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 Patients with a type of breast cancer known as HER2 positive, which
makes up about a quarter of all breast cancers, who were given
Perjeta on top of older medicine Herceptin and chemotherapy lived
15.7 months longer than those on Herceptin and chemotherapy alone.
That is the longest extension to survival ever seen for a drug
studied in metastatic breast cancer and also an unusually good
result for any type of metastatic cancer, where disease has spread
to other parts of the body.
The result is a vindication of combining medicines that fight tumor
cells in a variety of ways.
Both Herceptin and Perjeta are antibodies designed to block the
function of HER2, a protein produced by a cancer-linked gene.
Perjeta, also known as pertuzumab, binds to a different part of the
same protein, which makes combining the two drugs extra effective.
"The results, I think, are phenomenal," lead researcher Sandra Swain
from the Washington Hospital Center told the European Society for
Medical Oncology (ESMO) annual congress in Madrid on Sunday.
"The survival improvement of nearly 16 months ... is unprecedented
among studies of metastatic breast cancer."
Perjeta, which was approved by regulators two years ago, was tested
in the Roche-backed study involving more than 800 women.
Researchers had previously reported the Perjeta drug regimen
significantly extended progression-free survival, or the period of
time patients live without their disease worsening, but the final
overall survival data has taken longer to collect.
The median overall survival time was 56.5 months for those given
Perjeta against the already impressive 40.8 months for patients
taking only the older drugs.
Looking at the study results a different way, the risk of dying was
reduced by 32 percent for women who received the Perjeta regimen
compared to those who got Herceptin and chemotherapy.
While both Perjeta and Herceptin have side effects, including rash,
diarrhea and a potentially adverse impact on heart function, using
the two drugs together did not make these issues any worse.
"I think these data are really compelling," said Eric Van Cutsem of
the University of Leuven, who was not involved in the research.
"When you see in breast cancer such a big change in survival with
not a lot of cardio-toxicities then that is really
practice-changing."
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REMARKABLE RESULTS
Swain and Javier Cortes, another researcher on the study from the
Vall D’Hebron Institute of Oncology in Barcelona, said the results
suggested using Perjeta should now be the standard of care for HER2
positive breast cancer patients.
A favorable reaction from oncologists will underpin expectations of
strong sales for Perjeta, which analysts currently expect to sell
$3.1 billion a year by 2018, according to consensus forecasts
compiled by Thomson Reuters Cortellis.
But it poses a challenge for healthcare providers, since Perjeta and
Herceptin are costly injectable drugs and the multiple-drug regimen
promises to strain budgets.
In the United States, the monthly price of Perjeta is approximately
$5,900, while Herceptin costs around $5,300, a Roche spokeswoman
said. Prices in Europe are lower.
For Roche, Perjeta is an important new product that should help
defend its position in breast cancer, following the success of
Herceptin, which was first approved in 1998.
The company said the latest data would be submitted to regulatory
authorities around the world for inclusion in the prescribing
information for Perjeta.
The Swiss drugmaker also has another related drug called Kadcyla,
which is also being tested in combination with Perjeta. Some
analysts believe Kadcyla's prospects could be curbed if results from
that combination are not better than the impressive findings
reported this weekend.
(Editing by David Holmes and Michael Urquhart)
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