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 The condition, known as erythropoietic protoporphyria, causes severe
burning skin pain after several minutes of direct sun exposure. The
pain can last for days and sometimes causes redness and swelling.
Even bright lights or sunlight coming through a window can trigger
it.
Victims sometimes refer to themselves as "shadow hoppers," said Dr.
Manisha Balwani, co-investigator in the U.S. trial.
Adults who received the implanted drug reported that they could
spend significantly more time in the sun than those who received a
placebo implant, although the increase was not always dramatic
because people with the condition have developed a powerful aversion
to sunlight that is difficult to overcome.
"In these trials, the biggest improvement is in the quality of life.
It made a huge difference," Balwani, of the Icahn School of Medicine
at Mount Sinai Hospital in New York, told Reuters Health.
"It's a severe condition with extreme photosensitivity, and this is
showing the action of a skin-darkening agent that is measurable and
significant," said Dr. David Fisher, chief of dermatology at
Massachusetts General Hospital, who was not involved in the
research. "It's a statistically significant but modest change."
The drug is Clinuvel Pharmaceutical's afamelanotide, which is sold
in Italy and Switzerland under the brand name Scenesse. The company
paid for the research.
The drug, given as a grain-sized implant every two months, promotes
the growth of pigment-carrying melanin in skin cells. It is
approved, but yet to be marketed, in the European Union. It is
awaiting approval in the United States. The current cost is E$32,250
per year (US$36,000), according to a company spokesman. No price has
been set for when it becomes available throughout Europe, probably
later this year.
Clinuvel has yet to develop or test a dose for children, even though
the hard-to-diagnose condition typically appears in early childhood.
It affects an estimated 5,000 to 10,000 people worldwide.
According to the new results, published in the New England Journal
of Medicine, among the 94 U.S. patients, six months of treatment
with the drug increased the amount of pain-free time following
midday sun exposure by 69.4 hours, compared to 40.8 hours with
placebo.
In the European study of 74 patients, nine months of therapy
increased the amount of pain-free time to 6 hours, compared to 0.8
hours with the dummy drug.
The exposure times in the two studies are very different because the
data were collected differently, said Balwani, and because "the
patients have this very ingrained behavior of sun avoidance. It was
hard for them to modify their behavior. We never really recognized
how deep this behavior was. We feel the effect could have been
stronger if these patients had gone out more."
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The number of pain attacks dropped from 146 among volunteers getting
placebo to 77 in those receiving afamelanotide.
The researchers also said that when sunlight sparked an attack, it
was significantly less severe and recovery time was faster. "The
shortened recovery time from phototoxic reactions is a benefit,
since these painful reactions can last up to several days and lead
to absence from school or work and lost productivity," the study
team writes.
In the European test, afamelanotide recipients logged significant
improvement in quality-of-life scores over placebo recipients
through the eight-month mark. But at the nine month point, one month
after the fifth and final dose, the scores were not significantly
different.
In the six-month U.S. test, drug recipients showed the biggest
difference over placebo at the second and fourth month, but the
quality of life was still better for afamelanotide recipients at day
180.
A second quality of life measure showed no significant change with
drug use.
The most common adverse events -- all of mild to moderate severity
-- were nausea, headache, nose and throat irritation and back pain.
"My suspicion is, at the end of the day, because darkly-pigmented
humans can still sunburn like crazy, melanin is not like a roof over
your head. So it only has a certain amount of efficacy," Fisher told
Reuters Health. "So I'm not shocked that the increase was modest"
with the melanin-producing drug.
"But I would love to see further analysis of subpopulations to see
where the efficacy would be greater and other populations where it's
not worth the trouble," he said.
"Most of the patients who got the drug had a very positive
response," Balwani said, so people with the condition "are waiting
for the drug. They're desperate for something to help them lead a
more normal life."
SOURCE: http://bit.ly/1IiiVgP New England Journal of Medicine,
online July 1, 2015.
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