel for this condition.
The U.S. Food and Drug Administration (FDA) reportedly has taken note, recognizing the possible medical
breakthrough in treating cancers in animals. Last month, the agency's
Center for Veterinary Medicine agreed to expedite its review of Paccal
Vet, a move that could cut the government review time in half and speed
up registration of the drug for market.
The FDA’s decision “will benefit our ongoing phase III study in the
U.S. and EU a great deal and an earlier launch on the very important
U.S. market,” Oasmia Chief Executive Officer Julian Aleksov said in a
If there are no hitches, Paccal Vet could hit the market within two years, one expert said.
In the meantime, oncologists like Dr. Robert Rosenthal caution against
the initial optimism and what appear to be stunning results.
“The results of the proposed study in the United States will be eagerly
anticipated, but such anticipation should be tempered until results of
that and the European work are available for more general critical
review,” said Rosenthal, a Veterinary Information Network consultant.
“That the adverse effects of the conventional carrier have been
eliminated is good news, but it certainly remains to be seen to what
extent any new formulation of paclitaxel is effective in the clinic.
“It is incumbent on all oncologists not to be too optimistic too early in a situation like this one.”
Still, researchers and veterinarians are encouraged by the
international scope of a Paccal Vet review and the investment Oasmia is
“We have a company looking to put money into the veterinary oncology
market and trying to come up with newer drugs that will help us,” said
Dr. Craig Clifford, a veterinary oncologist and director of clinical
research at Red Bank Veterinary Hospital in Tinton Falls, N.J. “It
takes a lot of money to get something approved for a specific species.
A lot of companies don’t want to go through with that.”
The U.S. study will tap a diversity of dogs from coast-to-coast. There
are 12 private veterinary clinics in 10 states and Washington, D.C. and
six universities participating in the trial. As of January, 40 dogs had
been treated and the goal is to enroll up to 220 during the next six
months, according to Animal Clinical Investigation, a Washington, D.C.
group overseeing the study's implementation.
Study subjects can vary in age, breed and gender but must have
higher-grade tumors and no prior radiation or chemotherapy treatment.
Dog owners pay only for the initial consultation fee. The remaining
expenses are covered by the drug company.
Results should determine the effectiveness and safety of Paccal Vet
compared to lomustine (CeeNu), a standard chemotherapy treatment for
high-grade mast cell tumors. Lomustine treatment has gained popularity
during recent years because it is fairly inexpensive, easy to
administer in pill form and the side effects are relatively small.
Dr. Tony Rusk, vice president of clinical affairs for Animal Clinical
Investigation, said the veterinary oncology community is interested in
having approved veterinary products in the oncology market. “We are
extremely excited and motivated in studies like this. It may result in
a veterinary product for cancer.”
That is good news for animals. Roughly half of all dogs 10 years or
older die of cancer-related diseases. It is estimated that one in four
dogs will develop some form of tumor during its lifetime. Certain
breeds such as Beagles, Bulldogs and Labrador Retrievers have a higher
risk of developing mast cell tumors.
Increasingly, dog owners are becoming more aware about pets with cancer and opting for treatment, Clifford said.
“People’s perceptions of pets have certainly changed in the last 20
years," he said. "Before the dog was the family dog. If the dog was
sick you put the dog down and got another dog. Now the dog is a family
member. We have more and more owners that are electing to go through a
chemotherapy for their pets."
Surgery usually is a first-line treatment for mast cell tumors,
especially low-grade forms, but it's generally considered ineffective
at stopping more serious, high-grade tumors. Combining surgery and
radiation therapy improves outcomes with high-grade mast cell tumors,
but radiotherapy requires the dog to be anesthetized and can be
expensive. Chemotherapeutic options for such tumors include human
medications like lomustine.
Veterinary oncologists also have considered the anticancer drug
paclitaxel (Taxol), a treatment for human breast and ovarian cancer, as
a potential chemotherapeutic for mast cell tumors, but there are
drawbacks. The drug is not water soluble and must be dissolved by the
castor oil-type elixir, Cremophor, before it can be administered
intravenously to patients.
However, Cremophor is known to cause severe side effects. To lessen the
impact, cancer patients need to take medications in advance and go
through a lengthy infusion period.
“Everybody wanted paclitaxel, but they didn’t want the Cremophor,”
Barber said. “The drug is highly toxic to dogs. I don’t think
paclitaxel is a fun drug for people, too.”
A 2004 study published in the Journal of Veterinary Internal Medicine
found that 64 percent of dogs receiving paclitaxel experienced allergic
reactions post treatment. Nearly a quarter required hospitalization,
and more than one in 10 died of sepsis.
For Paccal Vet, Oasmia scientists developed a new water-soluble
formulation that eliminates the need for Cremophor. The new treatment
requires no pre-medication, dramatically shortens infusion time and
eliminates serious side effects, according to company research.
Last month, Oasmia publicly detailed highlights from two clinical
studies in Europe. The infusion times were cut to about 30 minutes in
In the first study dealing with dosage amounts and different types of
cancers, 74 percent of the dogs responded to the drug. The phase III
study, focusing on dogs with serious mast cell tumors, showed a
70-percent response rate and a median of 235 days in which the disease
remained stable after treatment. There were no unexpected, severe side
effects, the company claims.
“A response rate of 74 percent is absolutely stunning,” Barber said.
“We may very well find this drug may have other implications in
treating other kinds of cancers.”
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