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 The decision marks the first U.S. approval for a promising new class
designed to help the body's own immune system fend off cancer by
blocking a protein known as Programmed Death receptor (PD-1), or a
related target known as PD-L1, used by tumors to evade
disease-fighting cells.
For Tom Stutz, a 74-year-old retired lawyer living in Southern
California, the Merck drug has meant a new lease on life. "I was
really ready to mail it in," before entering a pembrolizumab trial
in April 2012 after melanoma had spread to his lungs, liver and
back, he said.
Stutz, who still receives an infusion of the drug every three weeks,
said he has "gone from not being able to turn over in bed, to being
able to play tennis three days a week, and ride a bike 25 miles a
day."
He said side effects amounted to some itching.
"This is not a drug that attacks the cancer directly. It enables the
immune system to do the job that it is capable of doing," said Dr.
Louis Weiner, director of the Lombardi Comprehensive Cancer Center
at Georgetown University. "This is the first beachhead that's been
taken. It's going to be all out assault on many different types of
cancer."
Merck and others, including Bristol-Myers Squibb, Roche Holding AG
and AstraZeneca Plc, are racing to develop PD-1 pathway drugs as
treatments for a variety of cancers, including lung cancer. Some
analysts expect the new class could generate more than $30 billion
in annual sales worldwide by 2025.
Melanoma, the deadliest form of skin cancer, kills around 10,000
Americans each year, according to the National Cancer Institute.
The FDA said clinical trials of Keytruda showed that it shrank
tumors in around 24 percent of patients with advanced melanoma whose
disease worsened after prior treatment.
The agency had designated the drug a "breakthrough therapy," and
approved it nearly two months ahead of an Oct. 28 decision deadline.
Reuters reported exclusively last week that the approval was likely
to come far earlier than the deadline [L1N0R52D3].
Keytruda is the sixth new melanoma drug approved by the FDA since
2011.
"This is a patient population with few options ... We are highly
encouraged by the response rate and the duration of response," said
Dr Rick Pazdur, director of the Office of Hematology and Oncology in
the FDA's drug evaluation center. "The true benefit of these drugs
may be in patients who do not have metastatic disease, but are at
risk of recurrence."
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Merck said one of its first priorities was to see whether the drug
is effective in patients with earlier-stage cancer.
Keytruda will be priced at about $12,500 per month, which "is
consistent with other innovative oncology medicines," Merck said.
For patients with advanced melanoma, the median duration of
treatment has been 6.2 months.
Common side effects of Keytruda seen during clinical trials included
fatigue, cough, nausea, itchy skin, rash and diarrhea. Because it
stimulates the immune system, Keytruda has the potential for severe
immune-mediated side effects, including liver problems and colitis.
Merck is studying the drug in more than 30 different types of
tumors, said Roger Perlmutter, head of research at the
pharmaceutical company. Merck expects to present data from studies
in lung, bladder and gastric cancers at a European medical meeting
later this month.
Perlmutter said Merck's next FDA filing for Keytruda will depend on
which trials "yield the most powerful results."
Bristol expects to complete by the end of this year a "rolling"
submission for FDA approval of its drug, Opdivo, or nivolumab, for
certain patients with late-stage lung cancer. The company also plans
to file an FDA application by the end of this month for use of the
drug, which is approved in Japan, for patients with advanced
melanoma.
(Reporting By Deena Beasley; Editing by Bernard Orr, Diane Craft and
Ken Wills)
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