New promising drug in Hormone-Receptor positive breast cancer

New promising drug in Hormone-Receptor positive breast cancer

15 Dec 2014

New hope for women with advanced breast cancer that is hormone-receptor positive was given through a revolutionary study published by UCLA researchers. The final clinical results showed that the amount of time patients were on treatment without their cancer worsening was effectively doubled in women with advanced breast cancer who took the experimental drug palbociclib.

“Tumor cells stop growing”, according to the study author

Palbociclib, an investigational drug discovered and developed by Pfizer Inc, targets a key family of proteins (CDK4/6) responsible for cell growth by preventing them from dividing.

Results of the multi-year phase 2 study showed a significant increase in progression-free survival, in patients who were given a combination of the standard anti-estrogen treatment letrozole and palbociclib, compared to letrozole alone. "We're essentially putting the brakes on cell proliferation and causing these tumor cells to stop growing," said Dr. Richard Finn, associate professor of medicine at UCLA and lead author of the study.


51% reduction in the risk of disease progression showed in Phase 2

The research began in 2007. Once the phase 1 study was showed the drug was safe, the phase 2 study was performed in 165 post-menopausal breast cancer patients with advanced ER+, HER2- disease.

Phase 2 results showed progression-free survival was 20.2 months for patients who received palbociclib plus letrozole and 10.2 months for those who received letrozole only. The progression-free survival results indicated a 51% reduction in the risk of disease progression with the addition of palbociclib to letrozole.

Over 80% of the participants benefited from palbociclib

Results found that over 80% of the metastatic ER+ breast cancer patients in the study received some benefit from this treatment, said Finn and Slamon. The drug doesn't have side effects like traditional chemotherapy, such as infections, but does result in a lowered white blood cell count, which was very manageable.

A patient’s experience raise hopes for more positive results

Gloria Zollar, 78, mother of five, joined the phase 2 clinical trial in August 2010, after her UCLA oncologist discovered that her advanced breast cancer had spread to her bones. She has been on treatment since that time, over four years. But only one year later, doctors noticed that her tumors had stopped progressing, which allowed Zollar to remain active and continue playing golf.

With FDA having granted "Breakthrough Therapy" status in late 2013, a phase 3 international clinical trial is ongoing.


Source: UCLA's Jonsson Comprehensive Cancer Center

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