| April 6
April 6 Pfizer Inc's experimental breast
cancer drug in a clinical trial nearly doubled the amount of
time patients lived without their disease getting worse, but
overall survival was not yet shown to be statistically
significant, researchers said.
The Phase 2 study, which involved women with the most common
form of breast cancer, found that those treated with hormone
drug letrozole plus Pfizer's palbociclib lived for an average of
20.2 months before their cancer progressed, compared with 10.2
months for patients given letrozole alone.
The U.S. Food and Drug Administration has granted
"breakthrough" status for palbociclib. Pfizer is still
discussing a regulatory pathway for the drug and has not decided
whether to seek accelerated approval based on Phase 2 trial
results, said Mace Rothenberg, chief medical officer for
Pfizer's oncology unit.
Palbociclib is viewed as one of the company's most important
experimental drugs that some analysts believe could eventually
claim annual sales of more than $5 billion, if approved by
The trial tested the pill, which targets proteins involved
in cell division, in post-menopausal women with locally advanced
or newly diagnosed breast cancer that had spread to other parts
of the body.
The women had cancer that was both estrogen receptor
positive - meaning tumors grow in response to estrogen - and
HER2-negative, meaning that the HER2 protein is not causing the
cancer. Such patients make up about 60 percent of advanced
breast cancer cases.
The initial data showed overall survival of 37.5 months for
the combination treatment, compared with 33.3 months for
patients given just letrozole, an estrogen blocker sold by
Novartis AG under the brand name Femara.
Researchers said that because only about 30 patients in each
arm of the 165-patient trial had died it was still too early to
define the drug's impact on survival.
"The curves are starting to separate ... It hasn't reached
statistical significance, but patients are still being
followed," said Dr. Richard Finn, associate professor of
medicine at the University of California, Los Angeles, and a
lead author of the study.
Side effects seen in the trial, including low blood cell
counts and fatigue, were manageable, he said in a telephone
interview ahead of the study's presentation on Sunday in San
Diego at a meeting of the American Association for Cancer
Hormonal agents, like Femara, have extended survival for
women with estrogen-positive, HER2 negative breast cancer, but
there have been no big advances in treatment for nearly two
decades, said Dr Judy Garber, a breast cancer specialist at
Boston's Dana-Farber Cancer Institute and AACR representative
not involved in the palbociclib trial.
"This is garden variety breast cancer," she said. "When it
recurs, all we really have are other hormonal agents ... This is
the first new drug to really show promise."
Pfizer is conducting Phase 3 trials in breast cancer
patients as well as earlier-stage trials in other types of
Companies trying to develop treatments similar to
palbociclib include Novartis and Eli Lilly & Co, which
presented Phase 1 data at the AACR meeting.
The small trial found that Lilly's drug, LY2835219, used on
its own, shrank tumors in 25 percent of women with metastatic
estrogen-positive breast cancer, and stabilized the cancer in 55
percent of the same group of women.
(Reporting by Deena Beasley; Editing by Anthony Barker)